AeroNautical Posted September 20, 2013 Share Posted September 20, 2013 I'll be picking up a 29 spline Chrysler 8.25 axle this sunday, but it's off of a cherokee. Does anyone have the specific measurements for rewelding the perches to MJ SUA? What about driveshaft length with an ax15 and 231 combo, 3 inch lift short bed? Any writeups for a disc brake conversion using a grand cherokee? The search function is honestly hit or miss most of the time, and I got no hits for any of these. Link to comment Share on other sites More sharing options...
FrankTheDog Posted September 20, 2013 Share Posted September 20, 2013 The pinion is an inch longer on the 8.25 than on the D35. So your drive shaft needs to be an inch shorter. Lots of info on google for the disc swap. May be better off with discs from a Liberty. They came with 8.25's with discs. Link to comment Share on other sites More sharing options...
kolton Posted September 20, 2013 Share Posted September 20, 2013 If your doing all that work and still wanting to convert to disk, why not just use the 8.8? Comes with 31 spline and disks. Link to comment Share on other sites More sharing options...
92tanMJ Posted September 20, 2013 Share Posted September 20, 2013 I'll be picking up a 29 spline Chrysler 8.25 axle this sunday, but it's off of a cherokee. Does anyone have the specific measurements for rewelding the perches to MJ SUA? What about driveshaft length with an ax15 and 231 combo, 3 inch lift short bed? Any writeups for a disc brake conversion using a grand cherokee? The search function is honestly hit or miss most of the time, and I got no hits for any of these. I HIGHLY doubt you'd find this here. Try google, I'm sure theres a bunch of them out there. My guess would cherokeeforum has one, NAXJA has one, and theres probably one on Jeepforum as well but chances are its copied over from one of the other two. If your doing all that work and still wanting to convert to disk, why not just use the 8.8? Comes with 31 spline and disks. :agree: Link to comment Share on other sites More sharing options...
SW86 Posted September 20, 2013 Share Posted September 20, 2013 the pinion is an inch longer on the 8.25 but you should still have play in your slip yoke on the 231 to make up the difference. especially with a 3" lift. i don't know anything about the ax15 but with my aw4, 231 and spring over, i didnt have to change anything to the driveshaft. there are several disc brake conversion write ups out there. its VERY straight forward to do. i had no issues doing mine off a 96 grand. as far as perch spacing, (IIRC its was like 41 or 42" and some change but don't hold me to that), just remove the old axle, slide the new on in and bam you've got your spacing. pinion angle is more what id be worried about. slightly more involved then a eye ball perch job lol i prefer the 8.25 over the 8.8. not really any serious reasons why, just preference i guess. although ive seen more people in my local club have more issues out of the 8.8 than any with the 8.25 ever had. shafts, carriers, tubes letting go, etc etc... i don't think anybody has broken a 8.25 29sp shaft yet. even guys on 37s when guys on 35s break 8.8 shafts like candy. could be driving style though or just flat out bad drivers or crappy ford parts :rotfl2: Link to comment Share on other sites More sharing options...
AeroNautical Posted September 20, 2013 Author Share Posted September 20, 2013 Believe me, I kept my eye out for 8.8s. All the ones I found nearby either were geared wrong (3.07), missing axle shafts or just asking way too damn much. I'm getting a good deal on this 8.25, it's geared the way I want it and I've heard they are near D44 strength anyway. Don't the perches have to be rewelded on an 8.8 also? Link to comment Share on other sites More sharing options...
kolton Posted September 20, 2013 Share Posted September 20, 2013 Yeah, perches have to be welded as well. I've never personally broke an 8.8. And I've trashed on them. Weld the tubes, perches and shock mounts and call it good. Same with the 8.25, I'd weld the tubes anyway on it as well while you have it out. Check the pinion bearing as well, had a few JY ones be bad when installing on my friends jeeps. Link to comment Share on other sites More sharing options...
AeroNautical Posted September 20, 2013 Author Share Posted September 20, 2013 the pinion is an inch longer on the 8.25 but you should still have play in your slip yoke on the 231 to make up the difference. especially with a 3" lift. i don't know anything about the ax15 but with my aw4, 231 and spring over, i didnt have to change anything to the driveshaft. there are several disc brake conversion write ups out there. its VERY straight forward to do. i had no issues doing mine off a 96 grand. as far as perch spacing, (IIRC its was like 41 or 42" and some change but don't hold me to that), just remove the old axle, slide the new on in and bam you've got your spacing. pinion angle is more what id be worried about. slightly more involved then a eye ball perch job lol i prefer the 8.25 over the 8.8. not really any serious reasons why, just preference i guess. although ive seen more people in my local club have more issues out of the 8.8 than any with the 8.25 ever had. shafts, carriers, tubes letting go, etc etc... i don't think anybody has broken a 8.25 29sp shaft yet. even guys on 37s when guys on 35s break 8.8 shafts like candy. could be driving style though or just flat out bad drivers or crappy ford parts :rotfl2: Glad to hear it, brother did that disc swap on his 8.25 so I'll just get him to do it, haha. Plus, with 31x10.5 tires, I doubt this axle will ever come close to snapping. I've got a dana 35 in it now, if I take it out and just mirror the perches from it to the 8.25, I'd imagine it'd measure out perfectly, right? Link to comment Share on other sites More sharing options...
kolton Posted September 20, 2013 Share Posted September 20, 2013 You'll have the perch measurements correct, but you'll still need to measure pinion angle. Do this with the weight of the vehicle on the axle, and just snug the u-bolts up to hold it in place. When you get your correct angle and perch width, tack your perches in place. I always retard my pinion angle just a little to compensate for axle wrap. But that was on my bronco so idk if these have that tendency or not. It wouldn't hurt to check your pinion angle at full droop after you tack everything in place either. Link to comment Share on other sites More sharing options...
SW86 Posted September 20, 2013 Share Posted September 20, 2013 this guy knows the business ^^ :thumbsup: Link to comment Share on other sites More sharing options...
92tanMJ Posted September 20, 2013 Share Posted September 20, 2013 SW86, on 20 Sept 2013 - 13:01, said: the pinion is an inch longer on the 8.25 but you should still have play in your slip yoke on the 231 to make up the difference. especially with a 3" lift. i don't know anything about the ax15 but with my aw4, 231 and spring over, i didnt have to change anything to the driveshaft. there are several disc brake conversion write ups out there. its VERY straight forward to do. i had no issues doing mine off a 96 grand. as far as perch spacing, (IIRC its was like 41 or 42" and some change but don't hold me to that), just remove the old axle, slide the new on in and bam you've got your spacing. pinion angle is more what id be worried about. slightly more involved then a eye ball perch job lol i prefer the 8.25 over the 8.8. not really any serious reasons why, just preference i guess. although ive seen more people in my local club have more issues out of the 8.8 than any with the 8.25 ever had. shafts, carriers, tubes letting go, etc etc... i don't think anybody has broken a 8.25 29sp shaft yet. even guys on 37s when guys on 35s break 8.8 shafts like candy. could be driving style though or just flat out bad drivers or crappy ford parts :rotfl2: This is why I prefer the 8.8 over 8.25. Numbers from January edition of Fourwheeler, page 60. COT: Continuous output torque rating MOT: Maximum output torque rating Dana 35 rear axle COT: 870 MOT: 3480 (and everyone knows the 8.25 is a little bit weaker than the D44.- so it would go here) 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 Link to comment Share on other sites More sharing options...
SW86 Posted September 20, 2013 Share Posted September 20, 2013 i can dig that. ive just had luck with the 8.25, so its what ill choose everytime. personal preference as stated ;) Link to comment Share on other sites More sharing options...
relyt120 Posted September 20, 2013 Share Posted September 20, 2013 Writeup on Liberty KJ discs on 8.25" Cherokee XJ Conversion - NAXJA Forums -::- North American XJ Association TeraFlex Rear Disc Brake Conversion Kits 4354400 - SummitRacing.com Link to comment Share on other sites More sharing options...
kolton Posted September 20, 2013 Share Posted September 20, 2013 this guy knows the business ^^ :thumbsup:Haha suspension is one thing I do know about. After doing around 15 swaps over the years on mine and friends vehicles.... It's second nature at this point... I do not suggest doing it this way though. It was all I had and it was my first swap. Spend the money on tall jack stands. Cinder blocks are strong, but it's some scary chit when they collapse. Thank god I was up by the front axle when it happened! Link to comment Share on other sites More sharing options...
mvusse Posted September 20, 2013 Share Posted September 20, 2013 As far as fitting Grand Cherokee disc brakes on an 8.25, all I had to do was drill out the 2.75" center hole to 3" to fit on the larger axle tube. Bolt holes lined up perfectly on the flange. Link to comment Share on other sites More sharing options...
92tanMJ Posted September 20, 2013 Share Posted September 20, 2013 i can dig that. ive just had luck with the 8.25, so its what ill choose everytime. personal preference as stated ;) I know, I'm just saying....not trying to cause any butt hurt Link to comment Share on other sites More sharing options...
AeroNautical Posted September 21, 2013 Author Share Posted September 21, 2013 Awesome amounts of help, thanks. I have another question, however. This weld job is a bit out of my league, so I'm taking it to a shop. Once I find pinion angle, what do I tell them? I figured it'd just be easier to give them the 8.25 AND my D35 and say mirror it. But if the pinion angle is different between the 2 axles, obviously that won't work. Link to comment Share on other sites More sharing options...
mvusse Posted September 21, 2013 Share Posted September 21, 2013 If you're staying with the a stock style driveshaft, the pinion angle does not change depending on the length and height of the pinion. It needs to be PARALLEL to the transmission or transfer case output shaft. Technically it needs to be 2 or so degrees below so it will be parallel under load on the highway. So "mirror this" will be correct. Link to comment Share on other sites More sharing options...
ride172 Posted September 21, 2013 Share Posted September 21, 2013 http://comancheclub.com/topic/18925-looking-for-driveshaft-lengths-of-stock-trucks/ This thread has driveshaft length for stock mjs Link to comment Share on other sites More sharing options...
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