The car is a 86 GXL with the adjustable suspension, and I was wondering if any of you guys had any tips on replacing the master cylinder? Even a quick little walk through and what to expect would be nice. On the paper that came with it, it said something about bench bleeding which I never heard of and Im not sure of what that is.

 

drain it first, stuff a rag underneath it, bench bleed the new one, buy speed bleeders . . . speaking from experience

bench bleeding is exactly what it sounds like clamp the master cylinder down safely on a bench top and pump brake fluid through it to remove air bubbles quicker. Buy yourself speedbleeders and have fun

 

I see, would it be possible to do this without bench bleeding? I wouldn't mind doing it but i dont have the tools necessary. Such as vice and a way to keep the bleed it. What could go wrong with out the bench bleeding, since im not changing pedal height or even touching the pedal. Although I will invest in those speed bleeders.

 

The reason you bench bleed it is that if you don't, your MC may not prime and push enough fluid through the lines, ie the air may be so compliant that nothing moves forward. Even with the speed bleeders.

Give this a try, you don't hae to have a vice, just put the brake fluid into the tank and use your hand to crank the rod in and out a few times till fluid comes out the holes. That will be better than nothing.

 

Couldn't you bolt the master cylinder to the brake booster and then "bench bleed" it in place using the pedal before you hook up any of the brake lines? I don't know if it would work since the rod that pushes the piston in the master cylinder may not be long enough to get all the air out but it might be worth a try anyway if you don't have a way to attach the master cylinder to something solid and bench bleed it outside of the car. I have installed 2 so far in my car but I always bench bled them in a vice before installing it in the car.

Edit: NAPA (and probably most parts stores) sells a kit that has plastic nipples that thread into the holes in the master cylinder body and it comes with tubes to connect to the nipples and you feed back into the reservoir for bench bleeding. You should think about picking that up too... it will keep the mess down (and brake fluid off your paint) no matter where you decide to bleed your master cylinder.

 

You could do a benchbleed on the car with the lines not hooked up, but brake fluid might spilll here n there

 

You don't need a vice. I was able to just hold the MC in one hand and push the piston with the other (using a screwdriver). Was a little tough but not too bad.

 

thanks, I will see if I can manage to do it just holding it. Other than that I may have to throw it on the car and bleed it with out the lines hooked up.

Thanks again everyone