Grub Screws to set Clutch Toggle Lever Height

[Jamie]

I am starting on the clutch for my Ruby and notice that it has had grub screws inserted where the heel of the toggles has worn a groove in the plate. The screws are now worn and need replacing. However, how do you actually use them to set the height of the levers? Unless I am getting confused, the heads of the grub screws are covered up when the clutch is assembled, meaning that you cannot use them to adjust the height. Is it simply a case of guessing the correct setting, bolting the whole thing together, measuring the height and dismantling it again to adjust, repeating this until they are correct? If this is the case, does it need to be on the engine to get the height or can it be done on the bench?

Regards,

Jamie.

[Andy Bennett]

Jamie
I had mine welded up and milled flat, but my understanding is that you set the height of the screw to the old height of the groove, so removing the wear. So you aren't actually using them to adjust the clutch, but you are using them to reset and effectively remove the differing levels of wear in the 3 toggle grooves.

Andy

[Chris KC]

I don't think it's quite as critical as some would have you believe Jamie, the main thing is to get them roughly even.

[Howard Wright]

Hi Jamie

With the Ruby clutch I think you may have mousetrap springs which will prevent the following operation.  I think some people ditch the springs?

I drilled and tapped for grub screws that could be adjusted from the outside.  Assemble the clutch then pull back each toggle, adjust then check the height above the crankcase lip.  Once happy I marked the height, Loctite the screws and punched the edge to be sure.  If the slot of the screw is perpendicular to the axis of the toggle wear hopefully won’t be a problem.

Cheers

Howard

[Barry Townsend]

I did mine with the clutch on the engine. Whilst I had to disassemble a couple of times I found that with some careful measuring I quickly got it right

[John P]

I've just been through this on a 3-speed clutch when I fitted a new clutch cover plate that had already had the grub screws fitted
and found that getting the depth of slot even was quite critical.

As a retired engineer I initially thought I could get it correct by measuring each toggle lever from the face of the crankcase and then converting these measurements into the amount to take off each grub screw bearing in mind that any change over the grub screw is multiplied by around 3 when it comes to movement at the toggle end.   I did this to try to eliminate any other errors caused by wear in the toggle levers or their pivots.

Although I checked and double checked my measurements this didn't really work out and when I ran the car for the first time the clutch disengaged fine but I had a really bad vibration through the clutch pedal.

Based on some suggestions on here I then filed each grub screw to achieve exactly the same slot depth to an accuracy of around 0.1 mm and this time the results were fine.

The dimension I ended up with from the ends of the toggle levers to the crankcase face was just under 5/16" but if I did the job again I think I would have tried to get a bit more clutch disengagement as I still get a bit of a crunch when engaging first gear.  That being said the problem I have is probably due to wear in the thrust race housing which I may try to rectify when I have the time.

John.

[Jamie]

Thank you for all of the replies and suggestions. I am relieved to realise that at least I was not missing anything obvious regarding accessing the heads of the grubscrews. I shall presevere, having finally managed to drill out the remains of the old, heavily worn grub screws which had been brazed in by a previous owner.

Regards,

Jamie.

[John Mason]

They don’t have to be grub screws. On my flywheel this mod was done by a friend who is known to some in the Seven community Walt Wheaton who drilled and tapped the flywheel then screwed in normal hex head bolts from the non clutch side of the flywheel. They were then brazed in place and the heads ground off.

John Mason.

[Jamie]

Thank you for all of the replies and advice. Looking in the companion, I noticed a suggestion about putting rollers under the levers to move the fulcrum point. Has anybody tried this and, if so, is it a worthwhile modification? I can see the logic, but wonder whether it makes any difference in real life.

Jamie.

[Ivor Hawkins]

Hi Jamie, I cut up an old drill to make the rollers in one of my old Rubies and it certainly made the clutch lighter and perhaps a bit smoother.

I’m used to the standard clutch and wouldn’t bother doing the mod again unless my arthritis in my ankles gets worse, but I’m glad I tried it.g