Lotus Elan

Heavy clutch, short pedal travel

PostPost by: alanr » Fri Feb 22, 2019 4:22 pm

The clutch on my +2S/130 is very heavy with what seems to me quite a short pedal travel making the gearchange less than perfect.
I only acquired the car last October and have not run it on the road much yet.
Having nothing to compare it with I am wondering if this is normal? Does the +2 have a reputation for a heavy clutch with short pedal travel?
I recently replaced the slave cylinder due to it leaking (P Matty replacement)and the free play adjustment on the bellhousing clutch lever arm has a mere 1/16th-1/8th play as normal. The internals ..pressure plate/disc etc. are an unknown quantity.
The pedal does not go down to the floor/bulkhead and I assume it is hitting a pedal travel stop. I am slightly nervous about adjusting this travel stop due to the effect increased travel will have on pressing the clutch pressure plate in the bellhousing.
Advice and thoughts appreciated.

Alan
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PostPost by: oldelanman » Sat Feb 23, 2019 8:27 am

Short pedal travel and high effort could be the result of fitting a 3/4" dia slave instead of the correct 7/8" dia. ... externally they look identical. You may have been supplied with the wrong item.

Have a look here......lotus-gearbox-f37/clutch-slave-cylinder-diameter-t35834.html

If you had the symptoms before you changed the slave cylinder then the master cylinder may be incorrect. Unfortunately, in either case, the only way to tell for sure is to physically measure the bores.
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PostPost by: alanr » Sat Feb 23, 2019 8:39 am

Thanks for the input ,however the slave cylinder is 7/8ths bore the same as the one I replaced it with.
What should the correct clutch master cylinder bore be?

Alan
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PostPost by: oldelanman » Sat Feb 23, 2019 8:57 am

The master cylinder should be 5/8" dia.
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PostPost by: Concrete-crusher » Sat Feb 23, 2019 9:13 am

Re short travel, have you checked for wear in the clevis pin, many of the new cylinders are supplied with incorrect push rods and your expected to use your existing pushrodehich could be worn.

Also check the slave cylinder is not moving backward when activated, I needed to add a shim to mine behind the circlip

Heavey clutch would be to do with the pressure plate or friction between the clutch plate and shaft

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PostPost by: oldelanman » Sat Feb 23, 2019 9:29 am

Steve,
Good point re using the old pushrod but wear and free play would give rise to longer pedal travel not shorter wouldn't it ?
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PostPost by: derek uk » Sat Feb 23, 2019 11:13 am

This can happen when the clutch diaphragm loses its action and flattens out. When working normally the pedal action softens after the initial movement to "release" the plate. Non-diaphragm spring clutches have the same, often heavy feel throughout the pedal travel. Diaphragm clutches were developed to give a much softer action but still retain the normal, or better, holding pressure.
Unfortunately, the cure is to change the clutch, it might well be the original.

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PostPost by: alanr » Sat Feb 23, 2019 12:29 pm

Yes my fear is that it is the pressure plate.
I think I need to remove the master cylinder first though and check the bore and also pushrod to eliminate hydraulic possibilities.
It is the short travel that is slightly baffling although I suppose if the pressure plate is tired and old that might explain it also being heavy.
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PostPost by: JonB » Sat Feb 23, 2019 2:20 pm

I'm watching this - have the same heavy, sticky clutch action on mine.
Late 1972 Elan Plus 2S 130/5 - UK - Unit 50/1115L
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PostPost by: alanr » Sat Feb 23, 2019 3:37 pm

Hmmm...I am unsure if it is good to know that somone else has the same problem! However the upside is at least I now know that is not just me having a feeble left leg! :wink:
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PostPost by: joe7 » Sat Feb 23, 2019 6:02 pm

Rather than removing the master why don't you just get the part number off the side. Also there are different exterior cast marks that indicate the bore size. They are a cast ring around the outside of the cylinder bore. One size has 1 ring and the other would have 2 rings. I forget which is which but knowledgeable people on this site probably know.
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PostPost by: alanr » Sat Feb 23, 2019 6:07 pm

joe7 wrote:Rather than removing the master why don't you just get the part number off the side. Also there are different exterior cast marks that indicate the bore size. They are a cast ring around the outside of the cylinder bore. One size has 1 ring and the other would have 2 rings. I forget which is which but knowledgeable people on this site probably know.



A brilliant idea...Hadn't thought of that! :D

Thanks,

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PostPost by: JonB » Sun Feb 24, 2019 12:49 pm

Alan, just so you know, I checked my clutch slave and master cylinders and they are correct, yet I still have a heavy, sticky clutch action which prevents smooth gear changes. I measured how much force is required to press the pedal and it is 23Kg!

I drove vincereynard's car Toad (a 130/5 like mine, but with all new clutch components), and it was still heavy, but easier to move because there wasn't any stickiness. I would be happy with that action on my car. I also tried the clutch in another car (a very beautifully restored example), and it was heavy too; relative to a modern car.

I think that's the point. Modern cars have so much better clutches and we have become used to them. I guess "they all do that, sir" is the situation here. Best you can do then is make sure the mechanism is up to snuff, once you have eliminated the hydraulic side of things. And that includes the short flexible section of hydraulic pipe just by the bell housing (if yours still has this); I can imagine that swelling and causing problems. I think mine is still the original piece, so I will be replacing the whole run with braided pipe (eventually).
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PostPost by: alanr » Sun Feb 24, 2019 2:22 pm

Hi Jon,

That information is exactly wanted I wanted to know thank you! :D
23kg!... that is quite a lot of push needed and if you have tried other cars and say that they all feel heavy the same then maybe I just have to get used to the way it is and as you say ensure it is the best that it can be.
Mine has had the original flex tubing changed to a short stainless steel flexible braided section under the bellhousing which connects to a solid pipe up to the master cylinder so I think that is all ok.
I do though need to check the numbers as suggested on the master cylinder to see if they are correct some time this week.
I also still think though that I am not getting full pedal travel so I will probably investigate that a bit further before I either accept it as it is or pull the engine and box out which of course will be a last resort!

Many years ago I served an apprenticeship in a main Ford dealership and I don't remember the gearboxes being quite as notchy though as mine currently is. The synchro's are fine just the change is not smooth as though the clutch needs to clear a bit more...Maybe time has led me to forget how the gearboxes really were back in the day.
It of course doesn't help that my daily driver is a BMW with a virtually seamless 8speed automatic gearbox!
Thanks again for the info,

Alan.
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PostPost by: alan.barker » Thu Feb 28, 2019 9:07 am

Is the shaft where pedal pivots rusty
Alan
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