Front Brake Question, Venting Clearance and Bleeders Options

[Highland]

This is a '73 with rebuilt calipers and proportioning valve. I first gravity bled the brakes in the recommended order. I then switched out the top bleeders to speed bleeders and bled the brakes twice waiting a couple of days between the first and second speed bleed. So far I've used roughly 1.3 L of brake fluid.

Questions:

1) My front left caliper seems fine, but the front right seems to bind. I cannot get a shim between the pad and rotor. When I spin the wheel it goes around maybe a bit over one revolution before stopping. Is there a way to adjust this? Will the clearance set when I drive the car and start braking harder? Is this a result of air in the line? (Car is not driveable now, no engine)

2) When I did the gravity bleed with the normal bleeders brake fluid wept from the bleeder threads. Should a sealer be applied to the threads to prevent this? The speed bleeders seem to have a thread coating and do not leak from the threads when open.

[yeahmag]

The fronts don't have a venting clearance. Is your rotor new? If not, it may be slightly warped. Are your calipers rebuilt? If not the pistons may be a bit stuck in the body.

I've not gravity bled before. I would personally suggest using a Motiv Power Bleeder "dry" (no fluid inside) and keep an eye on the fluid level. Normal bleed screws do not have a sealant.

[Highland]

Thanks. The calipers are new from PMB. The rotors are not new, but by rotating the wheel they do not "feel" warped out of spec.

Starting to think it's a bleed issue. On the rears I found I have to manually hold the e-brake in the release position during bleeding. So much for 1 person speed bleeding. (IMG:style_emoticons/default/dry.gif)

[yeahmag]

If you have a dial indicator and magnetic base you can measure the run out on the rotor. The money is well spent on the Motiv product.

[taylspin46]

Slightly retract the pads off the rotor. Spin the wheel making sure it rotates freely and evenly without bearing noise or excessive free play. Reapply brakes. If problem returns suspect caliper piston sticking.

[rjames]

Thanks. The calipers are new from PMB. The rotors are not new, but by rotating the wheel they do not "feel" warped out of spec.

Starting to think it's a bleed issue. On the rears I found I have to manually hold the e-brake in the release position during bleeding. So much for 1 person speed bleeding. (IMG:style_emoticons/default/dry.gif)

I was able to bleed mine solo pretty quickly after installing speed bleeders, and this was after installing a new dry MC.
The Motive pressure bleeder only helped me with getting fluid through the MC. The old pumping the brake method worked fine to bleed the system though.

I don’t understand your comment about having to hold the e-brake in the release position. Is your venting clearance on the rears set correctly? Are your e-brake cables configured correctly?

[Highland]

I was able to set the vent clearance on both rears but couldn't activate the e-brake with the handle. After further investigation I found it was cause the e-brake lever was already pulled back (toward the engine bay). I cycled the lever several times by hand then stuck a screw driver between the e-brake lever and stop pin and bled a bunch of bubbles out.

The lever is no longer against the stop and I can get it to grip and release by hand, but the lever does not automatically return to the release position. I'm guessing it's cause I still have air in the system in the wrong place.

Is the spring under the e-brake lever suppose to spring the lever to the release position?

Is it common for the brake calipers (front and back) not to retract when freshly rebuilt and require cycling to break-in?

[Highland]

Okay, I think I have things almost sorted. I was using aftermarket pin clips on the front brakes which seem to cause some binding. I switched back to my original pin clips and everything appears normal now. The confusion about the rear e-brakes not returning to the release position was because the rebuilder put the return springs backwards.

On the rear brakes the right side seems to be performing normal. The left rear e-brake does not fully engage when the handle is pulled. Vent clearance is set to .01". I blead the brakes again with the same results. The cables are adjusted with no slack in the release position.

So any advice on what's going on with the rear e-brake? Is this a result of air in the lines? The car is not derivable so I cannot drive and bleed until a later date. My understanding is the inner pad is suppose to force the rotor against the out pad. How is that possible if the calipers and rotor are fixed?

I just want to make sure there's no possibility of a caliper assembly error. I normally wouldn't be concerned but they assembled the e-brake springs backwards (in both calipers) and also assembled another unrelated drive component backwards, so I think they had a newbie working on my parts. (IMG:style_emoticons/default/sad.gif)

[yeahmag]

Make sure the cable and lever are moving when the e-brake handle is pulled. The mechanism is purely mechanical and is independent of the hydraulic system - bleeding it more won't help this problem.

If the cable and arm are moving, try "seating" the pads on the problem caliper all the way in (adjuster stops turning), then reset the venting clearance.

[bbrock]

Make sure the cable and lever are moving when the e-brake handle is pulled. The mechanism is purely mechanical and is independent of the hydraulic system - bleeding it more won't help this problem.

If the cable and arm are moving, try "seating" the pads on the problem caliper all the way in (adjuster stops turning), then reset the venting clearance.

In addition to the above, you can also unhook the cable and try cranking the lever by hand. If you don't get any piston movement doing that, it is possible the builder forgot to drop the little push rod in on reassembly. Without it, moving the arm will do nothing to the piston.

[Highland]

Thanks.

The arm does move when I pull the handle.

The pads are gripping, just not tight enough. Wheels off the ground, I can't turn the tires on the right rear by hand. On the left rear I can turn the tire by hand sliding against the pads. It also seems to loosen over time if I just leave the e-brake on, but maybe that's my imagination.

I'll trying bedding the pads against the rotor with the adjusters. How tight can I turn the adjusters? Don't want to break anything.

Don't know if this matters, but I'm reusing the pads and rotors. They both seemed nearly new and I kept track of pad position.

[yeahmag]

You'll know. Just snug. You can set them one at a time so you know the pad is touching the rotor - it won't move...

[barefoot]

Slightly retract the pads off the rotor. Spin the wheel making sure it rotates freely and evenly without bearing noise or excessive free play. Reapply brakes. If problem returns suspect caliper piston sticking.

Due to an extensive time at the body shop from when I put rebuilt calipers on and when i got it back ready to drive, I had sticking calipers. A short piece of 2 X 2 and a mallet beating on the caliper bodies freed them up OK

[Highland]

Make sure the cable and lever are moving when the e-brake handle is pulled. The mechanism is purely mechanical and is independent of the hydraulic system - bleeding it more won't help this problem.

If the cable and arm are moving, try "seating" the pads on the problem caliper all the way in (adjuster stops turning), then reset the venting clearance.

Tried this procedure today. It seems to help, but I can still turn the tire by hand. I've got the cable set really tight so the right e-brake arm moves more than the left e-brake arm (which is functioning correctly).

- Could it be a pad issue? To my armature eye the pads look fine, but perhaps they are glazed?

- Since the e-brake actuates I assume the pill is in there. Is it possible the wrong pill is in there? Do 911's or Alpha's, etc. use the same diameter but slightly different length pill?

Any other ideas?

[Larmo63]

If you have everything set up and built correctly, they will sort themselves out as you drive it a bit.

[bbrock]

- Since the e-brake actuates I assume the pill is in there. Is it possible the wrong pill is in there? Do 911's or Alpha's, etc. use the same diameter but slightly different length pill?

Any other ideas?

If the piston moves when the lever is pulled, I think you can rule out the pushrod and anything else internal. I think Larmo63 is right that you probably just need to drive it a little to get everything settled in, then readjust the vent clearance. Mine required a bit of fiddling to get the e-brake adjusted properly with all new or perfectly refurbished parts from the brake handle to the pads.

[Highland]

Cool. (IMG:style_emoticons/default/biggrin.gif)

I just wanted to get the rear brakes sorted as much as possible with the engine out; just a lot easier to get at things.

[rhodyguy]

Does the 'T' shaped pivot behind the handle move freely?

[IronHillRestorations]

Is it possible you've got the rear calipers swapped?

[Highland]

Yes, the T handle moves freely. The troubled right lever has more travel than the working left brake.

I can't think of a way to install them backwards. Is it possible?

The e-brake is working, just not fully locking the right rear wheel.