Re: ANOTHER #%*!:( BTV failure

Posted by John Payne On 2010/10/11 1:17:43

G'day Mates,

I somewhat reluctantly join this discussion because of a) my inadequate knowledge of power boosters, b) because earlier this year I installed a BTV that had just been rebuilt by Karps of CA and c) the obviously strong views for and against BTV's. I opted to stick with the BTV because the previous one had lasted for 27 years and even then, only the boost function had failed. That is, the brakes would work but took plenty of leg power to operate, more than I had to spare.

I have a '56 Patrician with push button auto and had just replaced the front wheel bearings, had the wheel cylinders re-sleeved and after bleeding the brakes, found I had no boost. My assumption was that perhaps the pumping for the bleeding had interfered somehow with the boost side of things. The replacement BTV was subsequently fitted, filled with Dot 4 low moisture absorbent fluid and has been driven for about 2,500 miles and given no major braking problems. The only issue I'm aware of, and it's certainly an annoyance, is that the level of boost is too low meaning required pedal pressure is too high, although nowhere near what it was with no boost. Previously, before the boost of the other BTV gave up the ghost, pedal pressure was dynamite and care had to be taken to keep my head out of the windscreen.

Karp's have since told me that BTV's have no external adjustment so I'm either stuck with it the way it is, try again getting it rebuilt, or look at an aftermarket replacement system. I'm not against the latter but would really have great difficulty with a system that requires much modification to fit. I've checked the level of vacuum at idle and it's around 22" of mercury, and the system only loses about 2" overnight which seems OK. I suppose I have to do some more serious mulling over about which way to jump. Cheers, John