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Upgrading Chrysler 8.25

LBEXJ

LBEXJ

NAXJA Member #721
Location
Parke County, Indiana
Copied from: Re: 4.56 gears for chrysler 8.25 29 spline (from Rawbrown in a thread from "Wanted"):

take the 8.25 case to a machine shop and have them chuck it up in a lathe. they can open up the ID for the 29 spline shafts. then all you need are side gears or a locker...
Click to expand...

I have a Chrysler 8.25 (27)spline in my '94. The plan for this summer is to upgrade the rear axle (actually both F&R). I was thinking about locating and installing a Dana 44 or Explorer 8.8 in the rear but have since wondered about doing this modification instead. From what I understand, I'll only be able to go up to 4.56 gears but I can live with that. I also want to install a Powertrax.

My questions are: What are the details involved in doing this? Will I eventually be able to add disc brakes to this axle? Is it true the 8.25 (29)spline is nearly as strong as a Dana44?

My "Final Goal" is to be able to experience trails like Tellico, Paragon, Moab, and even maybe the 'Con without having to use all the bypasses. I want to be able to drive there and back. I'd like to be able to run 35's on the trail.

The current plans are: This spring, add a SYE w/double cardan drive shaft and install more skids underneath. This summer upgrade the axles F&R, add ~2" more lift, and upgrade the steering.

Can I get some advice? I'd appreciate it if I could ...

Les
 
Surely someone has upgraded their 27 spline 8.25 axle instead of replacing it ... :eyes:

BTT
 
lbexj said:
Surely someone has upgraded their 27 spline 8.25 axle instead of replacing it ... :eyes:

BTT
Click to expand...

I upgrade my 27 spline 8.25 to 29 spline Yukon shafts from Randy's, while I was in there I dropped in an Airlocker and 4.56 R&P, I've been running 33" Jungle Trekker II which is similar to Swampers. Has been holding up so far but I wheel in M'sia which is mostly mud, ruts and some rocks..

Hope this helps..
 
Thanks ... yes it does. Was there anymore to it than having the case bored and side gear changed (or locker installed)?

Les
 
i have a 94 8.25 and i put 29 spline dutchman axles in, 4.56 yukons and an arb with 33" mtrs
 
lbexj said:
Thanks ... yes it does. Was there anymore to it than having the case bored and side gear changed (or locker installed)?

Les
Click to expand...

It was just a remove and replace kinda job, if you're not putting in a locker I believe you have to change the spider gears otherwise there was no boring of the case.

You may wanna try wheeling it with your 27 splines and see how it goes.. the only reason I did the 29 spline was cos I wanted the Airlockers and they only make it for the 29spline.
 
Thanks Moneypitxj ... was it just a matter of remove and replace for you?

KLZJ - I wheel it plenty and it works fine. I just want to make the axles stronger for more difficult trails. If I am going to do any gearing and lockers, I want to make sure the axle will hold up. I don't have money to burn if ya know what I mean ...

hense the other question ...

Is a 29 spline 8.25 axle nearly as strong as a Dana44? I'd like to know if it is a decent "foundation" axle ...

Les
 
yes you either have to machine the case or or get a new/used 29 spline case. but you can also toss in a detroit for about the same, if you can't find a used case for free.

just some notes of comparison between the 8.25 and d44...
8.25- c-clip
d44-bolt in shafts
8.25 tubes-3"
d44 tubes-2.75"
8.25 shaft dia-1.21" (29 spl)
D44 shaft dia-1.30" (30 spl)
 
Thanks Rawbrown ... I assume you're talking about the Detroit Softlocker? Yes ...That would be better than the Powertrax ...

I guess the biggest difference between the Dana44 and 8.25 is the C-Clip issue. I was not aware of that ...

Les
 
Well just my .02 cents is that if you end up going to a new axle skip the D44 it's not that much stronger than the 8.25 and just get a ford 8.8 the match up is perfect for the XJ rear end. Your looking at a stonger rear end. and 95+ models come with disk breaks. not sure around your parts but they sell these at junk yards here in CO for like 150. some come with 4:10 even. even if you get the ones with 3:55s your still going to up grade the gears like you said 4:56s on 33s would rock. only have to weld on spring perches and shock mounts. when doing that you can weld on the shock mounts higher so there out of the way unlike the 8.25.

I've thought about this for some time and that seems to be the best all around upgrade axle to go with. They come in explorers and we all know how those get tossed to the junk yards and what not.
 
What part of the case on an 8.25 did you have to bore???????? I switched from 27 to dutchman 29 spline so I could run a ARB and it was a direct swap. Slide out the 27s and slide in the 29s.
 
I run 35s on my stock 8.25 29 spline, no problems no breaks, yet.

I would just buy a used 29 spline 8.25. I am sure you can get one for $150 or less. Also If your wanting to really upgrade get a 9".
 
"Case" is the offiicial? name for what we mear mortals call the "carrier".

Listen to RawBrown - it was MY diff he's talking about! :twak: It hurt, but I got over it...

bburge
 
I have not ruled out using the Explorer 8.8 at all especially if I can do disc brakes at the same time ... I just was not aware it would be possible to upgrade from 27 spline to 29 spline using my current 8.25 axle. What is involved in upgrading to disc brakes on the 8.25 axle? Most everything I've found online, as far as tech goes, involves mods to the Dana axles ... very little with the Chrysler.

I'm exploring what my options are so I can decide which way to go with it. I appreciate everyones comments.

Les
 
the actual carrier. since you put in an arb you repalced the case. but if a no-slip is used then the case is re-used, hence then need to open up the journals a little bit.
jeepme said:
What part of the case on an 8.25 did you have to bore???????? I switched from 27 to dutchman 29 spline so I could run a ARB and it was a direct swap. Slide out the 27s and slide in the 29s.
Click to expand...
 
I wouldn't spend the money on the 8.25. For the trails you want to run with 35" tires, you are going to want disc brakes. An 8.8 is simply less expensive. The 8.25 also has a tendency for gear noise with lower gears, even when properly set up. It can be loud enough to really bother you if you put some miles on it.

Strength on the 8.25 is marginal for 35" tires. Depends on your style and the trail. Anyway, I built a 29 spline 8.25 with alloy shafts, disc brakes, low gears, etc, and got rid of it because of noise and vibration that not even a rebuild could cure. I should have just spent the money on the high pinion rear axle (Currie 9") I have now. Smooth, quiet even at 65 mph (I don't drive the beast any faster) and the difference in rock crawling clearance is huge. I used to drag my 8.25 pinion all the time even with 6" of lift and 33" tires.

It's not a bad axle, but ultimately if you want to play with the big dogs there isn't a stock XJ worth spending a dime on.

Nay
 
Danno said:
it's really easy to go with the Ford 8.8 and have disc brakes. It really does make a big difference. It's stronger than a d44 also.[/QUOTif i change to a 8.8 with disks..........do i need to do anything with the brake portioning valve..........or will the hydralic pressure be ok at the rear........oh yeah i run a `99 xj classic........they are the same bolt pattern aren`t they.......
Click to expand...
 
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