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MG Midget and Sprite Technical - mixing brake fluid?

so i've got a new midget

but i have to remove the calipers to do some jobs and after that bleed and top of the system.

how do i know what fluid to use?

the previoes owner does not know what has been used
he says he got some fluid from magic midget (they only sell 5.1) but he has had the MC refurbed after that

i have found a bill with dot 5.1 on it but it is from 2004 (before the MC refurb)

so i am confused and i do not want to thrash the hoses etc

can you mix dot 3, 4 and 5.1 ?

how about dot 5 (without the .1)

how to check what is in the system?
Onno Könemann

See if the stuff in the calipers strips paint.
Brad
B Richards

DOT 3, 4 and 5.1 as well as most racing fluids are compatible and will strip paint.

DOT 5.1 is Silicone and isn't compatible with anything else and won't strip paint.

Older Citreon and Rolls Royce use a mineral fluid which isn't compatible with anything else.
Daniel Thirteen-Twelve

Daniel, I think your first and second lines contradict each other :+?
IIRC DOT 5 & 5.1 are not compatible with DOT 3 & 4 as per your second line?
Late Night?
Graham.
Graham P 1330 Frogeye

Onno, here is a link to a dutch p.d.f. file about compatibility of brake fluids. Basically the silicone brake fluid is purple and not compatible with yellow/goldisch colord non silicone brakefluid.
http://www.bardahl.nl/uploads/media/B53500NL.pdf

Pascal
pjw Seezink

I think you'll find you can tell them aprt by tasting it
MarkDJ

Hi Graham,

My original statement is correct.

DOT 5 is silicone and DOT 5.1 isn't and this has always been the case.

DOT 3 and DOT 4 are NON silicone and so will mix with other NON silicone brake fluids which are DOT 5.1 and most racing fluids.

Not all silicone fluids are purple and even those that are don't necessarily stay that colour.
Daniel Thirteen-Twelve

Dot 3, Dot 4, Dot 5, Dot5.1, they all taste bad to me.

Onno if your in any doubt, just flush the system through with a heap of the fluid you intend to use,
Brad
B Richards

IIRC Silicone and normal brake fluids can be mixed but then you loose the benefit of the silicone.

So the only check you have to do is to check if its silicone. If so (feels a bit sticky between the fingers and wont burn as normal brake fluid does) top up with silicone otherwise use a good brand brake fluid. My guess DOT 4. If you have to much money or if you are racing often maybe the 5.1 is a good choice.
Bas Timmermans

On the other hand if you mix Silicone with non silicone you gain some of the disadvantages of Silicone.

Daniel Thirteen-Twelve

:-)
Bas Timmermans

silicon fluid will not mix with the glycol fluids although it does not react either. I converted to silicon and after many years, split the calipers only to find a small, rusty pool of residual glycol fluid at the base of each caliper piston.

If existing fluid is amber and not purple, I suggest using ATE DOT 4.
Glenn Mallory

This thread was discussed between 24/10/2008 and 26/10/2008

MG Midget and Sprite Technical index

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