Machining Lugs
Turbo Mini Forums

Hi All,



Here is my clutch minus the diaphragm. The car has only been on the road a couple of days and after going to SRE to be set up Neil said the clutch is slipping.

This only seems to happen in 3rd and 4th under acceleration. Neil could not set the car up as this was happening so the fuelling is not quite right either and the moment.

It is a lightened flywheel, backplate, and an orange diaphragm.

Now I have read on a couple of threads about machining the lugs down. Is this on the back plate. Do you think this is what I need to do? If so how much is needed to be taken off?

Just found this on another forum.


It won't make a difference to the operation of the clutch but it will affect the clamping force. Personally i'd say stick with the standard 2 driving straps but you'll still probably need to mill down the backplate lugs to gain full clamping force anyway.

IIRC my lugs are machined down to 23.5mm measured from the face of the backplate to the top of the lugs and with 2 driving straps holds 200 lb/ft without a problem. best thing to do is assemble the flywheel setup on the bench and make sure that the spring on the diaphragm is sitting flat, if not then you'll need to do some machining to get full clamping.

It doesn't usually make a difference on a nat asp car as they don't make enough torque to get the clutch to slip but as soon as you add a decent amount of boost it'll find the limits pretty quickly.

I had 1mm taken off mine. I originally fitted 3 sets of straps, but am going to take it apart and take one off. Clutch is not fully disengaging in my case.

I thought that more straps reduced the clamping force? I had .7 mm taken off my lugs and have 3 straps fitted. Not got it out on the road with this setup yet.

You need to remove the clutch & flywheel assembly. Put the diaphragm back on & look to see if the pressure part of the diaphragm is sitting flat/horizontal when assembled.
Put it the assembley on a flat surface & look from the side. The pressure plate should sit at 9 & 3 o'clock. If it's at 8 & 4 you need to remove material from the lugs until it sits level. This will give maximum clamping force.
Hope this is understandable ? LOL

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yes, as Phil says the spring needs to be flat, or close to it, then when you press the clutch the spring goes "over centre" and is lighter on the foot ad thrusts

I had 2mm off mine

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Thanks chaps,
I'll strip it in the morning and let you know how I get on. I understand I think the position of the spring and will posts photo tomo.
Any ideas on how to determine how much you need off?

put a bit of studding throgh the middle of the fly wheel with some big washers, set a dti up and compress it and measure the difference.

Hi Chaps,

Ok so here we have the clutch assembly on a bench.

Phil when you say the positions 9 and 3 / 8 and 4. What are you referring to, the position of the springs in a clock face?

Sorry imp not quite getting it, maybe you guys can tell by the photos?

I understand I need to take some off the lugs but just how much is the question.
Cheers

Edited by 1275min on 7th Apr, 2013.

Looking at the assembley in the same direction as the photos. Look at the ring/pressure plate & imagine the left & right hand sides of it are clock hands.
If the plate was sitting flat it would point at 9 & 3 o'clock, if it needed material off the lugs they would point to 8 & 4 o'clock.

Phil.

WWW.TURBO-MINI.COM

No point going over the same ground that someone else has already done, in a very concise manner

So have a read of this http://www.minimania.com/article/153/Clutch_FAQ__non-Verto_

Thank you guys.

I'll let u know the outcome of my findings.

Hi chaps,

Ok so I did what wS suggested and set the flywheel etc up on a bench. It turned out that 0.97mm needed machining off the lugs so the diaphragm sits 9-3.
This was done and now the clutch is all back together.
Now having a slight issue that I can not engage any gear unless the return stop is wound a such a long way that the slave cylinder arm is not being driven by the piston.
So I'm running 2 drive straps at the min.
Should I fit 3?
Looking forward to your feedback lads.

I'd be fooked without this forum I tell ya!

Has anyone had to leghthen the metal rod which is driven by the slave cylinder or am I missing a part of the puzzle?
The reason I ask is that I can only get the car in gear when the adjusting bolt is wound out to a point that the arm can not physically be driven as it's not in the slave cylinder any more.

Edited by 1275min on 12th Apr, 2013.

I've had to get a longer rod for mine.

you shouldnt need a longer pin, removing material should have no real bearing on any adjustment needed.

how old are the arm and plunger? if theyre worn it can cause this.

Mine is all brand new and need about 5-6mm on the pin.

Mine is also brand new parts. Im Pleased to here you apbellamy also had to do this.
I was not sure if this was the done thing.

Also can you guys confirm the more drive straps you have the more clamping pressure you have?

Sorry,
also would one of you be able to measure for me how far your clutch arm moves as the clutch peddle is depressed.
Mine does not seem to travel far at all and i would like to rule out a problem with the new plastic type master cylinder, the slave cylinder is new too, might have to try bleeding it again.

I have 3 straps and my clutch is not disengaging properly. It will be coming to bits again...

Clutch is working fine now lads.
I had to legnthen the arm that the slave cylinder drives!

Really appreciate all your help.