Jump to content


Photo
- - - - -

Clutch Puzzle -

engine

Best Answer Wazzy , 12 April 2019 - 05:55 PM

I now have a working clutch!

 

Thanks for all the advice - all of which was helpful and acted on.

 

If you are interested this is how it went;

 

I was always concerned that the fault might be the master cylinder as it came with a faulty seal but still wasn't working with a new seal. So I swapped the master cylinder for another (new) one. I also changed to DOT 4 hydraulic fluid. These changes did not appear to make any difference but, in the process I found that one of the pedal box bolts was not tightened all the way in. The thread in the baulkhead  was blocked by a splodge of POR15 paint which we had used to protect the floorpan. This sets really hard so gave the feel of a bolt which was tightened but actually wasn't. After tapping out the thread there was an improvement because the pedal box wasn't twisting when the pedal was pushed down. However there was still only 0.5" of travel. As I had already bought a replacement slave cylinder I decided to change this next. On removing the slave it was clear that it wasn't working well - the piston was sticking - not clear why. Changed the slave and I'm now getting 5/8" movement at the slave pushrod and a clutch which engages as the pedal reaches the halfway point. More importantly - the car is drivable!

 

Thanks to all of you who took the trouble to reply to my post. 

 

Tim

Go to the full post


  • Please log in to reply
20 replies to this topic

#16 Moke Spider

Moke Spider

    Crazy About Mini's

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPip
  • 8,546 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 13 March 2019 - 06:25 PM

Thanks again for the replies and ideas.

 

In answer to you Moke Spider;

 

  1. I see your point that changing the push rod will not change the length of travel - only the arc of movement.
  2. I have the normal gasket under the master - its quite a thick card one - and everything is bolted down tight.
  3. The push rod was renewed when I renewed the slave cylinder - the push rod was the same length as the original - and the slave is the type without a circlip.
  4. The clevis pin is in good condition and a good fit in the clutch cover.
  5. I think the suggestion you make about the nut in the master cylinder will not change anything due to what we said above in (1).
  6. Setting the stop adjustment back 1 'flat' gives about 0.004' clearance but that didn't help.

Your other suggestion, about putting a washer between the thrust bearing and the shoulder of the plunger, I can see would change the position of the operating arm relative to the stop adjustment nut. Again though this would not change the travel of the push rod. Also, I would have to dismantle the clutch to do this and again to undo it if it didn't work. I wouldn't mind doing this if I knew it was the issue but if the hydraulics don't seem to be working as they should my gut feeling is sort that out first. I hear what you say about silicone fluids. As I've said I was careful and in terms of time for micro bubbles to settle - leaving it a couple of weeks at times. 

 

It seems to me that my next steps should be to;

  • swap the master and/or slave cylinder (even though they are new) and see if doing that gives better travel

Or

  • Change to DOT 5.1 hydraulic fluid

Unless there are any other suggestions which one first do you think? And any tips on cleaning the old DOT5.0 out of the system before putting the 5.1 in?

 

Thanks agin for your help everyone.

 

Tim

 

Tim,

 

Thanks for your comprehensive reply and I agree, changing anything at the Arm or Push Rod won't help, however, there is one item to check here and that is the Angle that the Arm sits at at rest. You probably need to post up a photo for us on that. If the Angle of Arc that the little Ball on the Arm moves through is not 'through' 90 degrees to the plunger, then the Plunger itself will have reduced movement, but given the short travel at the Slave, I don't feel this is the issue here.

 

Given the Slave doesn't have a Circlip, then the issue I feel is 'upstream' from the Slave.

 

If you look in the back of the Pedal Box, where the Clevis Pins are for the Master Cylinders, with your foot off the pedal you should only have no more than about 4 mm here from the under side of the Pedal, to the bottom of the 'Box'. If you have more than that, then for some reason, the Master is not 'sitting' low enough to get a full stroke. It could be a short Push Rod in the Master for some odd reason, a bent Pedal Box a bent Pedal, worn Clevis hole in the Pedal.

 

I find that with 5/8" stroke at the Slave, the clutch take up is at about 1/2 pedal travel, ie, well off the floor, when they get down about that 1/2" mark,they start taking up just off the floor as you are seeing.

 

Also, regarding fluid, if you are changing away from the Silicon Fluid, I wouldn't recommend going to DOT 5.1 for a road car. The higher the boiling point of Glycol based fluids, the more hydroscopic it is and it will absorb moisture fast. I ran it in the Race Car and was advised to change it out immediately after every meeting and again before every run. I felt that was excessive but learnt the hard way soon after using this fluid. For road use, a DOT 3 would be sensible.



#17 imack

imack

    Super Mini Mad

  • TMF+ Member
  • PipPipPipPipPipPip
  • 588 posts
  • Location: Orpington, Kent

Posted 13 March 2019 - 06:46 PM

You could disconnect the pipe in the master cylinder and fit a bleed nipple instead and see if you get a hard pedal feel. At least you'll know if the master cylinder is ok and free from air. You'll obviously get a little bit of free play at the clevis pin.

#18 Wazzy

Wazzy

    Just On Tickover

  • Noobies
  • Pip
  • 5 posts
  • Location: Leicester

Posted 13 March 2019 - 11:27 PM

Sorry for delay in replying been trying to work out how to add photos - hope what I've done works.

 

Primary gear and crankshaft were 0.005" and 0.002" respectively.

 

The plates were parallel and the set up of the flywheel and pressure plate was checked by John at Guessworks for me.

 

It's a fairly solid new clutch arm - replaced because the ball on the old one had worn out - the ball end has not bent or got distorted. The clutch pedal position seems normal to me - just a bit below the height of the brake pedal.

 

I am only getting 3/8 movement of the push rod though.

 

Tim

 

IMG_2389_zpsqr7gx4k2.jpg

IMG_2390_zps3ngk0drt.jpg

IMG_2391_zpsmfi62wgd.jpg

IMG_2398_zpsfryp9xba.jpg

IMG_2402_zpshjcnsgrk.jpg



#19 nicklouse

nicklouse

    Moved Into The Garage

  • TMF+ Member
  • PipPipPipPipPipPipPipPipPipPipPip
  • 11,779 posts
  • Location: Not Yorkshire
  • Local Club: Anonyme Miniholiker

Posted 14 March 2019 - 12:08 AM

imgur is better for hosting.

 

cant say i can see anything odd other than i have the return spring in place when i bleed mine. the push rod angle looks like mine as well. all looks new so really it can only be air or a faulty part.

 

what i would be doing is pulling the slave rubber back and illuminating the piston in the slave and making sure that one the rod is touching it and that the piston moves as soon as the pedal starts moving.



#20 Wazzy

Wazzy

    Just On Tickover

  • Noobies
  • Pip
  • 5 posts
  • Location: Leicester

Posted 12 April 2019 - 05:55 PM   Best Answer

I now have a working clutch!

 

Thanks for all the advice - all of which was helpful and acted on.

 

If you are interested this is how it went;

 

I was always concerned that the fault might be the master cylinder as it came with a faulty seal but still wasn't working with a new seal. So I swapped the master cylinder for another (new) one. I also changed to DOT 4 hydraulic fluid. These changes did not appear to make any difference but, in the process I found that one of the pedal box bolts was not tightened all the way in. The thread in the baulkhead  was blocked by a splodge of POR15 paint which we had used to protect the floorpan. This sets really hard so gave the feel of a bolt which was tightened but actually wasn't. After tapping out the thread there was an improvement because the pedal box wasn't twisting when the pedal was pushed down. However there was still only 0.5" of travel. As I had already bought a replacement slave cylinder I decided to change this next. On removing the slave it was clear that it wasn't working well - the piston was sticking - not clear why. Changed the slave and I'm now getting 5/8" movement at the slave pushrod and a clutch which engages as the pedal reaches the halfway point. More importantly - the car is drivable!

 

Thanks to all of you who took the trouble to reply to my post. 

 

Tim



#21 cal844

cal844

    Crazy About Mini's

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 6,247 posts
  • Local Club: www.scottishmini.net

Posted 12 April 2019 - 09:53 PM

Glad to hear the issue is solved





Also tagged with one or more of these keywords: engine

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares