• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR6 TR6 Brake Question.

Share this page

mlarnoldTR6

mlarnoldTR6

Member
Offline
Today while stopped on a steep incline in traffic I noticed that my brake pedal very slowly and gradually sank toward the floor. I never lost braking and the pedal came back to a normal, firm position with one pump of the pedal but gradually sank again. The brakes continued to function properly all day and the car stops and brakes without pulling. The reservoir appears full. Does this sound normal? Is there a seal in the master cylinder which might be failing or some other problem? If so, rebuild or buy new?
 
Sounds like a brake master cylinder seal. I can't speak for the rebuilding, but I think new MC's are pretty costly. I remember having luck with a rebuild 15-20 yrs ago, but it all depends on the condition of the MC bore.

Others please feel free to chime in.
 
My guess would also be the master cylinder is causing this. The seal can be replaced and if the bore of the master cylinder is too worn it can be reamed out and sleaved with stainless steel.
Also check the "actuator rod" if that is what it is called (attaches to the pedal with a clevis pin) as corrosion of the rod gives a rough surface and tears the new seal.
I just replaced the master cylinder on my TR4a, easy job on my car if you have someone to help with bleeding the sysrem afterwards.
Simon.
 
If you have ever had good luck with re-building a mastercylinder, I say go ahead and do this one too. If you have not then DON'T Its a little tricky and lets face it a clear saftey risk. After all 190$$ wont buy a single wing anymore!!
Mad dog
 
Thanks for the advice. New MC it will be. I've heard we have to be careful about what kind of brake fluid we use in LBCs. Could someone give me a tutorial on the differences in brake fluids and which ones to use. Thanks.
savewave.gif
 
I agree with the recommendation to buy new. Suggest you source the MC ($168.) from Kai Radicke at https://www.wbclassics.com/index.html
Kai is an avid supporter of our TR6 hobby and worth the business.

Regarding brake fluids: if you don't autocross or otherwise stress your braking system, I recommend silicone (DOT 5) fluid. It is non-hygroscopic, doesn't eat paint, but is expensive (about $18 or so a quart). Otherwise, stick with Castrol LMA DOT 3 glycol. Either fluid requires periodic renewal (silicone every other year, LMA annually) to remove moisture.

Rick O.
72 TR6
 
Important point I forgot: if you convert to silicone, you MUST flush the entire hydraulic system to remove any trace of glycol and moisture. This is best accomplished by running denatured alcohol (Lowe's/Home Depot sells it by the gallon)through the system.

Rick O.
 
Back
Top