Back on the Road - New Differential
 

A couple of weeks ago many of you helped me as I worked through diagnosing the issue, finding a rear differential, and discussing service opportunities for a dropped rear.

What happened? In a nut shell I was gently accelerating from a stop to merge when the car seemed to bog down. Then BANG! it was like I drove over a log. This was the issue, every few feet = a bang, as I said earlier, watching this from the outside passenger side, it was like something whacked the rear wheel from the rear when the bang occured. I could see it move forward when this happened.

Well it turned out to be a bad differential. A study of this on the WWW showed it could take from 4 hours to 8+ hours to replace. I had it towed to my mechanic in Flemington, NJ.

I always like to close the loop by sharing how much these jobs cost for your future reference. I was quoted: $700 for a differential, up to 8 hours of labor.

Flemington Foriegn Cars here in New Jersey spent a good bit of time getting the old defective one out and finding a replacement that they will warranty. They received a rear that had a different flange on it than one that would match our XK8's. It had to go back and be exchanged, delaying the job. Then they ran into a hell of a time getting one bolt out. Looks like they had to destroy it and replace it to finish the job. In fact I will follow up with the part number as an FYI, it cost well over a hundred dollars to get a replacement bolt - you should know about this so I'll post the part #.

I was concerned, they put over 16 hours into the job. The good news is I got her back today. I am happy to say they stood by their quote, they are honest people, I only paid for 8 hours. Sstill by the time you add tax and that bolt, it was a $2.000 job.

Yes, I drove an old Ford Bronco for nearly 3 weeks, so I admit getting back into an XK8 is a night and day difference, but besides that somehow the ride has changed for the better. For some reason before this failed, I was spinning the rear right tire all the time with even the slightest turn when under power. Of course ASC kicked in but this happened so often I verified the tread, all was the same on both sides. By elimination it must have been related to the failing rear end. No unusual slip now at all.

I don't know if it is related, but the ride seems tighter, more "together" than before (yeah, what scientific terms right?). Yes I know the placeboo effect is wonderful but gosh I'd swear things have changed for the better. I can't explain it but so what I'm driving with a big smile now.

Thanks again for all the help and coaching when this happened. John

The XJ diff can be made to work with a new companion flange and CUT THE PINION SHAFT EXTENSION.

I have done it but I can understand the reluctance to modify unknown parts!!!!!!!!!!!!!!!

No warranty is a scary one way street when you modify parts.

Glad to hear about a final outcome.

bob

Out of curiosity, have you asked for the old diff back? Might be an interesting post-mortem disassembly and a great opportunity for free education. Maybe even a few good pictures in it for us, too.

Glad to hear it all worked out for you, thanks for the update.

Congrats on the repair. Your chosen shop truly values its customers, no doubt about it. Keep us posted on your experiences with the new differential....

Fmertz no I let it go. I wonder how much it weighs. Normally I just assume the mechanic had to return it as core charge, but when I think about it, no one's going to have the parts to rebuild it anyway, will they.

John,
Thanks for posting the outcome & good to hear you're back on the road.

M

As promised, here's the bolt to watch out for:

MMB2860AA

It cost me $168!

Looks like I paid for a nut too. Just in case it is for the aforementioned bolt, that part number is JFX214051, It only costs $10.05.

Who knows, maybe someday down the road someone else will run into a differential replacement. Just wanted them to be prepared for this little surprise :).

John