[Washout]

1970 GT

I've noticed that when I apply the brakes the frontend darts to the right, the harder I brake the worse the problem is. I rebuilt the calipers and the master cylinder about 6 months ago and have only recently started driving the car enough to start noticing this issue. I'm guessing that the left caliper is getting less pressure than the right for some reason causing the control problem. It might be my calipers but I'm leaning toward it being a fault in the master cylinder. I already changed both front flex lines and bleed all the brakes.

What do you guys think?

Gregg

 

[kwilford]

Pulling to one side while braking is usually related to either:

1) seized caliper or wheel cylinder
2) flex hose or brake line blocked
3) Brake fluid or oil on one side's pads or shoes
4) badly worn rotor or drum on one side
5) badly worn or glazed pad or shoe on one side
6) weak brake shoe springs on one side, or missing components
7) sticking pad or shoe
8) leaking caliper or wheel cylinder
9) excessive brake lining dust (I'm not making this up, its in the FSM!)
9) different tire pressures side to side
10) front suspension worn or misaligned
11) loose caliper bolts

I doubt that a master cylinder will cause pulling to one side, since both sides of either the front or rear circuit are actuated by the same piston.

HTH

 

[Washout]

Thanks Kwilford,
I've already eliminated most of the possibilities. I guess the most likely suspect is the left caliper may have one of the pucks that is not traveling as it should, this would allow the right side to over brake the left causing the darting. I rebuilt the calipers and they were in really bad shape, completely frozen up. I guess it's time to try some replacements.

 

[opelgtguy]

Hi Gregg:
Have you replaced the rubber brake hoses ? Sounds similar to a problem many of us have had, where the hoses look fine on the outside, but have
sort of swelled closed on the inside, creating a check valve effect and not
allowing the brake fluid to pass freely back and forth.
Just a thought.
HTH,
Rick

 

[Gary]

This can easily happen if you don't support the calipers when you remove them and let them hang by the hose. (Don't ask how I learned this one...)

 

[Dmcbrass]

I agree with everything that has been written. Master cylinder can not cause this. I had this happen on a full size chevy van. I replaced both calipers (since they had 135,000 miles on them), but still had the problem. I replace the right brake hose and the problem went away.

 

[Washout]

I suppose I could have gotten a bad hose, I replaced both of them when I rebuilt everything. I guess I could swap the hoses and see if the problem moves to the other side.

 

[kwilford]

My vote is with a sticky caliper. If they were "frozen", are you sure you did a real fine job of cleaning the bores and pistons? If so, how, without disassembling the caliper (which is a definite NO NO, by the way. DON'T do it!). And how shiny are the pistons now? Are they pitted even a bit? If you have any doubt as to the perfection of your caliper rebuild, get a set of re-built calipers (both sides) and let the rebuilding shop worry about how clean your old calipers are. I would only attempt a caliper rebuild if the only problem was a leaky seal. As soon as I thought a caliper bore might be corroded, I would get a new caliper, as I don't have the equipment to properly hone the bores, and the inner sealing rings to re-assemble the caliper halves once they are split (which common consensus says they aren't even available, which is why you should NEVER split a caliper)

 

[Scott McDonald]

Don't get in a hurry though...

I had to wait two weeks, while my caliper was on order. If they aren't back ordered, I would replace it ASAP.

BTW-if you, or anyone else, happen to be sent a Manta caliper by accident, it will work only on the right (US passenger) side from my understanding. This of course does you no good, as your having trouble from the left (US driver) side.

 

[Washout]

You got me there Kwilford, I did split the calipers in order to hone and rebuild the set, I must have missed the note about that being a big no no. I had been waiting for almost two months on a certain west coast used parts supplier to deliver on his statements that " they went out yesterday". I finally got frustrated and got rebuild kits and did them myself. I'll start looking for some rebuilts now, thanks guys.

 

[Gordy]

Front Brake Hoses

My GT was pulling to the right pretty bad. I replaced the left front brake hose, thinking that the left must not be working too well for it to pull to the right, bled it, and took it for a test drive. Same problem...still pulled to the right.
Next replaced the right side hose and took it out and it stops straight and true!
Also found when I was under the right side that the right bottom control arm bolts were very loose! I had begun to have an issue where the tire would rub on the wheel well housing when I would back up. Now I know why!