Lotus Elan

Clutch pedal travel and clutch pedal stop

PostPost by: huggy59 » Sun Nov 20, 2022 9:08 pm

Engine rebuilt back in car with new clutch and master/slave cylinder (correct sizes and 2mm freeplay)

My problem is clutch operate perfectly on 2/3 of lenght however on last 1/3 (pedal to the floor) I'm unable to get any gear (don't engage).

A the moment I put a litlle piece of fuel hose on master cylinder rod to limit movment to the first 2/3

Question is:
- A bump stop could be needed on clutch pedal as per accelerator one ?
- What can I do to avoid this problem without making a bump stop ?

Thanks !!
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PostPost by: pptom » Sun Nov 20, 2022 9:40 pm

I had a similar problem with a new clutch (heavy duty one) in the end I decided that the last bit of pedal motion pushed the clutch too far and caused it to lock back up as if it was back on.
I thought it could have been pushing the pressure plate centre against the friction plate centre.
It was always just ok when driving, but if I wanted first or reverse it just wouldn't go in until, like you, I released the pedal a bit to 2/3 travel and it was perfect.
I'll have a look tomorrow as I can't completely remember how I got around it and don't want to send you in the wrong direction.
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PostPost by: mbell » Sun Nov 20, 2022 10:20 pm

Make sure the adjustment rid is adjusted correctly on the slave cylinder, should have two mm of free play (with spring removed).

What car is it? The plus two legal box does have a legal limiting bolt for the clutch. But sure about the elan.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: huggy59 » Sun Nov 20, 2022 10:23 pm

Thanks for your answer.
Rod free play is correctly adjusted.
It is a baby Elan s2
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PostPost by: huggy59 » Sun Nov 20, 2022 10:26 pm

pptom wrote:I had a similar problem with a new clutch (heavy duty one) in the end I decided that the last bit of pedal motion pushed the clutch too far and caused it to lock back up as if it was back on.
I thought it could have been pushing the pressure plate centre against the friction plate centre.
It was always just ok when driving, but if I wanted first or reverse it just wouldn't go in until, like you, I released the pedal a bit to 2/3 travel and it was perfect.
I'll have a look tomorrow as I can't completely remember how I got around it and don't want to send you in the wrong direction.


Many thanks !
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PostPost by: 512BB » Mon Nov 21, 2022 9:19 am

I would be trying to understand what is causing the problem and then working out a fix. How about removing the rubber boot from the clutch lever on the bellhousing, and then getting a helper to operate the pedal whilst looking into the housing with a light to see what is actually going on.

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PostPost by: types26/36 » Mon Nov 21, 2022 9:23 am

huggy59 wrote:Engine rebuilt back in car with new clutch and master/slave cylinder (correct sizes and 2mm freeplay)Thanks !!

You say it is a new master cyl but does it have the correct length push rod ? I believe new m/cyls can have the wrong push rods fitted.
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PostPost by: huggy59 » Mon Nov 21, 2022 11:09 am

types26/36 wrote:
huggy59 wrote:Engine rebuilt back in car with new clutch and master/slave cylinder (correct sizes and 2mm freeplay)Thanks !!

You say it is a new master cyl but does it have the correct length push rod ? I believe new m/cyls can have the wrong push rods fitted.


Interesting thanks.
Master cylinder have an adjustable rod since it’s rebuild.
So perhaps rod is too long now.
However it is needed to have all 3 pedals at same level
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PostPost by: types26/36 » Mon Nov 21, 2022 12:45 pm

Have a read of these threads as push rod lengths are discussed.
viewtopic.php?f=42&t=43397
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PostPost by: pptom » Mon Nov 21, 2022 3:49 pm

Hard to say if mine were the original master and slave after 50 years, but at the time of recommissioning the car I only changed the seals (now both new)
The only difference in my case we're the pressure and friction plated (helix from qed)
Also, mine is a +2.
What I did was to fit a bump stop in the cabin, at the top of the clutch pedal. It's just an m8 bolt attached to the pedal box support bracket. (I also made the support bracket, so don't know if that is original.
Unlike messing with the pushrod length it keeps the pedals at the same level.

IMG_20221121_141559_copy_864x1152.jpg and
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PostPost by: huggy59 » Mon Nov 21, 2022 9:53 pm

512BB wrote:I would be trying to understand what is causing the problem and then working out a fix. How about removing the rubber boot from the clutch lever on the bellhousing, and then getting a helper to operate the pedal whilst looking into the housing with a light to see what is actually going on.

Leslie


Yes will do.
For tonight I just looked at slave cylinder: nothing strange when operated 2/3 for full lenght.

HOWEVER I discovered I'm able to get any gear on full lenght with engine switched off.
Engine started at idle: Impossible to get a gear on full lenght (but perfect at 2/3)

Strange isn't it ?
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PostPost by: huggy59 » Tue Nov 22, 2022 7:32 am

pptom wrote:Hard to say if mine were the original master and slave after 50 years, but at the time of recommissioning the car I only changed the seals (now both new)
The only difference in my case we're the pressure and friction plated (helix from qed)
Also, mine is a +2.
What I did was to fit a bump stop in the cabin, at the top of the clutch pedal. It's just an m8 bolt attached to the pedal box support bracket. (I also made the support bracket, so don't know if that is original.
Unlike messing with the pushrod length it keeps the pedals at the same level.

IMG_20221121_141559_copy_864x1152.jpg


Thanks for sharing.

Need to double check but I think my pressure and friction plate is Helix HD
At the moment I use a small piece of fuel hose to limit clutch pedal travel to 2/3.
It works well but I would prefer to understand what happens on the last 1/3 of travel.

Image

I will lift car and had a under inside bellhousing engine stoped and running. Perhaps I will understand more.
We keep in touch !
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PostPost by: Craven » Tue Nov 22, 2022 11:51 am

There is some talk that with a diaphragm clutch you can go over the max opening point and the diaphragm starts to close again.
FWIW
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PostPost by: huggy59 » Tue Nov 22, 2022 1:24 pm

Craven wrote:There is some talk that with a diaphragm clutch you can go over the max opening point and the diaphragm starts to close again.
FWIW


I think your are right.
It is the only cartesian explanation but still not understand why it happens only when engine running.

Will have a look asap under ther car to see if i can find some evidence of "over opening" when fully operated.
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PostPost by: mbell » Tue Nov 22, 2022 3:00 pm

What bore are the clutch master and slave?

A miss match could cause increased slave movement to master, that might cause the clutch behavior.
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