clutch won't engage

cbnjulie · 09-11-2005, 03:10 PM

I have a 1980 MGB with 50,000 miles. Actually, it has 49992 miles and the wife and I had planned a special trip to pass 50 on but the time never seemed right and the car ended up sitting for the last 3 months. In the interim, something has gone bad with the clutch system. I started it up this morning with the intention of crossing the mileage threshold. It started fine- as always, but the clutch would not engage.

Am I looking at hydraulic system or clutch? It will go into gear (as evidenced by the car starting and immediatly dying in any gear) but pushing the pedal won't put it into neutral so as to select gears.

Any help most appreciated. We've loved the car up to now. I'd like to get it back on the road as soon as possible.

Thanks!

CB

Flash75 · 09-11-2005, 07:47 PM

CB,
Have you checked the clutch master cylinder for fluid level and leaks? That would be the first area to look. You probably have a hydraulic problem. After confirming the clutch master cylinder is full look at the clutch slave cylinder under the car on the right side near the rear of the engine. You will see the push rod connected to the clutch operating lever. Look for leaks around the slave cylinder push rod, this is a common area for leaks.
If it looks ok, have an assistant operate the clutch pedal while you observe the push rod. If it is operating correctly it should travel about 1/2" with the clutch pedal depressed to the floor. If it moves less than 3/8" you probably need to rebuild or replace one or both cylinders. Usually I have found the slave cylinders pitted, if it is a rebuild will not hold. It would be a good idea to replace the flexible hose at the same time the cylinders are repaired. Do the job right and it should last 10-12 years. If you decide to rebuild or replace the cylinders, remember you will need to bleed the system after it is filled with fluid. If you have additional questions post again. Do you have a Haynes or some other MGB repair manual? Hope this helps.

Clifton

MGBSS63 · 09-11-2005, 09:38 PM

Check master for fluid. Sometimes it goes low.Pump the pedal after topping.Pump it about an inch or 2 down about 10 times then fully stroke it about 5 times. Repeat if you start to feel pressure until pedal feels normal sometimes this gets the air out without bleeding old trick.If fluid ends up on ground do what Clifton said to do.mgbss63

cbnjulie · 09-12-2005, 02:52 PM

Reply to the two fine posts:

My clutch pedal pressure appears normal. I checked the master cylinder under the hood and it appeared clean (leak free) but I went ahead and topped off the fluid (I had the correct fluid from replacing the lines about 2 years ago). I'm hoping the slave has gone bad- I'm going to check that next. As I'm not Mr. Mechanical I will probably buy a new part rather than try to rebuild. I have the Haynes Manual so I can get the correct part diagrams, etc. I can't imagine that it could be any thing other than the hydraulics as you gentlemen have indicated since the clutch has worked flawlessly up to now and seems to have lots of life left in it.

By the way, the very precise descriptions of parts and their locations has been a great help to me- I want to thank you for the care and consideration that you put into your responses. I can follow directions but I don't know car parts and locations so well. The help from your fines posts is very appreciated.

I'll post details as the come.

Thanks again and humbly yours,

Chris

cbnjulie · 09-12-2005, 03:40 PM

I don't seem to have any leaks around the master or slave. I measured the stroke of the clutch around the slave with a ruler and I'm only getting about 3/8" out of it. Is that master or slave, or both? As I said, I don't seem to have any fluid leaks- it was still at the level that I topped it to yesterday and no fluid around the parts or hoses.

Thanks,

Chris

MGBSS63 · 09-12-2005, 04:12 PM

After starting it won't go from neutral to 1st?I've had the clutch sieze between the pressure plate and flywheel from sitting . I was able to push start it in gear and work the clutch till it pops free.Give yourself plenty of space and if it doesn't work pull shifter into neutral or turn off switch.Can you hear any noises coming from the clutch area ? Like throwout bearing or broken pressure plate.If you have good pressure on your pedal and you have good stroke at slave only thing left is clutch job. mgbss63

cbnjulie · 09-13-2005, 09:41 AM

The clutch isn't noisy- I'll try and push start it and see if I can work it free that way. I'm at a loss. I have a good European mechanic in town but I'd have to tow it and pay whatever outrageous fees they charge for the engine pull and clutch job.

Thanks,

Chris

MGBSS63 · 09-13-2005, 01:46 PM

Still confused by your original statement that it will go into gear after starting but then you can't shift to neutral and any other gear.When you 1st start in neutral will it go into 1st gear or reverse?mgbss63

Flash75 · 09-13-2005, 06:14 PM

Chris,
3/8" pushrod travel should be enough. It sounds like the hydraulics may be ok. MGBSS63 mentioned a stuck clutch. This link should provide information on how to unstick a stuck clutch. It's an MGA site but the procedure is the same;
http://www.mgaguru.com/mgtech/clutch/ct_104.htm

You may want to bookmark his home page. It's an excellent resource site for MG owners. Much of the MGB is similar to the MGA.
http://www.mgaguru.com/mgtech/index.htm

Clifton

cbnjulie · 09-15-2005, 07:33 PM

To Clarify:

The gears are fine. If I place the shifter in 1st (or any other gear) and start the motor it will try to start and lurch forward. Applying the clutch will not disengage the gear.

-Chris

cbnjulie · 09-15-2005, 07:49 PM

Quote:

Originally Posted by Flash75

Chris,
3/8" pushrod travel should be enough. It sounds like the hydraulics may be ok. MGBSS63 mentioned a stuck clutch. This link should provide information on how to unstick a stuck clutch. It's an MGA site but the procedure is the same;
http://www.mgaguru.com/mgtech/clutch/ct_104.htm

You may want to bookmark his home page. It's an excellent resource site for MG owners. Much of the MGB is similar to the MGA.
http://www.mgaguru.com/mgtech/index.htm

Clifton

Thanks so much for the help on this- turns out it was a stuck clutch disk. I followed the link that you posted and just used the 1st method- it came right undone! The wife and I will pass the 50,000 mark this weekend!

Thanks guys for the help- without the advice here I would have easily been out hundreds if not thousands of dollars.

All the best,

Chris Brandt

Flash75 · 09-15-2005, 08:12 PM

Chris, Good to hear you didn't have to make some major repairs.

Clifton

MGBSS63 · 09-15-2005, 11:41 PM

Happy motoring!!! mgbss63

kenlowe · 08-09-2012, 03:00 AM

My 1977 MGB clutch works perfectly, but from time to time, when depressing the clutch pedal, I feel something is still spinning. Then a soon as it started, it stops for a couple of hundred miles. If something is not working in the clutch, surely it would happen all the time and not just now and again

MGBSS63 · 08-09-2012, 09:42 AM

Throw out bearings can be intermittent.MGBSS63

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