| Re: [GMCnet] Brakes and brake fluid [message #64322 is a reply to message #64317] |
Sun, 15 November 2009 07:55   |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma:
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Senior Member |
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| Robert Mueller wrote on Sun, 15 November 2009 07:03 |
G'day,
Another anecdote; Harley Davidson used Dot 5 for years but changed back to
Dot 3 a couple of years ago. I think the fact that water could gather in
slugs was the reason. Now you've got to be careful not to get it on the tank
and front fender if you add brake fluid.
Regards,
Rob Mueller
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The reason I heard Harley switched from DOT 5 to DOT 4 was the cop bikes were getting ABS and the ABS unit mfr specified DOT 4, no DOT 5. Harley supposedly originally went with DOT 5 because of the paint damage issues with DOT 3/4.
The Vette has had DOT 5 since before 81 and I have overheated the brakes a number of times (high speed autocross on racetracks) and never lost pedal. The Harley brakes have also been overheated (track days at Road America and Blackhawk Farms) with no loss of brake pressure. In both vehicles I knew the brakes were hot as I had severe brake fade from hot pads, and from the smell. On the Harley if I did not flush the brake system annually I would loose pressure when I went over high Rocky Mountain passes, brakes were cold. I had that happen twice before I figured it out. DOT 5 absorbs air and the air came out under low pressure forming bubbles. Not fun but the Harley has a big engine and lots of manual gears so engine braking is very effective. The Vette has never been into the Rockies with DOT 5 in the system. But if I am going to take the Vette there it will get a flush before I go.
On the GMC, based on my experiences with DOT 5, I will be using DOT 4 in two colors.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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