XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

My clutch still will not work

 
  #1  
Old 07-03-2019, 07:12 AM
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Default My clutch still will not work

So, I changed my slave cylinder after suffering bad clutch drag (see earlier post). Seems that the old slave cylinder had been weeping fluid from the piston, so I thought that was the cause. It was a pig to bleed the system and after several attempts I bought one of those pressure bleeders which worked well and enabled me to change all the fluid as well.

Unfortunately, I still have the same clutch drag – no improvement whatsoever! Despite the firm pedal the top inch or so of pedal movement is just floppy. Not so much free play more that the pedal just doesn’t seem to connect with anything.

I’m wondering if I should have a go at the master cylinder (could the piston be sticking?) or bite the bullet and send the car off for a new (expensive) clutch.

Thanks for reading and all comments and ideas appreciated.

Cheers,

LeeP

 
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Old 07-03-2019, 07:34 AM
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Never worked on a straight drive Jaguar. But that pedal behavior sounds master cylinder related, and a rebuild there is certainly a cheaper first step than a new clutch.
 
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Old 07-03-2019, 09:54 AM
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I agree, and would certainly rebuild the Master cylinder for the clutch. Also make sure your clutch pedal is at the same height as the brake pedal. If not there may be some adjustment to a return stop, or something of that nature. You should feel strong resistance somewhere in the first inch. Then solid pressure all the way to the floor. If you correct all the issues with the Master cylinder, and pedal assembly, and still experience drag. That leaves the clutch itself. I have seen people lube the splines when replacing the clutch, which about 6 months later causes the disc to stick on the splines and causes drag, I've also seen rust do the same thing, as well as a broken, or damaged disc, causing drag. So for your sake, I hope a rebuild of the Master cylinder cures your problems. Hope it helps.

Jack
 
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Old 07-04-2019, 06:49 AM
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Originally Posted by 89 Jacobra View Post
I agree, and would certainly rebuild the Master cylinder for the clutch. Also make sure your clutch pedal is at the same height as the brake pedal. If not there may be some adjustment to a return stop, or something of that nature. You should feel strong resistance somewhere in the first inch. Then solid pressure all the way to the floor. If you correct all the issues with the Master cylinder, and pedal assembly, and still experience drag. That leaves the clutch itself. I have seen people lube the splines when replacing the clutch, which about 6 months later causes the disc to stick on the splines and causes drag, I've also seen rust do the same thing, as well as a broken, or damaged disc, causing drag. So for your sake, I hope a rebuild of the Master cylinder cures your problems. Hope it helps.

Jack
Thanks Jack. I also think it is worth trying the master cylinder rebuild first - hopefully I can get it out ok.

The clutch pedal is the same level as the brake pedal if you lift the clutch pedal up. At the moment the top inch or so of movement is just loose and doesn't seem connected with anything. Time will tell.

LeeP
 
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Old 07-04-2019, 07:55 AM
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If.the slave has gone what made you think the master cylinder wasn't in the same condition? They both had the same sh** fluid running through them.
 
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Old 07-04-2019, 08:51 AM
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Agreed the the m/cylinder might be faulty/worn

But.....

Could the clutch damper be faulty?

Item #8 below

https://www.jaguarclassicparts.com/u...up-to-v-148944


I'm not familiar with the internal workings of the damper so I dunno if it might/might not be part of the problem. Just tossing it out for discussion

Cheers
DD
 
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Old 07-04-2019, 02:22 PM
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In principle, what does a clutch damper do, Doug?
 
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Old 07-04-2019, 02:41 PM
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Originally Posted by Greg in France View Post
In principle, what does a clutch damper do, Doug?
I think the idea is to slow down the fluid flow a bit to soften the engagement. I never heard of them till fairly recently. other cars have them as well. They're often bypassed when they give trouble....or if a sporty guy likes a sharper engagement.

Cheers
DD
 
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Old 07-04-2019, 02:43 PM
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Originally Posted by Greg in France View Post
In principle, what does a clutch damper do, Doug?
Interesting point Doug raises. I have no idea either but they seem to be unobtainable so hope mine is OK.

Managed to loosen the 9/32 inch Allen keys holding the master cylinder to the bulkhead tonight and lying on my back (in a very tight space!) managed to find the clip and clevis pin securing the master cylinder to the pedal so I am going to have a go at the weekend. The master cylinder rod has quite a bit of end play which reflects in the floppy pedal. Have a rebuild kit so will try that first as new units are quite expensive.

Will keep you posted.

Cheers,
LeeP
 
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Old 07-05-2019, 12:20 AM
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Originally Posted by leep123 View Post
Interesting point Doug raises. I have no idea either but they seem to be unobtainable so hope mine is OK.

Managed to loosen the 9/32 inch Allen keys holding the master cylinder to the bulkhead tonight and lying on my back (in a very tight space!) managed to find the clip and clevis pin securing the master cylinder to the pedal so I am going to have a go at the weekend. The master cylinder rod has quite a bit of end play which reflects in the floppy pedal. Have a rebuild kit so will try that first as new units are quite expensive.

Will keep you posted.

Cheers,
LeeP

I'm curious as to why there is excess end play, in the clutch rod? I mean it shouldn't be tight but a 1/32nd to a 1/16th of an inch of end play is more then enough. It just shouldn't be tight / solid. It needs a little bit. Is it adjustable? or is it possible the piston is stuck down a little in the bore of the master cylinder? Sounds like you may well find the problem. Hope it helps.

Jack
 
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Old 07-06-2019, 08:36 AM
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UPDATE

Got the master cylinder out. Easy job really only took half an hour. Hardest part was standing on my head under the pedals to disconnect actuating rod from clutch pedal.

Lots of black crud in reservoir and piston was very sticky over the first quarter or so of the total movement and not returning fully. On disassembly more crud, worn seals and hopefully, at last, the cause of the problem...……..the return spring was broken into 4 parts partly scrunched into each other. Hopefully this explains the floppy pedal and also the clutch drag as I guess the piston wasn't getting a full stroke to work the slave cylinder. Even though I had a rebuild kit the spring seems unobtainable - unless anyone knows differently? Anyway I think it is time for a new master cylinder as those broken, sharp spring ends couldn't have been doing much good sliding up and down the bore.

Researched clutch dampers. They are fitted to a number of cars and the idea is they smooth out the disengagement / engagement if you operate the clutch too fiercely. Also fitted to diesels to prevent vibration coming through the clutch pedal. They seem unobtainable for XJS but there are several fairly cheap ones for Land Rovers on eBay that look very similar - might be worth further research. Apparently if they go down you can bypass them with some adjustments to the plumbing.

So, off in search of a reasonably priced master cylinder. Will keep you posted.

Cheers,
LeeP
 
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