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MG MGA - Clutch Hydraulics

Ok its about my TR6 but I need help and that forum is verry small. (Similar set up to my MGA)

My son has my 75 TR6. When he pushes the clutch pedal to the floor, the car still creeps along. Not at speed but it still moves.

He topped off the fluid and it still happens.

Any suggestions?

Help

Russell
R Egge

My guess would be a rubber hose that is ballooning under pressure. If it were a cylinder, it would usually disengage and then gradually engage more and more as the pedal was held down. If it were a slave cylinder you would most likely see leaking fluid.
Jeff Schultz

Does it grind when putting into gear? My first thought is all the is air not fully bled out of the system. If the slave cylinder and hose are in good shape and system is bled then you need to check for wear in the moving parts. Check pushrod and cleveis pin althought that alone is not enough but with worn clutch lever bushing and pin and worn release bearing of the carbon faced type alot of slop may need to be taken up before the release lever moves on the pressure plate. If all that is good then you need to check the pressure plate.
Charles O'Brien

Its a new clutch.Less that 500 miles
R Egge

Most likely incomplete bleeding. No experience with TR's (but restored my daughter's Dolomoite Sprint, clutch was a constant headache!) but MGA's and MGB's are notoriously awkward to properly bleed.
Barry Bahnisch

I have never managed to bleed the MGA clutch properly in the conventional way so I now bleed it backwards from the slave to the master cylinder as follows; with everything connected and the master cylinder full of fluid and left to settle for an hour if freshly filled from dry, I then push the clutch operating lever back towards the cylinder by hand slowly and steadily and then let it return by itself and repeat three times. Takes about a minute and a half for the complete bleeding operation and works everytime. The same may apply to a TR.
Lindsay Sampford

Lindsay That sounds interesting. Please define clutch operting lever? Where is it? Transmission? Not sure of the term.

Thanks in advance.

Russell
R Egge

Hi russell, proper name is "clutch withdrawl lever" it's the lever that goes through the transmission casing to operate the cluch release bearing. The outside part of the lever that attaches to the clutch slave cylinder is the part you press towards the clutch slave cylinder. Use hand force only, do not use a lever, you could damage the slave cylinder seals with excessive force. Just push the lever back as far as you reasonably can, it doesn't have to go all the way. What you are doing is pushing the air out of the slave cylinder and back up the pipe to the master cylinder where it will escape to the reservoir. Air prefers to rise through a liquid, that's why this method works better, and as you do it with bleed nipple closed, there is no chance of any air getting back in. Works for an MGA!
Lindsay Sampford

Bleeding most probable but:
Were the hydraulics rebuilt with the clutch change? And the pushrod adjusted properly?

It is common to have slave cylinder problems after replacing clutch, since the slave piston will be operating in a different section of the bore.

500 miles is almost too late to have hydraulic problems, unless they've been there since very shortly after the clutch job. Release mechanism trouble is quite likely.

TR use a different arrangement to MG. The slave pushes an adjustable pushrod, which has to be adjusted with wear or replacement of parts. The pushrod operates a lever that is part of a cross shaft through the bell housing. A tapered bolt holds the actual release lever/fork to the shaft inside the bell housing. The release lever moves a ball throwout bearing on a sleeve.

Trouble with this is very common if the mechanic replacing the clutch doesn't know what he's doing - the taper bolt breaks if too loose, or too tight, or because it's Tuesday; or it falls out. It is supposed to be safety wired, but they fall out anyway. Sometimes the bolt is in place but broken, allowing slop that increases rapidly until total failure; the unwary miss this when replacing the clutch. The bolts are made of cheese, frequently the hole in the shaft is incorrectly finished; such as TRF produce much better ones. Additionally, those of us with experience often arrange additional securing methods to keep shaft and fork together. It is standard practice to always replace the shaft and taper pin when doing a clutch, and in fact it is very common to have to cut the shaft out with a torch because the pin is broken off inside the shaft/fork. I taper ream the hole to match the pin, use Loctite, and crossdrill the shaft/fork for a 1/4" rollpin, which gets safety wired along with the taper pin.

FRM
Fletcher R Millmore

I agree with FRM that the tapered locating bolt (image item 9)is a curse.
In case you do not understand how the slave pushrod is adjustable, it is done by choosing the best of the three holes where the pushrod connects to the lever (image item 13).


Mick

M F Anderson

Earlier cars (TR2-4) had adjustable pushrods with a return spring; these had to be adjusted for freeplay; I've seen these on TR6 too, possibly retrofit. And the pushrods had a bizarre threaded clevis pin, which was known to fall out sometimes.

FRM
Fletcher R Millmore

I have attached an image of the adjustabe slave pushrod that FRM mentions.
The pushrod is threaded and has a locknut.
This was on early TR's but your TR6 could have it.


Mick

M F Anderson

This thread was discussed between 03/06/2010 and 05/06/2010

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