66 power brake bleeding - revisited

[Gary P.]

Picking this up again from Monday's post...After replacing the front brake lines and manually re-bleeding, the car still pulls to the left. I did notice that there was sediment in the jar that I bled the brake fluid into Sunday and I'm assuming that wouldnt be that unusual. In the 16 or 17 yrs I've owned the car I've never touched the master cylinder, and my guess is that there's probably a fair amount of particulate floating beteween the mc and the calipers. Tomorrow I'll pull the calipers and see if there is any leakage that wasn't visible when assembled. Other than leakage, is there anything else to look for to identify what the problem could be? These are Dr. Rebuild SST calipers that are ~10 yrs old but with only a few thousand actual miles on them. Maybe at this point the best thing is to replace them.
Thanks, Gary

[Larry S.]

Re: 66 power brake bleeding - revisited

Gary was it sediment or was it two disimular chemicals? The reason I ask is when I got my car it had regular brake fluid and silacon mixed together .(It did not cause the pulling problem).your encountering But I did flush all the fluid out.With evidence of sediment I would think you should be doing an entire flush on the system.

I dont want to keep recomending this motive tool as the cure all of all brake problems But it makes real simple work of bleeding and flushing a brake system.

Good Luck and be safe

[Steve Vaughan]

Re: 66 power brake bleeding - revisited

It would seem a complete fluid flush after 10 years would be appropriate but unliklely to solve a pulling problem. A verification of smooth movement of each claiper piston would seem to be the next step.

I have also recently tried the pressure bleeding approach on a 67(with the Motive bleeder). It worked very well for the bleed operation. However, I have not yet found a good method to remove the master cylinder pressure cap after bleeding without creating a mess of fluid dribbling down the sides of the MC. Larry, how do you prevent this?

[Timothy B.]

Re: 66 power brake bleeding - revisited

I haven't used the Motive bleeder, but it would seem to me that if the pressure adapter cap had two "dip tubes" that extended down into the master cylinder slightly, that the mess could be avoided. Does the adapter that comes with the Motive Products bleeder have extension tubes??

With a good cap seal and the MC starting at say, half full, then the air pocket at the top should prevent the fluid line from reaching the top. The air would compress somewhat but as long as there is a tight seal there would always be space at the top.

[Steve Vaughan]

Re: 66 power brake bleeding - revisited

Tim, great idea. The pressure cap I am using does not have dip tubes but I think the the problem is that I have a very minor leak at the sealing surface which allows all the air to escape which then allows over filling the fluid bowls. I'll fix the minor leak at the lip seal before next bleeding occasion to see if that will keep the fluid level below the rim.

[Larry S.]

Re: 66 power brake bleeding - revisited

Steve when you are complete with your bleed and you are satified that it done.Disconect your power bleeder hose.and then allow the balance of whats in your hose go into the master.Opening up a bleeder to allow it to gravity drain out..You only need to let the smallest amount out just to get it below the lip in the master.do the same for the fronts and you still have a perfect bleed your just letting some of the fluid out.Remember you just drop the level a tiny amount.

[Larry Sherman]

Re: 66 power brake bleeding - revisited

My bleeder cap has a solid round section about 1 1/2 in. in diameter and 1/2 in thick that protrudes into the master cyl. When you take the cap off, the level lowers by that cubic amount. Larry

[Joe L.]

Re: 66 power brake bleeding - revisited

Gary-----

Quality stainless steel brake calipers are, pretty much, a "for life" kind of thing. However, the pistons and, especially, piston seals are definitely NOT a "for life" kind of thing. You may need to rebuild the calipers if you are experiencing problems with them, but you shouldn't need to actually replace them. The type of problem that you're experiencing may be caused by a leaking caliper piston seal, a stuck piston, brake fluid on the pads, or an obstruction of some sort in the line. Often, the problem may be found on the side of the car OPPOSITE the pull direction.

[Gary P.]

66 power brake bleeding - revisited

Looked like sediment to me Larry. I've always run silicon fluid so it shouldnt be dissimlar brake fluid. With all of the recommendations about the motive bleeder I am definatly going to pick one up. Thanks for your help -Gary

[Mike McKown]

Joe said it very well.

If you are now getting a good "squirt" as you put it out of your bleeders since you changed the lines, I would move to the calipers for the problem.

[Gary P.]

66 power brake bleeding - revisited

Joe - I just got through pulling the calipers and the right front was wet. It looked dry when assembled or maybe I didnt get under it enough to really see what was going on. This is the first time I've had one fail that doesn't sling fluid all over the place. Also, I never noticed the fluid level dropping. I'm going to drop them off tonight at a local Corvette shop for a rebuild.
Thanks for the help - Gary

[Les Jacobs]

Re: 66 power brake bleeding - revisited

Gary I haven't followed the entire thread, but I did have a brake pulling problem that drove me crazy until I discovered it was a collapsing hydraulic line. Light braking was ok, but heavy braking resulted in a 90 degree turn .

[Gary P.]

66 power brake bleeding - revisited

This was driving me crazy as well. My 66 was pulling hard to the left and I was having some difficulty bleeding the brakes. That was when the discussion and recommendation of the Motive brake bleeders came in. Since the calipers outwardly appeared dry, it was suggested that I had a collasped hose but after replacing both front hoses the car still pulled. At that point I pulled the calipers and found the RF leaking. There's also pretty major sediment in my lines from rust in the master cylinder and the rubber seals in the calipers that I have to flush out.
Gary