GM Hydroboost problem
I have some hydroboost questions that I hope someone can answer. I have a ‘91 Chevy C1500 with a built-for-street 406 in it. I’ve had the truck for 15 years and the brakes have always sucked no matter what I’ve done to them with stock components. Over the last few weeks, I have converted it to hydroboost and rear disc brakes (all at the same time) but I’m having some issues.
The truck will put you through the windshield when you hit the brakes hard, so my initial problem is finally fixed. The problem I have now is that the pedal has to be almost to the floor to do it. Yes, it’s well-bled, and I should mention that the pedal is firm when it gets to the (almost) floor.
I looked at the geometry of the pedal and pushrod and saw that it was at an angle. I looked into it and found that there was a difference between the hydroboost pedal and the vacuum version, so I got that taken care of, yet still no change.
I should mention that the hydroboost and master cylinder were both reman units, but I don’t think them being defective is my issue since the truck does stop good.
The master cylinder IS a hydroboost master cylinder.
Here is where I think my problem is. There is a pushrod between the hydroboost and master cylinder, that I “think” is too short. I’m using GM components, so I am not sure why it would be too short, which concerns me. There are two different lengths of this pushrod, however there is more than an inch difference between the two, so I don’t think the longer version is going to be correct either as that would stick it out of the end of the hydroboost unit and that would clearly not be right.
One other thing that I noticed is the pushrod retainer at the end of the master cylinder is supposed to sit in a grove. The groove is only a quarter of an inch inside (meaning the master cylinder would only be able to stick inside a quarter inch) and my master cylinder pushes it back further (maybe 3/4”). I’m not sure why this is either, but it’s something I wanted to mention.
So my next step (unless someone on here has some mind-blowing resolution) is to lengthen the pushrod to the master cylinder. It doesn’t feel like something I should have to do, but I think it will correct the problem. I’m just concerned that something isn’t right because I shouldn’t have to do that.