REGEAR 1986 COMANCHE 2.5L 5 SPEED MANUAL

[SLOTMAN]

It's on 33 inch tires what gear ratio do you think would be appropriate I was thinking 488 because of the lower torque of the four-cylinder motor versus the six and having the OverDrive 5th gear would allow it to do some freeway driving still but will 488 fit in the stock pumpkins it already has posi in the rear and do you think it would be worthwhile to put some type of posI in the front while it's apart and if So what kind

[89 MJ]

Short answer: 4.88s are probably about right. 

 

Long answer: I'm guessing you have the D35 in your truck still. If it does have the D35, you're on borrowed time with 33s. I'd look at swapping in a 29 spline Chrysler 8.25 out of an XJ or out of a Liberty, an MJ or XJ D44, a Ford 8.8 out of an Explorer Sport Trac (the regular Explorer ones are narrower than the stock MJ rear), or a D44 out of something like a Rodeo or Passport, as outlined here. The way you are going to use the truck and the terrain around should be taken into consideration too. Here is a Tire Size vs Gear Ratio chart that might help you too. 

 

[ghetdjc320]

I will say, I wheeled plenty on a D35 with a built 4.0 and 4.56 gears on 33's (Cooper stt pro's). There are a few things that can make them last: use a limited slip or truetrac style setup vs a locker such as a Detroit or any of the lunchbox lockers. The smooth engagement of a limited slip helps with unnecessary R&P along with axle shaft strain/shock. Second run some 1541 shafts. I used a set from Revolution axle and gear. And third, you can run a truss setup if you like. I used one from TNT and it was a lightweight yet well engineered piece that was easy to install in just a couple of hours. Fourth, make sure your gears are setup correctly. 

Some will say don't invest anything into a D35 but there are some advantages to consider: it fits the truck, they are light weight, they have plenty of clearance under the pumpkin, they have good aftermarket support, you already have the axle, most of the parts are fairly cheap compared to other axles. 

[89 MJ]

1 minute ago, ghetdjc320 said:

Some will say don't invest anything into a D35 but there are some advantages to consider: it fits the truck, they are light weight, they have plenty of clearance under the pumpkin, they have good aftermarket support, you already have the axle, most of the parts are fairly cheap compared to other axles. 

This is a good point. I believe it was you who said that 35s under an 8.8 give as much clearance as 31s under a D35. It’s a good option when upgraded, but on a budget, I’d recommend swapping. 

[ghetdjc320]

Just now, 89 MJ said:

This is a good point. I believe it was you who said that 35s under an 8.8 give as much clearance as 31s under a D35. It’s a good option when upgraded, but on a budget, I’d recommend swapping. 

Very true, depending on what's available around you, a swap may be a cheaper alternative with more upgradeability down the road. 

[89 MJ]

18 minutes ago, ghetdjc320 said:

Very true, depending on what's available around you, a swap may be a cheaper alternative with more upgradeability down the road. 

This. It might be worth pricing out building the D35 compared to buying a different axle, welding perches on it, and putting a locker or limited slip in it. 

[SLOTMAN]

Thanks a lot for all the suggestions a lot to think about and research before I make a final decision