Re: Power brake and standard trans.

Posted by HH56 On 2011/1/16 10:48:30

I am talking boosters only. Believe the masters are the same on the last few conversions mentioned here - 1" dual or tandems.. Yours and Turbo's were are in a different location with different pedals and power units so not quite sure if same feel or response would happen there. Jerry also used the same universal booster and cylinder but IIRC, his is with a different pedal ratio.

Boosters I am asking about is the universal 7" single diaphragm Craig used and is happy with vs the 7" dual diaphragm the other guys used--and is the one I'm thinking of using. Force out data is so different, am asking some questions.

Example: Assuming same pedal input, according to the comparison chart, at 15" vacuum and 100% efficiency, 7 single is 289 additional pounds force out whereas the 10 single (which 7 dual is supposed to be almost equivalent to) is 589. With all else being equal, a fairly substantial difference. Reason I asked about vacuum was each additional inch raises force out by approx 25 pounds so 20" vacuum on same units, same conditions would be 385 and 785. Again, substantial difference. Any real world would be less because units are only 80-90% efficient.

If the pedal is sensitive on those duals or with little travel or effort before brake action that might be an issue if I go that way rather than use the single. If the feel and action is good to the guys that have it, then will probably stick with that unit and ratio since I have it and not think much more about any changes. With the shorter unit though, some advantages. Could possibly revise the levers and get the rod down in a more original position and probably all under the floor with no bulge. Much as I'd like the shorter single benefits, am still concerned. Most of the guys writing brake articles recommend duals if possible.

I know the only real way is to measure actual line pressure between BTV and the others but am aways off from being able to do that. Don't want to buy a single just for that purpose but will probably wind up doing it just because I am curious. The master is going to make a huge difference as well. 3/4" master puts out less volume but almost twice as much psi as a 1", all else equal. BTV with ram and even smaller bore should even increase that psi.

With the conversions so fresh, just wondered how they feel compared to BTV--or even modern cars. I know that is not oranges to oranges comparison since principles are so different but just curious.