Classic cars forum & vehicle restoration.
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Wed Aug 20, 2014 8:18 pm Post subject: Clutch hassles |
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I think I've got this one figured out, but bouncing ideas around never goes amiss. Basically, while out in the Herald last week, I had a couple of occasions where the clutch wouldn't disengage. Hydraulic seals, I thought, and so spent today fitting new rubbers to master & slave cylinders. Now, when I do any work on the Herald that involves having the gearbox tunnel out, I always go for a test run before putting it back - it's a bit of a fiddle and so I want to make sure that the problem's sorted before it goes back in. So off I went on a short circular run - including, incidentally, one of the steepest hills for a few miles around. No problems, looks like it's sorted, back home to refit the tunnel, carpet, and radio - nothing else - then in for a bite to eat and some clean clothes. An hour later, off out again - only now, the clutch feels like it's on its last legs, hardly any bite, slipping like hell even in low gears on the level. I've driven a couple of cars (and a bus) that developed clutch slip due to ordinary wear, and it just doesn't come on suddenly like that - it develops slowly. Therefore, it seems to me that this is essentially still a hydraulic problem. For one reason or another - most likely some small piece of debris getting into the system - the piston in the slave cylinder is either sticking or at best retracting very slowly when the clutch pedal is released. Now it's a while since I had time to clean out and tidy up the garage and so there's junk piled everywhere - I ended up sat on the concrete outside working on a few sheets of newspaper. Far from ideal conditions, so it looks like the only thing to do now is do the job again once the garage has been cleared, unless anyone can think of another cause?
Trouble is, I can remember other times when the garage got into this sort of state, and I reckon it'll be the best part of a week's work to put it straight again I guess I could replace the cylinders outright, but they're not cheap and in any case I haven't got much faith in the quality of the new stuff. The bores and pistons of the old ones looked fine so in theory new seals should do the trick - I know it doesn't work for everyone but I've never had problems before now. |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Wed Aug 20, 2014 8:29 pm Post subject: |
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Hi BB,
I think the hydraulics could certainly cause a failure to disengage but am I not right in thinking that the slave cylinder can only push on the clutch operating rod and has no connection allowing it to pull.
If you think the thrust bearing is pushing on the clutch assembly then perhaps there is a partial seizure of the operating lever pivot.
It should be easy to check as there should be some free play on the lever when the anti-rattle spring is removed and it should move very easily.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Wed Aug 20, 2014 10:18 pm Post subject: |
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Hi Peter,
You're right in thinking that the slave cylinder can only push on the clutch operating rod - it's that operating rod that pushes the slave's piston back into the bore (the seperate return spring had been deleted by this time), and returns the fluid to the master cylinder. What I'm thinking is that if there's some kind of blockage preventing the fluid returning to the master cylinder then the piston can't return, in that case the release mechanism is still engaged to some degree and, of course, the clutch will slip. I've had brakes that intermittently locked on almost solid because of no more than a few tiny flakes of something or other in the wheel cylinder, and that's what I'm thinking of here, particularly given that the clutch worked perfectly on the first test run.
Of course it could be something else entirely, it would be a hell of a coincidence but entirely consistent with the natural cussedness of these things |
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47Jag
Joined: 26 Jun 2008 Posts: 1480 Location: Bothwell, Scotland
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Posted: Wed Aug 20, 2014 10:35 pm Post subject: |
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BB,
I'm guessing that there is a flex hose in the circuit. I've seen reports of the inner lining coming adrift and acting like a one way valve. Worth a check.
Art |
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peter scott
Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh
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Posted: Thu Aug 21, 2014 12:50 am Post subject: |
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Yup! BB, I think both you and Art are thinking clearer than me.
I'm remembering that issue with old brake flexies now.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Thu Aug 21, 2014 12:17 pm Post subject: |
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Hi Art,
Oddly enough there isn't a flexi section in the line, and never was as original - just a solid line formed into a loop to "spring" with movement, which doesn't seem to cause any issues. Some people do replace them with a modern braided flexi line that stretches all the way between the two cylinders, but I think it's more a matter of preference than anything else. I do know where you're coming from though, I've had that same issue with brake hoses, both old ones and lousy quality remanufactured items. |
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PAUL BEAUMONT
Joined: 27 Nov 2007 Posts: 1281 Location: Barnsley S. Yorks
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Posted: Thu Aug 21, 2014 12:45 pm Post subject: |
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I had a similar problem a few years back with (dare I say it?) a Fiat Uno. this suffered from clutch slip and the previous owner reckoned that this was the slave cylinder (it was one of only a few Uno's with hydraulic actuation). Investigation showed the problem to be the actuating shaft which was all but seized in the gearbox casing. it would slowly return if left long enough, but on drive off with quick successive use of the clutch, it with slip like nothing on earth. Resorted to an assistant with crow bar returning the arm whilst I pumped the pedal and a lot of penetrating oil was used.
Also just check that you have fitted the recuperating seal in the slave cylinder the right way round!
Paul |
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V8 Nutter
Joined: 27 Aug 2012 Posts: 587
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Posted: Thu Aug 21, 2014 7:41 pm Post subject: |
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Looking on the black side. A common problem small Triumphs suffered from when the clutch was getting worn, was the thrust washers on the back main falling out. As they worked their way out they would cause the clutch to do strange things until they finally dropped out altogether allowing the crank to float backwards and forwards.
I hope it's not that because it is not an easy repair |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Wed Oct 29, 2014 8:49 pm Post subject: |
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Time for an update on this one - it's taken from before my original post until today to get round to doing anything on this, though at least the scrap copper, brass, lead and batteries I cleared from the garage first netted me £65 Changed the seals again, they're cheap enough that I figure it's a false economy not to do so while it's apart, and blew through everything with plenty of compressed air. Nothing much to see, though on closer inspection a couple of the smaller parts near the valve seal in the master cylinder are worn perhaps more than they should be, and a small spring washer had split, but you get one of those in the repair kit. Been for a good run this afternoon and thinking of taking it to the shops tomorrow as all seems well, but I think if it gives further trouble it's probably new master cylinder time, unless there are any NOS floating around..?
No problems to be seen with the release mechanism inside the bellhousing, there's a hole to see through and it's springing back promptly. While I was there though I've put a few drops of oil where it'll work down into the pivot. One other problem these can suffer with is the pivot pin dropping out, but I replaced the original with a shouldered pin several years ago to prevent this - and in case it was thinking of working its way out of the top, drilled the bottom for a splitpin, so fairly sure the problem didn't lie here |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Thu Oct 30, 2014 12:16 am Post subject: |
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If a new master cylinder is not available at a sensible price you could always recondition the old one with a stainless steel sleeve. |
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JohnDale
Joined: 19 Mar 2008 Posts: 790 Location: Kelvin Valley,Scotland
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Posted: Thu Oct 30, 2014 2:31 pm Post subject: |
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Hi BB, don't know if the Herald uses the same slave cylinder as the 2000,
pt# TKC2786 but these were used on all sorts of vehicles inc Landrover. I recently purchased one from Total Parts Limited in Skelmersdale for the princely sum of £5.20 + £3.50 carr. & vat = total £10.44. Their part number is TKC2786BM & is listed as Landrover, but is the same as the 2000 & fitted
perfectly - just about as cheap as a seal kit but less work & it's new.
All the best,JD. Just found the phone number 01695 556448. _________________ 1958 Ford Zephyr Mk2 Convertible
1976 Ford Granada Ghia. |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Fri Oct 31, 2014 9:31 pm Post subject: |
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Shopping trip completed with no incident so looks like it's sorted for now |
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