Howdy all...I haven't posted here for a long while but before I go throwing money at this issue I decided to first consult the gurus here. My '70 has seemingly always had issues with brakes, but up to now they have barely been tolerable. Now, no more...

A couple weeks ago I brought the Vette and one other car to the Del Mar car show, and since I could only drive one car at a time I had a (good!) friend drive it back to my house afterwards. When he rolled into the driveway smoke was pouring out of the left front wheelwell...

Prior to this the car would always pull to the right under braking, but now it appeared that the left front caliper was sticking or grabbing somehow. Today, I finally got around to replacing the left front caliper. Initial attempts to fill/bleed the caliper with my Motive power bleeder did nothing until I got in the car and pumped the pedal a few times, and this only after I started the car to get some vacuum assist. Eventually the pedal came up and got very firm, so I buttoned everything up and took it down the road a bit, which is when it got weird...

After a couple blocks' driving I pushed the pedal moderately, and just like before the car pulled noticeably to the right. If I took my hand off of the wheel and applied pressure to the brake at the same time the wheel rotated to the right on its own. A couple successive pedal applications produced the same result, but as I was driving down the road AFTER stepping on the brake I now noticed that the wheel seemed to be pulling to the LEFT(??!?!??). Releasing my grip on the wheel confirmed this as well- that when I was just rolling along the left caliper was now dragging and pulling the wheel to the left, but when I stepped on the brake pedal it seemed the right caliper was then overpowering the left one somehow and pulling the wheel to the right. Fortunately, I had only gone about a mile from the house, because when I pulled back into my driveway smoke was again rolling out of the left front wheelwell.

My first suspicion is that the proportioning valve is sticking, but I don't really know these systems well enough to confirm that. The front brake hoses are old, and I'm gonna replace those regardless, but before I go and throw more money at it I'd like to get some input from the brake experts here...any takers?

Thanks guys...

 

I just went through this issue on my '82 this past weekend. It pulled dangerously to the right. When I went to bleed the left caliper nothing came out of the bleed port. Turns out it was the left front brake line was so corroded that it would not allow fluid to pass through. I had a brand new line for my '81 lying around so I used it. Problem is SOLVED! And my 82 vette stops on a DIME just like it should, no pulling to the left or right.

 

Rubber lines collapsed on the inside.

 

I'll bet a new hose will solve the issue. I'd replace all of them.

 

 

Ya, I would replace all the hoses. If the calipers or master cylinder are questionable then replace them too. If the steel lines are rusted, them too. At the end of the day, getting good parts on it so it drives nice and is reliable is much better than messing around replacing a part here and there hoping to get it working but ending up broken down again a few months into the future. We replaced everything but the steel lines on Dad's car for the same reason and it's worked perfect for the 3 years since we put it together.

 

Both front calipers are relatively new, and I fabbed and installed a new drivers' side steel line today because the tube nut was frozen onto the old one...I think the best way to go right now is to replace the rubber hoses and see if that makes a difference. I also spliced a new piece into the passenger-side steel line a few years ago, but I can't account for the condition of the remainder of that line...I may wind up having to replace the whole line after all...

Thank you for the help guys...

 

Like as has been said already, either a collapsed line or a sticking piston. I'd replace all the rubber lines while I'm at it.

 

Now that I've had a day to think about it I'm starting to realize how sensible it is to replace the hoses...

Obviously the left-side hose is so clogged up with crap or whatever that when I stepped on the pedal to bleed the new caliper the pedal just stopped until I added the pressure from the power bleeder, vacuum from the running engine, AND the pressure from my foot on the pedal. Once fluid finally makes it through the goobered-up hose into the caliper it can't escape and the caliper drags.

If I had the time and/or money to just replace everything in the system wholesale I would do that, but I don't. I'm already not thrilled about replacing a caliper that wasn't bad...I did order new lines this morning and should have them soon, so I'll post up results of swapping those out when i get that done.

Thanks again for the insight guys...

 

When you replace the hoses use the braided stainless ones. They are not that much more and you will never have to deal with it again. I got mine right from Auto zone.

 

FYI... the master cylinder generates a lot of pressure... typically, bug guts (etc) won't hold back the pressure. What actually happens is the inside layer of the multi-layer brake hose deteriorates and folds over on itself, blocking (actually slowing down) fluid movement in both directions. Because of the high pressure generated by the master cylinder, some pressure gets past the blockage and forces the pads against the rotor. It bleeds back slowly, dissipating over time (maybe overnight) when you let up on the pedal, but while it's there, the pad continues to rub on the rotor... causing it to heat up... and the car to pull.

 

I should get the new lines today...like I said earlier, once I had time to back away and think about it this is the diagnosis that made the most sense. I did think about getting braided lines...I have them on my race car for obvious reasons, but for this car which is essentially just an occasional cruiser the rubber ones will be fine. The OE lines lasted over 40 years- I'll be 96 by the time these wear out at that rate!

 

Got the new lines yesterday (Rockauto.com; $16 shipped) and put them on. While I was tightening the passenger side I noticed a puddle of brake fluid on the driveway under the driver's side...grrr.

Last weekend while replacing the caliper I also had to fab a new brake line from the proportioning valve to the rubber line on that side because the nut on the old line was corroded onto the line and could not be turned without twisting the line. When I installed the new line it didn't leak, but when I put the replacement rubber hose on it did, so I bent up and flared ANOTHER new line...which FINALLY worked.

I sorta half-a$$ bled the brakes by pumping as much air as I could into the calipers then pulling it out with a vacuum pump, and once I had what felt like a reasonably firm pedal I took it around the block.

Night and day...while I still had to push fairly hard to stop the car because the calipers were full of air, the car stopped nice and straight no matter how hard I pressed on the pedal. I'm really kind of amazed that one partially-blocked brake hose could produce such a dramatic effect, but now I know. I'll properly bleed the calipers this weekend whan I can get an extra body to assist. Everything should be good then.

Thank you guys for the info...a new proportioning valve ran anywhere from $60 to $100, so you saved me at least that much. If I had posted this prior to replacing that caliper I'd be another $65 ahead of the game.

 

Birdsmith........thanks for the valuable update.....
I spent 12 hours trying to bleed my project-brakes after flushing lines/rebuilding the M/C /Calipers/before I decided the experts might know more than a r-o-o-k-i-e concerning replacing collapsed rubber flex hoses--which I finally replaced....
Now the brakes work perfectly.....since I won't be doing any high-speed racing/braking--I wont be adding a vacuum booster to the system(like I thought that I would need)---the $$$$$ $avings will go toward new pads/tires!)

Thanks Expert Members!

 

If one person can learn from my tribulations then it was slightly worth it! What was deceiving was that the old lines didn't look at all bad externally. That gives me an idea-I'm gonna cut those suckers open and look at 'em- maybe post pics too!

 

Since you have to replace the brake lines you might want to consider spending a little more and going with either a set of Goodridge or Russell stainless steel braided lines instead of the OEM style rubber.

There are threads on this forum and others discussing the benefits.

 

Thanks again for the advice, but check a couple posts back. Not knocking steel braids or Teflon, but if y'all look at any photos of 1960s F1 or Indy cars, you'll see good old' rubber hoses feeding their brakes...

 

you better take a better look they have a black protective sleeve on those lines. they are not rubber hoses.even in the 60's