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Clutch Won't Engage Despite Much Work


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#1 markandamini

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Posted 02 July 2019 - 01:41 AM

1978 mini  (canada)

1275 engine

this is my 5th mini.  owner since 1990's

 

i'm baffled.  Late last year i was drove to work.  No problems at all.  No issues regarding the clutch .. everything was working just fine.  Went to work and when i  came back i could not get it into gear after it started.  Not at all.  Pumped the clutch and no help at all.  Got it home and put it away for the winter thinking i'll take my time to fix it.  Since then i replaced the slave cylinder, bled repeatedly, did adjustments as per manuals, bought a clutch kit and installed (diaphragm, clutch plates, springs, seal).

 

No luck.  Same problem.

 

when clutch pedal is depressed the arm swings and the plunger moves in, but i still can't get it into gear.  It seems like everything is working as it should from the outside of the clutch, and the parts inside are mostly new now.

 

Any ideas?

 

 



#2 Moke Spider

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Posted 02 July 2019 - 05:36 AM

If it 'just went' like this from (literally) one moment to the next (noted there was a park up in between), I'd say the ball on the end of the Clutch Arm has broken.

 

One thing you can do here to check if this maybe the case, open the cover on the clutch cover that you'd open to access the timing marks on the flywheel. This is all done with the engine off.

 

Rotate the engine until one of the bolt heads on the diaphragm is visible through the hole. There's 6 bolts there altogether but only 3 of these are bolted up to the diaphragm.

 

Have someone operate the clutch. While the clutch is being operated, measure the movement on this bolt head. You need a minimum of 0.75 and preferably 1.0 mm movement here.  I find I can do it OK with a steel rule but you may want to fit up a dial gauge.

 

If you find that you're not getting this movement, then you can remove the Clutch Arm, usually with the Clutch Cover on. Check the ball on the end of it, as these wear, though, I suspect yours has broken. If this is worn or broken then along with the Arm, I would suggest replacing the Plunger too as these also wear equally as bad.

 

Also check the Clevis Pins and also the Clevis Pin Hole in the Clutch Cover as these also wear.

 

Due to the high leverage ratio, it doesn't take much wear in this set up before trouble starts.



#3 Rorf

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Posted 02 July 2019 - 05:48 AM

I note you did not replace the clutch arm and as Moke says the ball could be warn or broken off. Has the clutch arm being heat bent to cater for wear - a very common practice by non savvy mini owners. Another poor practice is extending the clutch arm push rod to also compensate for ball wear.

 

Replace the clutch arm as well as the bearing plunger. 



#4 Moke Spider

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Posted 02 July 2019 - 07:12 AM

I did also mean to include,,,,,

 

If you are getting the 1.0 mm movement at the Diaphragm Bolt Head, then it's likely the Primary Gear has seized on to the Crank.



#5 andyapanel

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Posted 02 July 2019 - 11:34 AM

I would check the master cylinder.

Good luck



#6 markandamini

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Posted 02 July 2019 - 03:38 PM

Thanks for the suggestions folks.  Here are my responses:

 

1. not the master cylinder because the arm moves when i push the clutch.  Doesn't that mean that the master and slave are working?

2. don't think it's the ball or arm.  Definitely not wear, as that would come slowly.  Potentially could be broken but i did have it off and did not notice it (although i did not specifically look for it either).  I'll look tonight.  Good idea about measuring movement through the timing hole.

3.  Clevis pins:  Had it off and put in back in.  Seems OK.  Tight fit too (no wear)

4. Primary Gear seized on to the Crank.  Possible.  Is there a way to check without taking the whole thing apart?  Dang....I hope it's not that.



#7 Moke Spider

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Posted 02 July 2019 - 08:31 PM

Usually when the Ball on the Arm breaks, they don't break right off, but crack from the loaded side and then bend back. It's not much and if you're not specifically looking for it, it's easy to miss.

 

In regards to checking for a seized Primary Gear, if you are measuring the movement at the diaphragm, then I'd be taking the Flywheel & Clutch out again. At that point, with the Gearbox in Neutral, you should be able to spin the Primary Gear.



#8 Cooperman

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Posted 02 July 2019 - 08:34 PM

If is a pre-verto clutch, check the linear movement at the top of the arm. It must move between 0.5" and 0.6". When the clutch pedal goes from fully up to fully down.
If it does, then do as Chris suggests and check the ball end on the arm.
If you fitted new primary gear bushes they may be too tight and the primary gear is jammed on the crankshaft.

#9 markandamini

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Posted 03 July 2019 - 04:05 PM

OK I think i figured a few things out.  It is a pre-verto clutch by the way.

 

1.  Diaphragm does not move when i push in the clutch.  Actually good news i think, as it means the problem is on the exterior (I really don't want to pull my clutch apart AGAIN).

2.  Arm moves, but not enough.  When i pump the clutch it moves more.  Yes I bled it and yes the reservoir is full.

3.  The cap for the master cylinder leaks!!!  Could this be the issue?  Does the actual reservoir get pressurized when you push in the clutch?  If not i need a new master cylinder.  IF it is pressurized then all i need is a new cap.



#10 gazza82

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Posted 03 July 2019 - 04:24 PM

 

3.  The cap for the master cylinder leaks!!!  Could this be the issue?  Does the actual reservoir get pressurized when you push in the clutch?  If not i need a new master cylinder.  IF it is pressurized then all i need is a new cap.

 

Hate to say this .. but no.



#11 Rorf

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Posted 03 July 2019 - 05:10 PM

Remove and strip the clutch master cylinder, clean up and install new rubber kit or even better a new master cylinder. Like the brakes the fluid needs to be changed every few years as the brake fluid absorbs moisture.

 

If that doesn't solve your problem then it is clutch out again time.



#12 Pigeonto

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Posted 03 July 2019 - 05:11 PM

I reckon the slave cylinder piston is stopping on the circlip at the end of the cylinder bore, before the clutch has released sufficiently.

2 ways to rectify :-

Weld in 10mm extra on the push rod or heat and bend the long arm towards the slave cylinder



#13 markandamini

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Posted 03 July 2019 - 05:13 PM

It's about 40 years old i guess so i think i'll go with the new master cylinder.  Not sure i want to risk a rubber kit on something that old.  Thanks for your help everyone!



#14 KTS

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Posted 03 July 2019 - 05:59 PM

I reckon the slave cylinder piston is stopping on the circlip at the end of the cylinder bore, before the clutch has released sufficiently.

2 ways to rectify :-

Weld in 10mm extra on the push rod or heat and bend the long arm towards the slave cylinder

 

..and i reckon that's a guaranteed way of pushing the crankshaft through its thrustwashers and destroying it  ;D


Edited by KTS, 03 July 2019 - 06:00 PM.


#15 Pigeonto

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Posted 03 July 2019 - 06:51 PM

 

I reckon the slave cylinder piston is stopping on the circlip at the end of the cylinder bore, before the clutch has released sufficiently.

2 ways to rectify :-

Weld in 10mm extra on the push rod or heat and bend the long arm towards the slave cylinder

 

..and i reckon that's a guaranteed way of pushing the crankshaft through its thrustwashers and destroying it  ;D

 

Errrmmm, not sure if you're familiar with the  Mini's clutch release mechanism but the length of the pushrod doesn't determine the amount of disengagement. In anything of that nature there has to be excess available and then a limit stop to set it up against having too much of the action actually happening. Have a look on the end of the plunger and there you'll notice 2 x  15/16" nuts. The factory thought of this and provided them for exactly the situation you have envisaged. So as it can't happen. It's all there in your Haynes or any other workshop manual. There's a procedure to follow in adjusting them. They're called ' Throwout' or 'Overthrow' adjustment nuts. I have used both of the methods I mentioned, sometimes one is better than the other, depends on the situation. 






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