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I am in mid overhaul of brakes (installing new hoses with remanufactured calipers & new brake pads).
One of my caliper mounting bolts is nearly rounded off, I need new ones. From forum research it seems like size is 7/16-20x1.125" bolts. Mine is 1.375" long in the rear and has a shoulder near the head. Looks like the corvette vendor bolts don't have a shoulder.
Is the original bolt supposed to have a non-threaded portion near the head?
What is the proper bolt length? 1.125" or 1.375". I understand if it is too long it can hit the back of the rotor.
I found my bracket for the passenger rear brake hose not attached to anything. On the driver side rear it is firmly attached (welded? not sure I can't see it) to the frame. Are there any tips/tricks for securing this bracket to the frame?
In right side of passenger rear wheel well, connection from brake hose to hard line. Caliper mounting bolt which was on car, about 1 3/8" long. Shoulder approx 5/16" long, split locking washer about 1/8" thick.
Last edited by roamin' around; Jan 17, 2021 at 05:05 AM.
Yes, that is the correct caliper mounting bolt.
Hex head bolt lengths are typically taken from under the bolt head to the end of the threads, not the total length.
If you want the correct bolts with the shoulder Paragon Corvette has these in sets. Front and rear bolt lengths are different.
If you use hardware store bolts, make sure they are Grade 8. Normally these bolt lengths will be in 1/4" increments so be careful about that.
Paragon Front Link:https://www.paragoncorvette.com/p-35...-bolt-kit.aspx
Paragon Rear Link:https://www.paragoncorvette.com/p-35...-bolt-kit.aspx
Also looks like the brake line support bracket weld has broken away from the kick up area.
Paragon RH Bracket Link:https://www.paragoncorvette.com/p-35...t-bracket.aspx
It also a good time to replace ALL of your flex brake hoses.
Last edited by bmotojoe; Jan 17, 2021 at 08:30 AM.
Thanks for the quick reply. The Paragon rear lists 1 1/8" as you mention, but the front brakes don't have a length specified. On Van Steel brakes, the bolts for front and rear are same P/N and 1 1/8" long. I don't see the length at any other sites. I'll probably just take off a bolt from the front and take it to the hardware store. Will update this thread with my front bolt length.
By the way, yes I will be replacing all the brake hoses
Last edited by roamin' around; Jan 17, 2021 at 02:46 PM.
Took out a bolt from the front, has no shoulder, is 1 1/2" long including head, threads are about 1 1/4" long. So seems like front bolts are 1/8" longer than rear. See pictures below.
Anyone know if front bolts should have a non-threaded region near the head?
Front caliper mounting bolt. 1/8" longer than rear caliper mounting bolts.
Last edited by roamin' around; Jan 17, 2021 at 06:14 PM.
That non-threaded portion of the bolt shank just helps to position the parts properly to each other. The O.D. of the threads is smaller than the O.D. of the non-threaded shank.
Basically...less slop between assembled parts. But, I don't think you need to worry about the difference, as long as you are using grade 8 bolts.
Thanks everyone! I won't worry too much about the shoulder then. Nevertheless, I will try to get the right bolts and locking washers from a chevy dealer tomorrow. If they don't have it, I'll measure the stack up and see if 1 1/4" bolt will fit without hitting the rotor.
By the way, any recommendations how to disconnect the hose from the RH block when the flange weld is loose/unattached from frame (see picture below). Only thing I can think of is vice grips to hold the block, and a line wrench to try and loosen the hose. I'm afraid of damaging the block.
Passenger rear wheel well, looking up at brake hose block. The metal bracket is NOT welded to the frame, so it is tough to brake loose the hose.
The block is brass and is readily available (and not expensive) from the Corvette suppliers if you mangle it. Wrap the block with a couple layers of electrical tape before you clamp on the vice grips.
Be sure you have a tight fitting wrench for the nut. Damaging the nut is far more likely than the brass block. You stand a good chance of rounding off the nut if you are not careful.
A "shoulder" type bolt is there for a reason. Not just for looks, but rather by design. Always replace with like material.
Like '71 said, the shoulder spots the brake parts dead center. Without the shoulder, its like using too small of bolt in the casting.
You don't want to Bubba the brakes.
The shoulder should receive a smear of anti-seize and the threads should receive LocTite.
You are replacing the flex hose anyways, just cut it.
Because the bracket weld is broke this may allow you to move the brass block around to a area where you can use a larger adjustable wrench to support and grip the block from twisting.
It is always helpful to have part numbers when going to the part counter at the dealer. Rear bolts are GM #3843384 Front bolts are GM #186645.
If you are going to use 1-1/4" hardware store bolts for the rear, look into getting hardened split lock washers rear only, the hardened washer is a little thicker than a standard split lock washer.
Hardware store didn't have 1 1/8" long bolts, it appears no one locally has it. I went to auto shop they took off 1/8" from the 1 1/4" bolt now its the right length. This will be the temporary fix until I order the correct bolt.
One other thought I had is to use a 1" bolt without the 1/8" washer, the stackup should be the same as a 1 1/8" bolt. I could use some thread locker to serve as function of locking washer. I will go with the shortened 1 1/4" bolt.
Last edited by roamin' around; Jan 18, 2021 at 06:24 PM.
You are replacing the flex hose anyways, just cut it.
Because the bracket weld is broke this may allow you to move the brass block around to a area where you can use a larger adjustable wrench to support and grip the block from twisting.
It is always helpful to have part numbers when going to the part counter at the dealer. Rear bolts are GM #3843384 Front bolts are GM #186645.
If you are going to use 1-1/4" hardware store bolts for the rear, look into getting hardened split lock washers rear only, the hardened washer is a little thicker than a standard split lock washer.
Three Quick Brake Questions
