ragni

Car: 1994 LT-1

I changed out the front wheel hub assemblies and I was torquing down the brake caliper bolts as per the GM shop manuel to 166 lbs +- 15 lbs when one of the bolts sheered.

I thought that torque spec seemed excessive.

Can any member give me the proper torque specs for these (2) bolts.

janarvae

Replaced front rotors, pads, clips, and pins this past month on my 91 non-J55 brakes. 166 ft-lbs +/- 15 is exactly what I read in several posts regarding brakes on the forum. I used the original caliper bracket bolts with Blue Loctite as they are hard to source.

I guess it was just time for you to replace those bolts. When I was researching, I had found that the FSM recommends changing those bolts EACH time they are taken off. However, several forum members said it was unnecessary. I cleaned the old threads with a wire brush and made sure they were fine as well as the straightness of the bolts.

I believe neither MidAmerica, Ecklers, nor Corvette Central sell the bolts, and could not find them at NAPA, AutoZone, or Advance Auto Parts either. One CF member had some luck with the GM dealer who had to import the part number into the database as they had never been ordered before. You might want to try there if you can't find them anywhere else.

65Z01

and the thick washers too.

I got new bolts & washers at the local Chevy dealer for the 1st caliper work but reused them the 2nd time I had the calipers off.

On my '88 the torque spec is 137lbs-ft or 185N-m.

Arkybill

I had the calipers and rotors off last summer. I don't remember what the torque spec was for the calipers, but, do remember it was high and had the + or - 15 ftpds in the spec. As I was using a regular torque wrench, I set it at the -15 ft (off the spec-not at -15) and it was PLENTY tight. If they come loose, you'll hear the rattle way before they fall off.

This kinda like the pin that holds the caliper on the bracket, put it it from the wheel side. that way if the C-clip comes off, the pin will back out and hit on the wheel-you'll hear this funny clicking sound from the FRONT of the car and when you look, you'll have some grooves in the wheel spokes, BUT, the pin won't fall out without warning you.

bill

ragni

Thanks for the help. Two additional points:

1) I progressed with the wheel hub assembly change (remarkably easy by the way) to the other side and noticed something that I forgot to mention yesterday and that is that the two brake caliper bolts broke free VERY easily. In other words, there is no way they were torqued down to a high torque settng like 166 lbs.

2) My car's front brakes were upgraded to the Grand Sport brakes by the original owner. I can't find any different torque specs for those brakes.

Does anyone know if the Grand Sport brakes have a different (lower) torque spec? I know it doesn't make sense but I have to ask.

Thanks, Rich

c4cruiser

The basic reason that the FSM says to replace the caliper bracket bolts is that new bolts come with a threadlocker already applied. It seems strange that dealerships don't typically stock these bolts for brake work on customer cars when the FSM states to not re-use the old bolts

The bolts are a metric 10.8 strength rating (equal to an SAE Grade 8) and should easily have taken the 166 ft-lb torque. Auto parts stores will not have this bolt and if the dealer can't find them , you may have to go to a supply store that specializes in fasteners (nuts. botls, etc.)

Existing bolts can be re-used as long as the bolt threads are cleaned of any old threadlocker and you re-apply something like Loctite Blue. Don't use the Loctite Red as it requires heat to remove the bolts.

I torque the caliper bolts on my 87 in two steps; the first to 75 or 80ft-lbs and then to spec. That helps balance the force at each end of the caliper bracket.

FWIW, the bolts for my 87 are GM part # 14084051


GS/J55 brakes should have no bearing on the torque specs.

Sidney004

I torque to 160 ft-lbs without any loctite. I don't use loctite because I race the car and check the bolts regularly before an event. I have never found one loose and I have never replaced the bolts. I do torque progressively as well; 100,140,150 and finally 160.

ragni

Thanks all. I checked in at NAPA today and sure enough as per janarvae's above post they don't have them. I sure hope my local Chevy dealer can get them for me. Otherwise, I'm SOL.

If anyone has any leads for other sources, please let me know.

Thanks, Rich

Sidney004

Check and see if there is a location near you.
http://www.fastenal.com/web/aboutUs.ex
They will have the 10.8 grade

janarvae

Yea, tell me how that turns out with the Chevy dealer. It just sucks that most auto parts stores don't carry them. Mine was my daily driver and I was freaking out trying to find new ones before I saw a post on the forum saying Blue Loctite was good enough.

I'm glad you mentioned this - I've been trying to find a good fastener store and this is exactly what I was looking for. Luckily, I've got one in my city and every one surrounding it. I just hope the OP finds them at the Chevy dealer or has a fastenal close by.

ragni

The Chevy dealer had em in stock @ $6.33 each. I picked up 2. I'll change em out next weekend before I start on my rear wheel bearing project. A portion of the stud is hanging out so I think I'll be able to work it out with pliers or vice grips or something. We'll see. Otherwise it's the easy-out procedure.

Any tips welcome.

Thanks again, Rich