Brake Question

Today I took my newest little car a 1955 Chevy Sedan Delivery out for a spin. I was cruising along at about 45 or 50 MPH and let off of the throttle and the front end just nosed dived like I was on the brakes ( I wasn't ). It still pulled hard but everytime I let off of the throttle it did the nose dive thing. I decided to just get it home and that is when I noticed the burning brake smell, no smoke from the brakes but that burning smell was very strong and it was still nose diving, and that was under throttle. The brakes never did "lock" up but they were difinitly on.

A few details about the car. 55 Chevy Sedan delivery, supposed to be a fresh build and the motor is supposed to be a 383. I know nothing about the internals of the motor, but it is a strong runner idles very good and is responsive, tranny is a turbo 350. It does have front Disc brakes and drum rears. Also has a 7 or 8" power booster and a GM master cylinder.

Anyone got any ideas??? Or maybe a place to start?

Roland

If it nosediving it is deflnitely coming from the front discs. It could be one of the pucks in the caliper is sticking and has the pad close to the rotor.

Yeah, jack it up and try spinning the wheels. Betcha at least one of them is hung / hanging up! I agree with SSD, sounds like a frozen piston/caliper.

My only comment is "DANG" that's a sweet looking Tri-5 Delivery:cool:

just make sure your rubber caliper hoses arent kinked or twisted . on another note .. is there a particular reason nomads had the open rear wheelwells when wagons and sedans did`nt ? ..

Check the brake pedal rod going into master cylinder (under dash). If it is a little too tight or hung up in wrong spot it can make brakes drag. I had a 55/56 swing pedal setup in my '29' sedan that did that once. Good luck

If this is happening when you let off the gas,think about it,when you let off the gas it causes a change in engine vacuum and what part of your brake system operates off vacuum? Anyone want to make a guess?

Thanks for your response guys!

I went out and looked at the car this morning and noticed that there was no "free play" at all on the brake pedal. Could this mean the push rod is extended to far?? I don't know if the brake requires free play like the clutch does.

Sunset, Stuck pad, yep that could be it for sure. however the car seems to stop in a straight line so I guess both calibers would have to be stuck. Humm

Hoss, Both rubber lines are not kinked, they both are also brand new as are all of the brake hard lines, all of them, could this be an indication that they was a problem before I bought this car? Also Hoss this Sedan Delivery is not a Nomad, those wheel wells were done by someone in the past I am sure. Looks very much like the wheel wells on a Nomad though don't they?

jeffB2, I hear what you are saying, but I believe the brakes are applied all of the time, thus the burning smell like asbestos, when the car was under power. It only nosed dived when you let off of the gas. I don't believe that vacuum or too much vacuum could be the problem. Correct me if I am wrong here as I obviously don't know what is wrong, that is why I am asking for advice. But would too much vacuum apply the brakes without any input from the pedal?

MelloYello, Man your handle explains perfectly why you like this car, COLOR. Right?

DirtCop, I think maybe (??) that you might have something there, thus the no free play on the pedal. Man I hope it is that easy....

Thanks Again guys Roland

you need free play about a 1/8 the push rod maybe adjustable if not you could make a shim plate between the fire wall and master out thin plate or some have a rubber rebound bumper under the dash you can thin that down as well for more free play . make sure the brake switch is not bottoming out as well

Hombre,
Like Pat says you want a bit of free play in the pedal on a power brake pedal. My approach is at rest you should be able to pick up the pedal just a bit, pulling the pushrod away from the diaphragm to be sure that there is no pressure on the diaphragm, which is a little different than freeplay on a clutch. Some are threaded to adjust, or shims like Pat says, or even grind down the pushrod to gain some clearance.

some brake push rods are encapsulated so it will not fall out of plunger bore of the master cylinder some held with a clip and other ways will work to . i have made new push rods that i could adjust start with a 3/8 fine thread grade 8 bolt hex head and work the hex in to the ball tip of the push rod most of the time older car /trucks in the bone yard will have the threaded clevis end for the pedal make sure after you get the rod were you want make sure the push rod can not fall out and the jam nut is lock down on the push rod