It's looking like I need to switch out the rear differential on my 98.5 2.8 tiptronic.

Is there a DIY writeup for replacing the whole unit? I can only find fluid change writeups.

General Questions:
+ How much does the diff weigh? I'm hoping to do this job solo, with a transmission jack. I'm guessing 80 lbs.

+ Where do I find the diff code and where can I figure out compatibility. i.e., will any B5 differential work or do I need one with the same code.

+ To get at the prop shaft bolts, do I need to unbolt the exhaust like you do to access the front differential/output shaft bolts, or is there a way to remove the heat shield and access the bolts with the exhaust in place.

 

You might need a friend when you lift it out. Don't know the weight, but it's pretty heavy if you take it ou in one piece (meaning, with the front part bolted on)

I pulled the exhaust. Don't know if you could do it with that in the way, and it's so easy to remove - why not?

 

May I ask why you are removing the differential? Did it fail on you? Stripped the plug thread?

 

The clutch packs in my differential are shot.

The less I have to do underneath a car on jackstands, the better, and I'm doing this project solo, so I'm hoping I don't have to drop the exhaust too. Plus, the exhaust is original with the exception of the flex pipes -- 170k miles on it.

I found a used differential locally. It's from a 99 manual trans 2.8 car. Anyone know if this is the same differential used in a 98.5 tiptronic 2.8?

 

Scratch everything I said. I thought you were talking about the rear diff.

 

Correct, rear diff. Something in the rear diff is totally shot. Maybe clutch packs is wrong terminology, but the unit is toast.

 

Yea, there are no clutch packs. Usually a bad pumpkin shows up when you turn the wheel in a parking lot and hear/feel the back wheels fighting each other....because they are.

I think the exhaust is one of those things that saves you 15 minutes and costs you an hour. And if you have the original flexes at 170,000 miles, they're going to go soon any way. You only have to take the exhuast apart to the sleaves in the middle of the car. You shouldn't put much stress on the flexes any way.

If there is any leaking out of the half shaft seals, change em. When the pumpkin's out, it takes like 4 minutes per side. Literally. 4 year old could do it on a good day. The input shaft seal is more involved, but if there's significant leaking there, I'd tackle that too. Most diff failures are caused by lack of fluid.

 

Theres a three letter code on your options identification tag like DAK, and another code like CJP for your transmission type. The tag is either in the trunk or inside the door opening and it tells you what rear axle ratio the car came with. You MUST match the differential to the transmission ratios. Some jackass but a 3.89 rear axle in my sons 4.11 transmission ratio A4. Took 30K before it ate the rear axle, but probably 90% of the torque was going to the front axle the entire time the car was being driven. Get the transmission and axle codes off the option tag and I can probably find the ratios for you. I attached an image to one of my posts about 4 months ago about driveline binding that has a couple of the ratios, but I have most of them in a spreadhseet if you come up with different codes.

 

I didn't know they made various differentials for our model. Thanks.