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 Post subject: Clutch trouble
PostPosted: Sun Apr 24, 2022 1:34 pm 
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848cc
848cc

Joined: Mon Sep 23, 2013 8:54 pm
Posts: 163
Location: Adelaide
Hi,
My mini seems to be "dragging" the clutch, it crunches when changing gears, particularly on downshifts, no matter how carefully I rev match and shift, it seems to happen when going into every gear except for when completely stationary.
The engagement point is quite high, like in the last 20mm before your foot comes off the pedal.

The master is fairly new, slave, clutch and all pins are new and there doesn't now seem to be any significant wear or slop in the system.
I set the 1/4" stop to give a small gap when the arm is pulled without the spring attached. I have bled the system, and generally messed about with it.
I read mini mania's guide, googled around, watched some videos and came up with nothing else to try.

I measured the movement at the throw-out nuts, using feeler gauges while someone else held the pedal down. I got 2.7mm of travel (3.8mm at rest and 1.1mm when pedal pressed)

It's an 1098 on a magic wand 850 gearbox

I'm hoping someone can help me before I take it to a mechanic, or pull the engine/gearbox out to inspect the clutch


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 Post subject: Re: Clutch trouble
PostPosted: Mon Apr 25, 2022 8:44 am 
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Joined: Wed Sep 08, 2004 9:27 pm
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Location: Wodonga - Vic/NSW border
Hmm... well, just on those throwout stop nuts. They're there to stop the clutch from pushing too far and pushing against the crankshaft. So you shouldn't have any gap when the pedal is pressed. The manual says to push the pedal, screw the big nut in to contact the housing, then release the pedal and do the nut up another .020". If you have a gap when the pedal is on the floor then the nuts aren't doing anything

However, how long has the 'dragging' problem been happening? Has it always done it while you've had the car? New gearbox build? Anything changed recently?

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 Post subject: Re: Clutch trouble
PostPosted: Mon Apr 25, 2022 2:36 pm 
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848cc
848cc

Joined: Mon Sep 23, 2013 8:54 pm
Posts: 163
Location: Adelaide
I'll try and adjust the throwout nuts later today, see if that does anything

The car has been off the road for seven years, engine and all parts were taken out, and put all back in, I think it was ok before that, but not totally sure.

I've found out the magic number for the clutch to move at the top of the arm, at the slave push-rod is .55" I'll be checking that today too.

I really hope it's not related to the primary gear or something similar to this:
https://www.youtube.com/watch?v=pC91HqVCjFc


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 Post subject: Re: Clutch trouble
PostPosted: Mon Apr 25, 2022 5:09 pm 
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Location: Wodonga - Vic/NSW border
andrew9 wrote:
I'll try and adjust the throwout nuts later today, see if that does anything

The car has been off the road for seven years, engine and all parts were taken out, and put all back in, I think it was ok before that, but not totally sure.

I've found out the magic number for the clutch to move at the top of the arm, at the slave push-rod is .55" I'll be checking that today too.

I really hope it's not related to the primary gear or something similar to this:
https://www.youtube.com/watch?v=pC91HqVCjFc



Throwout stop nuts won't stop it from crunching on downchange

As for the video, very doubtful.. the issue that video is referring to is so unlikely it's not funny, it's like googling for why I have a cough and believing the top result that says I have lung cancer

If you want to rule out any clutch/primary gear/idler gear dragging issues, put the car up on stands, take the wheels off (handbrake on, chain it to the fence, wheels under the car, etc. etc) and put it in gear with the engine running and someone pushing their foot on the clutch. See if the wheels can be stopped (both wheels, at the same time) without using the brakes. They will both turn a bit because they're just in the air with no resistance and the primary gear will want to spin with the crankshaft, but if the clutch is fully disengaged you should be able to stop the wheel hubs with the brakes, then hold them with your hands and they wont turn...

If it's been sitting around for a long time it may just be that there is some gunky oil on the synchros and they're not able to grip properly. What sort of oil did you put in it?

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 Post subject: Re: Clutch trouble
PostPosted: Tue Apr 26, 2022 4:40 pm 
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848cc
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Joined: Mon Sep 23, 2013 8:54 pm
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Location: Adelaide
I measured the clutch arm travel at the slave end, right on about 15mm, so more than .55" (13.97mm) so I think that rules out any issues with the hydraulics and pedal components.

simon k wrote:

If you want to rule out any clutch/primary gear/idler gear dragging issues, put the car up on stands, take the wheels off (handbrake on, chain it to the fence, wheels under the car, etc. etc) and put it in gear with the engine running and someone pushing their foot on the clutch. See if the wheels can be stopped (both wheels, at the same time) without using the brakes. They will both turn a bit because they're just in the air with no resistance and the primary gear will want to spin with the crankshaft, but if the clutch is fully disengaged you should be able to stop the wheel hubs with the brakes, then hold them with your hands and they wont turn...


I just did this, both hubs stop by themselves after pushing in the clutch. I had car in gear with both turning, push in the clutch and they both slow down and stop fairly quickly

simon k wrote:

If it's been sitting around for a long time it may just be that there is some gunky oil on the synchros and they're not able to grip properly. What sort of oil did you put in it?


Some 20w/50 mineral oil, Shell HX3 I think. It was changed last year. I was planning to change it again soon, I've only driven it around the block a dozen times.
Is Shell HX3 20/50 not suitable? I have another bottle and was planning to use it again


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 Post subject: Re: Clutch trouble
PostPosted: Tue Apr 26, 2022 6:39 pm 
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1275cc
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Location: Wollongong, NSW
How far is the slave to the end of the travel? If the arm starts too far out it’s possible to run out of stroke.

You should be able to pop the boot of the slave to see the piston

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 Post subject: Re: Clutch trouble
PostPosted: Wed Apr 27, 2022 7:32 am 
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848cc
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Joined: Tue Jan 23, 2018 4:52 pm
Posts: 36
Location: Wollongong
I recently had similar problem with our van. The problem was the geometry of the clutch slave cylinder, lever arm and connecting pins both ends of the lever arm. My clutch stopped working and I discovered a crack on the end ball of the lever arm. I replaced the arm with an old one I had, put it back together and found all the settings were wrong in that the slave cylinder shaft was hitting its limit before the clutch fully disengaged. As a work around I put a small socket on the slave cylinder end of the slave cylinder shaft, effectively making the shaft longer, so that the shaft pushed the lever arm further out, and thus push the clutch plate in further, adjusted the the 1/4" stop out until I had clutch disengagement. I bought a new lever arm and compared with the old one that I had put in and found the old one had a slight bend. Fitted the new arm, and an adjustable slave cylinder shaft for future problems and all working great now.

Bazzz

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 Post subject: Re: Clutch trouble
PostPosted: Wed Apr 27, 2022 7:48 am 
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Tim, Bazz - shouldn't be an issue with hydraulics or clutch arms, the clutch is disengaging fully...

If it was one gear then you'd say it was the synchro on that gear, I just did one on my clubby, 2nd gear synchro... easy... but all 4 gears is something else. That's why I'm thinking oil. 20/50 mineral is right, I've never used Shell oil. I'm currently using Gulf Western - supercheap put it on special for about $10 from time to time so I grab it when it's cheap.....

Matt Read, Dr Mini etc. didn't come back after the great outage. They might have known straight away

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 Post subject: Re: Clutch trouble
PostPosted: Wed Apr 27, 2022 4:54 pm 
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848cc
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Joined: Fri Oct 06, 2017 6:39 pm
Posts: 141
Location: Perth, WA
Does the clutch 'drag' when you take the return spring off? I was driving around fine without one until somebody pointed out I was missing a spring. So guess what happened when I put a spring on? It started to crunch gears as it was partially engaged.

I followed the instructions here and adjusted the overthrow nut and it fixed it up...
https://www.moke.com.au/in-the-garage/g ... the-clutch


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 Post subject: Re: Clutch trouble
PostPosted: Fri Apr 29, 2022 9:55 pm 
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848cc
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Joined: Mon Sep 23, 2013 8:54 pm
Posts: 163
Location: Adelaide
I took it for a bit more of a drive the other day, it mostly crunches down changing from 3rd to 2nd, often takes a few goes to even go in.
Often a bit of a crunch when shifting up from 2nd to 3rd, and also down from 4th to 3rd, but always goes in first time.
It seems to go into 2nd easy enough when rolling at walking pace, but not when going any quicker.
Seems to shift up from 1st to 2nd well.
Maybe just syncro wear on 2 and 3? It's easy to get into 1st while still rolling as long as revs are matched, maybe a slight crunch but still better than going into 2nd. And obviously 1st has no syncro so should be harder to shift into than 2nd, but it's not.

It'll be a week or so until I drive it again, going to see what an oil change does, if anything.


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 Post subject: Re: Clutch trouble
PostPosted: Thu May 19, 2022 6:05 pm 
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998cc
998cc

Joined: Fri Apr 01, 2011 8:33 pm
Posts: 1077
Two things to try ...both mentioned but you haven't commented... Does the slave piston run out of travel?? (remove the boot, push in clutch and look) and take the slave spring off, go for a run and see what happens...

Cheers, Ian


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 Post subject: Re: Clutch trouble
PostPosted: Thu May 19, 2022 8:11 pm 
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998cc
998cc

Joined: Sat Jun 21, 2008 12:43 pm
Posts: 782
Location: Narellan NSW
Does it crunch when stationary or only when moving ?


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 Post subject: Re: Clutch trouble
PostPosted: Fri May 20, 2022 8:26 pm 
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sounding more like the gearbox is just overdue for a rebuild... especially what you say about 2nd gear

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