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MG MGA - Clutch problem

Hi, A friend of mine has a problem with her clutch. She owns a TR7 (also owns a MGC) She has replaced her total clutch system that would include clutch, pressure plate, throw out bearing, master and slave cylinder and hose. The problem she is experiencing is that after abour 30-40 min of driving the darn thing just will not go into gear. She thinks she may have a heat related problem. The people who replaced the clutch are not as experienced in English car as, Perhaps, they could be. Any help would be appreciated. Thanks, Neal Turner TR7 4 cyl
Neal Turner

Neal - I don't know anything about TR7s (other than they have een dericively called a flying door stop), but on the MGBs, it is sometimes difficult to get all of the air out of the slave cylinder when bleeding the system. Yhe following procedure has always worked well for me.

After standard bleeding procedure, remove a bit of the fluid from the master cylinder, get under the car and and disassemble the slave cylinder to clutch throwout arm as necessary to get a phillips screwdriver into the slave cylinder in place of the normal push rod. Push the piston in the slave cylinder all the way back into the cylineder, reassemble the linkage and rebleed in hte normal fassion. This will usually push any remaining air from the slave cylinder back up the hydraulic line, where it can be blead off in the normal fassion. You may have to repeat this a couple of time to get rid of all of the air, but it is not as difficult to do as to write about it. Good luck - Dave
David DuBois

When it wont go in gear do you mean that the gears grind and the lever wont more far enough ? Or do you mean the lever goes in gear with no grinding but the car wont move?
R J Brown

Hi, The gears grind and there does not seem to be enough clutch pedal to allow free movement. The slave is thought to be the problem. As if it does not move enough to free the clutch. Thanks, Neal Turner
Neal Turner

The slave moves in direct relation to the amount of fluid sent to it. If the problem is in the slave it will leak fluid externally. The problem is air in system or a bad master cylinder or no freeplay at the master cyl. When installing the master cylinder the length of the rod from the pedal to the cylinder needs to be adjusted. If the rod is adjusted too long then the master is not allowed to return fully. If it doesn't return fully it doesn't uncover the return hole inside. When that happens the master cant get another "bite" of brake fliud. It is then almost impossible to bleed the system. The master cyl must have freeplay, the pedal must move slightly without moving the rod that goes in to the master. After verifying that there is freeplay at the master SLOWLY bleed the system. Pumping franticly on the pedal only airates the fluid. I have found that the surest way to bleed the cluth is to open the bleeder at the slave and cover the hole with the tip of you finger. Then have an assistant push the pedal to the floor and stop then you release and then reapply you finger to release any pressure then reseal the bleeder then the assistant pulls up the pedal and pushes it down once. One bite relase one bite release. Continue this pattern soon the fluid will force your finger off the bleeder and your finger will act like a one way valve for the fliud/air mix as you assistant slowly one stroke at a time pumps the fluid through the system. Soon you will feel that there are no more bubbles of air ir the system. After a couple more strokes just to be sure have your assistant hold the pedal down on the floor while you close the bleeder. Remember to keep an eye on the fluid level in the master cylinder and keep it full while bleeding. I have seen profesional mechanics with 20+ years unable to bleed a clutch because they didn't set the freeplay correctly or the have an asisstant pump 5-10 times between openings of the bleeder and just pump the fluid full of air. I have heard more than once a frustrated mechanic say "I've pumped almost a gallon through and there still is air in the lines, I don't understand it"
Almost all the trouble people have bleeding brakes or clutches comes from lack of patients and airating the fluid or having no freeplay at the master. One additional note silicone brake fluid airates easier, that is why some learn to blame it when their overly vigorous methods are the real culprit.
I hope this helps those of you that have had trouble bleeding brakes.
R J Brown

Anouther method that works at least as well as to finger over the bleeder method is to place one end of a length of rubber vacume hose onto the bleeder and the other end into a container (I use a clean plastic soda bottle) of clean brake fluid (just an inch or two). Then pump the brakes (or clutch) while you watch the bubbles in the bottle. No more bubbles, no more air in the system.
John
J.H. Hall

If it won't go on any gear, the pilot shaft may be sticking in the flywheel bushing when hot.
w.g cook

The final secret to successful clutch bleeding is to push the piston in the slave back as far as it will go into the cylinder, and hold it there while your assistant presses the pedal. You will need a strong lever to do this, but it makes bleeding the clutch significantly faster as there's much less space for the air to get into, and it has to go straight out of the bleed nipple.
dominic clancy

Help,

I've just fitted 4 pot calipers to a TR7 and try as i might i just cannot get the system to bleed. I know how to bleed brake and have been doing it 20 years. What happens is that after lot os bleeding, the first full push of the pedal goes to the floor and the subsequent ones build a little pressure. Pause a bit and the pedal goes to the floor again. I've checked all 8 pistson are mving freely and there is no excessive movement of the pads (taking all the moving fluid). I'm down to thinking that it must be the brake master cylinder seals and that as the 4 pot calipers have a greater mvoing volume of fluid, the master cylinder must be working a tip top condition if it is to pump enough fluid into them to clamp the pads onto the disks. Ideas anyone?

Nick
Nick

Why is this board suddenly being invaded by TR7 types - are we more mechanically able, friendlier and better at responding to questions?

dominic clancy

Dominic, Yes, you all are. I have found out that the problem is with the slave hose from Moss. It is a manu defect that allows the hose to expand. Moss is to fix the problem with a stainless wrapped hose soon. Now the problem has been solved with a copper pipe with proper end fittings. Thanks for all your input, Neal Turner
Neal Turner

This thread was discussed between 03/10/2005 and 15/10/2005

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