quaility of rubber seals

[Dieter H. Marschall]

Hello everybody,

yesterday I replaced the seals on the main brake cylinder of my TR6. I had bought the after market repair set for € 38.00 - so they were not cheap quality.

After dismantling the brake cylinder I found out that the old seals had desintegrated to some soft and slimy substance.

After I had put in the new seals (using some red Girling rubber grease) and refilled the brake system with DOT 4 fluid and bled the system, the brake did not build up any pressure.

Frustrated I drove home to get another seal repair set. When I came back to the garage I tried the brakes again - and they worked. Obviously it took the brake fluid some time to make the seals swell and make them tight.

Of course I now keep wondering, what else the brake fluid will do to the seals.... I hope they do not desintegrate again!

My question now is: Where can I get main brake cylinder seals (new or new old stock), which certainly do not desintegrate with DOT 4 brake fluid? The problem with NOS seals might be that over the years they have aged... I am prepared to pay good money for good quality!

Kind regards - from Germany,
Dieter.

[ChasR]

Seals that have stood me in good stead recently are ones manufactured by Caparo/AP. However, I have only come across County seals for sale on Stags.

[martin]

Hi Dieter, it's quite possible that the brake grease blocked some small aperture, until the fluid dissolved it. Avoid new old stock seals, they deteriorate badly over time, though they don't look it. I'd have thought your best bet for seals would be a UK supplier, Paddock, TRGB etc. Cheers, Martin.

[Dieter H. Marschall]

Hello, Martin - and others,

I use Dot4 brake fluid, not DOT3. Dot4 seems more aggressive to rubber seals. Could that be the reason, too?

Kind regards,
Dieter.

[martin]

Hello, Martin - and others,

I use Dot4 brake fluid, not DOT3. Dot4 seems more aggressive to rubber seals. Could that be the reason, too?

Kind regards,
Dieter.

That's not a phenomenon I've ever come across, I would doubt that there's any difference worth noting between Dot3 and Dot4. Martin.

[Dieter H. Marschall]

.... maybe I should just throw all the rubber bits into a glass with DOT4 and wait what happens. If I only build in the ones that did not start getting slimy, I should be on the safe side. Right?

Kind regards,
Dieter.