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8.25 upgrade??

H

HoodRichXJ

NAXJA Forum User
Location
Winston Salem, North Carolina
Okay, i have been trying to gather as much information about several different rear end swaps and im still looking before i make any moves. Right now My Xj has the 8.25 rear 29S and 3:55 opens, with 35's. I want several things in a new rear including discs, lower gears, and a locker. Right now im kinda toying with the taco rear idea i like it and its feasable $ money wise. But i was also thinking of maybe just upgrading the rear new shafts, discs and whatnot. Can anyone give me any kinda input or thoughts as to what i might run into with upgrading the 8.25, i have read its a pain to regear and noises are common, and being that my xj is my DD i wanna have something quite yet fairly stout as well while keeping in mind that it does see some wheeling almost every other weekend. thanks steve
 
Get a ford 8.8 from a 95"+ Ford Explorer or Mercury Mountaineer. If you need more info on the swap go to mountainoffroad.com If you want a good axle to put & into since you don't haven anything into your 8.25 yet. You will get good disc brakes with it(95'+), 31 spline axle shafts, and big axles tubes etc. You should be able to get some $ for your 8.25 since it has 29 spline shafts from someone else if you list it for sale. For that person it will be an upgrade from their dana 35 or early 8.25 27 spline axle. You can also gear a 8.25 to 4.88 and it has a nice strong r&p like the ford 9" the 8.25 does have a reputation to being loud when geared, I never noticed mine, but swapped mine out for a xj dana 44 anyways. The 8.25 also had alot of inconsistencies during its run I have heard.
 
Big Red said:
Get a ford 8.8 from a 95"+ Ford Explorer or Mercury Mountaineer. If you need more info on the swap go to mountainoffroad.com If you want a good axle to put & into since you don't haven anything into your 8.25 yet. You will get good disc brakes with it(95'+), 31 spline axle shafts, and big axles tubes etc. You should be able to get some $ for your 8.25 since it has 29 spline shafts from someone else if you list it for sale. For that person it will be an upgrade from their dana 35 or early 8.25 27 spline axle. You can also gear a 8.25 to 4.88 and it has a nice strong r&p like the ford 9" the 8.25 does have a reputation to being loud when geared, I never noticed mine, but swapped mine out for a xj dana 44 anyways. The 8.25 also had alot of inconsistencies during its run I have heard.
Click to expand...
Just a correction.

I thought the 8.8 has 30 spline shafts.

But, I'm positive the 8.25 cannot be regeared lower than 4.56.
 
Okie Terry said:
Just a correction.

I thought the 8.8 has 30 spline shafts.

But, I'm positive the 8.25 cannot be regeared lower than 4.56.
Click to expand...

The ford 8.8 and ford 9" both came with 28 or 31 splines. All Ford Explorers had 31 spline shafts and the 95'+ also had disc brakes. 4.56 is as low as you can go with the 8.25 the ford 8.8 can go to 4.88 or now lower gears are coming out for it from some places.
 
Ive been running my 8.25 with Dutchman shafts and an ARB for 4years now on 35" tires and have never broke or have any complaints. The niose thing is only if you buy cheap gears or they are not set up properly. It also depends on what you want to do with your rig, I wouldnt change my rear axle unless I was planning on going bigger than 35's (which i see no need for) and If i did some day want to go bigger I would just get a 60 they are cheap and stronger than a 44 or an 8.8. The 29 spline 8.25 is very comprable to a 44 strength wise the only bad thing about an 8.25 is 4.56 gears are as low as you can go.
 
Dana 35 rear axle COT: 870 MOT: 3480
Dana 44 rear axle COT: 1100 MOT: 4460
Ford 8.8 28spline COT: 1250 MOT: 4600
Ford 8.8 31spline COT: 1360 MOT: 5100
Dana60 semifloat COT: 1500 MOT: 5500

Sorry, no numbers for the 8.25 :-( Anybody got those?

COT: Continuous output torque rating
MOT: Maximum output torque rating
Numbers from January edition of Fourwheeler (with the typo on the Dana 44's MOT fixed), page 60.

Notice that: 225 ftlbs x 3.83 = 861 ftlbs (4.0L/AX-15)
Jeep on!
--Pete
 
Are you sure that is right Pete? I'd expect the 44 to come in between the 28 and 31 spline 8.8, close to the 31 spline. I doubt those #s on the 44, unless the shafts are necked down or something to make them weaker. Oh well, I have a pair of extra 44 shafts and if I break shafts and run through my spares, then I'll get some 4340 alloy ones. I knew I should have gotten the 8.8, but the 44 was a bolt in. Also you can get replacement xj 44 shafts from 98'+ TJs both stock and aftermarket, they are the same size.

Do you have any info on the ford 9" 28 and 31 spline or are they about the same strength as the ford 8.8 for each 1?
Troy
 
All I have is what was in the article (and somebody was kind enough to fill me in on the Dana 44 MOT from a website). No idea how accurate any of it is. There are no specifics on years or models (and absolutely nothing about the 9" or AMC 20), just the raw numbers you see there. Doesn't list what part is expected to be the weak link either. I'd never seen torque rating numbers before, and I too was surprised by the good showing of the 28 spline 8.8. But that surprise could simply be from comparing the hard numbers to opinions I've read on the internet. I'm inclined to believe the FourWheeler article until I can find some competing numbers. Anybody got any?
Jeep on!
--Pete
 
EricsXJ said:
jeepme,

I agree with everything you said about the 8.25. What made you decide to go with Dutchman shafts (1541-H) over say Yukon 4340 chromoly?
Click to expand...


When I was upgrading, the Dutchmans where the only ones available. But if i ever brake them I will definately go with the Yukons.
 
Last edited:
there is no such thing as 4340 shafts for a rear axle application. the strongest you can get in a SF axle is the 1541h. if you got the dutchman imports shafts then you allready have Yukons.
jeepme said:
When I was upgrading, the Dutchmans where the only ones available. But if i ever brake them I will definately go with the Yukons.
Click to expand...
 
ahhh good to know. Thanks Ryan
 
Rawbrown said:
there is no such thing as 4340 shafts for a rear axle application. the strongest you can get in a SF axle is the 1541h. if you got the dutchman imports shafts then you allready have Yukons.
Click to expand...


Why is that? So 1541 is roughly 15% stronger than stock and 4340 about 30%, based on the Dutchman website? It's not possible to make 4340 shafts for the rear? What is 300M and what application and strength does that material have? I know it's not cheap.
Troy
 
1040- YS: 106k TS: 120k
1050- YS: 146k TS: 162k
1541H YS: 164k TS: 181k
4340- YS: 210k TS: 228k
300M- YS: ---k TS: 270k
All numbers in psi

From the same Fourwheeler page as the other data. The chart says 300M is the aircraft grade version of 4340 (chrome-moly).
Jeep on!
--Pete
 
Rawbrown said:
there is no such thing as 4340 shafts for a rear axle application. the strongest you can get in a SF axle is the 1541h. if you got the dutchman imports shafts then you allready have Yukons.
Click to expand...

My bad. I didn't know that and saw the 4340 in their catalog but didn't notice that was just their front shafts. They don't specify what they use for the rear. They mention 4340 is not good for bending. Is that why nobody makes rear shafts in 4340, because the shafts bend?
 
Thats exactly it. CrMo has great resistance to rotational stress but does not handle bending stress very well. you can use it in a FF rear axle such as a D60. I would guess that Warns M35 FF conversion is CrMo also.
The 2 major shaft MFG's is Superior and Yukon. In my book they are the same. its just that the Yukon's are less expensive since they come from another country.
 
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