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Strange clutch problem

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Strange clutch problem
#1
  This topic is about my 1977 MG MGB
Kats Bee Jim and Kathy Buckalew
Kingsville, TX, USA   USA
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1977 MG MGB "Esmerelda (for Now)"
1978 MG MGB "The Parts Store"
1979 MG MGB "Barbi"
1980 MG MGB Limited Edition (LE) "Elvira"
The clutch in our '77 MGB has me scratching my head. In the morning when it is cool outside the clutch pedal pretty much goes straight to the floor, making me shut the car off, engage reverse and then restart the engine so I can back out of the driveway. No problems with the forward gears. Later in the day when the outside air has heated up, the clutch does not present ANY problems at all. The pedal is good and high, engaging and disengaging as it should. I have checked the fluid level many times and it is topped up to with in 1/2 inch of the MC top. Could the MC be by-passing fluid internally when the engine bay is cool and operating normally when there is heat in the system? Jim

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tomkatb Avatar
tomkatb Larry Baygents
Dayton, Ohio, USA   USA
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1963 MG MGB
Maybe! It is very difficult sometimes to know which part is defective.

How old are the master, slave and hose?

My guess is the master, however I am from the "replace all three" schools of thought.

In 43 years I have never been towed.



L.W.(Larry)Baygents
63B
77 Spit

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Kats Bee Jim and Kathy Buckalew
Kingsville, TX, USA   USA
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1977 MG MGB "Esmerelda (for Now)"
1978 MG MGB "The Parts Store"
1979 MG MGB "Barbi"
1980 MG MGB Limited Edition (LE) "Elvira"
Hose and slave are new, not sure of the master age but it is not original. I have a master replacement now I have to install it. Thanks, Jim

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tomkatb Avatar
tomkatb Larry Baygents
Dayton, Ohio, USA   USA
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1963 MG MGB
Replace or service the copper gaskets!

In theory they are not reusable. Many do. Many have bleeding issues.

Easily annealed.

In a new 72 B the brake master failed at 30,000 miles. Others last forever. This was when I allowed others to touch my car.

I use only 1 brand of brake fluid, LMA and have been lucky. Stick with one. Being from the world of chemistry we do not like mixing stuff.



L.W.(Larry)Baygents
63B
77 Spit

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Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
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The clutch MC is the most temperamental in the whole chain of parts. The seal on the piston also acts as a valve mechanism, therefor as a minimum change all the seals with the MC in place.
If you do not mind the expenditure just replace the whole MC by a new one and indeed renew the copper washers on the banjo junction or anneal them.
"Slave cylinder often gives up in sympathy with the master" says Porter, but I myself have replaced many MC's/seals and very few SC's. Hoses last for a very long time eye rolling smiley

PS Afterwards prepare yourself for the bleeding, which may go easy or not. See the numerous posts on clutch bleeding variants

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RAY 67 TOURER Avatar
RAY 67 TOURER Ray Marloff
Fort Bragg, CA, USA   USA
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1967 MG MGB "My Girl"
Definitely a master cylinder failure. It has all the hallmarks of one. No loss of fluid is the biggest giveaway. RAY

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Kats Bee Jim and Kathy Buckalew
Kingsville, TX, USA   USA
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1977 MG MGB "Esmerelda (for Now)"
1978 MG MGB "The Parts Store"
1979 MG MGB "Barbi"
1980 MG MGB Limited Edition (LE) "Elvira"
That's what I was thinking Ray. Now....what is the annealing process for the copper washers?? Jim

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