15 replies to this topic

[peasoup39]

In final stages of the rebuild of my 1098 engine. 

Have assembled the flywheel cover onto the engine and find the pushrod going into the slave cylinder only goes in about  one quarter of the stroke of the cylinder which seems totally inadequate for proper operation of the clutch.

I have stripped the operating arm off the cover again and it is assembled correctly as the bits will only go together one way. When assembled the arm adjusting screw stop  in the cover has a clearance of about 3mm which i have not altered since strip down so that seems correct but i cannot believe that the cylinder only operates on the last 25% of its stroke. Its 50 years since i stripped my last mini engine so cannot rely on memory.

The flywheel assembly all went together correctly and the clearence was correct on the transfer gear so i am a bit stuck.

Any suggestions please.

[alex-95]

Are the stop nuts on the 'wok'/flywheel cover hitting the wok or is the slave only travelling so far and the nuts aren't touching the wok? The gap between the nuts and wok should be 6mm (maybe 6.5mm, have a look in the haynes manual).

[peasoup39]

Firstly should have advised that this is pre verto assembly

The stop nuts on the centre shaft are backed right off as the engine is not yet installed so cannot operate the slave cylinder to adjust them. My concern is that there will be  insufficient movement of the slave cylinder to release the clutch when it is installed.. It seems as if the clutch pressure plate is not far enough away from the engine in its current state so the release bearing is too far back. i did not take the release bearing off the spindle so it is in its original position before stripdown.. The friction plate is new but this does not affect the position of the pressure plate as it is on the 3  spring straps.

Excuse my ignorance but what is "wok" 

[KTS]

wok = clutch cover

 

if you can post up some picture, that would really help

[peasoup39]

Not very good at that but will reassemble it later and try to load up some pics. Thanks for your assistance

[mab01uk]

Have you checked the Clutch arm and its corresponding hole in the Plunger for wear or renewed them as any wear in them which is common will reduce the clutch arms travel?

The clutch arm is very prone to wear at the lower ball, which should be round, not worn flat on one side.

Also check that the eyelet of the pushrod is not elongated.

 

Bodge repairs for this problem sometimes seen on Minis include bending the clutch arm or sticking a spacer/nut in the slave cylinder.....

Edited by mab01uk, 23 July 2021 - 04:57 PM.

[nicklouse]

In final stages of the rebuild of my 1098 engine. 

Have assembled the flywheel cover onto the engine and find the pushrod going into the slave cylinder only goes in about  one quarter of the stroke of the cylinder which seems totally inadequate for proper operation of the clutch.

I have stripped the operating arm off the cover again and it is assembled correctly as the bits will only go together one way. When assembled the arm adjusting screw stop  in the cover has a clearance of about 3mm which i have not altered since strip down so that seems correct but i cannot believe that the cylinder only operates on the last 25% of its stroke. Its 50 years since i stripped my last mini engine so cannot rely on memory.

The flywheel assembly all went together correctly and the clearence was correct on the transfer gear so i am a bit stuck.

Any suggestions please.

Set the return stop bolt to 15-20 thou (see your Haynes manual for how) then adjust the stop nuts, again see manual, should be sorted.

[peasoup39]

Ok i think i have uploaded photos;-

photo1 shows clearance between spring straps and the flywheel. There is just over 2.5mm movement available before the straps would contact the flywheel which seems ok to me

Photo2 shows release bearing which seems correctly located on the spindle with the locating clip

photo3 shows position of the arm with the release bearing touching the pressure plate. The slave cylinder is only about 6-7 mm of stroke.

the ball on the end of the arm is not worn and the swivel pin and its bore are not worn or elongated.

Note If photos have not uploaded i will try again. 

Attached Files

•  clutch3.jpg   55.74K   1 downloads
•  clutch2.jpg   41.07K   1 downloads
•  clutch1.jpg   59.87K   2 downloads

[Spider]

I can see from the Angle of the Arm there's something not right.

 

Check the Pins and the holes they go in to for wear too, I've had a few where the Pin Hole in the Clutch Cover has worn.

 

It is possible too that the Flywheel for a variety of reasons / causes could be sitting a little lower than it originally was. To make up for that, a Washer is usually fitted between the Throw Out Bearing and the Plunger. Looking at your assembly there, it wouldn't need to be too thick, around 20 thou. Ideally, when at mid-stroke, the end of the Arm with the ball on it, should be perpendicular to the Crankshaft line.

[peasoup39]

Just rechecked the arm. No wear on the ball, no wear on the pin or the hole in the wok. best i can see there is no wear in the hole in the release bearing spindle.

The slave cylinder push rod has just some perceptible clearance in the eye but it is only a few thou so now i am confused.

I bought the car as a resto and have not driven it but it was driven out of the garage , onto a trailer and then off a trailer so before stripping it was working ok

[timmy850]

I added a washer as a spacer between the plunger and throw out bearing. It’s also important all the pins aren’t worn. I also had a hardened sleeve inserted in the plunger to add a bit of life as the new ones are a bit soft


You can see the big difference in the resting angle between the old worn out parts on the left and the new on the right. Previously the slave was out of travel before disengaging the clutch

[timmy850]

Also the plunger in your photo with a circlip, is that a later verto item and are they identical dimensions?

[peasoup39]

The photo left is what i seem to have got. The right hand photo is what i would expect it to be with the slave cylinder piston at least half way down the bore not the small amount it currently sits at. i do not know if the bearing assay is a verto type as i have not worked on minis for so long so i will get this checked.. As stated all pins, bores, arrms etc  show no sign of wear so i do not think the problem is there. Also on stripping engine all parts ie pistons, crank bearings thrusts etc were in perfect otder. They were all replaced and clearances checked  so it is not a case of crank end float being excessive

 i have a friend who is a mini expert. i think i should have a word with him to see his view. Engine not installed yet so i can take him the parts and get his advice. I am aware that the actual axial movement is very small. in my case it would be a max of 2.5mm as that is the clearance between the 3 straps and the flywheel. Installing the washer may be the solution or extending the pushrod to go further down the bore may be a simpler solution

[timmy850]

If you’ve got it out of the car, the best option is to improve the plunger side. As the leverage ratio is so large on the pre verto setup, a small improvement to the plunger side will make a huge improvement to the slave end. The closer the throw out bearing can be to the diaphragm (while allowing some free play) the better the angle will be on the clutch arm

Even though the ball on the bottom of the arm or plunger don’t look to be that worn, any play is magnified due to the leverage ratio. It’s so much easier to replace them now before you install the engine.

When the system is all refreshed and new the slave piston should be as far in as possible, so as the system all wears with use you still have sufficient travel in the slave

[Cooperman]

As a check, the linear movement at the top of the arm must be between 0.55" and 0.60" with stop bolt clearance set to 0.020". Make sure that the overthrow nuts are would out and do not set the overthrow stop until everything else is correct.