View Full Version : brake question
Corbusa
10-29-2019, 12:38 AM
I will be changing brake fluid ( its old) thoughts on me switching to Dot 5 ? thanks
secondchance
10-29-2019, 06:40 AM
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
10-29-2019, 07:04 AM
thanks Bro
Thomas ZR-1
10-29-2019, 11:53 AM
You should use DOT3, DOT4 and 5 are chemical more aggressive to the rubber seals in the brake system (rubber swelling).
spork2367
10-29-2019, 12:21 PM
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
10-29-2019, 12:36 PM
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
10-29-2019, 12:58 PM
"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
11-05-2019, 02:46 PM
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
11-05-2019, 07:33 PM
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
11-06-2019, 12:17 AM
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.
Gunny
11-06-2019, 09:23 AM
If you can get past the brand name, take a close look at Ford's PM-1-C High Performance Dot 3 brake fluid. That's all I used in my 90 ZR-1 and 94 LT1 (with upgraded ZR-1 brakes). I installed Russell speed bleeders and changed brake fluid prior to a track event/mountain run or annually, whichever came first. With the speed bleeders I could bleed all 4 in less than 15 minutes & didn't have to bother the wife to pump the brakes -- trust me, it was easier to install the speed bleeders than explain to my lovely bride the importance of bleeding the brakes so frequently.
spork2367
11-06-2019, 11:46 AM
If you can get past the brand name, take a close look at Ford's PM-1-C High Performance Dot 3 brake fluid. That's all I used in my 90 ZR-1 and 94 LT1 (with upgraded ZR-1 brakes). I installed Russell speed bleeders and changed brake fluid prior to a track event/mountain run or annually, whichever came first. With the speed bleeders I could bleed all 4 in less than 15 minutes & didn't have to bother the wife to pump the brakes -- trust me, it was easier to install the speed bleeders than explain to my lovely bride the importance of bleeding the brakes so frequently.
Prestone Dot 4 exceeds the specs on that and is cheaper.
lfalzarano
11-06-2019, 05:19 PM
If you can get past the brand name, take a close look at Ford's PM-1-C High Performance Dot 3 brake fluid. That's all I used in my 90 ZR-1 and 94 LT1 (with upgraded ZR-1 brakes). I installed Russell speed bleeders and changed brake fluid prior to a track event/mountain run or annually, whichever came first. With the speed bleeders I could bleed all 4 in less than 15 minutes & didn't have to bother the wife to pump the brakes -- trust me, it was easier to install the speed bleeders than explain to my lovely bride the importance of bleeding the brakes so frequently.
Gunny, how do you know when all the air is pumped out? Dumb question from when I did it as a two man job...[emoji16]
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