Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Silicone Brake fluid - Holy Grail

An important safety point is to put a label saying which fluid is used on the car either on the master cylinder or nearby and easily seen. If you have a handbook put one or make a note in the fluids section.
Personally unless I was doing a full replacement of the whole system I would stay with whichever fluid was in there. Both do a good job.
The only real difference is Dot4 needs replacement.

I use 5.1 in my oldtimer. I read 5.1 is mixable with all other. So I feel save.

Yes, I agree. DOT 3,4 and 5.1 are all inter- mixable synthetic fluids. Advantage with 5.1 is an even higher boiling point of 180C compared to DOT4 at 155C and DOT 3 at 140C.

I´M not sure. I think just 5.1 is mixable with all.

My experiences, when my 1969 4/4 was restored in the mid-1990s we put silicone fluid in for the brakes and clutch (joint 'tin can' reservoir). I refreshed the braking system this year, no sign of corrosion anywhere and no problems with braking/clutch in the intervening period - usage is a low mileage and a pure road car.

Andy

This from Google:

Can brake fluids be mixed? Yes, brake fluids conforming to DOT 3, Dot 4 and DOT 5.1 can safely be mixed although the performance of the higher specification products will be diluted. Silicone (DOT 5) and mineral-based brake fluids should never be mixed with any other types.

Rob
A article in this months Miscellary(could be in January) about rusting brake bits and the type of rubber compound to use. Something by Bosch i believe........those pesky Germans again!!

I see, Richard. Thanks for enlightenment.

Peter,

I support what you said. When I totally rebuilt my 1958 +4 in 1972-74 I replaced the entire brake system, Goodridge stainless lines, Kunnifer tubes and silicone fluid. Other than brake linings and infrequent cylinder repair I have been running silicone to this year. Drain and refill every 10 years. I was living in HK for 30 years so high humidity and reason for silicone.

When I bought my 86 +4 from the factory I asked them to fill system with silicone. They said law did not allow. So, after first service I purged entire system refilling with Silicone and new Aeroquip. Aeroquip or similar get rid of the soft pedal regardless of fluid. If you live in a high humidity area silicone solves the water and corrosion issues.

Moss Motors sell nice bright stickers saying Caution Silicone Fluid and also Caution Positive Earth if required.

Cylinder rubbers look like right out of the box when you change at 10 years.

I only keep the three wheeler(2012) on normal fluid.

Tom S

I can only say that when starting racing many years ago with inboard discs on an Alfasud after constant brake issues -I changed to silicone fluid and thoroughly purged the system -never had a problem again, we do have high humidity in Auckland.