Grub Screws to set Clutch Toggle Lever Height

[Dave Mann]

It's all very well measuring from the clutch plate, the more important reference is the bell housing face as I've come across two engines recently where the flywheel has been lapped onto the crank so much that the flywheel boss had to be machined to stop it bottoming on the rear main bearing.

[Jamie]

A good point, Dave, about lapping.

I have now lowered the fingers and are all just under 1.25", being 1.16", 1.19" and 1.2". Everything operates smoothly on the bench.

I shall leave them at this until the flywheel is in the engine and I can measure the height from the bell housing: unless others' experience would mean that I have now set the fingers too low.

Regards,

Jamie

[Hedd_Jones]

It's all very well measuring from the clutch plate, the more important reference is the bell housing face as I've come across  two engines recently where the flywheel has been lapped onto the crank so much that the flywheel boss had to be machined to stop it bottoming on the rear main bearing.

does anyone have this dim please?. Bellhousing face to 4speed toggle face

The engine I have taken out of the car, a 4 speed job, the clutch fingers are broadly 0.2'' from the face of the bellhousing. 

The engine that is going back in the fingers are currently nearly 0.5''. 

I am tempted by this roller method to cure having about 1/2cwt of blunt drills to choose from to make rollers. But it would be good to know what I need to be shooting for.

I agree wholeheartedly with Dave, the 1.25'' dim quoted from the clutch plate is not actually a datum. Its a variable!. Though I do accept that it will get me pretty close.

I'm not convinced the 0.2'' dim on the current engine is ideal as it has washers between the rear cover and flywheel, the linings on the plate (borg & Beck or N&B), and a clamp style clutch pedal, and a 3 sync gearbox on a 1934 low chassis case. So its far from standard for a 1934 chrome rad car.

Otherwise I shall measure the lot and see where I get by working the logic. I know from doing similar that 6mm works very well for a 3speed car with standard components.

[Parazine]

Hedd, I agree with 6mm for a 3 speed, works well.

Interestingly, I built up a 3 speed clutch over the Xmas holidays, this one used original (not replacement) levers. They were originally made of soft steel and bend easily to set the correct clutch height, unlike the modern replacements, which are glass hard.

Has someone making the replacement levers got the wrong end of the stick here?

[Hedd_Jones]

I have never felt the need to buy new levers yet, though this is the first 4 speed I have messed with. 

All the original 3 speed levers bend easily as you say.

[JonE]

Hedd, I agree with 6mm for a 3 speed, works well.

Interestingly, I built up a 3 speed clutch over the Xmas holidays, this one used original (not replacement) levers. They were originally made of soft steel and bend easily to set the correct clutch height, unlike the modern replacements, which are glass hard.

Has someone making the replacement levers got the wrong end of the stick here?

it's not just the material, its the fact that there is now a one size fits all... the original 3 speed pattern no longer exists so one has to bodge elsewhere to get back the slight travel lost. V. recent article by Dave Mann somewhere (PW mag?) 

But, we can't have reasonably priced parts AND supply and manufacture as per 1929. Tony's explanation over manufacturing processes, versus what people will actually pay, is extremely interesting. I'm presuming that there are still enough decent old levers in club parts boxes for people not to be unduly concerning themselves?

[Hedd_Jones]

Jon

I have plenty of spares. 

I also find this buisiness of taking out all slop in the clutch interesting. The whole affair is steel on steel with no formal lubrication. 

So long as the toggle to post pin in not like half worn through Ive never found a problem. You just set the toggles to the right height with force pushing them in, andmake sure they are all equal and the clutch works fine every time

I once got involved with a model engineer who had built up everything with weld then re machined it all to to what appeared F1 tolerances. Apparently after 2 or 3 tests the whole thing locked solid. 

One of the posts had picked up in the rear cover and that was that. As often happens when building up parts when steel on steel. But on distmantling the posts wouldnt turn in the pressure plate, and were very tight in the in the cover. Same goes for the toggles in the slots. 

Half an hour with a file, introducing what he termed 'slop', had it all working perfectly. He was most disgusted but gratefull.  

A bit of slop makes

[Steve Clare]

I used rollers with advice from Terry- It's an excellent mod, not just regaining the correct position for the levers, but making the clutch action remarkably smooth for a seven.

[Hedd_Jones]

Just to update. Used the roller method tonight. 2 different size rollers used. 

I shot for 6mm from a straight edge over the bellhousing, got a smidge over 0.25 inch. This is about 1.15 from the clutch plate. 

Seems to work on the stand.

[Dave Mann]

    Comparison of an original 3 speed toggle lever with a 4 speed one was in November 2021 PWA7 magazine.