Mark,
I know that when changing from DOT-4 to DOT-5 it is necessary to fully
rebuild the hydraulic system, changing all the rubber. Would I need to do
the same if I went from DOT 5 to AP 550 - or even to DOT 4 - or would it be
enough to flush with alcohol before filling?
Thanks for the suggestions.
John
At 11:06 AM 7/24/2001, you wrote:
>John,
>
>There are many different situations that people sometimes describe as
>"brake fade".
>
>In your situation (pedal going to the floor after hard use of the brakes),
>the cause is boiling for the brake fluid.
>
>Probable cause for that, in your case, is the DOT 5 fluid. DOT 5 fluid is
>silicone-based, and has a lower dry boiling point than racing-quality
>mineral-based fluids. In all probability, you are boiling the silicone
>fluid. I'll bet you have front disc brakes. Disc brakes are great, but
>tend to put more heat into the fluid than drum brakes (there is a large
>volume of fluid in the caliper, right next to the disc, with a large area
>for heat transfer).
>
>Suggest that you change to a good quality racing brake fluid, mineral
>based, like AP 550. If you do, just make sure you replace the
>mineral-based fluid frequently since it will absorb moisture & then the
>"wet" boiling point will be even lower than your silicone fluid.
>
>Regards,
>Mark Palmer
>
>
>>From: John Cowan <jfcowan@pacbell.net>
>>Reply-To: John Cowan <jfcowan@pacbell.net>
>>To: triumphs@autox.team.net, vintage-race@autox.team.net
>>Subject: TR-3: Autocross, brake fade
>>Date: Tue, 24 Jul 2001 09:21:38 -0700
>>
>> Took the TR-3 out autocrossing for the first time and enjoyed it quite a
>>lot. The car handles much better than expected, but the brakes faded
>>outrageously. By the end of a run, the pedal was nearly to the
>>floor. Here's my theory and I would appreciate any comments or suggestions.
>>
>>1. The standard shoes and pads I'm using fade quickly, necessitating more
>>force on the pedal: This is the most obvious possibility, but it didn't
>>seem to me I was pressing the pedal very much harder than usual (of course,
>>this could be an illusion).
>>
>>2. There is air in the brake lines: Could be. I'm running DOT 5 and
>>haven't changed the fluid in several years. On the other hand, under
>>normal driving, I don't need to pump the brakes for them to be effective.
>>
>>3. In any case, metal brake hoses would improve performance, so I
>>will install them and change brake fluid at the same time.
>>
>> Can anyone suggest a source for more effective pads and shoes to use on
>>an original '60 TR-3A? (but not *too* race-worthy, since the car is a
>>weekend driver and I don't want to trash the rotors and drums). The big
>>three don't offer anything except standard parts.
>>
>>Thanks.
>>
>> John Cowan
>
>
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