Rear ends

[Dammerung]

What are some recommended rear end swaps? Thinking about replacing the Dana 35 on my 2wd longbed. I’ve heard nothing but bad things about the 35. Another question is what’s bad about Dana 35s? What are main issues I should look out for?

 

 

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[schardein]

A friend of mine had an 87 YJ, completely stock.  Said it made funny noises, handled funny, and the rear end leaked.  I figured it needed replaced, and found a good D35 for cheap with the right ratio.  I didn't diagnose it at all beforehand.  When we pulled it out, the diff housing itself was cracked, and the driver side axle tube was loose.  He'd been driving it like that for about a year.  This guy isn't a four wheeler, we figure the previous owner must have caused the damage.

 

Doesn't really answer your question, but cool story, right?  I've heard some people say the D35 can break while parked in the driveway overnight.

 

Simple rear end swap is a 1986 factory AMC20 or 87-? factory Dana 44, both are rare.  Next easiest might be a factory option Dana 44 out of a Cherokee (XJ)(also rare).  The spring pads must be cut off the top of the axle and put on the bottom.  Next might be the Chrysler 8.25 axle out of an XJ, same thing, must move the axle pads.

[Strokermjcomanche]

What are you using the truck for ? What size tire are you running /will be running? What gear ratio do you have /want ? 

[Dammerung]

What are you using the truck for ? What size tire are you running /will be running? What gear ratio do you have /want ? 

It’s a daily driver, nothing off-road. I’m probably just going to run my stock wheels and tires, and gear ratio isn’t that bad. The 3.55 gears that I have now seem okay.


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[Strokermjcomanche]

8.25 Chrysler XJ axle is a good option in my opinion, especially if you have the means to weld new perches on . You can add disc brakes too if that's your liking . The axles are plentiful and come in 3:55 ratio. 

[Pete M]

if the dana 35 you have is working ok, then I would keep it.   Just don't spend any money on it beyond oil and brake shoes.  If anything serious goes wrong, invest that money into an 8.25 or Explorer 8.8. 

[Minuit]

9 minutes ago, Dammerung said:

 

It’s a daily driver, nothing off-road. I’m probably just going to run my stock wheels and tires, and gear ratio isn’t that bad. The 3.55 gears that I have now seem okay.


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My D35 has 183,000 miles on it, and those are puny numbers compared to what I've seen in junkyards. The gears still look absolutely fantastic, but the bearings howl. That's a wear issue, not a D35 issue though. I have an MJ D44 ready to be put together the way I want it, but do I NEED the extra strength the D44 provided? Nope, but I do have a bit of an obsession with overbuilding things and I wanted the correct MJ D44, damnit! I realize that my choice to buy, build, and install a D44 in my truck is not rational, because nothing I do poses significant risk of breaking my D35. "Backing out of the driveway" style failures are usually a result of previous abuse causing damage in the axle that slowly and sliently grows (for example, a crack in a gear) until one day it just breaks doing something mundane. If you search this forum, I know you'll find at least a couple of reports of people blowing up D44s in their driveway too. I remember reading them, but I'll leave that as an exercise to the reader.

 

Consider if you have an actual problem with the current setup before proceeding down this potentially expensive and annoying path. Anything but another MJ rear axle will involve its fair share of headache (and even swaping MJ35->MJ44 will most likely require you to shorten your rear driveshaft). A Chrysler 8.25 from a later model XJ is relatively easy, as is an 8.25 from a KJ Liberty. Most KJ Liberty axles come with disc brakes, as a bonus.

[Eagle]

8 minutes ago, Dammerung said:

It’s a daily driver, nothing off-road. I’m probably just going to run my stock wheels and tires, and gear ratio isn’t that bad. The 3.55 gears that I have now seem okay.
 

 

 

For that, the Dana 35 is fine. My '88 XJ has 287,000+ miles on the factory Dana 35.

[gogmorgo]

I just put new bearings in my '93 zj's d35 at 180,000 miles. I thought it needed them because the pinion was loose and it was making noise but turns out the yoke nut was just backed off. Looks like someone replaced the pinion seal and didn't put locktight on the nut. I would've stopped there and left just tightened the nut and left it, but I had already picked up a truetrac to stick in there. While I had it apart, I discovered the spider gears had been shredding themselves. Too much Yolo I guess. But other than that, the bearings had a little pitting on them but nothing unexpected for that mileage.

 

The D35 has lived long and healthy lives under many Jeeps. One of my MJs has over 300,000 miles on it, still with a d35 under the rear end. No noise or anything. Ironically I've broken d30 shafts on it more than once, but never an issue with the d35. I chose to keep it in my ZJ with 31's in part because it's cheap, light, and the smaller gears mean the pumpkin doesn't hang down as far as a beefier axle would. 

Now if you're planning to go bananas with your truck, lockers, massive tires, etc, the d35 isn't for you. But for a stock daily driver? Unless you do a ton of heavy hauling or towing, I wouldn't bother upgrading unless you know there's something wrong with it, although it doesn't hurt to have something ready to swap in if it does head south. 

In terms of swaps I'll second the idea of the KJ 8.25. Disc brakes already, and available in 3.73 and 4.10. Since you're 2wd you don't need to worry about matching the front, and I think you'd be a touch happier with 3.73's than the stock 3.55's, even on stock tires. Especially if you move extra weight around on the regular. 4.10 is probably a bit much for a 4.0 and stock tires, but should be good for something an inch or two bigger. 

[Minuit]

39 minutes ago, Pete M said:

Just don't spend any money on it beyond oil and brake shoes.

I'd volunteer a third thing to add to that list - ZJ disc brakes. Easy enough and very much worth it on the '90 and up axles.

 

If I were doing the work, I wouldn't feel bad about a bearing job on one. Sure as hell wouldn't pay for someone else's labor on a D35 though.

[Pete M]

good point.   personally I'd never spend money on drums.   (except for my new baby which will remain as original as possible)

[omega_rugal]

2 minutes ago, Minuit said:

I'd volunteer a third thing to add to that list - ZJ disc brakes.

 

from what i have seen, upgrading to disks with ZJ hardware is very easy, just need longer studs and to drill some new holes in a plate

 

for on road use, the dana 35 seems fine

[Minuit]

7 minutes ago, omega_rugal said:

 

from what i have seen, upgrading to disks with ZJ hardware is very easy, just need longer studs and to drill some new holes in a plate

I converted my '91 to rear discs not too long ago. On a c-clip axle, you don't even need to drill any holes. Other than replacing the studs with the ZJ studs, it's 100% removing old parts and bolting on new ones. The drilling holes part is for the 1989 and earlier D35s. The ZJ parking brake cables even fit, although they won't be routed correctly.

[89 MJ]

A Ford Explorer Sport Trac is great. Still has drums so you don’t need to change you master cylinder and it is wider than the regular Explorer rear end. 

[gogmorgo]

What's funny about this latest discussion is my ZJ has rear drums. They're cheap and work just fine, as long as you make sure to keep them adjusted. 

Yeah doing the bearings wasn't bad. It took me a weekend because I decided partway through I didn't want to use the cheap single lip pinion seal that came with the SKF bearing set and had to wait for a better one to show up. My advice there would be to make sure you've got a press to get the inner pinion bearing on and off the gear, and also have some way to hold the pinion yoke in place to tighten it before starting out. I ended up needing over 300 lb-ft to crush down the spacer before I had the appropriate bearing preload. And I did measure rotating torque... You'd want the tool to do that as well. I ended up using a 36" pipe wrench to hold the pinion yoke, and a ratcheting breaker bar to tighten the nut, after rattling it down as far as my cheap impact wrench would go. 

[dasbulliwagen]

I agree too, no need to swap it as long as you arent having any issues and you don't beat on it. Before my 4x4 swap what I assume was the original 35 under my truck had 340,000 miles on it with no noise. 

[TexanEliminator]

My 35 has 310k on it with no issues. I just changed the fluid 20k ago and it looked brand new in there. You know what they say...the squeaky wheel gets the grease. Not too many will get online to brag about their D35 but they sure will complain if theirs has broken. I fully intend to build mine soon with a super 35 kit, 4.10 gears, and an air locker. I won’t ever go bigger than 31s though or abuse it.

[Dammerung]

Reviving this because I believe my 35 is not long for this world. It’s started to howl at 45+ mph. So I want to put out a “subtopic”: what’s the CHEAPEST rear to put in? I want to get a rear end ready just in case. I’ve thought about the Chrysler 8.25, but what years are good? I also want to find a limited slip if possible with the 8.25.

 

 

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[Minuit]

47 minutes ago, Dammerung said:

Reviving this because I believe my 35 is not long for this world. It’s started to howl at 45+ mph.

 

Do not be surprised if it howls for a long time to come. Like a noisy, annoying cockroach. I've had a pinion bearing howl in my 91 since day one. Hasn't gotten appreciably worse in the 50,000 miles I've put on the truck. "weeeeeee!" I change the fluid every 20k miles or so. I tried thicker fluid and it did nothing to change the noise. I'm gonna let it go until I get my MJ D44 built up.

 

Cheapest? Another MJ D35. They aren't worth a dime and are pretty much the only thing that are a direct fit.

 

97+ for the 8.25. Some say it was a mid-96 change from the 27 to 29 spline axles, but I cannot verify that myself. The factory LSD was clutch based and, unless the axle has less than about 75k on it, is probably effectively an open diff at this point. The LSD carrier can be spotted by the shape of the non-ring gear side of the carrier. The LSD carrier is shaped like a cylinder. The open carrier has a much more rounded shape on that side.

[Dammerung]

Do not be surprised if it howls for a long time to come. Like a noisy, annoying cockroach. I've had a pinion bearing howl in my 91 since day one. Hasn't gotten appreciably worse in the 50,000 miles I've put on the truck. "weeeeeee!" I change the fluid every 20k miles or so. I tried thicker fluid and it did nothing to change the noise. I'm gonna let it go until I get my MJ D44 built up.
 
Cheapest? Another MJ D35. They aren't worth a dime and are pretty much the only thing that are a direct fit.
 
97+ for the 8.25. Some say it was a mid-96 change from the 27 to 29 spline axles, but I cannot verify that myself. The factory LSD was clutch based and, unless the axle has less than about 75k on it, is probably effectively an open diff at this point. The LSD carrier can be spotted by the shape of the non-ring gear side of the carrier. The LSD carrier is shaped like a cylinder. The open carrier has a much more rounded shape on that side.

Will a Chrysler 8.25 have a longer pinion length? I heard that the Dana 44 has an inch longer pinion. If so, do I need to cut the driveshaft or could I lift the truck? And if I had the chance, should I use the 8.25 or the Dana 44?


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[Eagle]

47 minutes ago, Dammerung said:

Will a Chrysler 8.25 have a longer pinion length? I heard that the Dana 44 has an inch longer pinion. If so, do I need to cut the driveshaft or could I lift the truck? And if I had the chance, should I use the 8.25 or the Dana 44?
 

 

Yes, the D44 and the 8.25 are both about an inch longer than the D35. If yoou're at stock height, you should cut the drive shaft for either. If you have a significant lift, you might not need a shorter drive shaft.

 

If you have the choice, I would prefer the dana 44. If you don't have access to a dana 44, the 97 and newer 8.25 is a decent upgrade from the D35.