after switching to 1 ton chevy axles, I went ahead and purchased the disc brake swap for the 14BFF. Then I found out that my rear calipers werent working and was told that I have to upgrade my MC. I went and bought an A1 Cardone 10-2754 from Oreilly's which is what was recommended by my friend who just did the swap on his 83 K10, only to find out that the vacuum booster has a smaller diameter hole and wont allow the new master cylinder to fit correctly. Is there a different MC that will work for a 78? or do I have to get a new vacuum booster for an 83, and will it bolt up to my 78 cab?
thanks
As far as booster-to-cylinder fitment, you'll want a master to match your booster's year, yes. You could switch boosters, but that's prolly more $$.
I've done two 14bFF disc conversions, and on my K5 I'm still using the original style master cylinder with no changes. She'll stop on a dime and give change.
On my pickup I ended up changing everything out, master adjustable prop valve, no combo valve, residual valves, you name it. I still had problems, particularly with leakage and bleeding. (Even pressure bleeding a crewcab just sucks due to the length of the lines.) Eventually I got that truck stopping, but I wonder how much of the bling-bling parts I paid $$ for were actually necessary. (Now that it works, you won't find me changing anything out to test!) She'll stop on a dime, more or less, albeit
without change (it's a crewcab dually, whaddya expect?
)
If you are having problems, I hate to say it, you should stick with original parts until you fix the problem. If your master is leaky or whatever, changing it for a different style might well fix it .. but it introduces another variable. Replacing a bad master with a good one of the same style would fix it too, and does NOT introduce more changes.
There are discussions as to whether the C/K30 masters output more or less pressure than the C/K10 counterparts for the bigger brakes, and whether that's a good or bad thing. I would change as little as possible, one thing at a time, until you work the kinks out. You may spend a bit more $$ this way -- I have a few extra master cylinders, boosters, etc for my three trucks -- but at least you get good (i.e. safe) brakes. Brakes (and steering, and lighting) are not to be trifled with
-- A
