11 replies to this topic

[steven]

i've got a 1981 austin mini hl its been stood outside for 10 years just replaced the clutch slave cylinder and re-built the clutch master cylinder the pedal now only goes down half way and the clutch does not operate just wondering if anyone had any advise on what to do next ?

thanks steven

[NZMINI1100]

Because you say that the pedal only goes down half way, I presume that would mean that something is seized. I'd say that the plunger is the likely culprit, but it could be worse. get someone to press the clutch pedal while you have a look and see if the plunger is moving, if it is moving still, then I would say that something is seized inside the clutch housing. hope this helps.

[steven]

thanks for that the plunger goes in but not far enough to engage the clutch

Edited by steven, 22 October 2012 - 05:17 PM.

[NZMINI1100]

The two throw out nuts aren't hitting the casing are they?

[M J W J]

Just to check. You have bled the system after fitting the master and slave cylinders, right? If not it would explain why you pedal moves and the slave cylinder doesn't move the clutch.

[tiger99]

We can rule out the need for bleeding, as the pedal would be able to be forced towards the floor if there was air in the system. Instead, it stops.

Apart from a broken, chewed or otherwise mutilated plunger, there are at least two possible causes, firstly the throwout stop is, as already suggested, not set correctly (check and adjust first), and secondly (Verto only), the slave cylinder is running out of travel when the piston hits the circlip. (Not all have the circlip, but I would not advise removing it.) It does that because an accumulation of wear in the lever ball end, plunger, thrust bearing, pivit pins etc, all give additional free play, which the self-adjust spring in the slave cylinder compensates for by moving the piston outwards, so it then does not have enough travel remaining to do the job. Some people have bodged this by fitting a longer push rod to the slave cylinder, generally by welding on an extension, but that is a dreadful bodge and should not be necessary. (OK to get the car working in the short term, but a proper fix should be found.) It may be that in these cases, the main problem is that the lever has bent, and a new one may cure the problem.

I would take apart and check all the external parts first, which is no big deal unless your car is an awkward one with a brake servo or other bits in the way. Check the lever end for wear (flats on the ball), and the pivot for slop (pin should be a good fit in the clutch cover and the lever). Same with the pin between lever and slave push rod. Lubricate with something like graphite grease and reassemble if everything is good.

But before doing any of that, get a torch, and become a contortionist for a few moments. Check that nothing is jamming the pedal or master cylinder push rod.

To set the throwout stop, first set the return stop clearance to 0.5mm (non Verto only). Loosen the throwout stop nut and locknut considerably. Check that pedal will now go to floor and get someone to hold it there. Tighten stop nut till it contacts clutch cover and then one flat more. Tighten locknut against it.

[steven]

thanks for the help, the clutch is the one with the longer arm not sure if thats verto or pre verto ?
i have checked the throw out stop witch seems okay
it was bodged before i got it there was a socket attached to the push rod inside the slave cylinder

im also going to start taking all the external parts off tomorrow checking/greasing along the way anything to look out for ?

thanks steven

[tiger99]

Pre-verto, so the bodge was possibly there to compensate for an operating lever which had bent.

[steven]

ohh, seems to be that way i will have a look tomorrow
is this a common problem/bodge ?

[tiger99]

It seems to have been common recently, but was almost unknown 20 years ago. As the cars get older, maybe people who press the clutch hard to the floor all the time are gradually bending the levers, or the clutch end covers are gradually distorting with age, because I can't see what else would be changing.

Unless, of course, the dimensions of some replacement parts such as the thrust bearing are incorrect, which would not be entirely surprising, giving the abysmal quality control practised by certain suppliers.

If anyone has other sensible ideas about why we are seeing this problem now, I for one would be very interested.

[steven]

i have asked a few people and they say the same thing
mine does not seem to be obviously bent but im going to renew it i dont think it would take alot to make it not work

thanks for the help i will keep you updated

[steven]

update: turns out it was a badly worn clutch release thrust bearing so replaced it and all is good now thanks for all the help