V8S Clutch problem
Discussion
I've just had new clutch master and slave cylinders, pressure plate, friction plate, release bearing - pretty much everything bar the pipe work. For some reason the clutch will only fully disengage with the pedal about an inch up from being fully depressed - go beyond that point and it starts to re-engage. Has anyone any idea why this might be? It's got my bloke flumoxed....All suggestions VERY gratefully received.
I had my slave and master replaced by Southways when the chassis was refurbed, (hopefully the nightmares have reduced Steve D) I ordered LR defender components to ensure ease of availability in future. For some strange reason the units that TVR used had a weird thread on them.
I went for LR Defender 3/8 unf x 24 Master
Delphi LL36195 7/16 unf x 20 slave
New pipe will be required (dash 4) but it means you can pickup spares without issue in the future.
Speak to Peter at Dingocroft, the guy is a walking encyclopaedia.
I went for LR Defender 3/8 unf x 24 Master
Delphi LL36195 7/16 unf x 20 slave
New pipe will be required (dash 4) but it means you can pickup spares without issue in the future.
Speak to Peter at Dingocroft, the guy is a walking encyclopaedia.
Racetech are absolutely confident that master Q0012 and slave Q0010 are correct. However, to solve the problem they do have a slightly bigger bore slave version available (from early Griff/Chim) which might help a bit, but they say that's not likely to be the cause. The pressure/friction plates came from Rimmer Brothers, apparently, matched to the engine gearbox numbers and I'm trying to find the part numbers from them. Racetech suggest there may be a second pivot point on the pedal and the wrong one is being used - I'll check that tonight, but it sounds too easy! My bloke's other suggestion is to drill a new pivot point on the pedal, which might do it but is not a very elegant solution...again, thank you all for your help.
I can't get my head round the hydraulics being the issue, frankly. Not without it making a mess on the floor anyway!
I'm wondering if it's got the wrong release bearing. Could be that the bearing is starting to push its way through the fingers as the hole in the middle begins to open up, which then releases the fingers slightly. Letting go of the clutch would then kick it back out.
That said, we use Racetech bearings here, and assuming you didn't fit the plastic one that sometimes comes with the kit, I can't say I've ever had that problem.
I'm wondering if it's got the wrong release bearing. Could be that the bearing is starting to push its way through the fingers as the hole in the middle begins to open up, which then releases the fingers slightly. Letting go of the clutch would then kick it back out.
That said, we use Racetech bearings here, and assuming you didn't fit the plastic one that sometimes comes with the kit, I can't say I've ever had that problem.
melv8s said:
...... Racetech suggest there may be a second pivot point on the pedal and the wrong one is being used - I'll check that tonight, but it sounds too easy!..........
If it worked OK before then it should work now.melv8s said:
...... My bloke's other suggestion is to drill a new pivot point on the pedal, which might do it but is not a very elegant solution...again, thank you all for your help.
I think you should check you have the correct parts before you get into doing this sort of thing.can you get your bloke (or another one) underneath watching the release arm as you (or yet another bloke) press's the pedal? if the release arm starts to return as pedal nears the floor there must be something weird going on with the hydraulics.
A bigger bore slave cylinder is going to reduce the amount of travel but that sounds like "buying a bigger bilge pump rather than fix the leak"
If, however, the release arm just goes forward (as it should) i'd say it's time some blokes took the gearbox out.
Totally agree with Philpott.
Dont start messing around with components until you have analysed the problem.
Get the car on the ramp or raised. Person 1 underneath looking at the slave cylinder.
Person 2 press the clutch pedal slowly right down and keep it down. Person 1 should see the slave cylinder pushrod come steadily out of the cylinder to pretty much its full travel (check if you want by putting a bit of stiff wire into the cylinder alongside the pushrod, it should 'feel' the cylinder piston). It should then stay there.
If it does then there is a problem with the clutch assembly not the hydraulics.
If it doesnt come out properly or starts to go back in then you have a hydraulics problem and you are going to have to strip that down.*
It is possible on some cars to put the clutch friction plate in the wrong way round, i.e. with the release side facing the flywheel. I THINK that would make it difficult to disengage and it might only disengage at full travel. I don't know for sure as I have always checked and never made the mistake. Philpott has more experience with the actual fitting and may know if this plate can be reversed in the Cologne/type9 transmission and what the symptoms would be.
Dont start messing around with components until you have analysed the problem.
Get the car on the ramp or raised. Person 1 underneath looking at the slave cylinder.
Person 2 press the clutch pedal slowly right down and keep it down. Person 1 should see the slave cylinder pushrod come steadily out of the cylinder to pretty much its full travel (check if you want by putting a bit of stiff wire into the cylinder alongside the pushrod, it should 'feel' the cylinder piston). It should then stay there.
If it does then there is a problem with the clutch assembly not the hydraulics.
If it doesnt come out properly or starts to go back in then you have a hydraulics problem and you are going to have to strip that down.*
- one minor point, do you have the slave cylinder in the right way up? The bleed valve must be above the inlet pipe, if not you are bound to get a big air bubble that wont come out however much you bleed it.
It is possible on some cars to put the clutch friction plate in the wrong way round, i.e. with the release side facing the flywheel. I THINK that would make it difficult to disengage and it might only disengage at full travel. I don't know for sure as I have always checked and never made the mistake. Philpott has more experience with the actual fitting and may know if this plate can be reversed in the Cologne/type9 transmission and what the symptoms would be.
Worth pointing out it's a V8S chaps, so while I'd normally agree on the advice above, on this car it's not as simple as on the V6. The push rod is different to the design on a V6. It's contained within the bellhousing, and also non-adjustable. On an LT box you can't really see what the arm/rod are doing unless you cut a big hole in the underside of the bellhousing. You can remove the slave, and then remove the dust plate on the bottom of the bellhousing, and you might see a tiny bit of what's going on with a torch having refitted the slave sans dust cover, but it'd be like trying to watch the neighbours TV through their letterbox.
I'm thinking could be release bearing related. Either the bearing itself isn't fully compatible with the clutch cover, or the two bushes that the release arm are acting on or worn, or moving in a way they shouldn't, causing them to go 'over centre' (not actually going over centre, as they physically can't, but giving the same effect).
The key point in this for me, is the fact the clutch disengages and then begins to re-engage the further you push your foot. I don't see how mismatched cylinders can cause that, nor the pivot point on the pedal. They could give you too much travel, or not enough travel, but I can't picture how they'd cause it to work and then not work. There's no pressure relief valves anywhere.
Assuming you do take the dust shield off, refit the slave and get someone to press the pedal and make it do what it's doing wrong. If you watch the arm very closely, you'll see if it backs off slightly as it's pressed, which means:
I'm thinking could be release bearing related. Either the bearing itself isn't fully compatible with the clutch cover, or the two bushes that the release arm are acting on or worn, or moving in a way they shouldn't, causing them to go 'over centre' (not actually going over centre, as they physically can't, but giving the same effect).
The key point in this for me, is the fact the clutch disengages and then begins to re-engage the further you push your foot. I don't see how mismatched cylinders can cause that, nor the pivot point on the pedal. They could give you too much travel, or not enough travel, but I can't picture how they'd cause it to work and then not work. There's no pressure relief valves anywhere.
Assuming you do take the dust shield off, refit the slave and get someone to press the pedal and make it do what it's doing wrong. If you watch the arm very closely, you'll see if it backs off slightly as it's pressed, which means:
- If it doesn't, then I'd say it's a problem with the clutch itself.
- If it does, it could be the release issues I mentioned, or possibly a duff master cylinder - it might be losing compression at the end of travel due to a damaged bore or something, meaning it works fine up to a point, and then leaks back past the seal. Pull it off and see if the servo's full of clutch fluid.
Thanks again all. As a small update: The release arm/fork was also replaced with the heavy duty version with the reinforcement patch on the back. Also the point above about the pivot point isn't right - having had a look this weekend the pedal is hinged at the top, the first hole (going down) has the spring and the second hole has the push rod for the master cylinder, so that must all be ok. He's used up all the adjustment on the pedal, but the theory put forward above about overthrowing the pressure plate must still be most logical...it's just a question of why. I'll take your combined wisdom above to my man on Saturday. Thank you again.
If I understood correctly, if you push the pedal down far enough to disengage the clutch and then push down even further, it reengages. Does it disengage again as you raise the pedal? If so, that definitely points to a mechanical problem in the clutch itself, and the suggestion about over-travel on the slave could be the explanation.
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