It has not been a good year for my '79 XJ based Aristocat Kit Car Last year it was the Overdrive this year it has been the clutch. It started slipping early this year & I booked it into a local repair shop & they replaced the Carbon thrust bearing & the Clutch assembly all seemed OK for a few months but I was getting problems with crunching gears & difficulty engaging reverse. The slave cylinder was leaking so I replaced it but problem persisted. a short while later I started getting violent judder when pulling away in first gear really bad, less violent using second gear. I finally took it to my local Jag independent repair shop & he had it for 3 weeks! he had the flywheel skimmed & found that the ‘new’ carbon thrust bearing had mashed into the back of the clutch thrust face. He fitted a new clutch assembly adjusted the slave bearing push rod as specified in the Jaguar repair manual but found that the clutch would not clear properly. - no obvious reason? In the end I consulted the Jaguar enthusiasts Club’s guru Ken Jenkins he said ignore the book, wind off the adjustment of the pushrod leaving plenty of clearance & see how it works. Well it did the trick! As an engineer it goesagainst logic but it works fine as long as you don’t push the pedal to the floor, if you do it crunches! all it needs is a short pedal travel to feel resistance & push about another 1/4-1/2" to change gear perfectly. I’ve given up making sense of it but as it works fine!!! Two clutches in a year+ labour ouch! But at least I’ve got a useable vehicle.
I assume your clutch pedal/box is non standard? Were they all the same type of clutch (eg diaphragm)?
Good news anyhow. How many years/miles did it take to first develop problems? Clutch operation is something I always check before re-installing engine/gearbox.
The clutch arrangement in the car is standard manual gearbox XJ pedal box master cylinder are original & standard no mods.As is the engine & gearbox. The first clutch was in the car for 17+ years no problems, well a new slave cylinder about 5 years ago when the seal went. The normal settings for the clutch were followed back then. The problem with the replacement clutch were not immediate but only after a month or two.
Well that’s blown all my ideas out the water! I agree with Ken, mind you.
Hi Keith,
I always tended to think that simpler setups were easier to maintain … were there any particular reasons to put in these carbon parts in the first place?
Which gearbox is fitted in your car? An LT77 five speed or the earlier four-speeder? If a system has been holding up well for 17+ years I’d avoid any changes … SNG has a 9.5" clutch kit for 225 quid in stock.
Hope, your solution is now good for the next decades to come!
Best holiday wishes
Jochen
75 XJ6L 4.2 auto (UK spec)
Hi Jochen,
It is the 4 speed & overdrive Jaguar unit as fitted to early XJ’s S1 &S2’s carbon Thrust bearings were common on British cars up until the mid to late 70’s very prehistoric! even my oldest 50s Beetle had a ball bearing clutch thrust unit!
Indeed, they still are around for IHC tractors, as I just found out … good to learn something new every day 
Good luck and best wishes
Jochen