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Brake fluid

Posted: Wed Aug 28, 2019 3:32 am
by timandgerda
I have completely rebuilt the brake system on my TC and was planning to use silicon fluid but have read that it doesn't give a firm pedal. Is this true and any advice on alternatives would be welcome. Cheers. Tim.

Re: Brake fluid

Posted: Wed Aug 28, 2019 10:08 am
by Marv
I recently rebuilt the brake system on a MGB and a MGA and changed both over to Silicone DOT 5.0 Silicone. Don't mistakenly get DOT 5.1 which is just a refined version of DOT 4.0 Glycol Based Fluid. I did not experience any loss of brake pedal feel in the changeover. In fact the only scenario I've read about spongy pedal and DOT 5.0 is that DOT 5.0 should NEVER be mixed with glycol-based brake fluid. If you do, it is not unusual to expect spongy brakes, poor braking performance, and even damage to caliper seals and hydraulic seals.

Re: Brake fluid

Posted: Wed Aug 28, 2019 11:56 am
by Tom Lange, MGT Repair
Silicone brake fluid is another of those subjects on which you will get polar opinions. I have used it for years, and strongly recommend it IF the system is entirely rebuilt/replaced, and IF you flush the system with alcohol first.

Dot5 does not like air bubbles, so agitate as little as possible and push down and release the brake pedal gently when bleeding. A vacuum bleeder proves its worth here! Getting all the air out of a silicone fluid system is harder (which is why you hear that it results in a soft pedal), but once bled with no air in the system, the pedal is hard as a rock. Be prepared to need to bleed it three or four times the first time, to get all the air out, but the end product is worth it, IMHO

Tom Lange
MGT Repair

Re: Brake fluid

Posted: Wed Aug 28, 2019 3:16 pm
by Steve Simmons
I fully agree with the above. While I don't use it in the TC, I do use it in several other cars including MGA, MGB and MGC. The only downsides I've found are a bit more difficulty bleeding, and cost / availability.

Re: Brake fluid

Posted: Thu Aug 29, 2019 6:35 am
by stephen stierman
I use silicone in all my old cars and have for years. As long as you renew all the rubber parts and thoroughly clean out the old fluid it is just fine. I would use nothing else as my cars often are not used for several months during the winter and there are no problems.

Re: Brake fluid

Posted: Sun Sep 01, 2019 1:58 am
by bloodysalmon
interestingly, how do people best 'bleed' the brakes, on your own ... how? Tools ... gizmo? :thumbs:

Re: Brake fluid

Posted: Sun Sep 01, 2019 1:02 pm
by timandgerda
Thanks all. I am going with Dot 5 and have an Eezibleed kit so will let you know how I get on (I haven't got the fluid yet so may be a while!)

Re: Brake fluid

Posted: Sun Sep 01, 2019 1:24 pm
by stephen stierman
My wife will pump the peddle, now if I could just get her to crawl under to access the rear bleeders...…..

Re: Brake fluid

Posted: Sun Sep 01, 2019 4:16 pm
by Duncan M
The ability of typical (DOT 3/4/5.1) brake fluid to evenly absorb moisture is actually a desireable characteristic, as long as the fluid is flushed every few years.