Why: Gear change/Axle swap

[Jeeper Creeper]

A buddy of mine gave me some 36" Swampers that I'm now running on my CJ. They look good and ride good but I'm told I should do a gear change and put full width axle's on. My question is "why" when everything seems to be fine?

[peteyg]

Technical answer:

Going to larger tires effectively changes your gearing, making you gears "Taller" (numerically lower). This increases the amount of work the engine has to do to maintain normal driving. This also has a large negative impact on gas mileage. When people say you need to regear, most of the time it's just to get you back to your stock gear ratio with the bigger tires. You get some of your fuel economy back, and the vehicle feels much more responsive.

In off roading, we generally like "Shorter" gears (numerically higher), because that effectively multiplies the amount of torque we are getting from the engine, and that greatly improves off road capability. There is some sacrifice in on-road performance, however. Your truck will feel more like a dragster, with really quick acceleration, but no top end.

Non-Technical answer:

If you feel like you are having to work the engine more to go the same speeds you used to, if you feel like it is a DOG going up hill, if you lost your 5th gear, then it's time to re-gear. Otherwise, don't worry about it. Once you get it in the dirt, you'll know if you need gears or not...

About full-width axles:

As you lift the vehicle to clear the tires, your narrow axles make the Jeep unstable. Putting in full-width axles increases the stability to compensate for the lift. It also looks cool.

The downsides are that it makes the vehicle illegal unless you put big ugly flares on it, and you lose some of your maneuverability. It won't turn as tight, and you'll find you do a little more back and fill. As with most modifications, it's a trade-off.

[Tom]

you have the narrow track cj5 so i would suggest going with full with axles to help lowering your center of gravity. they will give you a wider stance and stability.

[Jeeper Creeper]

Very well explained....thank you! Does anyone know what full width axles will fit under my CJ. I can't buy new so I would need to find something at a wrecking yard.
Also if I'm changing gears and axle's, would I need to change brakes...... would I be better off getting a complete rear and front differentials?

[peteyg]

Very well explained....thank you! Does anyone know what full width axles will fit under my CJ. I can't buy new so I would need to find something at a wrecking yard.
Also if I'm changing gears and axle's, would I need to change brakes...... would I be better off getting a complete rear and front differentials?

If you have something to cut with and a welder, ANY axles will fit in your Jeep. It just depends on what you're looking for.

For a CJ, if you want to go full width, you need early Dodge, Chevy, early Wagoneers, etc. to match the passenger drop front. In the rear, it really depends. If you go full width Chevy or Dodge, get a Ford 9" for the rear out of an early 80's F150 or Bronco. All of these options will require fabrication.

A REALLY good option for you that does NOT require any fabrication is to get a set of wide-track CJ axles. You get 2 inches wider axles and don't have to do a single thing to them. They bolt in, and if you re-gear before you get the axles, you can re-use all of that.

[Jeeper Creeper]

A REALLY good option for you that does NOT require any fabrication is to get a set of wide-track CJ axles. You get 2 inches wider axles and don't have to do a single thing to them. They bolt in, and if you re-gear before you get the axles, you can re-use all of that.

I like this option since I don't weld. I much prefer to the "not do a single thing" since I'm not that savey to do any fabrications. Would the CJ axles be something I would get at a wrecking yard or a local dealer?
Thanks for all the feedback.....

[peteyg]

You won't find CJ axles at the dealer. Check out wrecking yards (you might get lucky - it has to be an '82 - '86 CJ), and also watch the for sale sections on the 4 wheeling boards (here, Pirate, Jeepforum, etc.), and Craigslist.

[Jeeper Creeper]

Am I changing axle's just for more width or are they stronger built? If just for width, couldn't that be made up with a couple of wheel spacers and/or a wider tire?

[peteyg]

Am I changing axle's just for more width or are they stronger built? If just for width, couldn't that be made up with a couple of wheel spacers and/or a wider tire?

Yup, that's exactly correct. So if you're going to go to all the trouble, you might as go full-width. But then you're back into the whole big fabrication job thing.

[Jeeper Creeper]

My fear was snapping an axle because it might be weakened by larger tires. It sounds like a wider axle only does just that (wider not stronger) With this in mind I think I'll stay with my stock axle's and take advantage of my wheel spacers that are already in place.
Thanks for all the feedback.

[blackZZR]

Jeeper, you are running a D44 in that jeep, the wider rear diffs are AMC 20 so you will want to totally rebuild one of those with new 1 piece shafts, The front d 30 you are running has smaller u joints than a later cj D 30. plus they do not make stock shafts for it anymore, the alternative is to get chrome moly shafts with bigger u joints, a bit pricey but well worth it. Finding rear axles for that jeep would not be to hard, but finding them with matching gearing would be hit or miss. Plus any time you find axles of that age you may need extensive rebuild due to rust on bearing and seal surfaces.
Money being the issue, means repair money is also an issue. Sage advice is not to run over a 33 inch tire on your setup then.
Remember, the axle shaft breaks usually during a wheeling spike load, but it is not the amount of the load that breaks the shaft, it is the damage done to the shaft during day to day running of the jeep with the tires that are giving it trouble. On a daily basis they are putting loads on the shafts that tend to twist the axles, yes longer axles tend to twist more, with the twisting you get a break down in the integrity of the metal and that lowers the amount of spike load they can take.
So it is a trade off, if you want bigger tires you not only need to afford the tires but need to afford the upgrades that go with the tires. Or you may be paying for those upgrades while needing a ride. Whatever your final choice will be, free often means just a place to start spending money. The advice to go to wider axles was good advice for those tires. It seems to boil down to those tires. If repair/mod money is an issue, maybe rethinking those tires is at hand.

[Guest]

Technical answer:

Going to larger tires effectively changes your gearing, making you gears "Taller" (numerically lower). This increases the amount of work the engine has to do to maintain normal driving. This also has a large negative impact on gas mileage. When people say you need to regear, most of the time it's just to get you back to your stock gear ratio with the bigger tires. You get some of your fuel economy back, and the vehicle feels much more responsive.

In off roading, we generally like "Shorter" gears (numerically higher), because that effectively multiplies the amount of torque we are getting from the engine, and that greatly improves off road capability. There is some sacrifice in on-road performance, however. Your truck will feel more like a dragster, with really quick acceleration, but no top end.

Non-Technical answer:

If you feel like you are having to work the engine more to go the same speeds you used to, if you feel like it is a DOG going up hill, if you lost your 5th gear, then it's time to re-gear. Otherwise, don't worry about it. Once you get it in the dirt, you'll know if you need gears or not...

About full-width axles:

As you lift the vehicle to clear the tires, your narrow axles make the Jeep unstable. Putting in full-width axles increases the stability to compensate for the lift. It also looks cool.

The downsides are that it makes the vehicle illegal unless you put big ugly flares on it, and you lose some of your maneuverability. It won't turn as tight, and you'll find you do a little more back and fill. As with most modifications, it's a trade-off.

I agree. I have a 4:10 and 33" and on the Cajon Pass I am 4th (10%) and 5th (90%) going up. With the 3:07 it was 3rd and 4th. Now I can tell the motor is more at ease. 4:56 would have probably have been just right. So, with 36" what ratio are you running 4:56? Any thing less, and I would say re-gear.

[RangerRick]

Wide-Track CJ axles

Jeeper' I have a set of wide tracks with 4.10 gearing from the factory out of my 85 CJ-7 that are all original if you are interested. They are 4" wider total, 2" per side than narrow 81 and earlier CJ's were. The rear is an AMC corporate model 20, "C" code (open carrier 4.10 gears) differential and it has new wheel cylinders for the brakes and is complete drum-to-drum including parking brake cables and hard lines. The front is a Dana model 30 open carrier factory 4.10 gears. I'd recommend that you can re-use your 79 knukles, brakes & hubs because you will have desireable 6 bolt inner & outer hubs. This axle is also 4" wider than what you have stock up to 1981 and prior years CJ's. These are the ONLY bolt in, no fabrication solution if you don't want to custom cut or outbard your spring and axles. If you are interested, make me an offer they are listed on the parts forum for sale. Just a thought incase you don't want to fabricate..... Otherwise I have other ideas while still retaining Wide-Track width like a Ford 8.8 rear.