Thanks Barney for the advice. I will be putting my B through the replacement
procedure very soon. This will be a real help.
Don Hicks
Kent, CT
"70" BGT " Morris"
Barney Gaylord wrote:
> At 08:03 AM 8/9/98 -0400, Dave Iwansky <baldycotton@pop.mindspring.com> wrote:
>
> >.... My hoses appear to be replacements (MGA) but it definately has DOT5
> silicone fluid. I have always thought that the pedal felt a tad too spongy,
> but my PO said that it was normal for silicone, but now 'm wondering (per
> Chip) if there are indeed air bubbles mucking about in there.
> >
> >I'm in the process of rasslin' with new front disks, so based on your
> advice (both of you) it looks like it's time to go to Castrol GT/LMA.
> >
> >I'd be .... greatful if one of yous guys would give the whole rundown on
> what to do and how to do it.
>
> Okay, here's the $.02 on brake fluid according to barneymg. When I
> restored my car I replaced all the hydraulic parts with new. Thereafter
> I've been using DOT-5 fluid continuously for 12 years and 127,000 miles
> with no brake fluid problems whatsoever (except maybe slightly soft pedal,
> but I have a heavy foot, so I'd never notice that anyway). Nada, none,
> zip! I still have the same master and wheel cylinders and clutch slave and
> hoses and pressure switch, all working flawlessly with DOT-5 fluid.
>
> But I do religiously flush new fliud through the system at least every two
> years to get tho old deteriorated crap out of there. I believe that if you
> do this, the system will give you very long and trouble free service
> regardless of what fluid you use. I have seen well cared for cars go for
> 30 years on the original hydraulic components (although I wouldn't
> recommend it). I would not, however, risk using the mineral based version
> of DOT-3 fluid with natural rubber seals. And since I'm not sure which
> DOT-3 fluids may be mineral based, or which rubber seals may be natural
> rubber, I think I will never use DOT-3 fluid in any LBC. And IMHO, you are
> likely to buy yourelf trouble big time if you switch fluid types while
> leaving the old rubber bits in the system.
>
> I am however about to change out (renew) all of the rubber parts in the
> hydraulic system just on general principals (127K miles is general enough),
> especially concern for the health of the flex hoses. When I do this, I
> plan on switching over to Casterol GT/LMA DOT-4 fluid. WHY? Because:
> (1) I'd like to find out for myself if the difference in pedal feel is
> significant.
> (2) DOT-4 fluid is less expensive.
> (3) DOT-4 fluid is now more readily available than it was 12 years ago.
> (4) I now have confidence that with all fresh rubber bits in the system
> and good maintainance I will not be spilling brake fluid on the paint in
> the forseeable future
> (5) I'm not concerned about the higher temperature capability of DOT-5
> for racing applications (only with frequent flushings).
>
> And how to go about changing the type of hydraulic fluid:
> (1) Resolve yourself to changing out every bit of rubber in the entire
> system when you switch fluids, and procure all of the parts in advance of
> the job.
> (2) Flush the entire system with denatured alcohol before installing the
> new fluid. I believe the easiest way to do this is to do it before you
> disassemble anything. Remove as much of the old fluid as possible from the
> master cylinder, fill with the alcohol, and bleed the brakes in the normal
> manner until nothing comes out but clean alcohol at every bleed fitting.
> You will likely need at least two quarts of alcohol to do this. Then blow
> out the lines with compressed air, remove the flex hoses and all rubber
> packing, blow out the cylinders and steel lines again with compressed air,
> and let the system air dry for at least a few hours.
> (3) Then install the new flex hoses and all the rubber packing kits (or
> new cylinders), add the new fluid, and bleed the system in the normal
> manner until all air is out and nothing but clean fluid comes through every
> bleed fitting.
> (4) I still like my Eezibleed kit for a big job like this. The trick is
> to be sure that you have a pressure tight seal at every little hose fitting
> and where the cap screws onto the brake reservoir, so you don't blow fluid
> all over the place. And I've never had any trouble using 30 psi pressure
> direct from a car tire without reduction. I think you would have the best
> luck with an Eezibleed if you set it up for use with just one type of brake
> reservoir screw cap, test with air pressure only before putting in the
> fluid, and when you get it to work properly don't ever switch the screw cap
> to anything else, just leave well enough alone.
>
> That ought to do it.
>
> Barney Gaylord
> 1958 MGA with an attitude
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