OK, after some issues with the swap I'm working on now I have a little better idea of how to fine tune. In the past I used original hydroboost units or ACDelco units and have never had to tune the brakes.
The hydroboost lines will get hot but shoould never be scolding hot.
With that said, here a few tips on adjusting travel to compress the master cylinder piston.
1. If the rod is too short you may have these issues:
a) Excessive pedal travel
b) groaning from the booster
c) may not apply full pressure to the brakes
2. If the rod is too long the master cylinder is already depressed partially and may be past it's point of applying hydraulic pressure and causes the compensating ports to be blocked. Here are some possible issues:
a) Problem bleeding brakes
b) May not have any pressure applied to the brakes
If the pushrod is out of adjustment the brakes may grab, may drag and wont release. I'm not sure which (long or short) would apply to these problems.
But a god way to check the length:
a) Have someone push the brakes while you are watching the master cylinder
b) If you see fluid movement with the pedal depressed 3/8" to 1/2" the length of the pushrod is correct
c) If the pedal travels more than 1/2 before movement is seen the rod is too short
d) If nothing happens at all the entire length of travel, the rod is too long
I played with this car pushing the master cylinder in with my thumb and was able to get fluid to squirt out of the right rear wheel cylinder but once I hooked it back onto the hydrbooster, nothing happen at the rear wheel cylinder so my problem I believe is that the rod is too long and I should be able to just shim the master out a hair from the booster. We do not have adjustable units so that is the best way to adjust. If you are too short, I dont think we have any choice in the matter but to get a new one. I'm going to look into that a little more this evening when we disassemble a stock unit.
From the sounds of it, other than debris inside the unit that a buddy of mine had problems with, most of the issues you guys are having seem to be the rod is too long so a shim or two might be the answer! That may be expected from the companies who rebuild these units. Hope that helps guys!
