C-3 E-Brake adjustment

[John D.]

I had my trailing arms rebuilt over the winter. I seem to recall reading that there is a hole in the rotor to adjust the e-brakes. The rebuilt trailing arms do have a hole thru the rotor but not thru the hub. Am I incorrect regarding adjustment?

Thanks, John

[Harmon C.]

Re: C-3 E-Brake adjustment

The rotor must be put on so the hole lines up with the hole in the hub. If they are not rivited its an easy fix. Just remove the rotor and line up the holes.

[Harmon C.]

Re: C-3 E-Brake adjustment

Yes you can adjust the E-brake thru the hole and the cable adjustment needs to be made also so you need to read the repair manual for the correct steps.

[Craig S.]

Re: C-3 E-Brake adjustment

As others have commented the rotor needs to be aligned correctly with the flange so the hole goes through. The rebuilder should have done this, riveted the rotors to the flanges, and trued as a unit. Rotating the rotors is not a good idea as the runout is affected. GM built these assembles and trued as a unit, so the flanges are not necessarily flat, unless you have Tom's from International Axle. If you used someone like Bairs or Van Steel, they should have done this correctly. If your rotors are not riveted, I would mark their placement on the flanges, rotate to where the hole does align, set the brakes, remove the rotor, and place it back where the rebuilder shipped. However, chances are good if they didn't rivet the rotors, they didn't true the rotors to the flanges. I would check them with a dial indicator when rotating to insure you don't have any more than a couple thousanths of runout or you may get air in the braking system after bleeding. Craig

[Patrick H.]

Re: C-3 E-Brake adjustment

Craig,

For whatever reason, the larger rebuilders often do NOT line up the adjustment hole on the rotor with the hole on the spindle flange. Don't ask me why. So, just becuase they're not installed in the original type of configuration doesn't mean they weren't trued correctly. They then still true them as a unit, but just not mounted the way "we" like them so that we can adjust the emergency brake. I asked one of them about it, and he just told me to pull off the rotor (after marking it), reinstall with the e-brake hole lined up, adjust the brake, and then put the rotor back in the originally marked position. I have no idea why they don't true them the way we like them, but they don't. If I ever have a set done again, I'll make sure they are done the way I'd prefer.

The rivets aren't needed. The torque keeping the wheel onto the car is more than enough to hold on the rotor.

Patrick

[John D.]

Re: C-3 E-Brake adjustment

OK, so now I have the rotors riveted to the hubs in the wrong orientation. Short of drilling out the rivets if I can't get enough adjustment on the cable, do I have any other options?

John

[Harmon C.]

Re: C-3 E-Brake adjustment

I would wonder about the bearing set up if they rivited the rotors on not lined up to adjust the E-brake. Their is only one way to adjust the shoes and that is thru the hole they didn't line up. I would check the run out before drilling them out to see how they did on that part of the job. This is why I do my own work as I usually need to do it over if I hire it done.

[Patrick H.]

Re: C-3 E-Brake adjustment

John,

With the right equipment, it is actually possible to drill through the spindle and open up the hole for access. I'm not sure I'd do it, but it's possible. I don't know if it's possible to drill from the spindle side through the rotor, i.e. I don't know what else might be in your way.

If your rear bearing rebuild was recent, I'd take it up with the rebuilder. Otherwise you will be drilling some rivets.

Patrick

[Craig S.]

Re: C-3 E-Brake adjustment

Patrick - thanks for your response, I guess I assumed that the good rebuilders would index correctly, I always do my own since I have the tools and a metal lathe to true the assembly. I realize the rivets aren't needed, but I personally like them just as an originality thing. So when they true the assembly, do the face the flange and then true the rotor flange asm or just assume it is good to go if the flange is faced? Just curious. I know Internationl Axle keeps their lateral runout on the flange faces to withing 2-3 ten thousanths, so the issue is not present on thier forged asms. Maybe Bairs and others face the original GM flanges that accurately, not sure, or if they just turn the rotors mounted...Craig

[Craig S.]

Re: C-3 E-Brake adjustment- typos galore!

Sorry for all my typos....Craig

[Patrick H.]

Re: C-3 E-Brake adjustment

Craig,

I don't think they necessarily mess with trueing (truing?) the spindle. What I understand is they index the rotor in the position with the least runout, and then go ahead and turn it. I'm sure there is a reason for this, but I don't know what it is. All I can think of is that they are left with more brake rotor material if they do this, but that's only a guess on my part.

Patrick

[John D.]

Re: C-3 E-Brake adjustment

Actually the rebuild was in February and I paid top dollar for the set up t-arms complete. I guess I should have checked the indexing before I installed them. I caught the problem when installing the e-brake cable, no parking brake. It makes sence if they never adjusted the shoes.

I plan on calling the rebuilder tomorrow!

John

[John H.]

Re: C-3 E-Brake adjustment

Patrick -

Doing it as you describe (just truing the rotor after assembly to the spindle) avoids having to remove and re-install the lug studs in order to true the spindle face - I suspect that's why they do it that way (old production guy speaking)