Can't get the emergency brake to grip - solved

[TorqueHorse]

I recently replaced the back brakes with something not OEM from Rock Auto that showed up as comparable (Cardone 18-4327). This is my first brake job, so I don't know if it's me or the part. When a helper depresses the brake pedal, the pads on the left side grip and can at least resist the amount of force I can apply to the wheel with my body weight. However, when I pull the ebrake lever all the way up, the wheel still spins freely. I've adjusted the cable length in the center console area, but even with it maxed out and the lever arm on the caliper starting to come off the stop, it still won't compress enough. I've pumped the brakes and cycled the brake lever a dozen times, but it hasn't made a difference. The other side ebrake grips and releases just fine (but the resting gap is smaller on that side to start with). Also the discs are well over the min. thickness.
Tips appreciated!

Whole assembly & disc thickness ~12mm


Resting gap ~2mm

[rip]

Surely you mean the parking brake?
I wouldn't trust it in an emergency. I still remember several of us running out to a pub car park to stop my Elan rolling into Dave Eds' one after it slipped on the parking brake. (I usually leave it in gear but something caused me not to on this occasion).
They seem to be self-adjusting & vary in quality. Mine used to take about 9-10 clicks to engage even if the brakes were adjusted so tight they were binding. Dico looked at it in astonishment as his elbow nearly hit my roof when he engaged it, his one being completely different.

[Rambo]

Yeah, but Dico thought he could do handbrake turns in his

[TorqueHorse]

haha, yeah, we call the same thing lots of names
Yeah I don't know why it isn't 'self-adjusting' already. How else am I going to get to do this?

[Simon_P]

I've adjusted the cable length in the center console area, but even with it maxed out and the lever arm on the caliper starting to come off the stop, it still won't compress enough.

Not sure what that means "Maxed out" and our handbrake cable adjustment don't go together. The cable adjustment has almost nothing to do with the handbrake adjustment which is automatic - They are 2 separate things, so ease everything off and adjust the handbrake cable as described in the manual.

The arm is attached to a helical screw which mechanically moves the piston out and back. With the hydraulic brake applied movement of the cable brake will (should) overcome the clutch and self adjust. There is also a rubber coated metal ring that stops the piston moving back too far.
The first thing to realise is that the calipers are handed- Fine you might think its only a casting, but they are the opposite hand to the other application that you may have cross referenced, that may also appear to be fine, but it is the helix in the piston that makes it handed and the other application may have had the caliper mounted on the back of the disc rather than the front. Unless you have taken the caliper apart to change it, you may be winding the piston in rather than out, so it is never going to tighten-up.

Check that you have the correct handed piston ie when you pull the lever it visibly moves the piston/pad closer to the disc.

[dapinky]

The first thing to realise is that the calipers are handed- Fine you might think its only a casting, but they are the opposite hand to the other application that you may have cross referenced, that may also appear to be fine, but it is the helix in the piston that makes it handed and the other application may have had the caliper mounted on the back of the disc rather than the front. Unless you have taken the caliper apart to change it, you may be winding the piston in rather than out, so it is never going to tighten-up.

Check that you have the correct handed piston ie when you pull the lever it visibly moves the piston/pad closer to the disc.

with this -

Although the Cardone 18-4327 is listed for the rear right of the Chevy Lumina (so is used on the rear left of the Elan), it is always an outside possibility that it was incorrectly assembled, using the wrong piston, when reconditioned.....

If that is the case, then the hydraulic action will work fine, but the handbrake will never work. If you remove the handbrake spring and then remove the (11/16") nut which holds the handbrake lever on, you can get a spanner on the square drive pin (1/2" IIRC - or maybe 9/16") and turn it both ways without the limiting factor of the lever and cast 'stops'......

.... you can adjust it until the disc is locked, and then back it off a small amount so that it will lock within the movement range of the lever.

BE AWARE - IF YOU WIND THE PISTON IN TOO FAR BRAKE FLUID WILL COME OUT AS IT WILL DISPLACE THE RUBBER SEAL AROUND THE SQUARE PIN..... so just a bit at a time.

It *should* be imediately obvious if the piston is wrong by turning the shaft as you'll see it moving in or out depending on rotation direction.

[TorqueHorse]

Hmm, I followed the directions in the WSM, but it still didn't improve. When I pull the brake lever the gap closes by a little more than 1mm, so I think that rules out being on the wrong side. But when the brake is fully engaged it still leaves a little under a mm between the face of the pad and the disc. I also tested how the brake pedal works on this caliper again and there is a lot of 'dead travel' before it grips. To me it seems there is just too much gap between the disc and the pad to begin with (~2mm).

Fully engaged parking brake (you can see the light gap at the bottom which still allows almost free spin)


-
Thanks for all your help guys. you are posting advice faster than I can respond
I'll try looking at that trick with the nut at the back and report back!

[Simon_P]

With an assistant applying the foot brake. At the caliper move the lever through its full range by hand and release it. Does it go back to the stop under the force of the spring alone?

I've got two sets of Cardone calipers here with the wrong piston in, hence my comment, but you now have me questioning the logic of what I wrote dapinky. All I remember is thinking I'll swap them over later and rebuilding the original.

[TorqueHorse]

Okay @ Simon, I got my assistant to press the pedal, and yes I was able to move the lever and it snapped back with the spring. When I had the spring off and pressed the pedal again, the lever also moved on its own, in concert with the piston opening and closing.

My lovely assistant


Just FYI, I actually replaced both rear brakes with Cardone's and I just grabbed one of the boxes, so I'm not saying it for sure was that model or it's twin, but all the 'action' seems to work in the way I would expect for both, so I think I got the correct ones on the correct sides.

@ dapinky, I did what you suggested multiple times

.... you can adjust it until the disc is locked, and then back it off a small amount so that it will lock within the movement range of the lever.

(and it was 9/16's - which I bet you knew for sure, and you just didn't want to be a show-off right? )
However, it seemed like it would always land in one of the two positions below, once I got it aligned with the lever back on.

Before

After

Upshot: The 'after' position holds great now for the parking brake, and there isn't any dead travel when pushing the pedal...but I think it is too much friction at rest. I can keep tinkering with it, or maybe this will just work itself out after I brake the pads in a bit on the road?

[TorqueHorse]

Yeah on second thought, watching that video just looks like crap. I'll keep fiddling with it.

[Rambo]

Just my thoughts but....looks like your rear discs could do with a good clean. Or skim. You might find the pads work better.

I've used a flap wheel in the past to clean the rear discs of surface rust

[dapinky]

Another thought....... it's a bit of a faf, but you're getting used to that by now!.....

...have another go at getting the piston in the right place, but start from where it is 'too loose to lock the wheel'...... at this point, another 'click of the adjustment will make it too tight......... so, the plan is that you only want to go half a click - but you cant - except you can!....... you'll need to remove the caliper from the bracket, then adjust it a click, and then as you release the lever the piston will return into the caliper just a bit........ so then you replace the caliper on the car and it should be correct (maybe????) - the whole thing relies on the 'self adjusting' mechanism, which needs a certain angle of rotation of the lever to get it to take up the slack and self-adjust..... it sometimes gets to the position where it needs to adjust, but there just isn't enough range of movement on the lever, so this method ***may*** put it in range.

Failing that, removal of some of the nice new brake pad surface may be the only easy option......

[TorqueHorse]

Yes! The only good job is an improvised one?
I actually just took a flap wheel to both sides on both discs and they are noticeably better. Glad to see it wasn't a totally crazy idea @Rambo (and I'm pretty sure I have plenty of min thickness left -- will double check). I'll put the wheel back on and see how they spin and post an update. If it still doesn't work I will give your method a whirl, dapinky and report back.
Thanks again, folks!

[Simon_P]

I was able to move the lever and it snapped back with the spring. When I had the spring off and pressed the pedal again, the lever also moved on its own, in concert with the piston

snapped back sounds like you just let go of it. The reason for the question was if you ease it back, as you would releasing the handbrake, the spring needs to pull it onto the stop. Otherwise it has too much friction and won't self adjust.
The trouble with manual adjustment is that you haven't actually fixed it and in my experience of the issue you will be going through the same pain again when it needs adjustment.

It's difficult to tell if the adjustment is too tight without the wheel on as there is little mass. I recall from manually adjusting mini drum brakes that that looks about right. Only you can tell,make sure that they don't get too hot and make sure that they are safe!

[TorqueHorse]

Thanks for the tip Simon. I think I did what you were suggesting where the force of the spring is what wound the lever back to the stop, but regardless, I will continue to monitor the performance and report back if the grip 'decreases' over time. For now though, I'm pretty happy with how they work. The emergency brake grips well on both sides when engaged; the brakes grip when I depress the pedal; and the wheels seem to spin well enough when at rest.

Improved left rear

Right rear

Now...to figure out if that spongy feeling in the pedal is because I need to bleed the brakes again, or is the master cylinder going?