Gearbox bust?

[yosini]

Hi,

I lost all pedal travel the other week on my 1275GT, and when looking at the slave cylinder whist pressing the pedal it was slowly losing pressure. So I replaced the slave cylinder and it now holds pressure, but the pedal gets so far down - not enough to disengage the clutch - and seems to hit a solid stop, I've adjusted the lever to different positions but it still won't go into gear. I can put it into gear with the engine off, and if I stamp on the pedal whilst starting it will start and then as soon as you lift off even slightly it will creep forward in gear. It got too cold to tinker with the level adjustment any more, but should I persevere or is my clutch/gearbox stuffed? The clutch biting point was quite low to the floor before the slave cylinder went, but I don't think it would have died that quickly.

Cheers

Joe

[FWDRacer]

Have a look at the clutch operating arm - sounds like symptoms of the ball in the flywheel end having been worn away (ecentrically) so much that you can't get throw and hence clutch disengagement.

[Cooperman]

It sounds like the clutch adjustment is out somewhere. Check that the adjustment screw is set to 0.020" clearance when you pull the arm as far as it will go to the right by hand, check thatr bthe centre overthrow stops are not out of adjustment (undo them to chack for operation, then check the arm to make sure it's not bent or that the ball at the bottom is not worn or damaged.
I've prepared a fault analysis for clutch drag - here it is and I hope it helps:

CLUTCH DRAG
Clutch drag or failure to disengage is not an uncommon problem with the Mini.
There are several possible causes as follows:
A. HYDRAULIC SYSTEM
1. Wear in the pedal spindle or failure of the pedal to master cylinder clevis pin.
2. Failure of seals in the clutch master cylinder.
3. ‘Ballooning’ of flexible hose due to internal hose degradation or damage
4. Air in system due to inadequate bleeding
5. Failure of slave cylinder seals

B. MECHANICAL SYSTEM – WITHDRAWAL MECHANISM
1. Wear in top clevis pin
2. Wear in lower clevis pin
3. Bent arm
4. Worn or broken ball at lower end of arm where it engages into plunger.
5. Wear in plunger ball seat.
6. Incorrect setting of overthrow stop nuts
7. Incorrect setting of adjusting screw
8. Corrosion between plunger and clutch cover due to lack of lubrication.
9. Thrust bearing failure – accompanied by a lot of noise.

C. THE CLUTCH ASSEMBLY
1. Failure of clutch diaphragm spring due to fatigue or distortion
2. Centre plate hub not sliding on primary gear splines.
3. Clutch plate surface de-laminating or breaking up
4. Distorted clutch plate.
5. I fitted, clutch plate shock springs broken and causing a ‘jam’.
6. Primary gear not rotating freely on crankshaft due to either
i) Insufficient primary gear end float, ii) Primary gear bushes seizing on crankshaft, or iii) Primary gear bushes breaking up

[yosini]

Hi,

Thanks for the help - I got the chance to have a look this weekend altering the adjusting screw to your advised setting and then to various different other positions - none of which would allow the clutch to be disengaged with the engine running. I did notice that when the adjuster was screwed right in (so it wasn't holding the arm back at all) the two large nuts on the exposed end of the thrust bearing (?) spindle had some play - they would move and twist about 10 degrees. Not sure it that is normal or not.

From your breakdown - the only thing I reckon from section A is the master cylinder - is there any way of checking this, obviously it was working before the slave cylinder went, would be kinda bad luck for them both to fail or is that common?
The mechanical section - B - seems the most likely, the arm seems to move fine and I can't see anything that looks like it has failed so that negates 1-5, 6 however I'm not sure about - where are the overthrow stop nuts and how do I check them? 7, tried this. 8, not sure but the car was running fine and in regular (ish) use up until it failed. 9, there aren't any bad noises.
Section C - again not sure about.

Any suggestions, or a good Mini friendly garage near Greenwich SE London...?

Cheers

Joe

[haynes]

seem to remember the slave cylinders being difficult to bleed. Does it work of if you pump the pedal?

[yosini]

Hi,

It did take a while to bleed, even with an easy-bleed kit on, the pressure on the pedal feels strong, it does build up a slight bit more pressure if furiously pumped but still nothing shifts.

cheers

Joe

[cambiker71]

Does the clutch arm move at all? If so i'd say the ball at the bottom of the pivot has worn or the pushrod or both.

The ball at the bottom of this arm..

[Mr2Mike]

I've seen the ball on the end of the operating arm completely snapped off on a mini, but the end of the arm would still move the clutch release bearing a little bit.

[Skyedriver]

I've had the slave cylinder "lock" so that the pedal wouldn'T move at all. Absolutely solid

[yosini]

Hi,

A few more scuffed knuckles later and I managed to get the arm out - it looks ok to me, I took a photo and hopefully will be able to attach...

The slave cylinder is new and seems to move freely - what else can I check?

Thanks again in advance

Joe

[FWDRacer]

Close up of the arm/ball end please - looks a bit worn!

[yosini]

how's this one? presumably (like all mini bits) these are readily available and cheap?

Cheers

Joe

[annodomini2]

http://www.minispares.com/Product.aspx?ty=pb&p...

Change the pins while you've got it off.

Bottom
http://www.minispares.com/Product.aspx?ty=pb&p...

Top

http://www.minispares.com/Product.aspx?ty=pb&p...

Don't forget split pins:

http://www.minispares.com/Product.aspx?ty=pb&p...

Take pics of the clutch plunger and pivot points on the clutch housing aswell.

[FWDRacer]

yosini said:

how's this one? presumably (like all mini bits) these are readily available and cheap?

Cheers

Joe

Nice of you to clean it up for the picture

In fairness - I've seen a lot worse. This has some wear but shouldn't be causing the symptoms you've originally described on its own. Check all the pivots - is there evidence of troughing (wear) on the pins. Replace all a s a matter of course.

If the ball end is small (compare with new) they can be reclaimed - decent gob of weld and a grinder.

[yosini]

I'm back with an update....

Sunny weather at the weekend so I got the chance to replace all the parts - there is a very slight improvement in pedal but I still can't get into gear. If I start the car in 2nd with the clutch to the floor then it will start and the slightest lift on the pedal crawls the car forward normally, no weird noises or anything - seems as if there is nothing left of the clutch - would this happen so quickly - see top of message for description of how problem started.

Anything else to try or do I just take it into a garage - would anyone recommend anywhere near Greenwich?

Cheers

Joe

[guru_1071]

id say that the clutch its self is knackered in your car, if the biting point was that low to start with.


if you want to 'bust' your gearbox correctly you need to try harder.......


i did this to mine last saturday (and drove it 80 miles home!)




the bearing under third gear broke up, so third was moving on the mainshaft, this broke the mainshaft coller off and allowed the gear to strike the laygear, which chelped a few teeth off.

its all rebuilt now

[ginettajoe]

yosini said:

I'm back with an update....

Sunny weather at the weekend so I got the chance to replace all the parts - there is a very slight improvement in pedal but I still can't get into gear. If I start the car in 2nd with the clutch to the floor then it will start and the slightest lift on the pedal crawls the car forward normally, no weird noises or anything - seems as if there is nothing left of the clutch - would this happen so quickly - see top of message for description of how problem started.

Anything else to try or do I just take it into a garage - would anyone recommend anywhere near Greenwich?

Cheers

Joe

Before you look too far into things, try replacing the release plunger shaft (the main shaft through the outer casing) ..... the recess where the ball of the release arm operates can also wear suffiently to reduce travel. It isn't a common problem, but a small amount of wear on the ball, which is visible, combined with wear on the contact in the shaft can create your problem!! The problem you are having has been there previously, because the operating arm has been heated up and bent, when really it should be straight! The short cut to solving your problem would be to heat the arm with an oxy-acetylene torch until it is glowing red (where the slight bend is already) and with a bar, bend it in a further half to three quarters of an inch! HTH Howard

Edited by ginettajoe on Friday 9th March 01:18

[yosini]

Hmmm, interesting. I can see what you mean, but not sure that is where my problem is. At the moment the pedal travel seems to hit a 'stop' before the clutch is fully disengaged, and this is before the pedal hits the metal car body shell behind the pedal itself. I think if I angled the new arm more then I would just reach this 'stop' earlier in the pedal travel.

The weather is getting better and I am feeling the need to get the Mini back on the road so have to get it fixed very soon - might have to take it to a garage...

Thanks all, and if anyone can recommend a good Mini friendly garage around London Bridge or Greenwich or South East London then I'd appreciate it.

Cheers

Joe