Good question. All I can say is I flushed the system with an awful lot of
DOT 4.
Allen
>From: James Nazarian Jr <James.Nazarian@Colorado.EDU>
>
>After using DOT 5 for the past four or so years mine have started to leak
>as well and at $10 pint it is too much. What do I use to flush the system
>before rebuilding calipers and going back to dot 4.
>
>James Nazarian
>'71 B roadster
>'71 BGT rust free and burnt orange
>'74 BGT going by-by soon
>'63 Buick 215
>
>On Tue, 30 Nov 1999, Florrie & Allen Bachelder wrote:
>
>> Finally, after listening to the debate for years, ' thought I'd try DOT 5
>> myself last summer. Despite THOROUGH flushing, in less than 400 miles my
>> calipers were leaking. In 15 years and untold hundreds of thousands of
>> miles, I have NEVER had an MGB caliper leak. You can bet I was back on DOT
>> 4 LMA (and new calipers!) in a matter of hours! I learned my lesson.
>>
>> Allen
>>
>> >From: Tab Julius <tab@penworks.com>
>> >
>> >Not to dig up an old thread :) but recalling the conversation on silicone
>> >brake fluid and all that fun stuff, and came across this on the
>> >mgcars.org.uk site....
>> >
>> >--------------------
>> >A Tip for all MG's with Pressure Type Brake Light Switches
>> >by Paul Kile, Fair Oaks, California
>> >
>> >For all of you with MGs that have pressure type brake light switches (
>> >MGA's and MGBs/Midgets with single circuit brakes) - DO NOT use silicone (
>> >DOT 5 ) brake fluid in these systems, unless you want to replace your brake
>> >light switch every three months or so. Although none of the recent debates
>> >on silicone fluid seem to mention this, I have had three brake light
>> >switches fail on two different cars, both using silicone fluid. Others on
>> >the Internet have noticed this also. It appears that the silicone fluid
>> >acts as an insulator and prevents the switches from making contact.
>> >
>> >The solution? Stick with DOT 4 fluid and change it yearly, or put in a
>> >mechanical type switch on the brake pedal.
>> >
>> >--------------------
>> >
>> >'s true?
>> >
>> >- Tab
>> >'78 B
>> >
>> >At 01:54 PM 8/30/99 -0700, Max Heim wrote:
>> >>No, I think you are a little confused. *Silicone* brake fluid has never
>> >>been accused of dissolving seals (or anything else). That is its chief
>> >>benefit. DOT 3 or 4 brake fluid is notorious for dissolving paint
>> >>everywhere it drips. It has also been known to dissolve the seals on
>> >>LBCs, *except* for Castrol GT LMA brand fluid. Why is this? Who knows?
>> >>DOT 3 and 4 are performance specs, not materials specs, so it is possible
>> >>that Castrol uses a different formulation than Pep Boys, Mechanics Brand,
>> >>etc. At any rate, there is plenty of evidence in on this subject, and the
>> >>recommendation is clear:
>> >>
>> >>Use exclusively Castrol GT LMA brand DOT 4 brake fluid, *or* completely
>> >>flush your system and convert to silicone brake fluid (DOT 5, any brand),
>> >>since silicone fluid is incompatible with the other variety.
>> >>
>> >>Note that DOT 5 is not an "improved" spec compared to DOT 4, it is merely
>> >>a different chemistry with different benefits. DOT 4 = higher boiling
>> >>point; DOT 5 = non-corrosive.
>> >>
>> >>Some people may not have had any trouble with "off-brand" DOT 4 fluid in
>> >>their MGs -- if so, congratulations, but be aware that there are many
>> >>different sources for brake system rubber components . The next time you
>> >>rebuild, you might not be so lucky.
>> >>
>> >>'nuff said!
>> >>
>> >>
>> >>James Nazarian Jr had this to say:
>> >>
>> >>>I have had dot 5 (silicone) in my brakes and clutch of my mg for about 5
>> >>>years now and I haven't had a single problem. My understanding is that
>> >>>the original and early replacement seals couldn't stand up to silicone,
>> >>>but that the newer replacement seals (within the past 5 years or so) are
>> >>>designed with a slightly different compound will have no problems with
>> >>>silicone. I don't know the difference in the two kinds of rubber or
>> >>>fluids, but I would guess it is related to the same properties that make
>> >>>dot 3/4 take off paint and dot 5 prevent paint from bonding. So far I
>> >>>haven't had any problems with the silicone, but I think there must be
>>some
>> >>>truth to the rumor so I would make sure the seals in m/c and s/c are
>> >>>fairly new.
>> >>>
>> >>>James Nazarian
>> >>>'71 B roadster
>> >>>'74 BGT bastardization with big aluminum heart :)
>> >>>'63 Buick 215 cubic inch 'heart'
>> >>>
>> >>>On Sat, 28 Aug 1999, Larry Hoy wrote:
>> >>>
>> >>>> Ken Payne said (in part)
>> >>>>
>> >>>> > I used AP550 for a while ... and [it] seemed to be harder on some
>>seals.
>> >>>>
>> >>>> So can anyone tell me about rubber seals?
>> >>>>
>> >>>> What's the deal with certain brake fluids destroying certain fluids?
>> >>>>
>> >>>> Is this problem a thing of the past? Some how I gotta think that
>>today's
>> >>>> brake rubber parts must be compatable with DOT 3, 4, and 5 brake
>>fluids?
>> >>>> Can anyone enlighten me?
>> >>>>
>> >>>> Larry Hoy
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>
>> >>
>> >>--
>> >>
>> >>Max Heim
>> >>'66 MGB GHN3L76149
>> >>If you're near Mountain View, CA,
>> >>it's the red one with the silver bootlid.
>> >>
>> >>
>> >>
>> >
>>
>> mg-mg-mg-mg-mg-mg-mg-m-gmg-mg-mg
>>
>> Allen Bachelder
>> '73 B - "done"
>> '76 B - daily driver
>> '73 GT - awaiting front wings
>> '65 B shell - awaiting paint
>> '67 GT - awaiting everthing
>> '57 ZB - parts car or resto-candidate? - awaiting decision
>> '49 YT - in "progress"
>>
>> mg-mg-mg-mg-mg-mg-mg-mg-mg-mg-mg
>>
>>
>
mg-mg-mg-mg-mg-mg-mg-m-gmg-mg-mg
Allen Bachelder
'73 B - "done"
'76 B - daily driver
'73 GT - awaiting front wings
'65 B shell - awaiting paint
'67 GT - awaiting everthing
'57 ZB - parts car or resto-candidate? - awaiting decision
'49 YT - in "progress"
mg-mg-mg-mg-mg-mg-mg-mg-mg-mg-mg
|