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Fabrication

 

 
     Before anyone asks, yes this is the same FAQ that is on Quadratec's Bulletin Board. I'm known as OhioYJ on several of the major boards, and wrote this FAQ for the board, I've reposted it here for your convenience. The Quadratec board is full of great, helpful people, which is why I spend so much time on there.
 

     Frequently Asked Questions
Version 3.0

This FAQ is in no means a complete guide! This is meant to be a very basic outline, and to get those new to the Jeep community familiar with some "basics." I'd recommend reading through it, let it soak in, then start asking questions, we're all here to learn and enjoy our vehicles.
 
Jeep Basics
Jeep Designations:
Prepare for a trip:
Abbreviations:
Glossary:
What is an SYE and do I need one?
Things to check before wheeling:
Suspension and Lifts
Types of Lift:
What to expect with a body lift install:
SOA:
SOA vs SUA -
Whatís the best lift for my CJ / YJ?
Choosing a lift for a CJ / YJ -
Whatís the best lift for my TJ?
Choosing a lift for a TJ -
Can I remove my track bar?
Can I remove my sway bar?
AntiWrap Bars -
Shackle Reversal -
Axles
What gears do I have?
What gear ratio do I need?
Types of Differentials:
Vacuum Disconnect:
What is axle wrap/spring wrap?
Whatís a high pinion axle?
Some basic axle information:
Do I need a locker?
Can I run a locker on the road?
I want a locker, but which one?
Full Floating vs. Semi Floating Axles -
 Tires and Wheels
What size wheel should I run?
Whatís the biggest tire I can run?
How much air pressure should I run?
Beadlocks:
What is backspacing?
Understanding Tire Sizes:
Bias vs. Radial Tires:
What Tires Should I buy?
Winches
Choosing a Winch:
Basic Recovery Information:
Drivetrain
Rough Shifting -
What does a motor mount lift do?
What drivetrain do I have?
Electrical
Multimeter Basics:
Hooking up offroad lights:
Check Engine Light:
Relays -
Miscellaneous
My speedometer doesn't seem right?
Truck Bed Liner For Jeeps -
What kind of fluid do I need?
Tie Rod Flips -
Towing a Jeep -
Hi-Lifts?
Popular Swaps/Stock Parts Mix'n'Match:
Tech Section Links:
Who wrote this FAQ?

Jeep Designations:

CJ - 45-86 Short wheelbase Jeeps Round Headlights - Leaf Springs
YJ - 87-95 Wrangler Square Headlights - Leaf Springs
TJ - 97-up Wrangler - Round Headlights - Coil Springs
XJ - 84-up Cherokee - Unibody - Coil Front/Leaf Rear
ZJ - 93-98 Grand Cherokee
WJ - 99-04 Grand Cherokee
KJ - 02-up Liberty
MJ - 86-92 Comanche
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Prepare for a trip:

Trail preparation is very important. First thing is first, never go alone, always have at least one other vehicle.
 
Your vehicle at the very minimum should have/contain:
-Tow hooks
-Full size spare and stuff to change the spare
-At least one tow strap
-Basic first aid items.
 
Things that are nice to have
-Spare parts and tools to change them. Having spare u-joints doesn't help if you don't have anything to change them with.
-Hi-lift
-CB
-Tire plug kit
-GPS, compass, map, have something to point you in the right direction.
-Flashlight
-Lighter
-Fire Extinguisher
 
Be smart when packing for a trip, if your going in the middle of winter, carry at least one blanket, stuff happens be prepared. I always take spare clothes and shoes. On larger trips we take enough spare parts to build another Jeep. Divide stuff like this up, for example, I'll carry spare springs, axle parts, and tools. Another vehicle might have every thing to do with steering and brakes. Another vehicle will have fluids and filters. On milder trips we go a little less prepared, but still carry common things like u-joints, fluids, etc. Always tell someone where you are going and when you will be back. Try working on your Jeep with just the tools you carry in it, you will soon find out what you don't have in your tool kit.
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Abbreviations -

AAL - Add-a-Leaf
AT - All Terrain
BDS - Big ****'s Suspension, NOT Black Diamond Suspension
BB - Budget boost
BL - Body Lift
CV - Constant Velocity Joint
MML - Motor Mount Lift
MT - Mud Terrain
RTI - Ramp Travel Index
SOA - Spring Over Axle
SRS - Shackle Reversal System
SUA - Spring Under Axle
RE - Rubicon Express
SYE - Slip Yoke Eliminator
OBA - On Board Air
OME - Old Man Emu
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Glossary -

Add-A-Leaf (AAL) - Used to increase load carrying capacity or lift the Jeep.
AT - All terrain tire.
Beadlocks - A wheel designed with a ring that physically clamps the tire to the wheel.
Budget Boost (BB)- Spacers placed on top of a coil spring to lift the Jeep.
Body Lift (BL) - Spacers placed in between the body and the frame.
Motor Mount Lift (MML) - Lifts the motor for improved driveline angles.
MT - Mud terrain tire.
Spring Over (SOA) - Conversion for leaf sprung Jeeps, places the leaf spring on top the axle.
Spring Under (SUA) - Stock for leaf sprung short wheelbase Jeeps, the axle is mounted on top of the spring.
On Board Air - OBA, source of compressed air carried on a vehicle.
Slip Yoke Eliminator (SYE) - Eliminates the slip yoke on the rear of the transfer case.
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What is an SYE and do I need one?

A slip yoke eliminator does just that eliminates the slip yoke at the end of the transfer case. It does three things, strengthens the transfer case, won't allow fluid to drain out the tail house should your driveshaft get destroyed so it can't run dry, and most importantly it shortens the transfer case and allows a longer driveshaft to be used to improve driveline angles, and eliminate vibrations. This is a stock NP231 transfer case This is a NP231 with a SYE, notice the shorter tail house and the driveshaft bolts to the yoke, rather than the slip in version the stock transfer case has. You will need a new rear driveshaft. Many choose to install a CV style driveshaft when they do the SYE.
 
If you only have a 2" lift, don't need one. Some say they are needed for a 4" and above lift. My opinion, they aren't 100% necessary, if they were the kit would include it. However keep in mind, the SYE is still stronger, will allow extended U-joint life, and can fix vibrations caused by the drivetrain.
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Things to check before wheeling:

Itís very important to give your Jeep a once over before taking it out to beat on it. Leave the house with a sloppy U-joint, and it will blow apart on the trail, and usually at the worst possible time. Check your lug nuts, tire pressure, U-joints, steering system, and all your fluids. Give your suspension bolts and bushings a once over too. This only takes a few quick seconds to double check things, you'd much rather replace things in your driveway rather than on the trail. This list is more complete. Make sure you check these things again when you get back, as wheeling does take its toll on things.
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Types of Lift -

Suspension lift - This is what the name infers, itís a suspension designed to lift the vehicle. The upside to a suspension lift is it lifts the frame and everything high off the ground and allows for more articulation. The only real downside is the initial cost.
Body Lift - Not quite as functional as a suspension lift, but will allow you to clear larger tires. A body lift consists of spacers that go in between the body and frame, they only lift the body up, the frame will stay at the same height, and you gain no real articulation.
Spring Over - This is a conversion for leaf springs it will move the axle from on top of the springs to underneath the springs. You can gain 5-5.5" of lift from this, read the SOA section in this FAQ before thinking about this.
Budget Boost - This is a spacer lift for TJs, many like to start with this, its simple and cheap. A budget boost lift consists of coil spring spacers and new shocks, most are about 2" of lift.
Short Arm - Short arm kits are for coil sprung vehicles. They normally use basically stock length control arms. The ride isn't quite as good as impacts and such are more directly transferred to the body. This affect is minimal though, for many the short arm kit is a good solution, and can be half of the price of a long arm kit.
Long Arm - Long arm kits ride better and flex better than short arm kits. The control arm mounts are relocated to allow for better arm angles. The downside here is the price, depending on what you do, a long arm kit may not be necessary.
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What to expect with a body lift install:

There are a few issues to be dealt with when installing a body lift. The biggest thing is that the radiator must be relocated. Relocation brackets for the radiator can be as simple as a piece of metal with two holes drilled in them. This must be done because the body moves up, but the fan stays put, if you don't move the shroud/radiator the fan will chew it to pieces. In some cases it may be necessary to trim the floorboard around the shifter some to allow full movement between gears. Normally less than 1/8" of material needs to be removed, sometimes none. The other thing to watch is the vacuum hose to the brake booster, in some cases the current line is not long enough. TJs sometimes require adjustment of the shift linkage to the transfer case.
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SOA -

So I just weld perches on right? Not quite. What are you going to do about spring wrap? Like replacing leaf springs, or broken pinion yokes, because thatís what will happen when you start wrapping springs. What about steering, that drag link isnít going to clear the leaf springs? Did you get longer brake lines yet? Howís your rear pinion angle going to look? Spring over has its advantages, but it also has its problems. The extra leverage the SOA gives the axle can give you some serious flex. A rear anti-wrap bar should be considered a must, the front will wrap some too, but many get away without a wrap bar on the front. My front springs wrap some but nothing to bad. Next the bent draglink, yes you can bend that draglink to clear the springs, is this a good idea, not exactly. The correct fix to this would be a high-steer system. Depending on what you choose for steering you may or may not need a dropped pitman arm. There are several options here, knuckle swaps, aftermarket kits, I've seen solutions from $100 to $700 so do some research first. The brake lines can be relocated to make them long enough, but its still a good idea to get an extended set. If you expect U-joints and such to live a SYE kit is recommended, which will also require a new rear driveshaft.
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SOA vs. SUA -

SUA - SUA just like any lift has advantages and disadvantages. For many this is a good choice, as you can just bolt on a SUA lift and don't have consider anything else. A SUA lift will also offerer a slightly lower center of gravity compared to a SOA. SUA suspensions also control axle wrap very well. However to achieve the same amount of lift as a SOA conversion, the springs must have more arch, resulting in a stiffer ride/less articulation. SUA also reduces ground clearance as all the upbolts, springs and brackets are underneath the axle.
 
SOA - Even with all SOAs problems, it has some major advantages. The most important is better articulation. A SOA gives enough lift and still allow the use of flatter leaf springs, resulting in a better ride and articulation. Of course you still have to deal with caster angle, pinion angle, steering, and driveshaft issues. SOA also increase ground clearance, as it helps get everything above the axle.
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Whatís the best lift for my CJ/YJ?

There is no good answer here. You have four ways to lift your CJ/YJ, suspension lift, shackle lift, body lift, and SOA.
Suspension Lift - There are good and bad points to every lift kit, they are all different. Some will give you more lift than others, some will ride better, some are cheaper, and some come with extras (Ex: sway bar disconnects). I can only recommend you shop around a little, see what fits your budget, decide what exactly you will be doing with your Jeep, then ask opinions about various lifts.
Shackle Lift - You can gain up to 2" of lift from a shackle on a CJ/YJ. Some basics first though, a shackle that is only 2" longer than stock will actually result in 1" of lift. This meaning a 2" lift shackle is actually 4" longer than stock, trust me I tried running them for a bit, and they hang really low and get hung up on everything off road. Generally a 1" lift shackle is recommended, they will give the shackle some extra range of motion and clear military wrapped springs. Kwrangln's post explains shackles in depth.
Body Lift - As mentioned above this only lifts the body to clear larger tires, available 1" - 3".
SOA - This moves the axle underneath the springs resulting in a 5"-5.5" lift. Read the SOA section above before thinking anymore about this.
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Choosing a lift for a CJ / YJ -

Ok so you've decided you want to lift your YJ and you've read about types of lift for a YJ. But now what kind do you need? There are pros and cons of each kind of lift.
 
Body lifts are cheap, have a minimal affect on your center of gravity, don't require any other driveline modifications, and they are relatively easy to install. Of course on the downside, many don't like how they look, they don't provide any extra ground clearance for the frame, and they do place extra leverage on the body mount, however for the most part this isn't a huge concern.
Longer shackles will help articulation and help solve clearance issues with the rear crossmember. On the other side, a longer shackle has a tendency to get caught up on things off-road, and can make the Jeep seem a little wobbly due to the extra leverage the shackles have. They do give the frame extra ground clearance, but they also hang down low in the front and in the rear and get hung up on things frequently if you go to long. Kwrangln's post explains shackles in depth.
A suspension lift will replace your worn out suspension components and gains you ground clearance. Ride quality will depend which kit you choose, some ride better than others. On the down side, suspension lifts do cost more than other methods, can require additional driveline modifications, and does raise your center of gravity.
SOA can provide ample room for larger tires, increase your articulation, and still allow the use of factory springs. However with a SOA conversion, steering, spring wrap, and driveline angles must be addressed. Expect a SOA done right to cost at least as much as a bolt on lift, if not more.
 

Well now for my opinion, remember this is just my opinion, and the board is here for a reason so don't hesitate to ask questions. 4" lifts for a YJ/CJ start out just over $400 making them a hard deal to pass up. I would recommend a 4" lift for a YJ/CJ, just because many 2" kits are nearly the same price as the 4" kits. Shackles and body lifts should then be used to gain additional tire clearance if necessary. Remember shackles will help articulation and gain you frame clearance, so they should done before a body lift. Lift shackles are available in up to 2" of lift, but I would recommend you stick to 1" of lift. Unless you plan on running tires larger than 35", SOA is not the way to go. Remember too, that these are just recommendations for optimal results, if all you can afford for the time being is a body lift, I say go for it.
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Whatís the best lift for my TJ?

There is no good answer here. You have three ways to lift your TJ, suspension lift, coil spacers, body lift.
Suspension Lift - There are good and bad points to every lift kit, they are all different. Some will give you more lift than others, some will ride better, some are cheaper, and some come with extras (Ex: sway bar disconnects). They make short arm kits, and long arm kits for TJs, above in this FAQ these kits are explained. I can only recommend you shop around a little, see what fits your budget, decide what exactly you will be doing with your Jeep, then ask opinions about various lifts.
Coil Spring Spacers - Spacers are a cheap easy way to gain up to 2" of lift on a TJ. This is where many people start.
Body Lift - As mentioned above this only lifts the body to clear larger tires, available 1" - 3".
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Choosing a lift for a TJ -

Ok so you've decided you want to lift your TJ and you've read about types of lift for a TJ. But now what kind do you need? There are pros and cons of each kind of lift.
 
Body lifts are cheap, have a minimal affect on your center of gravity, don't require any other driveline modifications, and they are relatively easy to install. Of course on the downside, many don't like how they look, they don't provide any extra ground clearance for the frame, and they do place extra leverage on the body mount, however for the most part this isn't a huge concern.
Coil Spacers, or budget boost, is the way many people start out. Since they are a suspension lift, you will get extra ground clearance, but retain the factory springs so the ride quality will remain the same. Normally no extra driveline modifications will be needed, and the install can be done in a couple of hours.
Short Arm are your basic lift for a TJ. They retain basically stock length control arms, which can affect ride quality as road shock will be transmitted more directly to the body. As with any suspension lift you will be raising the center of gravity. A short arm kit is acceptable solution for most people. Additionally driveline modifications maybe required depending on lift height.
Long Arm is the ultimate bolt on lift solution for a TJ. The control arm mounting points are changed, which gives a better ride, better articulation, and better axle location. However a long arm kit is considerably more money than a short arm, and for many the extra cost can not be justified.
 

Well now for my opinion, remember this is just my opinion, and the board is here for a reason so don't hesitate to ask questions. For a TJ most people start out with coil spacers. If you just want to clear 31"-32" tires a budget boost is without a doubt a good choice. In my opinion I would go this route over a 2" spring lift. If you plan on running 33" or larger tires, you should be looking at a 4" lift. The long arm kit will perform better and ride better, however, they cost quite a bit more. Many choose a short arm kit, and it will function very well. Whether the extra performance is worth the big price jump, thatís up to you. While many use coil spacers on top of the lift springs, I would recommend you go with a body lift to gain additional clearance if necessary. Driveline angles are hard to keep right with a short arm kit as is, why add more lift into the equation.
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Can I remove my track bar?

On a TJ absolutely not. On a YJ you can. The track bar creates a bind in the suspension as it articulates, so removing it will help your articulation You can remove the rear track bar and the difference in handling will be so minimal you probably won't notice. Many people ditch the rear track bar as soon as they buy their Jeeps. However, removing the front will give the Jeep a more vague feel on the road. If your going to run without a track bar on the front, having good bushings in the leaf springs and the frame will go a long way to fight the vague feeling. I've driven mine for about a year with no track bars and no sway bars, and it will still go down the highway fine. That being said, my recommendation would be to actually ditch the rear track bar, but only remove the front when off-roading. When I was SUA I only undid the axle side of the track bar and tied it up to the frame when offroad.
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Can I remove my sway bar?

On a TJ, you can but you probably won't like the way it handles. On a YJ you would get used to it. A sway bar works by twisting. When one tire goes up and the other goes down it has to actually twist the the sway bar in the center therefore creating bind. Removing it allows for much greater articulation. However theres no real point to completely removing it, why not use disconnects. Sway bar disconnects will give you the extra articulation off-road, but then still give you decent handling on the road.
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AntiWrap Bars -

Antiwrap bars are designed to prevent spring wrap in SOA applications. Spring wrap is explained earlier in this FAQ. Normally most people don't have a problem with the front springs wrapping bad enough to justify a antiwrap bar. The rear however is a different story, it's not an option, you have to run one, in my opinion. Spring wrap will quickly destory springs or worse yet destory pinion yokes. This post shows the damage caused by spring wrap. Theres not much to a wrap bar, so you can fabricate one or buy one. There are many variations of the wrap bar, the best solution is your tried and true ladder bar style. A properly designed antiwrap bar will not bind your suspension. This post shows/explains wrap bars further.
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Shackle Reversal -

Many people don't really understand what a shackle reversal actually does. We all know it moves the shackle to the rear, but many don't understand why. The basic theory behind it is that it allows the axle to move backwards over bumps, making the whole motion smoother. Of course it improves ride quality, but also introduces some other quirks. This post will help explain some of the pros and cons of shackle reversal.
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What gears do I have?

There are several methods for figuring out what gears you have. First there should be a tag on your diff cover. You can see this tag is stamped 3.07. Next Dana axles have a bill of material code, which identifies everything in the axle this is stamped into the axle tube itself, and can be hard to spot as its very light. This picture shows a bill of material stamping. Once you have this number, you can decode it on the Dana website. You can roughly estimate the gear ratio, by jack the rear axle up off the ground and spinning a tire, if the pinion makes 3.5 turns for one turn of the wheel you can figure you have 3.55 ratio.
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What gear ratio do I need?

Doesn't take long to realize those new 35" tires make the Jeep a dog on stock gearing, and we don't even need to mention gas mileage. Going from a stock 27" tire to a 35" tire is roughly a 30% increase, if your Jeep came with a 3.07 ratio from the factory, you will now need a 4.10 ratio to keep close to factory gear ratio. Choosing the proper gear ratio though depends on many things, like how much highway driving do you do, how much time will this spend off road, what kind of off-roading do you do? Below are general rules of thumb:
 

6-cylinder
Manual | Auto | Tires
4.10 | 3.73 | 31 inch
4.10 | 3.73 | 32 inch
4.56 | 4.10 | 33 inch
4.88 | 4.56 | 35 inch
5.13 | 4.88 | 37 inch
 

4-cylinder
Manual | Auto | Tires
4.56 | 4.11 | 31 inch
4.88 | 4:56 | 32 inch
5.13 | 4.88 | 33 inch
5.38 | 5.13 | 35 inch
5.89 | 5.38 | 37 inch
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Types of Differentials -

Big misconception here, if you have a limited slip or a posi, it is NOT a locker. Get stuck somewhere and you will quickly find out it is not a locker.
 

Open - Open differentials are what the majority of stock vehicles have. They are just a case with 4 spider gears inside, this is where you get one wheel peel.
Limited Slip - This can be referred to by many names (Posi, Trac Loc, etc.). This is similar to an open differential but there are clutches on the sides of the spider gears to "lock" them together, however a limited slip can let just one wheel spin in situations. Limited slips also require an oil additive.
Locker - This is a type of differential that mechanically locks the axles together. Many lockers will disengage so the tires can still turn different speeds to go around corners, but under load they fully lock up. The are many types of lockers, full case, insertable, air, cable, and electric. A full case replaces the whole carrier which has the advantage of having a stronger carrier than using an insertable unit. The insertable units just replace the spider gears and use the stock carrier an advantage to these is that they are cheap, and require no special tools to install. Air, Cable, and Electric lockers engage only when you flip the switch, or pull the cable.
Spool - A spool fully locks the axle shafts together, it will never unlock. Both tires always have to spin the same speed.
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Vacuum Disconnect -

Various Jeeps are equipped with a vacuum operated disconnect on the front axle. With this setup the passenger side axle is actually two pieces, an inner shaft and an out shaft. When disconnected the shafts spin independently, meaning the passenger side tire is not connected to the differential. Here is an example of it unlocked. Here is an example of it locked. When unlocked the driveshaft will always sit still even when driving down the highway. This system usually gets a bad wrap, however, thereís nothing wrong with it. If yours is working, I'd say leave it alone. Post for troubleshooting this system. Post for how it works.
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What is axle wrap/spring wrap?

As you accelerate the axle will try and rotate upwards. The harder you accelerate the stronger this rotation force is. This force will actually bend the leaf springs into an "S" shape. Axle wrap is normally only a concern in SOA situations due to the extra leverage the axle has on the springs. This picture will help explain wrap. This post shows what axle wrap does to springs.
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Whatís a high pinion axle?

Many axles are available in high and low pinion versions. High pinions are not only stronger (when used as a front axle) but offer more ground clearance. Example of a low pinion axle. Example of a high pinion axle Due to the location of the pinion, a high pinion axle requires a reverse cut gear set. Low pinion axles are stronger than a high pinion as a rear axle.
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Some basic axle information:

Stock Axles:
Dana 30 - Dana 30s are available in both high pinion and low pinion versions. The Dana 30 is actually surprising stout for a small stock axle. Dana 30s come factory with 27 spline shafts, and can handle a 33" tire. Usually a 35" tire is pretty safe as well if youíre using aftermarket axle shafts.
Dana 35 - The Dana 35 is a weak axle, I would consider a 33" tire the upper limit of this axle. Its not if this axle will break, its when. These axles can sort of handle a 35" tire if you upgrade the shafts. You should generally do your best to avoid putting any money into this axle. Broken 35 Broken 35 Shaft
Dana 44 - Dana 44s are available in both high pinion and low pinion versions The Dana 44 axles can be found in the rear of some TJs and in the front of the Rubicons. The Rubicon versions do have slightly weaker housings though. Most 44s were 30 spline axle shafts. You can safely run a 37" tire on a 44.
AMC 20 - AMC 20s can be found underneath early CJs. They have completely round covers. Although they have a ring and pinion nearly the size of a 44, they still aren't very desirable. The weak point on this axle is the two piece axle shafts, upgrading to a one piece axle shaft will greatly improve the strength. Many have good luck wheeling this axle with one piece shafts and a truss. Still keep in mind it still a small axle and won't hold up if youíre crazy on the skinny pedal.
 
Axles Commonly Upgraded To:
Dana 44 - A good upgrade for many Jeeps particularly as a front axle. Again stick to a 36"-37" tire.
Dana 60 - Dana 60s can be found with 16,23,30,32, and 35 spline axle shafts. Many are full floaters which is a strong point. These are larger axles, and hang down a little low, but who cares when you can safely run a 38" tire.
Ford 8.8 - The Ford 8.8 can be found under nearly every car Ford makes. Many try to get them out of the late 90s Explorers as they had disc brakes, 31 spline shafts, and the larger 7/8" cross pin. The 8.8 out of an Explorer will also be almost stock width for a Jeep axle, and has the same bolt pattern for the wheels. 37" should be considered a maximum safe limit.
Ford 9" - The Ford 9" is also a fairly common axle, and is slightly stronger than the 8.8. The 9" does not use c-clips like the 8.8. They came factory with either 28 or 31 spline shafts. There are lots of tricks to making these stronger, so if going this route, search around. I'd also give this axle a 37" tire limit on a stock setup.
GM 14 Bolt - 14-bolts can make 60s look small, they are massive. Available in 30 and 33 spline axle shafts. This is a good strong axle for big motors and big tires. 14-bolts hold up to a 44" tire pretty well.
 
Those are the more popular axles, so I'll leave out things like Rockwells and Unimogs.
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Do I need a locker?

This depends. If your Jeep will spend its life on the road then no. If you plan on going offroad on a fairly regular basis a locker would make a big difference. Get stuck with open diffs and you'll quickly realize your 4wd is only really a 2wd, and its never the 2 tires spinning that you need to be spinning. Even with just one axle locked the difference will be night and day. Jerry Bransford has a good post on this.
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Can I run a locker on the road?

Selectable Lockers can be run on the road without any quirks or problems. Automatic Lockers have their quirks but can be run on the road. On nice dry roads other than the noises lockers make you won't even know its there. On wet or slippery surfaces some extra caution must be used, as the rear end will have a tendency to slide sideways, particually on take off. Nothing more than a regular old car with a posi unit, its manageable but you must be aware of it. Other than that the only thing you may notice is some increased tire wear, however, the first time you take it offroad you'll realize it worth the quirks.
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I want a locker, but which one?

With lockers you have several choices, lunchbox, full case, selectable, or a spool.
 

Lunchbox lockers - Lunchbox lockers are cheap and easy way to gain traction off-road. These lockers replace the spider gears in your carrier. These also have the added benefit of installing with regular old hand tools, and no differential setup knowledge is required. These can be done in the driveway in a matter of a couple of hours.
Full case - Full case lockers are more exspensive and work the same as a lunchbox locker. However a full case locker is still stronger because of the casing. However since the full case locker will replace your stock carrier your backlash will have to be reset, meaning some differential setup is required.
Selectable - Air, Electric, and Cable selectable lockers are available. A selectable locker has the advantage of being an open diff when unlocked. This eliminates all the quirks when driving on the road. Again you will have to replace the stock carrier with these so some differential setup is required.
Spool - Spools are slowly gaining popularity. You can get mini-spools for use with C-clip axles that replace the spider gears and use the stock carrier no differential setup is required. Full spools replace the whole carrier, and cannot be used with C-clips, some differential setup is required. Spools will wear tires quicker than a locker and everytime you turn a corner your axle shafts will get a slight tweaking from the tires trying to turn different speeds. While spools are harder on shafts and tires than a locker, they are the ulitmate in traction aids, it will never unlock. These should only be used in the rear axle.
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Full Floating vs. Semi Floating Axles -

Most axles underneath vehicles today are semi-floating axles. In a semi-floating axle the weight of the vehicle is carried by the axleshaft itself (Example of a semi-floating axleshaft). In a full floating axle the weight of the vehicle is carried by the housing itself, the axleshafts only job is to transfer torque (Example of a full floater axleshaft). This post will explain the difference further.
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What size wheel should I run?

Wheel size depends on many things. If off roading is your vehicles primary function a narrow rim maybe a better choice, as it will hold the bead better off road. If you run mainly on the road a wider wheel may actually be a better choice. Kwrangln's Post will help explain wheel widths
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Whatís the biggest tire I can run?

The largest tire you can fit under your Jeep depends on many things. These are general rules of thumb for safe limits that will still allow some room for articulation. Remember there are also other things to consider such as wheel backspacing, to ensure the tires clear things like springs or control arms. Also keep in mind axles have tire size limits too, put a 35" tire on a Dana 35 beat on it and you'll be calling a tow truck.
 

YJ
Stock = 30"
2" Lift = 31"
4" Lift = 33"
6" Lift = 35"
 
TJ
Stock = 31"
2" Lift = 32"
4" Lift = 33"
6" Lift = 35"
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How much air pressure should I run?

Kwrangln's Post will explain how to figure proper air pressure. No it isn't whatís posted on your door, and proper air pressure will be different from front to rear. You don't want to wear out those brand new mud terrains do you?
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Beadlocks:

Beadlocks will prevent tires from loosing a bead when air down. Coventional beadlock wheels use bolts and a ring to clamp the tire to the wheel. You can also make your current wheels beadlocks using weld on kits. Your third choice is internal beadlocks. This post will explain and show how beadlocks work. This post will explain the mounting procedure of standard beadlocks. Kwrangln has a good post about making your own beadlocks. Staun Beadlocks are a common example of internal beadlocks.
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What is backspacing?

When buying wheels it is very important to determine proper backspacing. Backspacing is the measurement of how far in the wheel mounting surface is. This picture will help some. Backspacing will determine how far out the wheels stick. Proper backspacing will also allow you to clear things like springs and control arms at full turn. This link will further explain backspacing. Popular backspaces range from 4" to 3.5".
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Understanding Tire Sizes:

Well most people understand that a tire that is 31x10.50x15, means the tire is 31" tall, 10.5" wide, and meant for a 15" wheel. However, not many understand that a 265/75/15 tire is the metric version of 31x10.50x15. 265 is the width of the tire in millimeters, in this case equal to 10.4". The middle part is what I find people are misinformed about. 75 represents a percentage, the profile of the tire, is 75% of 265 mm, or roughly 7.8". 7.8" of side wall on bottom and top, plus 15" of wheel, makes for an overall height of 30.6". The 15 still means for a 15" wheel.
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Bias vs. Radial Tires:

For the most part two types of tires are offered, Bias Ply and Radial tires. Bias ply tires are sort of old school, they have no steel belts in them of any sort. They are made using angled layers of rubber usually reinforced with nylon cords. Because of this design bias ply tires generally have to be thicker to be as strong. This makes them more puncture resistant, however they also weigh more and run hotter (Both of which affect many things, like gas mileage for one). Bias ply tires are more prone to flatspotting in cold weather than radial tires. The majority of tires made today are radial. Radial tires have steel cords and belts running through the layers of rubber. The steel makes the tires stronger with fewer layers. This means a radial tire will generally be lighter and run cooler. Radial tires tend to ride smoother, and handle better.
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What tires should I buy?

There is no good answer to this question. Every tire has its good points, and its bad points. Most people choose one of three tire types, AT, MT, or MT/R. Keeping this very simple, ATs are the most street friendly, have long tread life, and have great traction in rain and snow. MTs are generally a more aggressive tread with high void areas, making them work great in mud, but not they aren't the greatest in rainy conditions. Todays MTs have a decent treadlife all things considered. MT/Rs are sort of a modified MT tread, not quite as aggressive, but are more street friendly than a MT, generally longer treadlife, better wet road traction than the MT, and provide great traction on rocks. However they don't perform very well in the mud, so its a trade off. Many people who run mixed terrain with some street driving, choose MTs. People who run lots of rock, and a fair amount of street driving, choose the MT/R. Jeeps that will remain on the road most of the time, an AT tire is a good choice. This Tire Guide will show just a few of your many choices you have.
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Choosing a Winch:

Having a winch on your Jeep can save you a lot of headaches during the recovery process. I've gotten in situations where recovery of my Jeep would have been nearly impossible without a winch (and very dangerous). To figure out what size winch you need, use this general rule of thumb, Gross vehicle weight (located on the tag of your door, GVWR) x 1.5. Most short wheelbase Jeeps will need about an 8000 pound winch. Your common choices will be electric or hydraulic. Electric runs off the battery, this can be useful as you can operate your winch with the vehicle off, not for long though. Hydraulic runs off your Jeeps power steering system, they won't overheat like an electric winch and they are strong, but your Jeep must be running to use it. Kwrangln has an excellent post on winches.
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Basic Recovery Information:

Many people don't really understand how dangerous the recovery process really is. With all the stored energy in a strap or chain, it can come flying back at over 300 MPH. If you get hit by a strap, chain, shrapnel, etc, at the very least your friends will be rushing you to a hospital, assuming you are lucky enough to survive the impact. Now I'm not trying to freak anyone out, but recovery of a stuck vehicle is serious business, and you must respect the equipment. One could write a book about safe recovery practices, however, I'll just try and cover some of the very basic methods, and common mistakes.
 

As already mentioned here in the FAQ, at the very least your Jeep should have tow hooks, before you even hit the trail. Tow hooks are cheap and easy to install, especially on a Wrangler, so there is no excuse for not having them.
 
You should also have a tow strap, the strap should not have hooks on it. Its bad enough to have a strap come flying at you, but having a hook attached is even worse. Also make sure the strap is strong enough. Most tow ropes you find at the auto parts stores are not strong enough for recovery use. Most good straps are rated for about 20,000 lbs. In general chains shouldn't be part of the recovery process, they do have their place in recovery but can be dangerous if not used properly.
 
Hooking up a strap:
-Straps should be attached to tow hooks, on both vehicles.
-The strap should not be wrapped around a bumper, it can come loose, or worse yet the bumper can damage the strap, or worse cut it.
-Straps should not be placed on a hitch balls. A safer alternative is to actually place the strap in the hitch and attached using just the reciever pin.
-Never tie a knot in the strap to attach it, if you must wrap it around something feed the strap through itself to secure it.
-Double check where the other person put a strap, not everyone knows whats safe, if the other end comes loose guess which direction its coming.
 
During the recovery process make sure people are clear of the recovery area. I will normally actually try and hide behind a big tree.
 
Also remember many of these same things apply to winches, winch cables can break, hooks can come loose, a cable is even more dangerous than a strap. You have a long cable on the winch remote so there should be enough slack for you to stand back.
 
If you take care of your recovery equipment it should last a very long time. To help extend the life of your straps/cables, make sure you keep your equipment clean, try and prevent straps/cables from rubbing on things during the recovery process. If your strap/cable starts to fray, you should replace it.
 
Kwrangln has an excellent post on what happens when recovery goes wrong. Another good link, BillaVista's Recovery Bible.
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Rough Shifting -

Manual transmissions with a bunch of miles will shift rough, this is unavoidable. Many people quickly say the synchros are shot, and this is why the transmission shifts rough. However this isn't true, while replacing the synchros would help the tranmission shift smoother temporarily, they aren't the "real" problem. This post will explain shifting problems in manual transmissisons.
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What does a motor mount lift do?

A motor mount lift is designed to improve driveline angles. By lifting the motor up you tilt the transfer case down towards the axle. When installing a lift kit you can do a motor mount lift instead of a transfer case drop. Eliminating the transfer case drop will give you more ground clearance. Some also do a motor mount lift when installing a 1" body lift, because the body goes up one inch, the motor goes up one inch, no need to relocate the radiator.
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What drivetrain do I have?

87-95 YJ -
Front Axle: Dana 30 (High Pinion)
Rear Axle: Dana 35
Transfer Case: NP231
Transmission -
2.5 - AX5
4.2 87-89 - Peugeot
4.0 - 4.2 89-95 - AX15
4.0 92-95 Automatic 32RH
 
97-04 TJ -
Front Axle: Dana 30 (Low Pinion) Dana 44 Option (Hexagonal Cover)
Rear Axle: Dana 35 (Round Cover) Dana 44 Option (Hexagonal Cover)
Transfer Case: NP231 (except Rubicon) Rubicon NV241
Transmission:
4.0, except Rubicon - AX15 NV3550 - Option
2.5 - AX5
97-02 Automatic with 4.0 - 32RH
03-04 Rubicon NV3550
03-06 Automatic - 42RLE
 
CJ -
Front Axle: Dana 30
Rear Axle: AMC 20, Dana 35
Transfer Case:
Transmission:
72-75 V8 only - T-15
71-79 heavy duty 4-speed - T-18
76-79 heavy duty Automatic - TH400
76-79 3-speed - T-150
80-86 medium duty 3-speed Automatics - 999
80-86 light duty 3-speed Automatic - 904 and 909 (4-cylinder only)
80-86 light duty 4-speed - SR-4 and T-4
80-86 medium duty 4-speed - T-176, T-177, and T-178
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Multimeter Basics:

Ok so your Jeep won't start, but why, is the battery dead? For some reason people see meters as some mystical complicated device. Anyone who works on Jeeps should own a meter, and know how to use it. A meter can tell you if your battery is good, alternator is charging, if there is a break in a wire, if something is a good connection, test sensors like TPS/MAP/Crank/etc., and many other things. This post will explain how to use a multimeter.
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Hooking up offroad lights:

A set of 55 watt off road lights will draw roughly 10 amps. A set of 100 watt lights will draw close to 20 amps. This is generally more load than you want to place on any one circuit in your fuse panel, especially since those are supplying power to other things in the Jeep. The correct/safe solution is to use a relay. A relay will allow you to supply power to the lights straight from the battery. This post will show you how to properly wire a relay.
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Check Engine Light: -

The check engine light on most Chryslers can be retrieved by simply turning the key on and off three times. Turn the key to run position, back one click, run, back one click, run, the check engine light should start to flash on older Jeeps. One flash, pause two flashes, would be code 12. It should start with code 12 ends with code 55. It will repeat the codes three times before moving to the next code. OBDII vehicles (anything 96-up) use codes that contain both letters and numbers. Newer Jeeps with the digital odometers will actually display codes on the odometer. For example, it may display P0301, which would be a misfire on cylinder one. Almost all parts stores will scan OBDII vehicles for free, if you take it to a parts store write down the actual code number for your reference. Once you have some sort of code number, we can usually get you straighten around, and answer any questions you may have.
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Relays -

Think of relays as an electronically controlled switch. When voltage is applied an electric magnet is energized inside, and brings two contacts together. This picture will help explain how a relay works. Relays are handy to use to prevent switches, or circuits from being overloaded. In the Jeep community a common use of relays is for powering offroad lights, however, the factory also uses them to power various systems on the Jeep. This post will explain hooking up relays. This post will explain testing relays.
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My speedometer doesn't seem right?

When you change to larger or smaller tires or change the gear ratio in your axles your speedometer will no longer read correctly. To correct this you need to purchase a new speedometer gear. Replacing a speedometer gear doesn't take any special tools and can be done in a matter of minutes. Refer to this chart for selection of the correct gear.
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Truck Bed Liner For Jeeps -

Well after taking your Jeep off-road a few times, you'll most likely find cleaning and trying to get the carpet to dry sucks. I tried to keep the carpet for a while and gave up, it just never dried out, and always smelled like mildew/creek water. I gave up and took all the carpet out, and decided to use truck bed liner on the whole thing. This writeup will show whats involved in the process.
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What kind of fluid do I need?

Dana 30, 35, 44 axles - 75w90 gear oil (I normally use 80w90 itís more common and cheaper)
NP231 transfer case - Dexron III
AX5/AX15 5spd. - 75w90 gear oil (again I personally use 80w90)
93-04 Automatics - ATF+4* Some early transmissions will actually say ATF+3, ATF+4 is a better selection of fluid, the downside is that you can only purchase this at the dealer for the time being. DO NOT use a Dexron/Mercon fluid in your Chrysler transmission, do this and you will be buying a new transmission.
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Tie Rod Flips -

Flipping your tie-rods can help improve steering angles. This image will help explain. You basically have two options, re-taper your knunckles and switch to a larger tie rod end, or drill a straight hole in the knunckle and use a special tapered bushing. I prefer the bushings, as you can drill the hole out larger, install the spacer in, and reinstall the tie rods. Getting the tie rods up higher can help fight bump steer in some cases, and can help protect the draglink from being damaged off-road.
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Towing a Jeep -

Theres nothing wrong with flat towing a Jeep, in fact it's very simple. For any TJ/YJ or NP231 equipped Jeep the driveshafts can stay in. The transmission should be in park if automatic, or in gear if a manual. The transfer case should then be shifted into neutral. The rear shaft will spin the transfer case output shaft, but the NP231's oil pump is driven by the rear shaft, so it will get proper lubrication. If flat towing the key should be in the unlocked position so the Jeep will turn with you. If you have a CJ your stuck pulling the driveshafts. Anything with the Dana300 transfer case the driveshafts must be removed to prevent damaging the output shaft bearings.
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Hi-Lifts?

Hi-lifts are wonderful tools if used properly. They are capable of doing far more than just jacking up a vehicle. However a hi-lift jack can injure you very badly, or even kill you if not used properly. Kwrangln has a good post on how to use your hi-lift and what happens when stuff goes wrong.
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Popular Swaps/Stock Parts Mix'n'Match:

Many times rather than using aftermarket solutions, a good junkyard hound has cheap alternatives. Here are some of the more popular swaps/mods that people do, that aren't so mainstream. As with anything do some research before jumping into these modifications, they aren't all as simple as they seem.
 
-Dodge Alternator Swap
-Using TJ Flares on a YJ/CJ can give you the clearance of a set of cutout flares, gain an extra inch of tire clearance.
-XJ pitman arms can be used as a dropped pitman arm on a YJ/CJ.
-Make your 15 gallon tank a 20, without changing the tank.
-WJ knuckles can be used for improved brakes and a Hi-Steer setup.
-XJ High Pinion 30s can be used in TJs.
-Using Waggy springs on a YJ will gain you some wheelbase and lift.
-Many people ditch the Peugeot and the AX5 transmission to upgrade to the AX15, or even better NV3550 or better yet NV4500.
-YJ roll bars can be swapped into CJ7 to help protect rear passengers more.
-Relocating the brake lines from the top of the frame, to the bottom of the frame can make shorter brake lines work with your lift.
-Hand Throttles can be made using a bike brake handle, bike brake cable, and an electrical connector.
-Eliminating the vacuum disconnect can be done using the one piece axle shaft from a TJ or XJ.
-Factory YJ Brake Hoses can be used as extended brake lines on TJs.
-Various other master cylinders can be used to improve brake pedal on vehicles that have had axle swaps done.
-4.2 to 4.0 head swap.
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Tech Section Links:

 
Many people overlook our tech section, I've rounded up some quick links to just a few of the killer writeups we have over there. Theres lots of info over there too, be sure to check it out everynow and then.
 
Alternator Swap Beadlocks 101 Bed Lining a Jeep Tub Changing Pinion Bearings Cheap axle tube cleaning tool Flush Mount Taillights Full Floater vs. Semi Floating Hand Throttle Install HiLift jack safety Homemade beadlocks Hooking up Relays Hubs, Warn vs. MileMarker Low buck internal HiLift mount Multi-Meter Basics Manual Hub Wheel Bearing Maintenance Manual Transmissions Mounting Beadlocks Shackle Reversal Testing Relays Tire Guide 2.5 - 4.0 Throttle Body Swap U - Joint ID Understanding Shackles Vacuum Disconnect 101 What tire pressure should I run Will this tire fit this rim Winch basics Wrap Bars XJ Control Arm drop on a ZJ York OBA ZJ Front to rear coil swap

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Who wrote this FAQ?

OhioYJ. Cromwell, CdnJeepGirl, dillonjm, kwrangln, Ligoweez, mrbeerbaitnammo, rstarch345, TONKA, VtechTJ also contributed helpful information and ideas to make this FAQ what it is. Knuckelhead also reminds you to have drinkable water. :D
 
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