tore-norway Posted September 11, 2009 Report Share Posted September 11, 2009 Hello, I am working on my 1979 TR7 DHC. I have stripped down the engine bay for a respray. I have also dismantled all the brake-parts, and blown through the pipes with pressurized air. I have bought a new master cylinder and slave cylinder. I have bad experience from my TR6 with a leak in the master cylinder (DOT4, glycol based fluid) that removed some of the paint below (after a complete respray of the car this was very annoying). My question is: Has someone tried the silicone based DOT5 brake fluid? Is it recommended to use DOT5 for a fast road car? If I choose DOT5, how critical is it to clean all brake parts form the old DOT4 fluid? (The calipers remains to be cleaned.) Any experience will be of interest. Quote Link to post Share on other sites
hrgserv Posted September 11, 2009 Report Share Posted September 11, 2009 I tried dot5 (silicon) based fluid, in a new system i kept it 2 weeks before going back to conventional dot5.1 fluid as the pedal was horribly soft, the 5.1 cured the problem comletely! and before anyone says you didnt bleed the brakes properly, they were fine h Quote Link to post Share on other sites
Guest Wayne S Posted September 11, 2009 Report Share Posted September 11, 2009 (edited) I use DOT 5.1 in my TR7 and TR8. My Dad uses DOT 5.1 in his TR4. The calipers should be fine, the seals that tend to swell are those in the master cylinder and slave cylinders and since your renewing those it shouldn't be a problem. Its advantage is that its less prone to boil and is not as vicious on your paintwork. Edited September 11, 2009 by Wayne S Quote Link to post Share on other sites
Rhodri Posted September 11, 2009 Report Share Posted September 11, 2009 DOT 5.1 is synthetic, but it is NOT silicone. DOT 5 is silicone- confusing eh ?! Rod Quote Link to post Share on other sites
willywonka Posted September 15, 2009 Report Share Posted September 15, 2009 DOT 5.1 is synthetic, but it is NOT silicone. DOT 5 is silicone- confusing eh ?! Rod You will be able to find the answer to the question here at the bottom of the article. http://www.carbibles.com/brake_bible.html Quote Link to post Share on other sites
RogerH Posted September 17, 2009 Report Share Posted September 17, 2009 Hi Tore, if you want to use DOT4 or 5.1 why not re-paint in 2 pack. This is impervious to everything except a nuclear attack and is still available. Roger PS why didn't thet call it DOT4.2 or DOT6 - DOT5.1 is too similar to DOT5 there will be mistakes made Quote Link to post Share on other sites
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