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Triumph TR6 - Brake MC - What's normal??

Just finished a MC rebuild and bled brakes. I went to check the brake fluid level and I find the cap so damn tight, I think a vacuum's been created. Can't budge it open. Reservoir is still very full.

Is this normal, or a symptom of a darker problem? When the system initally leaked, it was also nearly impossible to remove the cap.

Maybe I just need another bowl of Wheaties?


Mati, I have found the same on 2 masters I have used, an older 1 that was originally on my car and to some extent the new and rebuilt one that is now on it I think some type of a vaccum is present or I also hope so. I had to use a rubber mallet to loosen it enough to where I could turn it by hand. My old master had an old gasket but the new gasket did not make it any easier to open. My new master is much easier comparitively speaking than the old, although during rebuild I did wash inside of the cap with fluid (dot5 silicone) so that may have made it turn easier maybe try that if yours is real tuff or rubber grease on the threads careful not to mix with fluid.
Regards, Keith
to hell with wheaties pour out a pint

Hi Mati

In my experience they are all like that. I think its just the type of seal and they are easy to overtighten going on. My pump filter top on the pool is the same and there is no vacuum there.
Not a good idea to hit them. What I have found works well are those boa constricter wrench deals with the rubber strap.

Bill Brayford

I sure love my old-fashioned TR3A. The cap on my combined master cylinder reservoir (combined for both the brake and for the clutch) has a tiny hole in the top of the fill cap with a plate inside which has another small hole in it, but offset from the other. The seal in the cap lets me tighten the cap down snug by hand and the vent hole allows me to remove it by hand.

They must have hired a bunch on new young inexperienced designers by the time the TR6 arrived on the scene.

Boy ! Do I ever love my simple TR3A !

Don Elliott, 1958 TR3A
Don Elliott

I had a local MG shop install my MC, the mechanic noticed the same thing in regards to the vacuum. My old unit had a small hole in the top so he just drilled a small hole in the new unit. That was seven years ago and have never had a problem since.
Mike Parkhill

Don-Have you noticed how much the TR3 brake/clutch resevoir resembles a can of rubber cement that has the brush in the lid? Knowing how money was tight when the TR was designed, I wonder if an engineer saw an empty can and a light went on in his head. Just a thought.

This thread was discussed between 31/03/2003 and 02/04/2003

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