20 replies to this topic

[dougie1142]

Okay in an attempt to get the car driving this week I'm failing miserably.

Next stump... The clutch. It won't disengage. I've tried rebleeding, I've set the arm up against the stop as per instructions and I've wound the overthrow stops out quite far for now.

Something that has struck me is that the arm might be starting too far away from the slave cylinder to begin with. Meaning I don't have enough movement left to actually press the clutch. Perhaps I've installed the clutch wrong inside the casing...

Here's a picture with measurements of how far away the arm is

https://flic.kr/p/2h7dfe2

Something else I've noticed is that if I take away the little stop bolt In the case and allow the arm as close in to the slave as it can go, attach springs etc the clutch pedal operates fine. If I remove the spring the pedal goes solid and you can press it with no movement in the slave. If I then put the little bolt in and adjust the arm to take out the slop, then attach the spring etc etc the pedal won't move.

Help much appreciated.

[dougie1142]

Okay I took the rubber seal off the slave and rigtt enough the piston is at the extremity of its movement so I can't physically move it anymore. Some else I noticed is that if I push the piston back with my finger, then leave it it automatically drives the piston out itself, is this normal?

Sounds like the Wok is coming off along with the clutch... Fun ?

[nicklouse]

sounds like the release bearing and or thrust plate is not right.

[dougie1142]

https://flic.kr/p/2h7egKG

Well the Wok is off. I'm not familiar with pre verto clutches, but I'm guessing something wrong here with the straps etc.

[nicklouse]

cant see anything majorly wrong there presuming nothing has been modded.

 

also check the ball on the arm. worn out/bent/missing is common as are worn out pivot pins and holes.

[dougie1142]

Thanks for your replies.

This was sitting in the clutch box, assumed old bearing but perhaps missing from somewheree?

https://flic.kr/p/2h7fg99

Pictures of the arm ball:
https://flic.kr/p/2h7hMEE
https://flic.kr/p/2h7fg7a

The plunger is a new item from Minispares.

[Tones61]

use a nut in cylinder as a spacer to test,if ok,we used to bend the arm :-)

[Rorf]

There is something wrong with your clutch pressure plate set up - those driving straps need to be parallel to the flywheel. You need to remove the flywheel and have your clutch set up correctly.

 

I would also say that the clutch arm ball is worn as well as the plunger socket as we;ll as the clevis pins as well as.................... basically you need to overhaul your whole clutch system, then it will be happy motoring for the next 10 years or so.

[Rorf]

use a nut in cylinder as a spacer to test,if ok,we used to bend the arm :-)

A botch job which will end in tears with crankshaft thrust bearings destroyed. 

 

I speak from experience

[dougie1142]

There is something wrong with your clutch pressure plate set up - those driving straps need to be parallel to the flywheel. You need to remove the flywheel and have your clutch set up correctly.

I would also say that the clutch arm ball is worn as well as the plunger socket as we;ll as the clevis pins as well as.................... basically you need to overhaul your whole clutch system, then it will be happy motoring for the next 10 years or so.

Agree the straps could do with some improvements, but the way they are now shouldn't impact disengagement.

I've ordered a new arm, not sure if it'll arrive in time for the weekend but I reckon the arm is more worn than I thought, or bent. Not got a spare to compare it to! Everything else seems in order...

[Magneto]

I had a similar problem with a car, all new components - every thing in the clutch assy was new. I finally wound up lengthening the push rod by 1", that set the cup down in the slave cylinder and it operated properly. Don't know why it was so out of whack - I checked every bit of it top to bottom and found nothing wrong, and after I lengthened the rod it drove like new. Heating the arm with an acetylen torch and bending it in would also work as mentioned above....

[nicklouse]

Strap position has nothing to do with this issue.

Adding a nut to the pushrod will not fubar your engine if you have the throw out nuts correctly set.

[GraemeC]

As with everything in our 'world' there are varying degrees of quality - I've had slaves that bottom out, slaves that hit the circlip, different length of pushrods (actually I think there may have been different ones 'back in the day).

Having everything new is certainly a step forward, but there can still be issues.

[Tones61]

use a nut in cylinder as a spacer to test,if ok,we used to bend the arm :-)

A botch job which will end in tears with crankshaft thrust bearings destroyed. 
 
I speak from experience

Me and a friend ran over 12 different minis in the 80s/90s doing this never had a problem,only perfectly working clutches

[rww]

Okay I took the rubber seal off the slave and rigtt enough the piston is at the extremity of its movement so I can't physically move it anymore. Some else I noticed is that if I push the piston back with my finger, then leave it it automatically drives the piston out itself, is this normal?

Sounds like the Wok is coming off along with the clutch... Fun

 

    So, from the above the slave cylinder piston is sitting (at rest) so near to the end of the cylinder that when you operate the clutch pedal the piston runs out of travel by hitting the retaining circlip.The clutch pedal goes solid, often unnoticed if near the floor. The clutch will not disengage.Lengthening the pushrod by fitting a nut or sleeve to it will overcome the problem but it is essential the 'spacer' is of such a diameter that it will pass through the circlip otherwise the problem  still exists.Yes, it is a 'bodge' but one that I first did in the 1960's and, as has been said above, is a reliable and safe method of overcoming the problem.

Whilst wear in the arm pivots, ball and socket are not ideal I do not believe these contribute greatly to the problem as when the main operating arm 20thou clearance is adjusted, the various excess clearances have been taken out of the operating linkage. In doing so however, the clutch slave piston will have been allowed/encouraged to move further towards the end of it's travel.

I had the problem only two months ago. I fitted a replacement clutch driven plate. The old AP paddle plate was approx 7mm thick, the Swiftune replacement was approx. 1mm thicker.A thicker clutch plate has the effect of moving the clutch backplate towards the engine, the spring diaphragm is bolted to it so the release bearing clearance is much increased. This had the effect of increasing the clearance at the 20thou setting point quite substantially which, at the time I did not take undo notice of and I reset the screw and locknut to 20thou.The clutch pedal went solid about 3/4 travel to the floor. A  sleeve over the slave pushrod successfully overcame the problem. It is a race clutch set up and has been set up with the diaphragm spring flat at rest but I used the same remedy on a stock engine only a few years ago and in the 60's.