Minor Clutch Adjustment

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martinng
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Joined: Thu Oct 10, 2013 5:31 pm

Minor Clutch Adjustment

Post by martinng »

A few words from the initiated re clutch adjustment please. When I started this seemed a simple job, but now I am not so sure.

As far as I can understand the original manual and subsequent technical descriptions there are two clearances to set in the clutch.
The manual reads "[adjust] until at least a 10-thousandths feeler gauge can be inserted between the end of the adjusting screw and the head of pressure pin beneath it, and there is a clearance of 3/32 of an inch between the end of each lever and the face of the clutch withdrawal race".

So .....
Are these adjustments made simultaneously, with a gauge of appropriate size located in each position and then the adjustment made so that there is a good fit at each point?
When I do this (see picture) and remove the gauges there is then about 1/4" of free play between the withdrawal arms and ball race, until the withdrawal pins 'bite'.
Due to the lengths of the levers involved an increase in this play would be expected, but this seem excessive.
Withdrawal arm with gauges in place
Withdrawal arm with gauges in place
R0041600s.jpg (73.92 KiB) Viewed 4404 times
Or .....
Should the two clearances be adjusted independently with a 10-15thou clearance at the withdrawal pins when the arms are just touching the ball race and the 3/32" clearance when the arms are just pressing on the withdrawal pins? This method would certainly require fewer hands to achieve, but since there is only one adjustment point, the two clearances are dependent on the accuracy of the parts and their assembly.

One thing I have learnt from my error is to tie string or wire on the 3/32" gauge (in my case a slim bicycle spanner) so that when it falls into the clutch housing it can be easily removed!!

Grateful for comments please, so that I am on the right lines before I adjust the other two arms.

Martin
Ian Grace
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Re: Minor Clutch Adjustment

Post by Ian Grace »

Martin,

This from the Service Sheet:

"ADJUSTMENTS

(a) Make sure that the clutch pedal has at least 1 in. clearance to the underside of the board.

(b) Adjust the withdrawal levers by means of the adjusting screws so that the toes of the withdrawal levers are each exactly 3/32 in. from the face of the clutch thrust bearing, making quite sure that there is clearance between the toggle lever and the spring keep. (To do this it is necessary to prepare a suitable gauge for insertion between the withdrawal lever toes and toes and the face of the withdrawal race. Any piece of clean metal strip a bare 3/32 in. thick will do).

(c) With the gauge removed there should bc a clearance of from .010 in. to .015 in. between the adjusting screws and the pressure pins on the three withdrawal levers. If this amount of clearance is not present the keeps should be sprung out with a screwdriver until this clearance is obtained."

Does that clarify?
martinng
Posts: 147
Joined: Thu Oct 10, 2013 5:31 pm

Re: Minor Clutch Adjustment

Post by martinng »

Thanks Ian, all is now clear. The words "With the gauge removed there should be a clearance of from .010 in. to .015 in. between the adjusting screws and the pressure pins" is the critical thing. I was beginning to arrive at this conclusion. I noticed for instance in the M type maintenance instructions, that there is only mention of the 3/32 clearance. The implication being that the 10-15thou looks after itself.

It is a pity that all the drawings of the clutch show both clearances on the same picture, whereas in fact the 10-15thou is only present as the 3/32 clearance it taken up as the lever ends are moved towards the clutch race.
Hey-ho, I will set about this task now with renewed confidence.

Incidentally where is the service sheet? I did look around for additional info but only found the M type C&M notes.
Martin
Ian Grace
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Re: Minor Clutch Adjustment

Post by Ian Grace »

All's well that ends well.

Actually, I just copied and pasted from a Service Sheet on the Gren Strickland archive in the Members' Area of this website - using my cellphone in Seattle. Frightening, isn't it?
martinng
Posts: 147
Joined: Thu Oct 10, 2013 5:31 pm

Re: Minor Clutch Adjustment

Post by martinng »

Ah well, I should not be such a lazy researcher!
Perhaps this Luddite should applaud the new technology after all.
Martin
martinng
Posts: 147
Joined: Thu Oct 10, 2013 5:31 pm

Re: Minor Clutch Adjustment

Post by martinng »

During adjustment I snapped a keeper spring clip and the new ones from Sports and Vintage are made from very stout spring steel - about twice the thickness of the parts already fitted.
They were impossible to adjust in-situ with a screwdriver as the manual suggests, so I spent the afternoon putting them on, checking the clearances then taking them off and adjusting them on the bench then repeating the process until they gave the correct result. i.e. prevented the withdrawal arms from touching the withdrawal race, but allowing a gap (10 thou the book says) between the adjustment screws andf the withdrawal pins.
Completed in the end, but a bit of a struggle, but the clutch now engages smoothly.
Ian Grace
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Re: Minor Clutch Adjustment

Post by Ian Grace »

Good job. Well done Martin. Hopefully no further adjustment will be necessary for some time.
martinng
Posts: 147
Joined: Thu Oct 10, 2013 5:31 pm

Re: Minor Clutch Adjustment

Post by martinng »

After all my confusion regarding clutch adjustment, I discovered today that there is a good thread on the forum covering all the issues I faced and with a wide range of solutions that I wish I had found at the time. However, all's well etc. and now to sort out the gear change problem I have and to discover why it is so noisy. I fear more threads to come.
Ian Grace
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Re: Minor Clutch Adjustment

Post by Ian Grace »

All part of the unique enjoyment of owning such cars, and being part of such a community.
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