Installing a Chrysler 8.25 from a Jeep Cherokee

[kajsdf]

hoping this thread isn't totally dead - i'm about to swap in an 8.25 to my eagle. i looked in the front axle thread as well but didn't find a solid answer - my gearing is 3.55 - 39 and 11 tooth count ring/pinion which equals 3.54545454545454 and on...

there seems to be some contradictory info in that thread - conclusively the 2.73 carrier (which i have) will support a 3.54 ratio but maybe not 3.55? are 3.54 and 3.55 close enough to run together, especially considering the viscous coupler of the 229 i am running?

what did you do or are you still a 2wd eagle?

thanks

[Draekon]

I believe 3.54 and 3.55 are close enough together that it will be fine.

[eaglefreek]

hoping this thread isn't totally dead - i'm about to swap in an 8.25 to my eagle. i looked in the front axle thread as well but didn't find a solid answer - my gearing is 3.55 - 39 and 11 tooth count ring/pinion which equals 3.54545454545454 and on...

there seems to be some contradictory info in that thread - conclusively the 2.73 carrier (which i have) will support a 3.54 ratio but maybe not 3.55? are 3.54 and 3.55 close enough to run together, especially considering the viscous coupler of the 229 i am running?

what did you do or are you still a 2wd eagle?

thanks

3.54's will work fine. It's such a small difference. I ordered some 3.54 gears from Rock Auto. They just arrived today, but I'm out of town for work and will have them installed when I get back home. I'm meeting with a guy this weekend in Billings, MT who had 3.73's installed in his Eagle Dana 30 and said it wasn't too difficult for his mechanic. I'll find out the specifics.

[carnuck]

You just need gears from a low pinion diff. The XJ isn't so you need them from a Grand Cherokee or something. I think the rule of thumb is 1% on the difference front to rear and it's better to be tall in front (PULLS you through the corner) I wish I had taken a pic of the gears we took out of my son's Grand Cherokee monday.

[eaglefreek]

You just need gears from a low pinion diff. The XJ isn't so you need them from a Grand Cherokee or something. I think the rule of thumb is 1% on the difference front to rear and it's better to be tall in front (PULLS you through the corner) I wish I had taken a pic of the gears we took out of my son's Grand Cherokee monday.

Just to help clarify , it needs to be a long low pinion gear set. Grand Cherokees are a mix of short and long low pinion. XJ's came with low and high pinion depending on year but are all short pinion. Jeep CJs came with long low pinion D30s.

[captspillane]

My blue SX4 was a 3.07 iron duke from the factory. The previous owner swapped the iron duke for an I6. The I6 had 2.35 gears from the factory and he must have mixed up which front diff was which during install. He drove it for years and I drove it for awhile assuming they matched. When I took it apart I confirmed that they were actually much different.

I checked the VC and it was still ok. It allows a lot of slip before it slowly engages, so it is forgiving.

If no damage occurred from years of driving with 3.07 in the rear and 2.35 in the front, I highly doubt your car will care about 3.55 vs 3.54.

[carnuck]

Are you sure you don't have the NP128? It does the same thing as the NP129, but no viscous coupler.

[captspillane]

It was a NP129 and still in good shape. The 3.07 rear surprised me the most, since that isn't common in an original SR4 Iron Duke. I was counting on it having 3.54 all the way around and I checked it several times before I believed it.

This experience pushes me further to use the 242. The Eagle is still quite capable with an open diff like the NP128, those with a burned out VC, or the 242 in full time. In slippery conditions I will value the fully locked diff instead of a VC.

[eaglefreek]

In slippery conditions I will value the fully locked diff instead of a VC.

In the beginning of the year, we had a few inches of snow, which is rather rare. However,  it quickly turned to a sheet of ice on the roads. There was one hill where people were struggling to get up. With my 242 in fulltime, my Eagle was struggling to get up. Put it in part time and got right up. I have no idea how well it would have done with a case with a VC, though.

[carnuck]

I know in the full size rigs that when the VC pukes it's "guts" that "oil" (really liquid silicate, ie: sand) destroys the bearings, etc in short order.

[Nightpath]

So I gutted my XJ, took off the rear axle and noticed that it's a 8.25. Any idea if I'll have any issues with the full XJ drivetrain swap? Using the AW4/NP242 combo. If there is going to be an issue I'm going to have to search for a D35 really fast.

[eaglefreek]

What issues are you expecting? I have the AW4/NP242/8.25 without any issues.

[Nightpath]

driveshaft fitment.

[carnuck]

It's a slightly longer input, but I used the original driveshaft. It comes close to bottoming out now but it's okay on road. Lifting more will cure it. You need the 8.25 U bolts and plates for the springs. You will also need to weld on shock mounts.

[eaglefreek]

driveshaft fitment.

Honestly, with all the work you will be doing for the swap, getting a drive shaft to fit should be the least of your worries.