Hi all,

I'm presently doing a bit of wrenching on a C3 (1981) that doesn't belong to me. Hoping for a bit of help with a few questions:

1. I heard a brake noise when driving the car, and yanked the rear wheel to have a look. Whoever was last into the rear brakes on this car left a caliper pin out. This resulted in the pads dropping down until they contacted something that made them stop dropping. In the case of the outer pad, this something was the hat section of the rotor. Over time, the backing plate of the pad has cut a nice groove in the hat section of the rotor. The groove mics out at around .055 deep. How much meat is there in the hat section of these rotors? Does this groove present any danger of rotor failure on a street-driven car? Images below:

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2. What's the lug nut torque spec on a set of these wheels on an '81?:

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3. What is the bracket that appears in the center of this photo? There's one on the left side of this car, and provision to attach one on the right side, but no bracket on the right side:

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Many thanks in advance for any assistance.

Be well,

SJW

 

Sorry, you're a C4 guy so The Brotherhood Of The C3's won't let me share info with you.

 

You can buy new rotors on the cheap. Why take a chance on failure?

As far as the other Q's I have no idea....

 

Looks like that braket is bolted on and homemade to me , the metal is not even strait along the angled edge, the other deal welded to the end of the mufler
looks factory it goes up and looks like it is stuck in some rubber, someone
with an 81 will chime in. Dont know how thick the metal is on the hat, I think you
should play it safe and replace it.

 

well i dont know too much about the thickness of the hat, but i am a nuclear mechanic and i can say that doesent look too good. i would replace it.

 

Cast aluminum wheels .......90ft. lbs. The brackets are stock.........PN 14028582 rear tow brackets 80-82 You are missing one.

 

I can answer #2, standard wheels are 80 lb. ft and aluminum are 90 lb. ft.

New brake rotors are only like $35

Murvette is also correct on that bracket. He posted while I was reading :P

 

The rotor hat is 5/16 inch thick in that area.

 

Okay, you're officially blackballed in the C4 section now...



Be well,

SJW

 

I agree, but, in this particular case, if the car can be safely driven (in a sane manner) for a short time with this cut in the rotor hat, I'd like to re-pin the pads and get it back on its wheels tonight. The car needs to go back to the body shop for some touch-ups, etc to close out a major bodywork/repaint job that's nearly completed now, etc.

While inspecting this car over the weekend, I observed quite a few things in the brake system that should be attended to in the not-too-distant future, and I'd prefer to tear into it all as one project, and for a variety of reasons, this week just isn't the time for that.

The hard line connection to this particular caliper is crusty enough that I'm skeptical it'll break free cleanly (I already leaned on it pretty hard with a line wrench, and it didn't budge), so I'm probably looking at line replacement, too.

The caliper also has a broken-off bleeder screw, so it'll need a caliper before it can ever be bled again. Which means it probably should just have all four calipers replaced w/ stainless-lined, as the condition of the others is also questionable.

Obviously, one of the pads now also has a nice little arc cut into it from abrading against the rotor hat, so the rear pads should be replaced, too.

I think you're getting the idea here...

Be well,

SJW

 

Thanks a bunch, murvette. The owner of this car is having trouble locating her shop manual right now, so I'm kinda winging it here with this one. Torque specs are good to know.

I presume the "tow brackets" were factory installed to prevent damage if the vehicle was towed from the rear with a sling-type tow truck like those I drove 25 years ago? If so, I think I'll just forget about the missing bracket on the other side, as this car's gonna ride a roll-back if it needs to hitch a ride nowadays...

Thanks again for the knowledge.

Be well,

SJW

 

This is what I was hoping to learn about this. Many thanks, BBShark. With over .250 of meat left in the hat, I'm confident that the car can be driven gently without danger for a few miles until I can tear into the entire brake system. This is good to know.

Thanks much for sharing the knowledge. Gotta love this forum.

Be well,

SJW

 

Torque specs are as noted. Probably okay to drive like that. They are pretty thick and that wear is minimal. Tow brackets. Hmmm. I didn't know that. I thought they might be some kind of impact deflector to shove things under the gas tank in case of a rearer or something. Most brackets I have seen on C3's feel kind of flexie - but they are mounted on the bumper so that would be normal. I know a guy who bolted a trailer hitch to his - go figure Donvorryboutthem.

(Hey - - can I post here with my C3 pics??)

 

I wouldn't worry about that rotor. If you want to be on the safer side of "cheap & fast", Take the rotor off and radius those sharp edges to reduce the chance of heat induced cracking.

I'm not sure I would even do that.

 

The idea that those brackets were impact/crash-related occurred to me also. I'd guessed that maybe they were intended to cause the spare tire to become more involved in absorbing an impact. It didn't even occur to me that they could be towing brackets. Learn something new nearly every day...

Yah, I think the rotor's okay to run as-is for a little while. This car's a driver. It won't get tracked, or driven all that aggressively until I can go all the way through the brake system, so I'm comfortable now with re-pinning the pads and letting it roll for the time being.

Thanks much.

Be well,

SJW

 

Not a bad idea. If I could get the line to break loose at the caliper, I might consider it. But, I think the line's gonna wring off at the caliper when I try to remove it, so I think I'll let that sleeping dog lay there until it's time to go after the whole brake system from stem to stern.

Thanks for the advice.

Be well,

SJW

 

That's what I would do too. I can't imagine your going to have a failure caused by that groove anytime soon.

 

I think you're right. With over 80% of the original thickness remaining below that groove in the rotor hat, I think that if a brake system failure occurs on this car anytime soon, it'll be something else that goes.

Thanks for your advice.

Be well,

SJW