Is there a fix to keep the replacement diffs from failing on the X100 and X308 ? My XKR started making noise on the decel. about 2000 miles later I sheared the teeth off the pinion during a hard acceleration. I changed out the diff on my XJR before it got bad enough to shear teeth. The axle or pinion bearings didn't have any excessive play in either of the failed diffs. Now that they are both replaced, I decided to fill them with 6.5 quarts of oil. Ran a line from the diff vent into a vented reservoir. Haven't been back the drag strip yet. Are these diffs just under-designed for the application?
Thanks,
Mike

 

Your application maybe, l have never had a problem myself with any jag diff in some 40 years.

 

The Local Jag Dealer acknowledged these differential failures are a known issue - more prevalent with the 370 HP cars than the 290 HP. But being warranty and factory service, the dealers are only familiar with replacing them - not resolving any under lying issues. Was hoping that folks who race Jags might be able to share some information.

 

14HU is just 8" vs 15HUs 8.5" . Design is wrong - angle between pinion and crown wheel makes extra stress for a single tooth. Material is not enough strong to handle this. You can make shot peening and some other treatments to the gears - that's all you can do. Other option is to go for 15HU - but then you have to solve the wrong gear ratio issue. $$$$ .

 

That might explain how I ripped half the teeth off the pinion under hard acceleration. Any ideas if the gear noise that developed a couple of thousand miles before the pinion tooth shear might be something else?
Both cars developed the gear whine on decel, while they were quiet when under forward load. I could see wear on the load side of the teeth of the decel whining diff that didn't break any teeth. So initially I suspected the factory oil level is insufficient for lubrication and cooling. What model cars in the salvage yard would I likely find the 15HUthat has the better pinion angle ? I'm guessing the 15HU fits in the 14HU diff housing...
Thanks again,
Mike

 

1. you buy used HU15 ( X300, XJ40, XJR6, Daimlers ) and make TCU re-program. Please note that just one source has been able to do that and cost was two years ago $2,700 It also possible that they do not make it anymore. TCU programming is needed because you can not find HU15 with 3.06 ..
2. You can ask from Count iblis if he can help you. Then you would not need to make TCU re-program. https://www.jaguarforums.com/forum/x...l-swap-209542/