I'm having some problems adjusting the clearances on a 1970 mini.

Has new or rebuilt parts throughout.

The main issue is that the clutch arm pick-up point where the throw-out bearing touches the diaphragm, is close to the end of the slave cylinder travel. There is only about 12mm travel left to disengage the clutch - which is not normally enough.

The clutch has been set up to make the diaphragm spring sit close to parallel with the flywheel, as per DrMini's recommendation in "How To" here:

viewtopic.php?f=25&t=100137

Does this modification move the throw-out bearing contact position or any other adjustments?

I can’t help on your question about the diaphragm setup, but it was suggested to me to add a spacer between the plunger and throw out bearing. Adding a few mm here adds up to a lot at the end due to the leverage ratio. I guess you want the throw out bearing to be as close as possible without hitting the clutch or bottoming out the slave


The improved angle is on the right. With a few new parts and the spacer it came in about an inch



viewtopic.php?p=1050614#p1050614

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Easiest way is to cut the slave push rod in half and weld in a piece of rod between the two halves. My "expert" used a piece of welding rod ... it's about the right thickness.

To get the correct length for the insert; push the slave piston back into the cylinder leaving it about half an inch from the closed end. Attach the out end to the clutch arm, pull it out until the release bearing touches the diaphragm. Measure gap, cut and weld to suit.

You can get fancy adjustable push rods but you'll run out of clutch before it ever needs adjusting...

Whatever you do, make sure the piston is way down towards the closed end of the slave bore when you set it up.

Cheers, Ian

Try http://www.moke.com.au I found it helpful.

Tim: Your first photo of the clutch arm has the pushrod and 1/4"UNF screw about where mine sits - too far out. The improvement in photo 2 looks to be about right as per how I think it should look. I have even taken the whole clutch cover off to check that I didn't leave out the throw-out bearing on the end of the carrier!
Have also thought about a spacer behind the throw-out bearing to make up the difference. May be the final answer.

Ian: My first attempt at adjusting clearances for this engine was with a new slave cylinder pushrod. I later found the pushrod that had been in the car before this rebuild. This pushrod had 12mm extra welded onto it by a friend years ago, presumably for a similar reason.
I understand what you are saying about moving the slave cylinder piston further down the bore to give a better adjustment range.

A popular solution in the good old days was to heat the arm with oxy above its pivot and bend it towards the slave cylinder.
Or, leave the circlip out of the cylinder works for me. The cheap new ones have no circlip.. or seal spreader, another story..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Bending the clutch arm (or welding an extension to the push-rod) was usually put up as a solution to excessive wear in the pivot points in the linkage.

I'm thinking that the parallel diaphragm spring setup you detail must mean that the distance between the throw-out bearing and the diaphragm are further apart than standard setups, so need to be considered.

P.S. The slave cylinders I use are resleeved and I use the speader cup from the old cylinders.

Are you using the later release bearing with the raised edges, or the flat one that's available again? The flat one is thinner, because it was designed for the old coil spring clutch, NOT the diaphragm spring.
When using it with a diaphragm spring clutch I fit a thick structural grade flat washer behind it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The bearing is the later style - not the earlier, flat faced type.
And a flat washer as a spacer sounds like a solution to my problem - as in one of Tim's photos.

Thanks all for your suggestions.

Hi Bill, did you re-fret the crank taper with flywheel on this rebuild? Any small margins here will also affect the throw out contact point against the diaphragm, i.e. moving the flywheel assembly away from the release bearing contact point.

Because the clutch arm has an operating ratio of ~5.7:1, a 1mm differentation at the ball of the arm (fulcrum point) will equate to ~5-6mm at the top of the arm where the push rod makes contact. HTH

Do you mean lapping the flywheel to the crank taper? Not this time - no signs of anything moving that shouldn't. But I understand what you are getting at.
Thanks for to comment.

Think I have solved this: watched Paul Hickey's video again on setting the diaphragm spring closer to being flat against the flywheel, then watched him install his modified clutch into a car and adjust the clearances. This modification to the spring definitely moves the spring housing further away from the throw-out bearing, increasing the dead space the lever has to travel before touching the spring housing.

Fairly sure the proper solution is a spacer like Timmy has used - when the engine is out of the car next!

Changing the push rod (or bending the arm as Doc suggests) is a cheap solution to the problem with out the delay and cost of an engine out.... or the painful effort of moving the thrust bearing in situ..

Cheers, Ian

You're right, Ian.
I have refitted an old pushrod that has about 10mm welded onto it. That should work well enough for now.

Another thing to watch these days is the throw out plungers wear excessively. Like in 3 months.
Originals were case hardened where the arm's ball rubs. Around HRC 50.
Current cheap plated ones are soft, measured HRC3 on a Rockwell tester. The more expensive ones weren't very much harder...
I have drilled a few new ones out and fitted a hardened steel bush.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

You can now purchase an adjustable push rod for the slave cylinder.