Hello!
I am an owner of a really early xjr8, says 97 in brittish papers.
I would really like to have some feedback on noise from gearbox or diff.'
I have done about 10 000km since I bought it and noise is still the same, nor higher or lower.
Very grateful for help!!!

I have this wierd noise between 50 and 70 mi/h (80km/h-110km/h).
Below or above it's silent? It's like a humming, that will change pitch if you release or accelerate. It can be covered by normal use of stereo soo it's not very high. It's not like the rumbling noise from a wheel bearing and does not change going turning from side to side. First I thought this to be connected to gearbox and maybe TC or it's lock-up.
I am not so sure know and have started to suspect diff. The strange thing is that it does not strike me as gear mesh noise as I have had this in my alfa 156, that tended to be more of a whining that would go away imidiatly if throttle was let go or pressed down. Also important, it does not change from cold to hot (we do now have quite low temperatures i sweden, giving that oil must be affected in visc)

Any thoughts by anybody?

One more... connected to oil in gearbox, happy for input here aswell...

Oil in gearbox was changed after about 115k miles, but the workshop filled the MB unit with 71141 Mobile oil??? As far as I can tell (and tech support at mobile also) it should be ATF 134 Mobile or the org shell oil.
Soo first q is: Have any of you heard anything about using that oil in the 722.6 gearbox??? It does change a little more roughly after change but workshop keeps it's line of it's just my old cars dodgy gb and don't want to change again... .
They did not empty converter but only belly pan and change filters, this as they did not know there was a plug on it. Soo probably there is a mixed fluid at present in....
Also worth meantioning is that they did find the connection to cable harnese to gb to be leaking during re-fill, this was fixed before topping up with 71141. Soo there where probably to little oil in for starters. IMPORTANT, the gearbox was however smoother before change than after...
Input???

All in all I am amazed of the big cat, what a smooth fast ride, if only i could get it a little more, hrrm thight (bushes and steering...)

Cheers! /Per in sweden with rhd jag

 

Sounds like a diff issue, at least that is one of the sources that can have this sound and it will change if you decell are accel. If indeed the case, it is better to refurbish it as over time it could ruin your diff, might be a good moment to put in a LSD ;-).

ATF 134 is indeed the right fluid, I have used lately the Mobil one. You are lucky in that you will have a drain plug in the toque converter (only pre 1999 cars), so you can drain it all.

 

Thank you very much for the input! Additional question, regarding rebuild. Is it worth trying first to just change the output bearing on shafts going to half shafts and wheels? Or is it just to make a full rebuild at ones. Question is really, which parts is most likly to be needed to change. My feeling is that if it is just as likly to be the pinon bearings or anything inside, that can't be done with diff in car and it's not really worth trying oneself...
Reg, LSD, well yes, but isen't that really costly? This is my daily driver, but as it's a rhd car from the mother land (GB) secound hand value will be low for it anyhow i sweden. And I guess that buying a used diff is really a pig in a bag...?

Oil for trans...
Ok, you seem to be quite experienced with jag's soo there is one more reason for really pushing the workshop to change oil again. I can't believe that they won't listen and take their responsibility, they really try to get away with it. Their only ref for using that particular oil was, "we have spoken to a person in GB and he says this is the right oil for you.
Than I have pushed to speak to manager and he will not get back to me. I will not settle with less than new oil for me to change my self. I simply do not trust them anymore.... and that really sucks!
Really like your SC rebuild project with Twin screw, will read more about, tuning is really one of my biggest intressts.
Cheers and thanks again for the input!
/Per in sweden...

 

The bearings on the output shafts could be done of course, but they are not cheap either. Sorry, but I can’t remotely guess what it can be, other than that the pinion bearings would be a good candidate (where the whining is from the gears). A rebuild is not cheap, it takes good time to remove the diff, and then an expert to rebuild the diff, and new bearings assuming that the gears are still ok. As you need to do the same work when building in a LSD, it is best to think about it if you do go for a rebuild. On the other hand you can get 2nd hand diffs very cheap, so you could drive until it fails and hope for the best.


Can’t tell what will happen to your gearbox when you use the 71141 oil, it will probably not disintegrate at once, but how it will work for the longer term, who knows…

Best is to stick to the specification provided by the manufacturer unless your shop is going to give an insurance on your gearbox that it will not be detrimental using a different oil then specified by the manufacturer (and also that they need to provide the proof). Good luck!

 

Comment, prof that they will never have.... !!!

I would like to give a warm thank you for your thoughts!

I guess that first try to pinpoint where the noise is from, if posible, by placing the rear on stands and running with wheels in the air. If diff seems to be the source, than a secound hand one will be the first choise. Any input if XJR and XJ uses same diffs for the v8s? (a std 3.2 or 4.0 will probably have taken less stress during it's life... )

Cheers and thanks!
/Per

 

As far as I know the diffs are all the same, just make sure when you buy it is a good one, as there is still the work to replace the unit. It would be a good time to replace all the rear bushings, if they haven’t been done yet, they must be ready to be done sooner than later.

Not sure if you can pinpoint the issue on stands (so with minimal load), at least I have never tried that.

 

One should defenetly change bushings, it does seem a little loose he he. Yes I have also thought of the very large risk that noise will not be present at zero load, soo it's a long-shot! Hmm, have done a bit of googling and it might be that 3.2 and 4.0 does not use same ratios.... Need to look into that deeper. Expensive here in Sweden though. They ask about 500Eur for a secound hand one ....

Cheers!

 

Only the Mexican market had a different ratio, the rest all have 3.06. They are very cheap in the uk obviously, maybe also even with shipping, there are several on eBay.

 

As much as out of curiosety as to really do any differance on my noise issue, I changed differential oil. The d i y shop had only 75w-90 oil so that was my choise. Oil that was in was really dirty (read darkish, but level was spot on), but more suprislingly, did not have any (to me) visable metal parts or even the traces of it? If a bearing inside the diff was to be on it's way, for sure that would leave something in the oil shoulden't it?
Anyhow, noise is there as always, and have not changed in type or speed it appers as a function of the oilchange ...
Further, I checked the diff with GB in neutral and both wheels of ground, checked for free-play both in U-shafts,diff output shaft, but also input shaft and tried to rotate to se if it all feeled smooth. Only free play that I found was on input shaft, axially and rotationally going back and forth. Othervise it felt smooth and as good as one could amadgen it ever was? . Axially it was maybe about 0.5mm and rotationally just enaugh to make a click click when going back and forth.
I expected something to feel more hmm, wrong, soo now I am not that sure that it all points towards that diff anymore. I would be soo frustrating if it was changed (with all involved work) and noise still persists. Just need to keep fault seeking as it seems. Anyone some other test to narow it down? Or is it a 95% to be the DIff? Could it be a rearwheel bearing maybe???

 

Could that be suggestive that the pinion preload is lacking?

There was also a recent thread about an unbalanced driveshaft making noise that turned out to be the transmission mount being worn out.

 

Thanks! I will look into that thread!
Cheers!

 

Workshop took it's responsibility and changed out the gearbox oil to 236.10 approved oil from MB workshop nerby. Result is however that the car drives exactly as it did on the 71141 oil, no differance what soo ever.
Soo, next thing to test is to try this self lerning shift point thing. I found the text at this forum, but it was actually written for MB or any other american cars i think. Can one be sure that procedure is the same for this JAG? It was written that one should make repetedly up downs for 1-2,2-3,3-4 and 4-5, each about 4 times and keeping pm between 1800-2400 I think? That must meen that one should conteract with brake to make box shift as intended? Any tried this on their cars with sucsess?
Cheers! (My spelling is so off with out grammar help he he, sorry for that)