So I went to bleed the brakes yesterday, so I could finally drive the car out of my garage. Problems started right off the get go. I had broken the bleeder valve on two of the calipers. The casing of my right rear caliper broke as I screwed the bleeder valve back in (with my hand) Went and replaced the caliper. There are 3 bleeder valves on this new caliper. I bled them all but still the pads dont close around the rotor when the brake is pushed down. The front left caliper works and closes but loosely, wont stop at a steady roll though. The front right and rear left will not bleed at all. I'm convinced I will have to replace the whole set up, any ideas in the mean time? Any help would be appreciated.

Mike

 

Mike,

You have to give a little more information. These aren't new brakes as you mention, so why do they need bleeding? Did you replace something in the system (line, etc.) or was the car just sitting for a long time and the brakes became soft? If the latter, then the only reason they would become soft is because you lost brake fluid somewhere, likely in the seals.

Also, how did you bleed them? Gravity or with a power bleeder or having someone press down the pedal while you open the bleeders?

Regarding the pads not clamping on the rotor, if someone presses the pedal while you watch the pads/rotor and they move, but not enough to clamp the rotor, then you still have air in your system.

If your master cylinder was empty at all then you have to bleed that before you can get the rest of the system working.

 

The brakes on our early vetts are junk.
They will need to be bleed from just sitting.
It has to do with the lip seal in the calabers.
I purchased a new seal kit for the rears and it fixed the problem for a week. My brake light came back on today and the rear brakes which worked good yesterday don't work at all today.

I have hours trying to bleed the brakes on my 75.
I even called my Mobil Mechanic over to help me out to no avail.
I ended up gravity bleeding them over a 2 day period and it lasted a week.

I havent pulled it apart yet to see if the pistons are leaking again but I'm going to throw money at the problem this time.
I'm going to buy rebuilt calipers just to get it over.

Why are these brakes so difficult, I don't know.
The best and most trusted brake and alignment place in town won't touch them. That should tell you something.

Ya know I'm actually bitter over the brakes on my Vette.

Ralph

 

Talk about a vise-like grip!

 

The car was sitting for a long time. It had no fluid in the master cylinder, I bled that today, I think that may have been an issue. Once I had bled the master cylinder, I refilled the fluid, I think this was a good sign because when I was bleeding the brakes I hadnt had to fill the fluid. Anyways, I will try to bleed the brakes again once the kid goes down for a nap.

I also tried to tighten the e-brake. I havent tightened it all the way up yet, but it's getting close and there is no tension on the rear brakes. What could cause this or do I just need to tighten all the way on the e-brake cable? All the cables appear to be in good condition.

 

"no fluid in the master"...you might consider first bench bleeding the master. on the rears you only bleed the ones facing forward, that third one is from a crappy rebuilder who should have put a plug in that hole. I have rebuilt quite a few calipers and rarely see a used piston I would reuse, unless they are truly LIKE NEW throw them away and buy new (while not a fan for my application now might be a good time to upgrade to o-ring pistons), as for seals use quality like from Lonestar, VB&P or NAPA.

 

patraw03- if your M/C was empty then you might try bench bleeding it to get rid of the trapped air. After you install it back on the car install the plugs from the bleeder kit and step on the break pedal, if it stays rock hard the M/C is good and you can then bleed the rest of the system. If the pedal goes down then the M/C must be rebuilt or replaced.

Ralphbf- If you bleed the brakes and they were good but went bad after a few miles of driving then you may have a run-out problem. Have the rear bearings ever been replaced?

 

Well I tried again today, all the calipers where clamping down but the brake pedal is still spongy. I rolled the car and applied the brakes, it stopped but with any kind of speed to the vehicle they wouldnt be sufficient. How do you bench bleed? I know the principle of it just not the specifics. Anyways, the e-brake works (thank god, I have a steep driveway)

 

You can get a M/C Bleeder Kit (in the help section) and attach the hoses to the M/C ports with the other ends pouring back into each reservoir. Tilt the M/C nose up, then nose down and tilted left then right. A few taps with a mallet in each position will help get rid of any trapped air.

 

Bench bleeding a M/C is usually done on the work bench prior to installing a new M/C to remove any trapped air within the M/C. You can accomplish the same thing with the M/C installed.

Your '69 should have a bleeder screw on the driver's side of the front and back reservoirs. Attach a small length of hose from each bleeder screw feeding back into its respective reservoir. Gently crack open each bleeder screw, check for leaks, and then slowly pump the brake pedal three to four times to release the trapped air. Close the bleeder screws, remove the tubes being careful not to spill any brake fluid on a painted surface. You should be good to go bleed each caliper in succession to finish the job.

You'll need to keep each hose below the level of the brake fluid during the pumping action so you don't just force the trapped air out and allow new air to be sucked in. I've used clear tubing to see what's going out and coming back in. It won't hurt to have someone else pump the brakes while you observe the action at the M/C. Depending upon the level of brake fluid inside the M/C, you may need to top off after finishing. Good Luck!

 

Eh...if you broke the area around the bleeder from hand tightening, I'm gonna say that caliper was awfully corroded. I had a similar prob with a 76 that had sat for a while. Which calipers have you replaced, are they all the same age, etc? Personally, I think if some calipers get replaced, but not all four, then it's only a matter of time before the old ones fail. Also, replace the old rubber hoses.