22 replies to this topic

[craig 1010cc]

Having some issues with a "new" engine we've just fitted into Pootle

Basic spec
Low mileage 1275 spi bottom end
Minispares evo1 cam
Cooper spi head
Rebuilt gearbox
2nd hand minisport light weight steel flywheel and back plate with a 2nd hand grey pressure plate (balanced set) and a new cooper s spec clutch plate

We got it all running, broke in the cam, went for a spin round the block all good. Went back the next weekend (2 days ago), retorqued the head etc and yesterday I drove him home. The journey was about 40 miles, mixed crawling through town and blasting along A roads. I arrived home and park up outside so I can move my van off the drive, firs him back up and park on the drive. I left him idelling to tweak the tick over (it had risen to 1500 rpm), set it to 1000rpm and went to drive him into the garage. Put the clutch pedal down and he stalled. Tried again, same thing. Tried a 3rd time with the revs up and as soon as the pedal was going down the revs dropped significantly.

So I switched off, opened up the bonnet to find the the throw stop nuts had made a break for freedom. Found the main one on the subframe. But now the pedal is really stiff (will only go 1/2 way down).

I've tried backing off the adjuster bolt, the clutch arm isn't dropping back to it and with the engine running, there is no nasty noises.

I'm stumped on this one

[mdtstar28]

Verto clutch is up for the job on that spec of engine

[Stevie W]

Hi,

The throw-out nuts prevent the crank thrust washers from being damaged by limiting the clutch throw. Your engine revs dropping when you press the clutch pedal are a-sure sign of overloading the crank thrust washers.

It sounds as though the mechanical part of the clutch (lever arm and plunger) have jammed where the absence of the throw-out nuts has allowed the hydraulic section of the clutch system to push them too far in.

You may have to remove the slave cylinder from the clutch housing to release the pressure or bleed-off a bit of hydraulic fluid to free things up! Next remove the wok to assess whats happened. I expect you may also have to remove the clutch lever arm to free things off if the ball end of it is jammed in the plunger hole, this would also explain the stiff pedal.

Hope this helps.....

Cheers, Steve.

Edited by Stevie W, 19 November 2017 - 06:21 PM.

[craig 1010cc]

Taking the slave off was my next step as it does seem that something has over centred . I did crack off the bleed nipple which made no difference, but this seems a good way to rule in or out the hydraulics

[nicklouse]

i would be pulling the arm out and checking its condition.

 

you do not need a grey for that spec engine a standard would have been fine.

[craig 1010cc]

The arm is only 2 years old. I do have a stock pressure plate, but the grey was balanced to the flywheel. I do have another arm o compare the current one too

[nicklouse]

the covers never need balancing as they weigh nothing.

 

and the arm being two years old means nothing.

 

but i think the flywheel needs to come off to check the primary gear is not being trapped or has failed.

 

then it may be engine out time.

[Spider]

Check everything as the other guys have suggested first for sure, but given the description and what you've done / checked since, I'm concerned that the crank thrusts maybe in back to front.

 

I would dearly love - for you - to be wrong on that.

[Cooperman]

If it was OK until the overthrow nuts came off then the overthrow nut setting is the prime suspect.
Therefore:
Undo the overthrow nut and locknut.
Remove the clutch arm return spring.
Set the stop-bolt clearance to 0.020".
Re-fit the spring and measure the lateral travel of the top of the arm with full pedal travel. It must be 0.50" to 0.60".
Push the pedal to the floor and screw in the overthrow nut until it just touches the cover. Release the pedal and turn the overthrow nut one FLAT further in. Use the locknut to hold that setting.
If the clutch does not disengage correctly start stripping the mechanism down.
It is not unusual for the revs to drop when the pedal is pushed down with a heavy rate clutch diaphragm. It should not drop more than about 100 rpm.
Never start the engine with the clutch depressed - ever!

[Rorf]

Trust you set your clutch up properly - diaphragm cone and the three straps parallel to the flywheel when all tightened up. Crank thrust bearings could be worn out if this was not done correctly especially considering the use of the grey clutch diaphragm.

[Spider]

Trust you set your clutch up properly - diaphragm cone and the three straps parallel to the flywheel when all tightened up. Crank thrust bearings could be worn out if this was not done correctly especially considering the use of the grey clutch diaphragm.

 

I was thinking similar here.

 

also, the clutch thrust bearing may have collapsed.

I know you've said the arm was new 2 years ago, but as Nick has suggested, pull it out. I doubt it would be worn much but I'm just wondering too, if the ball has snapped off.

[craig 1010cc]

thanks for the feedback :)

 

For a bit more clarity on the situation.

 

I'm pretty sure that the stalling was due to the overthrow nuts having gone awol and it overthrowing, I just can't adjust it back to check it due to the pedal being pretty much solid.

 

Apart from the cam change, the bottom end was untouched. So unless the thrusts would last 40k back to front, I think I can rule that one out.

 

When the gearbox was rebuilt, guessworks shimmed the idler gear and when we built it up I was very careful to check that the primary gear still turned freely/had acceptable float

 

On the initial drive (circa 40 miles), the clutch performed well, no drop in revs or crunching as it went in to gear (was one of the smoothest mini gearboxes I've ever tried)

 

As it sits at the minute, the lock nut is awol, the overthrow nut is wound well back at the minute, the return spring is off and the stop is wound in a good 5mm too. The clutch arm is currently sitting about 5mm clear of the stop bolt.

 

So, my plan is to 1st crack off the bleed nipple and get the wife to try and press the pedal down. This way I can rule out something having gone in the master/pipes.

 

Then remove the slave to see if I can get the arm moving properly and feel where the stop would be

 

Then remove the arm and compare it to another good one that I've got.

 

Hopefully one of the above will bring to light what went on the drive way

[nicklouse]

with that info I am not supprised nothing is happening.

the stop bolt needs 15-20thousands of an inch clearance or you will never get the clutch to work.

so first things first. press the pedal and what happens?

nothing it is rock solid? then I would look at the slave having sized.

as a note. with the return stop bolt set correctly and the overthrow nut being missing the clutch should still operate without any issues.

[craig 1010cc]

I know the clutch isn't going to work as it is setup up at the minute, I've backed everything off to try and get movement and then reset it all from scratch.

The pedal at the minute takes a lot of force (more than the unservo'd brake pedal) to get it to move 1/2 way down, the clutch arm is moving out, but I didn't have a rule to hand to measure how far it travelled.

[big john]

How old is the clutch flex hose?