Brakes pull to the Left

[robert campbell]

All,
I have a brake dilemma with my 67 Fastback. It has disc brakes, which are the Kelsey Hays “4 piston calipers”. The past few years it developed a “pull” under light braking but straitened out under hard braking. Very annoying. I had rebuilt the calipers before, in the 80’s so I thought it was time again. These calipers are a pain to rebuild and I made a special 90-degree scraper to clean the square groove out in the bore. I have had good luck before so I dove in again. Calipers were embarrassing full of “fluid turned to mud”. Pistons seem to be free, but hard to tell. They got all new pistons and a rubber kit. Took my time and no leaks. Also put on new rotors and new pads of course. Bred down and have a great pedal

Well, today was the test run. First stop and crap, still pulls to the left under light braking. Went down a bunch of hills and really “set them in”. Did a few panic stops and they work great in that case. Nice and straight to a stop. But they still pull to the left under light braking.

My thoughts are on the rubber hose to the caliper. I have heard of them collapsing. I will replace both. Rear brakes seem normal with no leaks. And I have had some cars with a blown grease seal on one side in the rear. No matter how bad, I have never felt rear brakes pull the front. Anyone? Front-end alignment seems spot on and steering is manual and very tight. I rebuilt a low miles 70 six cylinder Mustang box with that was in great shape. No wandering.

It seems that under light braking that the left caliper is getting more pressure or squeeze than the right. I can’t believe it is a steel line?

Any thoughts??

Rob

 

[somethingspecial]

Does your 67 have a proportioner valve? If so, It may be time to rebuild it. Mike

 

[franklinair]

I have experienced a faulty rubber hose causing this type of problem. Also, I've had a rear brake cause the same sympton. Try this: driving forward, and it pulls to the left. Drive BACKWARDS and lightly apply the brakes in the same manner as before. If it pulls in the opposite direction as evidenced by the steering wheel movement, the trouble is in the rear brake. Hope this helps.
Neil

Mike- the proportioning valve only affects front and rear pressures, not left or right.

 

[somethingspecial]

Thanks Neil for the info. Sorry Rob. My mistake. Mike

 

[robert campbell]

Neil,
My friend Bill has a name for this style of trouble shooting. Start with the cheapest stuff and go forward. He calls it BTSO! “Bolt that S__t On” until the problem goes away.

Way back in my mind I had a 65 Ranchero with drums that exhibited similar symptoms. Ended up being the rubber hose on one side. Of course it got two new ones. Cheap try to fix the problem.

Oh baby was the fluid (mud) in those front calipers embarrassing. Another note for our site. Flush those brake systems once in a while!! I bet this was mid 80’s fluid and it certainly was part of the problem.

I will replace the hoses and try your backing up thoughts. In a huge parking lot with no one around!!! Rob is not a stunt driver!! Thanks for the thoughts!

Rob

 

[PFSlim]

Rob

When we restored our GT/CS, we left the front suspension loose so we could align. We forgot (oh boy) to tighten before we made our trip to the alignment shop. I asked them to find why my car was pulling so hard to the right when braking. They called back and said they thought they found the problem and for me to come drive it after alignment. No issues since they tightened everything up.

Have you checked there yet??

Paul

 

[robert campbell]

Paul,
Car tracks perfectly and stops under hard braking perfectly. But I think I have a "forever" alignment from my local Firestone on it. Maybe something is loose. I may take a trip there first. That would be free!!! Free is good!!!

Rob

 

[franklinair]

'68 calipers with the larger single piston are so much more forgiving than the '67 4 piston calipers. I'm not 100% sure if they are a bolt-on swap. If my memory serves me, the '68 are "fatter" and the '67 style steel wheels won't clear the '68 calipers. But if you're running standard type wheels, they should fit OK.
Neil

 

[robert campbell]

68's are a nice upgrade. Should have done it. They are a "floating" caliper that "self centers" on the rotor. Would need to change to 68 spindles and all of the other things. Not sure on the tie rod ends.

Will try to muddle my way through this. Might just be an allignment or a brake hose! Ah, the joy of old cars! Of course if you can't fix these old ones you might as well give up! They are as simple as they come!

Rob