1985 442 master cylinder

[jociha]

Did the Cutlass 442 get a different master cylinder, with a larger or smaller bore? I have had a brake issue since I got the car. Not enough to not be able to drive it, I do drive it every chance I get. The problem is I can not lock up the front tires. With the original disk/drum set up I think it should. It stops fairly quick but not close to locking up the fronts. 2 new masters, 1 new booster, new pads and fluid and I gave up took it to a shop and they bled it again and again, can't explain it. Good vacuum, booster holds vacuum for days. When I stop, if I hold the pedal hard it will start to slowly go down some. Not sure if this is normal. Do these have an internal bypass? No leaks.

 

[Mat1227]

not sure if you got your brakes fixed yet, but was working on mine today (87 442) had a similar problem. Mine the rear brakes, only one of them would lock up, and the front would not lock up either. I changed a lot of stuff trying to fix it, today decided to start at the beginning, remove the master cylinder and bench bleed it, found out that when pushing the piston on it I had good flow from both hoses (bench bleeder kit) then the flow would stop to the front wheels and only the rear was getting any fluid, I have no idea why, I just ordered a new master cylinder. The 442 did not have a different master cylinder.

Raybestos MC39376 from Amazon. Was pretty inexpensive, $30 area.
Mark

 

[pontiacgp]

what condition are your flex lines in?

 

[truracer20]

As Pontiacgp said flex lines can break down and and expand under pressure which will reduce the force exerted on the piston.
And just for reference these cars, after I think it was 1984, use a quick take up master cylinder. This system retracts the front pads all the way off of the rotor. The caliper pistons should never be forced in without opening the bleeders with this system. Doing so damages the master cylinder and causes a spongy pedal. And these master cylinders need to be paired with the correct calipers, the calipers I believe use a different seal that retracts the piston farther. Quick take up master cylinders can be identified by a step in the master cylinder bore that is visible on the outside of the casting. They also shoot a geyser up at initial pedal application.

 

[jociha]

I will have to check the flex lines, I can't say I have looked at them when pressing the brakes. Would you see one blow up or bulge? With all the people that have looked at this I think it would have been seen but who knows. To add to my original thread, when I would push and hold the pedal then it slowly sinks almost to the floor, when I let off the pedal that is when the brake light would come on, till I pumped it a few times them hard pedal and light goes off. This is the third MC the original and two NEW of different brands.

 

[79wagonator]

You said hard pedal? Maybe your vacuum booster is on its way out. I just changed the one in my G20 van and What a difference!!

 

[79wagonator]

I would definitely consider upgrading to the ss braided hoses. for front calipers and the one over the rear. I bought the earls ones from summit. I noticed a significant improvement over the rubber ones. those things rot from the inside out too. So they may look fine on outside, but be crap inside.

 

[jociha]

I did also change my booster and front pads.

You said hard pedal? Maybe your vacuum booster is on its way out. I just changed the one in my G20 van and What a difference!!

 

[Mat1227]

Just a guess, but in your pictures it shows your lines have spirals, I'm thinking these would be very hard to bleed the air from, I would try shorter lines or get pre-bent lines that have the spirals in a vertical plane.

 

[truracer20]

I agree with Mat1227 Those lines will trap air and it looks like there is a kink in one of them.