Tyson wrote:
>I posted last week about leaking rear brakes on my 76 MGB. Recap: I
>rebuilt the rear wheel cyinders and neither leaked. However, one broke
>a bleeder, so it was unuseable. So I replaced it. Well the replacement
>leaked, so I was sent a new one (free). Well it leaks too, and also the
>bleeder sucks up air whenever the bleeder assistant lets off the pedal.
>The new cylinder leaks out of the "dust covers" as they're called in the
>factory manual...the two seals that go on the outside of the pistons.
>The brakes work well, but their effectiveness has already lessened in
>the 5 mile ride home. I could lock them up instantly as soon as I bled
>them, but can't now. The rear wheel is wet from brake fluid also. So
>there's a leak in the cylinder around the pistons, and from the bleeder
>also. Have I done something incredibly wrong, or am I getting crappy
>parts twice in a row (both lockheeds).
>
>Thanks
>--
Did you, by any chance, replace the brake pipes at the same time?
This is what happened to me today, perhaps a similar thing happened to you:
I went into a general car parts store today to get a new brake light switch
for my 70 MGB.
(The local Rover realership could'nt help me any more, though I bought the
same part there in 1991).
This salesperson goes into the store and comes back with an hydraulic
switch wit only one electrical terminal instead of two.
So I told him this could not be the correct part (probably an oil pressure
switch).
He goes back into the store and, after a long time, comes back with a switch
that looks very similar to the one I need.
However, the box says something about intended applications for Audi,
Volkswagen etc.
Now I get a bit suspicious. I tell him that I find it very unlikely that
German car makers would use a switch with (undoubtedly, for an MGB)
inch-size threads. But he ENSURES me that it is the correct part.
After returning, the switch screws into the hydralic connector just fine.
(BTW I've done this before. I found that if you do this fast enough, you
don't need to bleed the hydraulic system).
However, when testing, there is a leak, the brake pedal just doesn't keep
the pressure.
The leak is, of course, at the brake switch.
The salesMORON mistook the thread, M10 x 1 (metric) for 1/8" x 27 NPT.
The outright stupid thing is that I WARNED the IDIOT that it was unlikely
that Audi would use an inch-size thread!
Boy, how I hate this! Now I can go back to the store tomorrow and do the
same thing again!
BTW you can't really keep them apart. The metric part is 25.4 tpi andt the
NPT is 27 tpi, the outer diameter is the same and you just won't notice the
difference.
The moral of the story:
You REALLY have to look into the manufacturer's catalogs YOURSELF and check
carefully!
Today, I forgot to do this. As Lenin used to say: " To trust someone is
fine, but to check him is better".
As for Tyson's problem: It is not impossible that, if at the same time the
brake lines are replaced, someone MAY have used the wrong threaded nipples
(?) there.
Hope this is of some use.
Bert
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