Picked up a 96 xj 2wd 2.5 a few months ago with plans to start a no rush, not daily driver ls swap by the end of the year. Plan is over the next few months is to get it going straight down the road and to take care of any issues before I start the swap.

Looking at getting the rear end ready for more horses shortly. The current 8.25 I am guessing is a 27 spline 4.10 geared differential. On the floor in the garage I have an 8.25 29 spline 3.55 out of a 99 xj from the junkyard.

My questions are what gears do I want with this ls? This will be a road driven 2wd vehicle, no plan to off-road. I am pretty sure I want the 29 spline for better strength. I do not plan to go much bigger than stock on tires, maybe 30's at the most. I have never regeared a rear end. I tend to pick up on basic wrenching pretty quick. How hard is it to regear a rear end on the garage floor? Something I can do myself? Should I take it somewhere and have a shop do it? I hate paying for something I could do myself.

Opinions, what do you guys think?

This is the project.

 

Re gearing could be done at home but takes some special tools and skills.Google around you can find a lot of the info from the tools and how to see if you want to try it or not.As far as gearing most pickups run a 3.73 stock and a 4.10 or 4.11 is the towing upgrade gears.If you want to know what rpm you will run with what gear and tire size http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php

 

Excellent score on the 2door XJ!!!!!!!!


I would encourage you to rethink your plan of attack.

Leave the current 8.25 in place.
Install your LS and get it running.

The only cost loss you will have is the DS........may not be usable with final real axle.


With stock tires you will NOT grenade your current 8.25.....regardless of 27 spline.


If you later decide to regear and keep the 8.25 you can retain the existing housing and leave it in the XJ. Take the 29 spline carrier or find a locker or...? and transfer it over to the current housing along with the 29 spline axle shafts...........housings are identical.
If you are not comfortable doing it yourself.....take parts with the XJ and drive it to a competent shop for a regear after all other work is completed.



I would highly recommend that you consider a custom Ford 9" in the end. Rear discs, of course.

What I think you will find after it's all said and done....for a street machine......wheel hop and shudder will be uncontrollable if you are looking for hard launches on the street.
I'd look for solutions.
Look to some type of 4 link with coil overs...........other........
At a minimum I'd look to reconfigure the shock positions anyway......and of course you'll have to look a the fuel tank and exhaust too.


You've got a long road ahead and the rear axle should be your last consideration.


Just my opinion.

 

BTW.......

Do not scrap that 2.5. Good running/non-running 2.5s are getting real hard to come by.

Sell it to someone in need......you'll have no problem finding him.

 

Thanks for the info guys. I will be starting a bus thread when I start.

Don't quite have the confidence to do the regearing so I will probably leave as is and see how it goes.

Thanks again.

 

4.10s may be a bit deep for 30's

it'll probably be happier with the 3.55's in the 29 spline and will be stronger.

for comparison im doing ta 5.3 swap in my xj very soon and ill be using 4.10's with my 33's and should be just about perfect

 

I always end up finding a shop that will do it for $100. Pull the axle shafts, take the axle in and let them get it done. I don't really trust myself with gears either. Get an 8.8 or 9" when you're ready, don't touch the 8.25. Run what you brung until you have a HP estimate and transmission selected. Then select a good axle and correct ratio

 

Why do say fab in an 8.8 but avoid the 8.25. They are basically the same strength but the 8.25 is a direct bolt in. It's the same rear end Chrysler used in their muscle cars through the 70s.

 

Our 01 Cherokee with 3:07's and manual trans needed some scoot. I also wanted to use a Power Lok so I settled on the D44.

Found a local XJ D44 on Craigslist, bought the Tera Flex disc brake kit, and added 3:55's

The D44 is clearly lighter than a Chry 8.25 although not sure by how much. 50-75 lbs?

The 3:55 gears are a great improvement although the mileage has taken a hit. With 3:07's I could hit 22mpg Hwy. I have not done a long trip yet with the 3:55's but the city and light hwy combined mileage is noticeably less. Running 28" BFG's

I suspect the hwy mpg may have dropped to 19mpg. We shall see.

The Tera Flex kit worked well and I have had no issues after a few months, although, the E brake cables are still a bit stiff. Brake improvement is indeed noticeable. Spendy but overall a nice kit.

Definitely happy with the improved performance and glad to have a Power Lok on board when needed.

Cheers!

 

It also depends on what transmission you will be using. It's final drive ratio is critical to know as well as all the gear ratios from 1st,2nd,3rd,4th,OD. An LS has way more than enough low end torque to drive any gear set you want. You want great Daily Drive MPG drop in a set of freeway fliers at 3:07's or less

 

That's funny.. No confidence in a rear gear swap but what seems TOTAL confidence in a wiring nightmare?
I'd be just the opposite.. I am figuring out all my suspension mods first for my '96 like yours, but black (2.5/5spd/27 spline w/4.10's)
tubular upper and lower C/A's in front and just happened to find a Comanche locally and got it's D44 with 3.55's and LSD.
I'm going a LOT lower, so the spring UNDER will help tons, but may have to look into some 4" lift springs to give me some 'travel'.

Instead of an LS swap I already had a 5.2 that I rebuilt with a NV3550 for another project that hit a stop and is just sitting, so why not?
I think my tires are around 26 or 27" but can't remember.. They're 235/60/16 Blizzak that Tire rack had a close out on (67.00 Each!!)
The 5.2 came from a Grand Cherokee 'cause I wanted a roller block that I had decked .065 and had the cam reground to more of a chevy "hot cam" specs. But it's going to be carb'd

JeepDriver gave some real good advise..
I'm going to figure out the suspension/brakes first and get into the motor swap later. (there's still a chance that I may go with an LS.. Just hate wiring) Plus, I really think these prices on Gas is going to SKYROCKET after the election.. Back up to 5-7$ a gallon
so I might just keep the 4cyl in there for a bit. OR, find a 4.8 and 5/6spd and have it programmed for mileage.

If you wouldn't mind, pm me your number so we can talk. I'd like to gather info on what mounts and such you go with.

Errol

 

You will have to reweld perches on that 44. Comanche has the springs under the frame, where the xj has the outside the frame. That ends up with the perches about 5" narrower overall.

 

Sorry my friend, that should say "build' not "bus". Plan to use the Novak mounts and their headers as well. There is a thread someone where on here that they tried just about every brand of header out there and the Novak's are the only ones to fit without modding.

 

ii read some where that someone used a set of 2010 camaro ss manifolds with the novak mounts.