dual diaphram upgrade - pedal freeplay??

[Stangerize]

I finished the upgrade for the dual diaphram booster. How much freeplay should be in the pedal before it starts braking? It feels like I am depressing the pedal at least 1/4 the way before it starts braking. How can I correct this or can I?

[bvibert]

You shouldn't have much movement at all before the master cylinder starts pushing fluid. I think the booster us supposed to be adjustable by turning the part that actuates the MC. I've never done it, but the instructions for the MC that I recently replaced mentioned something about it. The directions said to have a helper push the brake pedal down slowly while you watched the fluid in the MC. If the pedal had to travel too far before you saw bubbles in the fluid then take the MC back off and turn whatever needed to be turned. Then test again. Mines a single diaphragm so I don't know if its the same or not.

[Mikel]

As Brian said, I would try purging the brakes.

[Stangerize]

Thanks guys. I do remember seeing that in the install instructions. I pushed the pedal down with my hand about 1/2" and saw it squirt up myself. I'll try bleeding it again but I'm pretty sure I got all the air out. I had a leaky wheel cylinder on the left rear. Maybe I'll check the other side and check the fluid again.

Thanks again guys.

[davez26]

Sounds like a little air in the lines. FWIW, when I did my booster swap, I had no problems except for a little less space to work with.

[bvibert]

Did you get it straightened out? When you bleed the rears make sure that you have the little plunger thing on the proportioning vavle either pushed in or pulled out depending on what kind you have. It makes a BIG difference.

http://www.ifsja.org/tech/brakes/brakevalvetool.shtml

[Blackjack]

Yeah sounds like air in the line. I did the booster upgrade to mine and had no change in the pedal.

[outagas]

Are the rear breaks adjusted right?

[chrism]

Having your parking brake properly adjusted will also make a difference.

[talntar]

Originally posted by outagas:
Are the rear breaks adjusted right?even with new parts i need to adj. my rears every few months.makes all the diff. here.hope this helps