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Clutch not releasing 100%, MY90 SE - Gearchange/Gearbox/Clutch - The Lotus Forums #ForTheOwners Jump to content


Clutch not releasing 100%, MY90 SE


Corban

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After fitting new primary and secondary injectors the other day I took her for a test drive. Everything was working just fine at first but when the engine gets warmed up the clutch have had a tendency not to release fully. I have put this down to the famous "red hose syndrome" and it has never been a major issue. However, this time, after reving to 6500 rpm in first, I couldn't change up to second gear. It wouldn't even go into neutral, stuck in first. Since I was very near my house I just limped home in first. Managed to go to neutral at a certain rev (guessing wheels/engine revs matched). Convinced the "red hose" was the culprit I changed to a braided one, expecting the problem to go away but it didn't.
Below is a table of tests/checks performed and some left to do:

clutchtable.thumb.JPG.d06208924cf0354f8d
With the rear of the car on axle stands, engine running and in first gear, the wheels rotate with clutch pedal depressed. Applying light brakes, the wheels stop without engine stalling (just a 100-200 rev decrease when idling).
I'd say it releases to 95%. I can not get it in reverse with pedal depressed, grinding gears. I have also looked at the gearchange translator but nothing seem to have come loose there.
I have locked the pedal depressed with a wooden block to see if the slave gradually returns indicating a leak in the system but after 30min the push rod is still in the same place.

If the fork is broken, will this be visible outside the housing or can it brake inside?
Is there a pivot point for the fork that can wear down?
The clutch release bearing I guess has some material that might wear touching the pressure plate?
The pressure plate itself worn down?

Suggestions of what the problem is and how to check it (preferably without removing the gearbox) are most appriciated :)

========================================
Torque times RPM equals horsepower!

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How does the pedal feel? Firm, extra firm, soft?

Draw a line on the translator and the cross shaft and see if the translator moves relative to the cross shaft when it is shifted. The pinch bolt can get loose.

The release bearing can fail, the clutch can fail, the fork can break inside the clutch housing, it should feel loose if broken..

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Henrik,

Nice table. 

Is the rod the correct one for the slave and master? Always assume PO's are complete morons, because a lot are and mismatch components so that adjustment per the service notes doesn't yield the correct results. Is the pedal attached correctly to the master's pushrod (two holes on the clutch pedal on the SE marked B for Brake and C for Clutch...check yours is right. Mine wasn't). Grinding in reverse is kind of common. Select 2nd prior to reverse and it usually disappears, otherwise if it's always doing that you need to fine tune the translator. 

+ 1 on the pinch bolt getting loose, I've experienced this although it didn't lock me out of gears, just made changing a chore. 

With the wheels off the ground the wheels do indeed rotate in neutral! There's friction between the gearbox and the engine (input shaft) that's just enough to move the wheels. You can probably stop them by putting your hand on them. 

Re adjustment screw, someone had screwed mine all the way in. Car was running like this for god knows how long, but yeah the added thread should work in favour. Any slippage when driving? 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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  • Gold FFM

Henrik,

I've had similar after changing the clutch on my previous SE. I was convinced it was bled properly, but couldn't get enough travel on the slave to fully disengage the clutch. During the replacement the pushrod accidentally got pulled out of the slave, so I know there was air in the system at some point. You could have the same due to replacing the red hose with a braided one. I must add when I installed the braided hose (2 years before the clutch change), I didn't have any problems with air at all, I just bled it on my own, 2 strokes of the pedal with the nipple open, and all was well. Which is why I never could understand why it was so hard with the new clutch. I released the pushrod from the clutch fork and put big pliers on the fork to see if it would disengage when moved manually, to be sure the problem wasn't the new clutch or how we fitted it. That did work, but took more travel than the slave was providing. I remember measuring 15mm, but not sure if that was the final travel. I pumped the slave, with the clutch pedal up and the reservoir open, and that got it working. We had to use the same trick on a Range Rover as well, also because traditional bleeding didn't seem to work.

As an aside, you don't need to have the engine running to check if the clutch is disengaging, simply put it in gear and jack up one wheel. If it can be turned easily, the clutch is disengaged. A bit more relaxed then working on a car on stands with the engine running.

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Thank you all for replying. I like to do tables when I'm troubleshooting. It easy to overlook the obvious otherwise :)
And it quickly shows actions taken when you ask others for help.

Advised by Sparky I did a rebleed with the slave detached and nipple pointing upwards and although I bled it with a suction device earlier I still managed to get two tiny bubbles of air leaving the slave. Pumped like 5 reservoirs through the system just to be sure and there were no more air bubbles visible.

This did give a better feel to the pedal, it now feels firm.

My rear wheels do not rotate when in neutral but they rotate in gear with clutch pedal depressed fully. Applying a light touch to the brakes stops the wheels without stalling the engine. It will loose about 100 rpm when I do this so I conclude that the clutch is not fully disengaging.
There is no slip when the clutch is engaged.

Things to check:

Length of pushrod, what is the correct length?

Remeasure travel of slave (15mm), what is the correct value?

Check again if the correct hole in the pedal is used. I have checked this by feeling with my fingers but I can't find any unused hole. Do all pedals have two holes?

The pushrod can be rotated using finger tips but not moved.

No visible damage to the fork. I can wiggle it by hand some millimeters, is this normal or should it sit firm? 

I think I will try Escapes method for bleeding before I remove the gearbox. Pumping the slave only (why didn't I think of this). Will save me lots of running around the car.

========================================
Torque times RPM equals horsepower!

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  • Gold FFM

The pushrod should be 12.5mm from the locknut to the end of the thread. But a small difference should not prevent the clutch from disengaging, the slave has some margin. And a longer length would only help in disengaging I experimented with the length when I had trouble, but it made no difference.
I can't find the travel of the slave in the workshop manual, but I think the 15mm I measured was before the clutch was disengaging fully. You can always measure yourself by detaching the slave and operating the fork manually.

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Good advice on measuring the slave stroke with the slave detached.
Maybe pushrod was the wrong word, I guess the 12.5 mm refers to the protrution of the adjustment screw. I was thinking about Vanyas mention of the "rod lenght", the length of the pin/rod that goes from the slave to the fork adjustment screw.
How long is it supposed to be?

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Torque times RPM equals horsepower!

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  • Gold FFM

Yes, I did mean the protrution of the adjustment screw. The rod in the slave, if not replaced, should match a standard clutch and slave of course (though we did once have to lengthen the pushrod on a Freelander to get the clutch to operate smoothly, never found out why).

When measuring the free movement of the slave, make sure the rod doesn't pop out! I actually meant you could move the clutch fork (with pliers or such for added leverage) and see how far that can and should move for full disengagement. Then compare to the travel of the slave to see where the problem might be.

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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  • 4 weeks later...

This week I got my new uprated clutch kit from PNM (30% stronger) and I plan to fit it this weekend. I have removed all that is needed to slide the gearbox back except gearbox mountings and bolts holding the gearbox and engine together. I even removed the turbo because it seemed a good time to do it with the floor out, and sent it away for an upgrade (hopefully back upcoming week).
My plan is to slide the gearbox back without separating the drive shafts (seen in some threads on this forum) but I am not sure on where to unbolt the gearbox from the chassie.

removeGB.thumb.JPG.66252243a069ebf9e22be
Removing no 44 and 45 looks like you'll have to remove the lower-inner mount for the hubcarrier strut (see below)
bulten01.thumb.JPG.56fa8883abddee8eadbf2
Should this be done with the wheels loaded or should they be hanging freely? Will things move away in an unforseen manner?
Advice on how to free the gearbox from the chassie is most welcome. Releasing from the engine seem pretty straight forward.

========================================
Torque times RPM equals horsepower!

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  • Gold FFM

Hi mate, PM answered.  You can undo those arm mounts with the wheels off the ground, no problem.  There won't be a lot of movement.  Good luck with the attempt!  Never tried it that way myself, but it's rumoured to be possible.  If not, you're only seconds from detaching the driveshafts at the yoke anyway.

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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I wouldn't do it - it will be like keyhole surgery without the correct tools - Removal of the driveshafts is not difficult, either use Sparky's method or get some good quality punches and drive them out confidently with a fairly heavy hammer - to avoid simply peening them in place.   NB your original clutch problem maybe an internal leak in the master cylinder    

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Hi corban

it depends on how much you can backward the gearbox and if you not detach the drive shaft , then alternative is 

removed the drive shaft nuts  and push back the driveshaft. i think you don't need to remove lower link.

it's easy to remove  old couch but it's hard to mount the new clutch with very short free space.

Good luck 

Yasuo

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  • Gold FFM

Yasuo - the lower link has to come out to allow removal of the gearbox mounting bolts.

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Success so far! :)
Removed lower link. Removed GB mounting bolts. Removed bolts connecting GB to engine. Before that I took the load off the engine on a wooden block and a jack under the sump and another jack with a rubber pad unstrained the GB. Expecting to use a lot of force and trying to remember where I put my crowbar, I figuered I would just wiggle the GB a little. Much to my surprise I could pull it backwards with ease just using my hands.
20151017_183102_resized.thumb.jpg.86c3eb
Got it all the way back :)
20151017_183029_resized.thumb.jpg.059902
This, I think might be sufficient space to change the clutch...
20151017_183044_resized_1.thumb.jpg.f73d
Should the clutch really be "bearded" like this...??? :lol: Think I might have found the problem. I DO NOT think it should look like this.
What has happened?
As I was on winning streak, I decided to try to loosen the bolts attaching the clutch to the  flywheel.... but the engine rotated as I did this and somewhere in the back of my mind an alarm set off about rotating the engine the wrong way, so I stopped to go inside and check which is the right direction for this engine and ask for advice on how to lock the flywheel from rotating.

Edited by Corban
baaaad spelling

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Torque times RPM equals horsepower!

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Sorry about lower link, Sparky is right, to remove bolts need to removed the lower links,

Remove the cluch bolts, I had no problem without lock the flywheel last time I did.

Yasuo

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  • Gold FFM

Use physics - take the bar across the geometric centre of the clutch, a sharp tug, and they'll move easily. They're pretty low torque.

  • Like 1

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Simple but genious Sparky, why didn't I think of that? Wont be much torque if I apply force on the spanner when it is pointing to the center of the flywheel.
Hmm... even at 90 degrees, pulling away from the center should work.

@Barry, thanks! reassembly might be another story...

Edited by Corban

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Torque times RPM equals horsepower!

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hmmmm.... don't think it should look like this...
20151018_101043_resized.thumb.jpg.d470b2
Summary of todays work, removed the old clutch and found the cause for my original problem. Debris from the broken clutch unabled total disengagement.
Bought a torque wrench and a center tool and the right kind of grease. Cleaned up the fork and its adjustment screw (push pin to slave) and refitted in housing. A little tricky to get the spring in the right position on the pivot.
Lined up pressure plate and center on the center tool and jiggled it into position. Torque tightened the bolts to 24Nm gradually while rotating the flywheel. Pushed the GB into place and this is where things started to go pear shaped. Think I got the splines right but it refused to slide into the flywheel bearing. After some two hours I removed the bolts that i managed to fit and slid the GB back again. Couldn't see anything wrong so I pushed it back again, this time with the intent to fit all the screws and keep the gap even all around. Tightened them diagonally but with 10 mm left it only increased tension. Then I got the idea to depress the clutch pedal, thinking this might release the tension and letting things center by itself if they were a little off. Much to my surprise when I returned from the drivers seat, I could rotate the screws with my fingers so something had happened. After that it was just tightening bit by bit, moving around the screws diagonally. So clutch and gearbox are back in place :)

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Torque times RPM equals horsepower!

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Good job man!!!! 

Re the lower links to the chassis - (if you haven't already discovered this): you'll need to compress the spring to get them to align with the hole. 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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Thanks!:)  I blame the clutch on the PO, I have only driven a few hundred kilometers and the PO took the car to a garage, complaining that the clutch didn't disengage when the car got warm. They cleaned THE SLAVE!!! I bought the car from the garage (PO got tired of waiting and decided to let them sell it for him) and put the clutch problem down to the red hose syndrome which they had never heard of!!! Garage used to be an autorized Lotus dealer but do I need to say they aren't anymore, havn't been for a couple of years but they still benefit from past meriths.

I used two jacks to connect the lower links again. One under the hubcarrier and one to push the link into place. Some wooden blocks and a hammer were also involved in this.

Hopefully my uprated turbo will arrive from the workshop this week so I can put the rest back together.
Can't wait to get her back on the road again :driving:

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========================================
Torque times RPM equals horsepower!

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