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A couple of years ago my BTV unit was overhauled as a precaution. I asked the rebuilder, Ed Strain, to make them less sensitive. Hitting the dash when a little extra pressure is inadvertently applied is not my idea of comfortable braking.

When the rebuilt unit was installed, it definitely was not touchy. It is a little stiffer than I would prefer, but for me, better a little too hard than too soft.

Bernardi

Hi Guys, thanks for all the comments and advice. Firstly, let me say that my knowledge of BTV's is very limited and I would be very wary about attempting a rebuild myself, which is why I opted for the Karps rebuild. Next, prior to the boost failing on the old BTV, I also had a system that would throw you through the windscreen if you weren't extra careful. The rebuilt one seems to work quite well but it has gone the other way and the pedal needs a lot more pressure. Of the two, I think what I have now is much better, although I would prefer a little more power assistance. To answer a couple of the questions asked, I was led to believe that once a BTV was rebuilt, that was it unless it was pulled down and rebuilt again taking into consideration any issues which need addressing, but I might be wrong here. Secondly, the wheel cylinders were the ones fitted to the car when I bought it so I assume they are the correct ones. I had a brake specialist recondition them using stainless steel bore liners. I suppose I should check whether the reconditioning process results in smaller bores, but I would have thought they would bring them back to standard. Maybe I'm just being too picky! Regards, John

John, when you rebuild any old car system, there's bound to be variation from car to car, so your experience might not be indicative of anything other than that. There's the "Feel" issue with brakes, and then there's the actual performance..which is more important. Typically, a mushy pedal is caused by either air in the system, or the vacuum boost not getting to the servo. Those could affect performance (and hence safety), so I'd check them out.

I wonder if the brakes have been adjusted on that car recently? I think people forget that the drum brakes on these cars are not self adjusting for wear as they are on modern drum brakes. A couple of mins with a floor jack and a brake spoon may make a world of difference.

Actually, this is getting more interesting.

Now I find out that the brakes were redone last spring right after they were done and then failed completely. Luckily no damage.

What would you expect if the power brake part was inoperative?

What would you expect if the power brake part was inoperative?

Extremely heavy pedal pressure required to facilitate a stop, even more so than with manual brakes. It has seemed rather likely from the get-go of this thread that the problem is with the power booster unit. A rather basic and simple test to confirm: press the brake pedal several times to eliminate any residual vacuum in the reserve tank; then with your foot on the brake pedal, start the engine. If the booster is operative the pedal will fall away under your foot. If not, the booster is kaput.

PS: As HH points out just after me, my comments assume the hydraulic section is intact and functioning and the booster action is in question.

Depends on what is meant by failed completely.

Did the pedal go all the way to the floor with not even a hint of stopping or did the pedal become so hard that 2 men and a small boy standing on the pedal would have had a challenge pushing hard enough to stop.

Unless something else in the system was replaced at the time, both scenarios points to the BTV. If the pedal went to the floor, the hydraulic section and most likely the compensator valve. If the pedal was hard, the booster section or a loss of vacuum. Either way, it sounds as if the BTV and vacuum supply needs to be completely gone thru by someone who understands them.

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"Now I find out that the brakes were redone last spring right after they were done and then failed completely"

Since u apparently ahve driven the car RECENTLY then what was done to fix the problem last spring????

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Yes...

The owner had them done at a regular shop that he has a lot of faith in. At this point, I do not share his enthusiasm....

Since it isn't my car, I am inclined to let this drop. he has problems, which he is aware of. What he does is his business.....