brake question

[Corbusa]

I will be changing brake fluid ( its old) thoughts on me switching to Dot 5 ? thanks

[secondchance]

Originally Posted by Corbusa

I will be changing brake fluid ( its old) thoughts on me switching to Dot 5 ? thanks

I wouldn’t. DOT5 is silicone based fluid and not compatible with our ABS.
Stay with DOT3 or 4.
DOT 4 I believe has higher boiling temp but shorter service life compared to DOT3.

[Corbusa]

thanks Bro

[Thomas ZR-1]

You should use DOT3, DOT4 and 5 are chemical more aggressive to the rubber seals in the brake system (rubber swelling).

[spork2367]

Originally Posted by Thomas ZR-1

You should use DOT3, DOT4 and 5 are chemical more aggressive to the rubber seals in the brake system (rubber swelling).

Dot 4 is completely compatible with Dot 3. In fact it's getting harder to find a brake fluid that is listed as Dot 3 and not Dot 3/4.

[Hib Halverson]

Originally Posted by Thomas ZR-1

You should use DOT3, DOT4 and 5 are chemical more aggressive to the rubber seals in the brake system (rubber swelling).

"Thomas ZR-1", are you able to offer some facts to support the statement that DOT4 and DOT5 brake fluids are "chemical (sic) more aggressive" such that they cause swelling of rubber seals?

Also, DOT5 fluid is silicone-based and is an excellent choice for old "non-ABS" classic cars where preventing corrosion inside the brake system is the prime concern and braking performance is secondary.

DO NOT use DOT5 silicon-based brake fluid in any vehicle with ABS. The viscosity of DOT5 fluids is incompatible with the rapid fluid movement required for an ABS to operate properly.

[spork2367]

Originally Posted by Hib Halverson

"Thomas ZR-1", are you able to offer some facts to support the statement that DOT4 and DOT5 brake fluids are "chemical (sic) more aggressive" such that they cause swelling of rubber seals?

Also, DOT5 fluid is silicone-based and is an excellent choice for old "non-ABS" classic cars where preventing corrosion inside the brake system is the prime concern and braking performance is secondary.

DO NOT use DOT5 silicon-based brake fluid in any vehicle with ABS. The viscosity of DOT5 fluids is incompatible with the rapid fluid movement required for an ABS to operate properly.

And the seals in braking systems haven’t changed material composition since 1990 when these cars were built.

[Great White]

I used Pentosin DOT 4 when I serviced my brakes last spring. It has a dry boiling point equivalent to most DOT 5 fluids (which are never to be used with our braking systems.)

[Corbusa]

Thanks for the replies , I still havent gotten to the brakes yet ( been working OT). Maybe I'll get to it over thanksgiving.

[Great White]

The talk of seal compatibility with fluids reminded me of this page from the "Fluid Power Data Book." Not sure if it exactly applies here or not, but it's still helpful information that has served me well over the years.