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MG MGA - Clutch Problem

I just changed the gearbox in my MGA from a close ratio back to a standard ratio as I had recently changed the diff from 4.3 to 3.9. I put in new clutch, push rod, clevis pin all the same as what came out. Gearbox front cover the same. When I took the slave cylinder off oil went everywhere. Anyway I have bled the system 5 times and can only get 10 to 11 mm (less than half an inch) movement and the clutch barely disengages. Any suggestions as it worked great before?
R J Watson

Check the rod adjustment at the M/C. I found mine to have 1/4" free play at that end. I adjusted it to have about 3/32" at that end and now I can get full disengagement. It gave the pedal about a 1/2" of free play.

Hope this helps.
C.R. Tyrell

I seem to recall that in some cases when bleeding the clutch it is necessary to operate the slave cylinder by hand to compress the pushrod to its full extent to remove air which becomes trapped at the very end.

May be worth a search in the archive for a better description.
J Bray

A better description here.

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2003040716545016345

John
J Bray

Thanks guys
I will try both ideas on the weekend.
Just in case I ordered a new slave cylinder as I remembered the end cap that the push rod goes into was really pitted, but there there were no leaks so I ignored it
Rob
R J Watson

Check out the very bottom comment in Barney's site on the clutch:

http://www.mgaguru.com/mgtech/hydraulics/ht106.htm
Gene Gillam

If you look at the picture on that page and read the description, you will see it is not necessary to dismount the slave cylinder to perform that operation. And you don't even need to disconnect the pushrod, unless you expect to get the piston to extend farther than it would when at normal rest position. The fluid supply port is at top of the cylinder, so any return stroke will expel air from the cylinder.

Cycling the slave cylinder manually won't do anything if the line is full of air. It depends on having some fluid in the line to begin with. If the piston will move even a small amount when you press the pedal, then cycling the pedal will eventually expel all air from the slave cylinder.
Barney Gaylord

MY SOLUTION IS TO CONNECT THE OPEN SLAVE CYLINDER BLEED SCREW WITH A LONG HOSE WITH THE OPEN END INSERTED INTO THE master cylinder RESERVOIR. I THEN PUMP 20 OR 30 TIMES AND THE AIR IS EXPELLED. OPEN THE BLEED SCREW JUST ENOUGH TO ALLOW BLEEDING AND NOT SO OPEN AS TO LET IN AIR ON THE RETURN STROKE. EVEN BETTER IS TO TEMPORARY SEAL THE THREADS. CHEWING GUM WILL WORK.
Frank Grimaldi

This thread was discussed between 06/11/2012 and 29/11/2012

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.