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MG MGB Technical - clutch problem

Recently purchased a 1979 mgb - hav been driving it daily - just recently, once in awhile reverse would grind going in giving you the feeling clutch wasn't fully depressed,fluids full never added. One day couldn't get into gear at all. So decided to replace flex hose & slave cyl as well hoping this might be a solution. But can't say yet if this was my simple fix of problem,because clutch pedal goes down to easily even though bleeding had ceased producing any air bubbles by using 2 man-clutch pedal-clear tube in jar of fluid off slave bld/nip. Will not go in any gear. I'm lost - thanks 4 any help
hdm harry


Not sure if this will help you but it's easy to try. I had a problem with my 1500 midget, after bleeding the pedal would go all the way to the floor and the clutch was only just disengaged. The solution was to take a length of wood and wedge it between the clutch pedal and the seat so that the pedal was in the fully depressed position. I left it overnight and next day as if by magic the clutch pedal was back to normal.
Bob Davis

Check that when you depress the clutch pedal you get about 5/8" movement at the fork going in to the gearbox. If not you need to bleed the system further. For a good bleed use a tube that is a tight fit over the bleed nipple then slacken the nipple half a turn and then depress the clutch pedal. Tighten the nipple with the pedal held down then release the pedal. Slacken the nipple and repeat the process until all bubbles stop flowing. The other method frequently described here is to connect the nipple of the RH front brake caliper to the clutch slave nipple slacken both and then pump the brake pedal until all air has been expelled through the clutch master cyl. Don't forget to keep a constant check on the master cyls to ensure that the brake does not go dry of the clutch overflow.
Iain MacKintosh

Bleeding from the top down is a beggar, bottom up is much more successful and easier. The easiest method of doing that is to run a tube from the right-hand caliper nipple to the clutch slave nipple (they are the same size), open the clutch nipple, apply *gentle* pressure to the brake pedal, then open the brake nipple. For each upstroke of the brake pedal close its nipple. Just use slow and gentle strokes.

If the clutch master is currently full then you will have to drain some out, by opening its nipple and using the pedal. You should be able to nigh-on fill the clutch master with just a few strokes of the brake pedal, which will hardly lower the fluid level in that at all especially with the dual master which I assume you have. But keep an eye on the fluid level in the brake master in any case, you don't want to have to bleed the brakes as well.

It's probably taken me as long to write this as it would to do the job.

A friends clutch pedal also became very light after replacing the clutch and slave, he was convinced it was doing nothing, but it had the full travel of the slave piston and it went in without grinding.
PaulH Solihull

I have had problems bleeding my clutch slave cylinder. My solution was to connect a clear vinyl hose from the master cylinder's reservoir to the open slave cylinder nipple creating a complete loop. Fill the MC, pump slowly and pause after each pump to allow bubbles to float to the top of the reservoir. Have a helper watch the vinyl tube for air bubbles. When they disappear the system should be properly bled. Tighten up the nipple and check for firmness. If not firm, repeat. Works great!!!
Frank Grimaldi

I don't see why that is any different to a short tube into a jam-jar, other than you are recirculating fluid where the jam-jar method isn't. You still have to push air bubbles down that long vertical pipe regardless.

I'm not saying it's 'wrong', just that it is no different as far as expelling air is concerned.
PaulH Solihull

I really can't understand why people find any difficulty in bleeding MGB clutch hydraulics - simply fill master reservoir, pump clutch pedal vigorously, hold pedal down for a minute and then let up fast, repeat until you have firm pedal.

Even works on Midgets that are notorious for difficult bleeding.
Chris at Octarine Services

Chris are you doing the pumping, holding, etc. without the jelly jar tube set up? Is the master reservoir uncaped when you do this?
J Mancone

Chris it works!
I had replaced the slave boot and after I reassembled it I had to bleed the system. Of course it wouldn't happen so I came here to ask what's next. Well I thought I would give Chris suggestion a try and it worked. Of course that was after I spilled the jelly jar of fluid and annoyed my wife by asking her to come and pump the clutch while I bled it. Thanks again, this site saved my butt again.
J Mancone

This thread was discussed between 28/09/2010 and 02/10/2010

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