Hey guys I now own a 98' XJR that has a problem with the rear differential. Basically you can drive it VERY slowly but it "pops" real hard about every foot or so causing the rear wheels to lock up for a fraction of a second and kind of "jump". This is about the best description I can give. I've been told (by non-jaguar-specialists) that there is a gear in the rear differential that probably has some teeth broken off causing it to skip that needs to be replaced. Sounds easier than it probably is.

Obviously there is an issue with the rear differential so my question is, can I just change out the entire rear end? I can currently buy a donor car that is the exact same car - same year, same model, same engine, even the same color. My car (which I'm restoring anyway) needs several parts that this car has so I think buying the donor car makes sense. I just want to know what the individuals on this site who are educated on this process think about a shade tree mechanic like myself swapping out the rear differential on this car??

Guys...and gals...I guess I'm simply asking; can I pull this off in my garage or should I just not attempt it? I'm just not in a position to pay a shop thousands of dollars to do the swap.

Thank you in advance for your opinions, insight and help...

 

Wow, I've never heard of that failure yet. I'd like to help, but you've come to the right place,there's lots of helpful people around.
Now, if you have engine or transmission questions, I can help. But all I can do here is offer moral support.
Good luck. They are great cars.

 

Your most economical choice is the differential swap. And, yes it can be DIY depending on skills and equipment. See various past threads detailing the steps.

If you are near JF member Motorcarman in TX, he has an independent Jaguar shop that you might consider.

 

Add my vote to go for it yourself. The rear subframe in these cars is a pretty easy swap out- but you need to be careful since it is heavy and you will be separating two heavy components- the car and the subframe! Good jackstands, level concrete, and a good floor jack or two are pretty important for doing this safely.

Not ment to be a step by step, but just to give you a general idea, here is what I remember- Plan it out for yourself. Lift the car to decompress the springs, with the tires still on the ground. Remove the brake lines, any fuel lines passing through the assembley, and the rear exhaust parts (that is probably going to be the hardest part). Remove th rear end linkages. Loosen both sides mounting bolts. After all ar eloosened, begin removing the three on each side rear to front. When the rear end is loose, raise car off of rearend with Jack(s), a little on each side at a time.

Of course, the primary goal here is to not drop the car,and especially on you! Make sure you only get under it when it is fully supported on jack stands properly positioned on the Jack rails and not put in a condition of side load. Do not take any bolts out that will allow something heavy to move. THINK before you make each move. Obviously (I think) the average guy cannot lift or hold up the rear assembly manually, and letting it fall COULD cause the car to jump off the stands.
Good luck.

 

I bought my car with a rear differential with very much play in it .
I have had it changed with a used one ,that was good for 10.000 miles Before i got the same problem it cracked and made loud knocking and Even saw movement of the rear wheels because of the cracked diff.

Now i just got my third diff and now...i hear rumbling noise ....i hope its Not the diff ...maybe because of all the stress that the driveshafts and the Rear wheel bearing got ,they are damaged too.

I am gonne change the rear wheel bearings first ,i hope the rumbling noise Comes from rear wheel bearings and not the third used differential that i Got from a non Supercharged XJ8

I tried a used differential from a non supercharged 4.0 breaker, because They had a life with less torque than a differential from a Supercharged Jag.

 

Thank you guys for all of your advice so far. I am going to tackle it myself but I have decided not to buy the donor car, I just don't have room for a second car. So that being said, I am now looking for the complete rear end. I was told by the guy that had the car before me (he researched this because at one time he planned to make the swap) that I will need to put a rear differential out of the same car (supercharged XJR) because of the gear ratio. He told me that the rear differential was specific for this model on about 3 or for different year models. I think he said it was considered a 306?? Does this make sense to anyone?

 

Sorry I didn't finish my explanation from the post directly above. He also told me that the computer was calibrated to accommodate the gear ratio in the XJR.

 

Any differential will work from 98-03 XJR or XJ8. They are all the same.

 

You need the 4.0 diff from any XJ8 or XJR .the 3.2 has another ratio.

Get a used one from Ebay for about $300? its a cheap fix

Also put new oil in it ,you can seach what oil it needs.

 

Coventry West sell rebuilt differentials if you happen to want to go that route.

 

Thanks to everyone for all of your input and advice. Now I'm off to find the correct differential. I know I'll be back here for help completing the project, I'll keep everyone posted!