so sunday was fun... i put on a shiny new rocker cover... then took the mini for a spin. monday morning, i got in the car and BOINK! the clutch doesn't work.

my local mini guru says to check the motion on the clutch next to the transmission and that that should be able to confirm his thought that it's a hydraulic issue. possible causes... fluid leaking from the clutch master cylinder, clutch slave cylinder or from the brake line connecting the two.

wednesday i have an extra pair of hands (and feet) coming over to help me diagnose the problem.

i have a new braided steel brake line in hand and thought i might go ahead and install it while figuring this out...

some questions...

1) is this as simple as it looks? uncrew the ends, replace old line with new line, fill up cylinder with fluid, bleed? or are there any hidden mini secrets i need to know?

2) do i need to bleed the entire brake system when bleeding the clutch?

3) anything you experienced mini owners would like to throw in? let me have it.

thanks in advance!
mike

 

First, there are separate MCs & systems for the brakes & clutch.

Check the stop nut on the clutch cover for adjustment. There should be .020" distance between t/o arm & the head of the bolt when the spring is off and lever pulled forward to make contact between the t/o bearing and pressure plate.

Look for fluid leaking down the clutch pedal arm from above. It would indicate failed clutch mc seals. But, the seals can also go bad w/o a leak. [they soften and cannot push sufficient fluid]

Also, the slave cylinder seal goes bad. Peel the boot off the slave a little and see if it is wet inside - indicating a bad slave seal. Finally the slave hose can leak and also can go bad internally where a piece of hose rubber actually blocks fluid.

The slave cylinder hose is different than the brake hose. If the seals are bad rebuild/replace the mc, replace the slave & hose with new.

Also, check all the fulcrum pins (1 where pedal attaches to mc, 1 where slave connects to t/o arm, and the pin for the t/o arm in the housing) for wear. These all get grooves worn into them and a little bit of wear on each adds up to a lot of lost travel. It doesn't take a lot of travel to disengage the Mini clutch. So, if you lose some at each pin it gives you trouble adjusting even with new hydraulics.

When you put it together use Castrol LMA brake fluid.

 

Covered all the points, MiniMad! ... even down to using the correct Castrol fluid ...

... mike, you said "doesn't work" as opposed to "slipping" but if you ever encounter a slip, the likely source is oil on the clutch plate; the "red" seal on the crank tail (or primary gear) wears easily and leakage is a good indication that the oil level has been too high/full.

 

When I got my 78 last year, the clutch dragged very badly, and the prior owner had worn out the synchros in 2 gears driving it around.

I checked everything mentioned above, but could not find an adjustment point that would let the clutch fully engage, and not drag on the bearing when released.

Finally on a web site I found one more hint.

The tip of the little ball on the bottom end of the clutch actuator arm can get worn enough that it does not provide enough throw.

There are two solutions.

Order a new arm, and wait for it to arrive in the mail.

or

Use your welder to build up the little ball. I did that, then carefully ground off the ball and kept trying to install it until I could reasemble the linkage. I swear it did not look any different when I got done, but the clutch works great now.

Maybe my problem was really with the socket, but building up the ball solved the problem. I am just glad it was a simple fix.

If yours went suddenly, the little ball might have broken off.

John

 

right, 8ball. there's no slipping. the clutch simply does not do it's job. when i press on the pedal, i can't change gears.

my plan is this:


1.check all pins and the gap as instructed by MiniMad... what happens if i need new pins? are those available from 7 or mini mania?
2. replace the hose. it's just nasty and i have a shiny new braided steel one ready for action.
3. refill and bleed the system
4. see if that works.
5. if it doesn't work, then i'll take out the master cylinder, slave cylinder and rebuild them. i have rebuild kits on the way and for $10 i'll try a rebuilt slave before i drop $70 for a new one.
6. hope to heck that works.

from what i have read, this is a pretty simple process. no sealant, goo or anything needed. just unbolt everything and take all apart and refit. am i over simplifying?

one other note off this topic... the bolts that i put on my rocker cover say not to tighten past 5lbs torque. why is that and what happens if i do overtighten? i guess it's possible to break the bolts but is there any other reason?

 

i know there's a joke here but i'm too worried that my little ball is broken to come up with one. anyone else think this could be the problem?

 

No you don't need to bleed the brakes.

Was the fluid low or have you been having to add some ocassionally?

If no, since it was (I'll asume) fine before (not near the floor already) and it happened overnight or since last driven its probably the master leaking internally.
After rebuildind which requires finger f-ing (for lack of a less colorful description) the bore with 400 grit sandpaper in a crosshatch pattern, check the inside for deep pits caused by water. That or dead seals, or possibly flatulant penguins will help you decide weather to rebuild or replace. Of course dead seals just kind of lay there
Bleeding clutches (unlike brakes) with everything new can take forever to build pressure Bench bleed the master before installing.(less paint stripping corrosive mess)You can do it by filling the reservoir,pushing the rod gently while holding a clear hose in bottom of the hole with the other end in the reservoir allowing fluid & air to escape on the in stroke & fluid from the reservoir coming part way back on the out stroke. If you try just hooking everything up & just bleeding from the slave cyl. that return stroke of the master just sucks the air back in. Hook every thing up , put a clear hose on the slave's nipple (hmm) crack the nipple open, pump slowly,1/4 to 1/3 throw. The fluid level should eventually start to drop in the res. & have some fluid making its way to the hose on the slave. Close nipple start pumping 1/2 stroke letting the pedal slip off the side of your foot (bang- jars loose air bubbles well untill building up a little pedal pressure). Now bleed normally.

Well thats how I do it anyway. Get rid of the seals & the penguins will leave (in) on their own accord.

 

uh, i've never touched the clutch master cylinder. i've had the car for about year. before you flame me, i'm learning, ok?

also, i just noticed that there's no spring on my slave cylinder and honestly, i don't recall ever seeing one. is that bad?

 

Yes,the valve cover only needs about 5lbs. to seal, any more just distorts the gasket & seals on the bolts. If you don't ask, you don't learn.The clutch slave return spring is actually to hold the arm with the throw-out bearing away from the spinning clutch diaphram.Get/ make one.

 

You can buy a cylinder hones at the parts store to hone the m/c & slave rather than doing it digitally, so to speak. If there is severe pitting in the slave, toss it. $70 seems like excessive dosh for a slave imho.

 

$70 wow. A through cleaning, careful application of JB Weld, jewlers files for excess, & a hone to match & you're safely home free. Teflon coat the bore or the entire thing (no more corrosion & longer seal life) Synthetic fluid eliminates the corrosive issues, but at least used to,have leaking problems because the seals would not swell making for a better seal.

 

so, i've learned a lot from this thread. everyone who posted has given me great information that has helped me get to know the clutch hydraulic system very well. enough so that i went ahead and replaced and bled the fluid in the system this morning... and voila! i'm back on the road!

on one hand, i was thinking that i should have done that before i posted anything, but on the other hand i don't think i would have had the confidence or knowledge of the system to make the move i did this morning.

so, i want to say thanks to everyone who has or will have answer some of my very basic querys on this site. it's a great resource and i hope that some day i can offer the same assistance to someone who will be in the position that i am now. i'm proud to be a part of this community.

sincerely,
mike