Lotus Elan

clutch adjustment question

PostPost by: Concrete-crusher » Sat Sep 22, 2018 2:54 pm

Since I fitted a recon gearbox a year ago , I have struggled with notchy gear changes and difficulty selecting 1st and Reverse

I have found today that if I adjust the slave cylinder nut to remove the 2mm free play and give it a few more turns , the gear selection problem seems to have gone away. I've not road tested this and have returned to the 2mm free play and found the gear selection problem returned.

The clutch plate is a new heavy duty plate , the clutch cover is a new old stock cover but without the thrust pad , I therefore have a spacer to give the required clearance.

so is it considered ok to tighten up the adjusting nut giving a bit more pressure on the clutch ? or will this lead to premature failure of the bearing

Or is it a bleeding problem ? I have tried several time to bleed the system to remove any air , its awkward like most lotus fittings being close to the exhaust downpipes

steve
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PostPost by: StressCraxx » Sat Sep 22, 2018 3:41 pm

Check the amount of travel you lose from "lost motion" due to slop in the clutch pedal lever and clevis, also the motion of the slave cylinder in the bell housing fit. I replaced the clevis on the master, the worn out pin and added an extra circlip to hold the slave cylinder tight in the fit.

You are right, leaving no clearance will quickly wear out the release bearing.

Regards,
Dan
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PostPost by: rgh0 » Sat Sep 22, 2018 11:40 pm

Your non standard clutch cover assembly may require more travel in the clutch throw out bearing than standard to fully disengage. Adjusting out the free play on the lever arm gets you that additional travel but will result in potentially a short clutch throw out bearing life as it will always be spinning as its always in contact with the clutch cover. An adjustable push rod on the clutch master cylinder pedal can help eliminate free play at the pedal and get extra travel but you need to be carefully to ensure the master cylinder fully returns to open the valve that adds any needed extra fluid from the reservoir.

You need to work through the details of your clutches operation and decide how best to compensate for the modifications made or alternatively revert to a standard clutch setup.

cheers
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PostPost by: alan.barker » Sun Sep 23, 2018 6:07 am

Try the old method to wedge the Clutch Pedal down and leave over night. Then try the next day.
You've got nothing to loose to try it.
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PostPost by: Concrete-crusher » Sun Sep 23, 2018 6:42 am

Thanks I have found excessive movement on the peddle and can see the clevis is elongated , I see lots of ads for new pins but none for the clevis , will have a ring around Monday to try to find both

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PostPost by: nmauduit » Sun Sep 23, 2018 8:32 am

Concrete-crusher wrote:The clutch plate is a new heavy duty plate , the clutch cover is a new old stock cover but without the thrust pad , I therefore have a spacer to give the required clearance.


you have a spacer where (and how thick)? any chance that this would have altered the resting fork angle, then effectively reduced the operating travel at clutch spring fingers?
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PostPost by: Concrete-crusher » Sun Sep 23, 2018 4:20 pm

The spacer fits inside the bearing carrier pushing the bearing forward 8mm , it doesn?t change the angle of the fork which sits nicely mid way in the bellhousing slot.

You need the spacer if you have a clutch cover without the thrust pad , you also need a rounded bearing

At least that?s what I was told

I?m pretty sure now the problem is the clevis which has elongated and results in quite a bit of free movement on the clutch peddle

The not so funny thing here , is I now have an expensively reconditioned gearbox waiting for me to fit to address the problem and it?s most likely a worn clevis and pin costing less than a tenner ahhh
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PostPost by: gus » Sun Sep 23, 2018 6:00 pm

IIRC as the clutch wears, the arm moves towards the slave cylinder. Adjustment is only so you can back it off and the actuator rod doesn't bottom out in the slave cylinder. I would loosen the nut and push the rod as far as it can go into the slave, pushing fluid back into the master. Then adjust the rod so there is maybe 1/4 or so play. when you step on the pedal it will require several pumps to get to normal.

Other wise I cannot see how the adjustment is going to do anything
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PostPost by: Bigbaldybloke » Sun Sep 23, 2018 7:31 pm

Just one other possible thing contributing to your problem, is the flexible hose old and expanding under pressure? This could reduce your slave cylinder travel under the extra load from your updated clutch.
Change is inevitable, except from a vending machine!
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PostPost by: gjz30075 » Tue Sep 25, 2018 8:57 am

I fixed worn clevis' by welding a washer on either side, essentially making 'new' holes.
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PostPost by: Concrete-crusher » Wed Sep 26, 2018 6:21 am

Well it seems problem solved. The answer was a new threaded clevis and new pin , it?s adjusted a few extra turns , I still have my 2mm gap at the slave cylinder and gears selection is fine at last

The original clevis is 80mm in length , quite short and I needed to grind away some of the new adjustable clevis to make it fit , also I cut down the threaded bar which was 80mm on it own.

With such a short clevis , does anybody know the actual bore length of the master cylinder ?

Last point and an observation , the bite point on the clutch has moved up , meaning more disengaging

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PostPost by: oldelanman » Wed Sep 26, 2018 8:13 am

With such a short clevis , does anybody know the actual bore length of the master cylinder ?


My master cylinder stroke is 36mm and pushrod length from clevis pin C/L to end 82mm.
If your new pushrod is longer make sure you still have some freeplay to ensure the piston returns fully.
Roger
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PostPost by: Concrete-crusher » Thu Sep 27, 2018 7:18 am

Thanks that?s interesting my original pushrod length from cl to end is 74mm and in effect I have increased to something like 76mm .

First it has cured the problem for now anyway , but also moves the peddle up to a higher resting position , so I?m wondering if some cars have 80mm rods is the hole in the peddle arm in a different position , otherwise the peddle would be too high ?

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PostPost by: nmauduit » Thu Sep 27, 2018 8:16 am

Concrete-crusher wrote:Well it seems problem solved. The answer was a new threaded clevis and new pin , it?s adjusted a few extra turns , I still have my 2mm gap at the slave cylinder and gears selection is fine at last

The original clevis is 80mm in length , quite short and I needed to grind away some of the new adjustable clevis to make it fit , also I cut down the threaded bar which was 80mm on it own.

With such a short clevis , does anybody know the actual bore length of the master cylinder ?

Last point and an observation , the bite point on the clutch has moved up , meaning more disengaging

Steve


once you have assured the proper operating play for the clutch mecanism at the slave (in your case say around 2mm when all plays further down are taken up) the pedal height can be adjusted at the master cylinder side (there should be enough travel on the pedal side to level them confortably to most people liking). On the Plus2 there may be a travel limiting stop to adjust in the end (bolted to the pedal lever).
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PostPost by: saildrive2001 » Mon Oct 01, 2018 7:09 pm

Steve where did you get the threaded clevis & rod from? The fixed rod & clevis has a mushroom head on it at the MC end what did you do about this?
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