Clutch return spring

[The Veg]

Found this thread looking into things with my clutch.

What I have found is that when the return spring pulls the arm all the way forward so that the piston is fully retracted, the amount of travel required to disengage the clutch is too great, causing a need to pump the pedal. I think that this is why after doing so, holding my foot lightly on the pedal made every push work as it should. The rod is adjusted to the far-end of the threads. If I remove the spring and pump the pedal a little, everything settles and works right and I can even get that nice 2.1mm adjustment- but as stated in replies above, it's apparently NOT right as the piston isn't all the way in (but that said, it doesn't pop out at the end its travel either). So either the rod is too short or something else is wrong. The rod-length is the easiest thing to check, so let's start there. How long should it be?

[2cams70]

There's no correct length for the rod. The length depends on whether it's adjusted for a worn or new clutch. The only set measurement is the clearance between rod and fork

[rgh0]

Sounds like you may have something wrong with the clutch set up if the adjuster nut is at the rear end of the threads but still to much free play with the clutch release lever

Using a different thrust bearing or pressure plate can create a different assembly height causing this problem

Do you know the details of the clutch assembly ?

I will check the length of the slave cylinder rod tomorrow when i am in the garage.

cheers
Rohan

[draenog]

According to Burton:

https://www.burtonpower.com/clutch-slave-cylinder-pushrod-nut-assy-mexico-2000e-gb2e200.html

Total length is 120.8mm.

[The Veg]

Sounds like you may have something wrong with the clutch set up if the adjuster nut is at the rear end of the threads but still to much free play with the clutch release lever

Using a different thrust bearing or pressure plate can create a different assembly height causing this problem

Do you know the details of the clutch assembly ?

This is entirely possible- has it been known to happen? I've never had eyes on the actual clutch as I've yet to have the engine out. I do know that (as mentioned in many of my question-posts) the car's second owner had the engine out and rebuilt it, incorporating some upgrades in the process. This was done around ten or more years ago but only about 400 miles ago, and the third owner wasn't very mechanically knowledgeable and put few miles on the car, so there is some knowledge-gap by the time it got into my hands. Anyway, I do know that the flywheel was changed to a new aluminium one, as I have seen the edge of it through the starter-hole and have seen the invoice for its purchase in the folder of documents that came with the car. As the car had 80K miles on it when the work was done, I would guess that the clutch itself was renewed, but I'll have to look through the receipts. I do also communicate with that second owner from time to time, who seems happy to hear from me and appreciative of all I'm doing for the car (I think he liked it and didn't want to sell it but life's circumstances got in the way). He may be able to shed some light, but was no expert and I don't know what guidance he used for deciding what to do.

This brings us to the need to see for sure what's in there, which means the engine comes out. Bummer, as I've been trying to push the whole project into the realm of drivability lately. I do however have a reason to take it all apart at some point: I bought a five-speed 'box about nine months ago that will have to go in at some point. And it came with a new clutch among the various bits, so perhaps getting that done might solve the current issue as well. Since the whole setup will change when I do that job anyway, I may just leave it as is for the time being and plan to do the gearbox-swap before too terribly long.

[lotusfan]

Found this thread looking into things with my clutch.

What I have found is that when the return spring pulls the arm all the way forward so that the piston is fully retracted, the amount of travel required to disengage the clutch is too great, causing a need to pump the pedal.

My initial reaction to reading that comment was to get you to check that the diameters of the slave and master cylinders were correct. Makes you wonder if the master cylinder is too small a diameter or the slave is too big.

You now have the correct push rod length so that can be checked.

[SENC]

Mine is right at 120mm, as noted above, for an Elan - assume it is the same for the +2? I do seem to remember reading somewhere here that some of the currently available rods aren't the right length, so worth checking. Do you have the correct positioning nut and lock nut, oriented correctly?

[RichardHawkins]

Veg,

When you said your clutch worked better with you foot resting on the pedal, I was reminded.

Not sure if this is relevant, but I was amazed by what I was told.

I was asking advice about clutches and release bearings from a manufacturer LuK (they are suppliers of clutches to many vehicle manufacturers). As you probably know current practice is to have a concentric slave cylinder, my question was about the detail of providing clearance between the release bearing and the pressure plate fingers. I was told there is no clearance, and that the thrust bearing was kept in contact with the fingers at all times by a light spring. I was also told that if the bearing was not in constant contact, it would skid every time the clutch was used followed by rapid wear and failure. I was also told that much work had gone into release bearing design and the lubricant used within it.

I am still surprised by this, but on reflection I have not had to work on a clutch or release bearing since the 1960’s.

My Lotus is a1968 S4 and when I took it apart I found a carbon thrust bearing. I am of the opinion that this bearing would not last in constant contact. Perhaps it took a while before someone came up with the idea explained to me by LuK

Anyone have more information?

Richard Hawkins

[h20hamelan]

Mine is right at 120mm, as noted above, for an Elan - assume it is the same for the +2? I do seem to remember reading somewhere here that some of the currently available rods aren't the right length, so worth checking. Do you have the correct positioning nut and lock nut, oriented correctly?

slaverod.jpg

+2s 5 speed would be different

[h20hamelan]

viewtopic.php?f=37&t=42397&start=75

Some good stuff in here

[The Veg]

Since the discussion of my clutch has moved to this thread, this is where I'll update it here.

To answer some things, I have now verified that the rod is the correct length and that nuts are installed the right way on it. I also did a measurement where I pushed the slave piston all the way in then pushed the arm the opposite direction until the release bearing came into contact then measured the 'wiggle room' and found it to be around 9-10mm. I did notice though that the diagrams of the rod show only the two nuts that push against the arm, while mine has a nylock on the far side of the arm as well- no doubt put there by an overzealous DPO. If I remove that nut I can close some of the gap, but that still puts the rod at the end of its adjustment.

As to the question of whether or not the clutch components are standard items, I'm not sure- but I did find receipts for everything although some are a bit cryptic:

Clutch Specialities, 23 Apr 2008:
1 Aluminum flywheel
and 1 of something listed only as '70 Lotus Elan' that cost almost as much as the flywheel (huh?)

Exchange Parts Co., 21 Apr 2009:
2 Facing
1 Flywheel grind

Tingle's Lotus Center, 17 Aug 2004:
1 Used "S"
1 T/O BRG
1 Press Plt
1 Disc
1 PLT BRG, length .590"

Paul Matty Sports Cars, 17 Sep 2004:
1 Release Bearing
1 M/Cyl Rep Kit 5/8"
1 Clutch Slave Cylinder Kit

So, as I surmised before, it's probably not possible to know the state of things in there without pulling the engine and opening the clutch.

With no return spring and the slave piston not fully retracting, I drove about 30 miles -best drive yet!- and the clutch performed perfectly for the first time I've experienced and the gearchanging was a delight. Keep fingers crossed that it all holds together until the 5-speed transplant.

[rgh0]

It sounds like you have some misfit of clutch components that will require engine removal to rectify. You're interim solution of removing the return spring is fine. The clutch will push itself back when the pedal is released and push the thrust bearing back as far as needed. The thrust bearing will be in light or no contact with the clutch cover thrust pad. This may result in an intermittent squeal or squeak when it touches or the bearing spinning continually with light contact which may or may not shorten its life ( and this may not be important given your plans).

If you want to, you could arrange some temporary external stop to allow the clutch lever arm and slave piston to only come back the distance required to have the small specified clearance and then reinstall the return spring.

cheers
Rohan

[2cams70]

If the internal parts of the clutch aren't standard and have been put together by someone inexperienced it is quite possible that a standard flat face release bearing and release bearing carrier has been incorrectly used together with a pressure plate not having a thrust plate on the clutch fingers (there's two types of pressure plate commonly available and it's easy to mix them up). The consequent excessive clearance between bearing and pressure plate would lead to the symptoms you describe. Suggest have an initial poke around with an inspection camera through the bellhousing clutch fork aperture but most likely the engine and gearbox will need to be separated to fix the issue.

[rgh0]

If the internal parts of the clutch aren't standard and have been put together by someone inexperienced it is quite possible that a standard flat face release bearing and release bearing carrier has been incorrectly used together with a pressure plate not having a thrust plate on the clutch fingers (there's two types of pressure plate commonly available and it's easy to mix them up). The consequent excessive clearance between bearing and pressure plate would lead to the symptoms you describe. Suggest have an initial poke around with an inspection camera through the bellhousing clutch fork aperture but most likely the engine and gearbox will need to be separated to fix the issue.

Yes that is probably the reason IMHO also, but until its pulled apart or inspected with a camera probe or like you say you will not really know. It can be made to work in the interim by the sound of it. Using a pressure plate without the platen and a round faced bearing like on the five speed would cause the lever to move roughly this amount and this may have been done if sourcing thrust bearings or pressure plates was a problem for the standard flat faced bearing and pressure plate with the flat faced thrust ring.

cheers
Rohan

[gjz30075]

^^^^^ most likely explanation so far, I think. Pull the fork boot back and take a peek. It might
require a borescope.