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MG MG Y Type - Replacing DOT 5 brake fluid

Two years back, as part of a complete restoration of my YT, I had opted to use DOT 5 Silicon brake fluid. Since the brakes feel a bit spongy and there is quite a long pedal travel, I want to change to DOT 5.1, of the non-slicon superior type.

After reading Michael Long's brilliant article, Brake Fluids - DOT 3,4,5 and 5.1, in the BBS' "Hints & Tips", I have the following question:

1. Is it sufficiant to flush the system and change all seals (as recommended on page 1 of the article), or
2. Must one also replace all brake hoses (as one could interprete the text on page 3).

I do have spare sets of Master- and Wheel Cylinder Sevice Kits, but I would hate (because too expensive) having to replace the nearly new hoses as well. Matter of fact, in that case, I would leave the Silicon hydraulic system as is....

Anton





Anton Piller

Anton,
leave your silicon brake fluid in, there is nothing better and trouble free. When it feels spongy, then one or more seals (or hose?) are not silicon proof and started to dissolve.

Best regards
Walter
Walter Prechsl

I agree with Walter. Keep the silicone - eliminate the spongy pedal with another bleed.

Tony
A L SLATTERY


Thank you Gentlemen
Anton
Anton Piller

Anton,

When bleeding the DOT5 fluid, it is not necessary to "Pump" the pedal. You will get a better "bleed" if you just have a helper apply the brake, bleed, let the pedal up gently , then repeat until air is purged.

I have just completed this proceedure with "soft" brakes on my YT. The car sat all winter, and when bled, I got a lot of entrained air out of the system.

Brakes are now solid and work as they should.

... CR
CR Tyrell


Thank you, CR

Interesting version - sounds right and will be applied :o)

Anton
Anton Piller

Even when pouring into the master cylinder, you should insert a flat steel strip to pour onto, so the fluid does not entrain air - slowly pour.

If you get air into the fluid it can take weeks for it to gather into bubbles that you can bleed out.

Good Luck - it's worth it in the end.

Cheers

Tony
A L SLATTERY


Tony

Tank you for the flat steel strip trick. One is never to old to learn :o)

Anton
Anton Piller

This thread was discussed between 24/03/2020 and 29/03/2020

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