Front brake issues

[76 PTO]

I have a 76 with front disk/rear drum. I have noticed a diminished pedal feel,and the rear lock up first. I dosent stop very well without pimping. I've seen a little fluid behind the master cylinder. I bought a 94 non abs 80 series master for a future rear disk upgrade. I think the stock booster has finally given up. I was wonder what is the best booster to replace it with? I've seen celia, 80series, mini truck, 60 series. I can also get a rebuilt one from a vendor on here. I don't mean no modifying things like a spacer and such. What setup would you use with my new 80 series master cylinder?

 

[76 PTO]

Sorry for some of the some of the spelling. Auto correct and cold medicine are not the best combo.

 

[Curt]

A sign of a bad booster is a stiff pedal, a low squishy pedal is probably master or air in the system. You mentioned you see fluid, master is most likely bad.

 

[Poser]

I've seen a little fluid behind the master cylinder.

Leaking fluid between the booster and brake master cylinder?

Have you removed the four bolts that secure the master to the booster to see exactly what kind of mess you may have going on?

I think the stock booster has finally given up.

Based on what kind of diagnosis?

Brake fluid leaking at the rear of the master is not a good thing and if not fixed early, can cause damage to the booster. However, if this leak is something that has just occurred, and not been leaking for a long time, your booster may be fine.

I was wonder what is the best booster to replace it with? I've seen celia, 80series, mini truck, 60 series. I can also get a rebuilt one from a vendor on here. I don't mean no modifying things like a spacer and such. What setup would you use with my new 80 series master cylinder?

80 Series, 60 Series, new unit from CityRacer would all be a decent option, in the event that you need to replace your booster.


Any booster, stock 40 series or not, will need to have attention paid to the relationship between the pedal free play and the free play between the booster link and piston in the master cylinder.

If these links are not adjusted correctly, it can cause the brakes to drag, or, excessive pedal travel to function.

 

[76 PTO]

I have a good Pedal to start, then it just goes hard with bad stopping. I have to pump to get a good pedal again. I thought the booster might be bad because the disks need more boost to work. The rear work , they will lock on the third pump.

 

[76 PTO]

I found a 89 mini truck booster for 129 on rock auto. Come to think of it , I have a fuel injected 350 that has stumbled a little when I hit the brakes.

 

[76 PTO]

I have not removed the master yet. I just saw it was wet there.

 

[shawnfj40]

It sounds like you have a bad master from what you have written. Remove the vacuum check valve from the booster and insert a long thin (dipstick) into the hole going straight down like you are trying to reach the bottom of the booster. I use a long zip tie for this. If it is wet at all when you remove it, the booster is not going to make it. The way to test if your booster is currently working is to pump up the brakes with your engine off and while holding pressure with your foot, start the engine. If you feel the pedal push down more with the engine vacuum helping, the booster is working.

 

[76 PTO]

I will check the booster today. Maybee I will switch masters to see if that fixes it first

 

[76 PTO]

Replaced the master with the 80 series one. The brakes are not spongey, they are hard as a rock, with poor stoping. The booster hisses when I hit the breaks. I assume it is bad. I think I will replace it with a 89 mini truck booster. I know there are many different boosters, but this one is 120 dollars new. Is there a better choice maybe?

 

[emac]

I bought a booster from cityracer for my 77. Worked out fine.

 

[Curt]

that master push rod may need adjusting.

any gasket between the master and booster?

 

[76 PTO]

I measured the master cylinders from the mounting flange to the plunger, and they are the same. no gasket. I know racer sells them. His I think are 250.00 and the other is 120.00. I do not really care about originality, I just want acceptable brakes.