Front Caliper Bolts Throwaways???
Thread Starter
Safety Car
Joined: Aug 1999
Posts: 3,750
Likes: 1
From: San Jose CA
Front Caliper Bracket Bolts Throwaways???
I am replacing my rotors today and thought I would check the Service manual just in case there were any quirks versus other cars I have done. The only thing I saw, was the Service Manual tells you to discard the caliper bracket bolts and replace with new.
So I head off to the local Chevy dealer to buy them. They don't have them, because they never replace them. Uhhh, the Service Manual says to discard and replace with new. He called a couple of other places and no one had them or heard of replacing them, nor did they carry them in stock.
So who has replaced rotors and not the bracket bolts? What is the deal?
[Modified by Grzldvt, 3:34 PM 9/5/2001]
So I head off to the local Chevy dealer to buy them. They don't have them, because they never replace them. Uhhh, the Service Manual says to discard and replace with new. He called a couple of other places and no one had them or heard of replacing them, nor did they carry them in stock.
So who has replaced rotors and not the bracket bolts? What is the deal?
[Modified by Grzldvt, 3:34 PM 9/5/2001]
Instructor
Joined: May 2001
Posts: 204
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From: Ridgetop TN
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
The manual says the same about the caliper bolts when you just change the pads.
I changed my pads/rotors, put some loktite on the bolts and reused them.
I got the same thing at my dealer. Not in stock. Had to order.
I changed my pads/rotors, put some loktite on the bolts and reused them.
I got the same thing at my dealer. Not in stock. Had to order.
Drifting
Joined: Feb 1999
Posts: 1,481
Likes: 1
From: San Diego CA
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
The service manual seems to be incorrect.
I've done a great deal of research on this since I change my rotors before and after each track event.
The bolts do not need to be changed. Just put on some Locktite Blue and make sure you use a torque wrench and torque the bolts correctly.
Mike
I've done a great deal of research on this since I change my rotors before and after each track event.
The bolts do not need to be changed. Just put on some Locktite Blue and make sure you use a torque wrench and torque the bolts correctly.
Mike
Race Director
Joined: Mar 2001
Posts: 19,948
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From: Bonneville Salt Flats
Re: Front Caliper Bracket Bolts Throwaways??? (Mike Schriber)
Calling for bolt replacement is a safety (read: legal CYA) issue, IMHO, but not a bad idea. However, this goes to show how well the average tech reads the manual--NOT! Having worked in and around garages I know many only look at the manual when they get stuck, normally assuming they can bungle through. Best of luck. (p.s. my father was a mechanic for nearly 50 years who taught me always to read the manual first, especially after the advent of auto computers. But, that was when we had "mechanics" and not parts-changers. Do I show my age? :eek: Probably. :D
Drifting
Joined: May 2001
Posts: 1,499
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From: Cincinnati OH
Re: Front Caliper Bracket Bolts Throwaways??? (Avanti)
I called 3 Chevy Dealers and asked about this. ALL of them said they never replace those bolts. An interesting side note - NONE of them had the bolts in stock either (which is a testament to them not replacing them). I used RED LocTite on mine (the RED stuff is HIGH TEMP).
-Jim
-Jim
Team Owner
Joined: Jun 2001
Posts: 26,714
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From: Houston, TX
Re: Front Caliper Bracket Bolts Throwaways??? (VetteMan2k1)
I called 3 Chevy Dealers and asked about this. ALL of them said they never replace those bolts. An interesting side note - NONE of them had the bolts in stock either (which is a testament to them not replacing them). I used RED LocTite on mine (the RED stuff is HIGH TEMP).
-Jim
-Jim
Thread Starter
Safety Car
Joined: Aug 1999
Posts: 3,750
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From: San Jose CA
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
Well, some interesting responses. Since I cannot get the bolts except on special order @ $7 a piece and it appears keeping the old and using LocTite works, I will go that route.
Thanks
Thanks
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Team Owner
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Re: Front Caliper Bracket Bolts Throwaways??? (jschindler)
I use red or blue and have not changed them after 30 or 40 times or more. After each track event I go back to street pads and rotors.
Race Director
Joined: Jan 2000
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From: Florida
Re: Front Caliper Bracket Bolts Throwaways??? (John Shiels)
I strongly disapprove of using threadlock compound on any application where any one of the following exists: (1) different metals are involved; (2) where rapidly changing extremes of temperature exist; and (3) where moisture exists. All THREE conditions exist at the Brakes, so they score a home run.
Using threadlock under these conditions can and will damage threads upon loosening, which is why GM recommends not re-using. In this application, the bolt threads take the deformation, since the ductile iron into which it screws is far harder (and also more brittle).
Why does GM use threadlock? Extra insurance that improper torque on the assy line will not result in brake failure. After that, it becomes the dealer/customer problem.
My solution was to discard the bolts (caliper and bridge, put in fresh 10.9 grade fasteners, and use anti-seize compound, the correct material to use in this application. (Always use 2/3 rated torque when using anti-seize). I then re-use the bolts for 20 cycles.
If you MUST re-use the original bolts (hey, it's your life), you MUST thoroughly clean the threads of any previous loktite residue, to prevent thread deformation on re-torque.
Using threadlock under these conditions can and will damage threads upon loosening, which is why GM recommends not re-using. In this application, the bolt threads take the deformation, since the ductile iron into which it screws is far harder (and also more brittle).
Why does GM use threadlock? Extra insurance that improper torque on the assy line will not result in brake failure. After that, it becomes the dealer/customer problem.
My solution was to discard the bolts (caliper and bridge, put in fresh 10.9 grade fasteners, and use anti-seize compound, the correct material to use in this application. (Always use 2/3 rated torque when using anti-seize). I then re-use the bolts for 20 cycles.
If you MUST re-use the original bolts (hey, it's your life), you MUST thoroughly clean the threads of any previous loktite residue, to prevent thread deformation on re-torque.
Thread Starter
Safety Car
Joined: Aug 1999
Posts: 3,750
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From: San Jose CA
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
So, I cleaned up the bolts with a wire wheel to the point they looked new, put a touch of Blue on them. I did this before I saw TTrotary's post.... which certainly is serious food for thought...
Thanks everyone.
Thanks everyone.
Melting Slicks
Joined: Aug 1999
Posts: 2,858
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From: Northern Calif/ San Juan Island, Wa
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
Grzldvt
I purchased new bolts at over $5 each from my dealer, when I replaced rotors. Replacing bolts is a waste of money. Gm Bolts have Loctite already added to threads. Clean your old bolts and add loctite. When I attended Bragg-Smith three day roadracing school. I asked if they replace brake bolts. No they do not, just add loctite. All the C5 roadracers also just add loctite.
I purchased new bolts at over $5 each from my dealer, when I replaced rotors. Replacing bolts is a waste of money. Gm Bolts have Loctite already added to threads. Clean your old bolts and add loctite. When I attended Bragg-Smith three day roadracing school. I asked if they replace brake bolts. No they do not, just add loctite. All the C5 roadracers also just add loctite.
Racer
Joined: Dec 1999
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Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
I just ordered 12 from my local chevy dealer for $1.50 each. Bolts are designed to stretch ever so slightly if they are tightened to spec. I feel replacing them every 3 to 4 cycles of reuse when changing out to race pads for road course driving is the right thing to do.
Drifting
Joined: Feb 1999
Posts: 1,481
Likes: 1
From: San Diego CA
Re: Front Caliper Bracket Bolts Throwaways??? (TTRotary)
I agree, but Locktite Blue is pretty mild as far as threadlockers go. None of the Chevy dealers seem to stock these bolts or use new ones when they work on the brakes. Then again, most Corvette owners don't change their rotors one or two times a month either (like us weirdos).
Another thing to consider... The dominant force acting on the bolts is shear. Most of the force is concentrated on the bolt at the print where the caliper bracket meets the suspension, trying to rip the bolt in half.
In real life, I've seen things on brakes that would keep you up at night, not result in any catostrophic failure.
Still, better safe than sorry, particularly on the track.
Mike
Another thing to consider... The dominant force acting on the bolts is shear. Most of the force is concentrated on the bolt at the print where the caliper bracket meets the suspension, trying to rip the bolt in half.
In real life, I've seen things on brakes that would keep you up at night, not result in any catostrophic failure.
Still, better safe than sorry, particularly on the track.
Mike
Instructor
Joined: Aug 1999
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From: Green Bay WI
Re: Front Caliper Bracket Bolts Throwaways??? (Grzldvt)
These bolts are TTY (Torque-To-Yield). To "yield" is to get the bolt to begin to stretch. Once loosened, they should never be reused. The weak point becomes the "filet" (where the shaft meets the head) once the bolt has been loosened.
The observation that the major stress is to shear the bolt as opposed to trying to pull appart may very well explain why there hasn't been any/many failures of these bolts. The brain trust at GM put them there, and recommend replacing them, there must be a reason.
IMHO, I would install the new bolts ASAP. After all, no one minds dumping $35 worth of oil after a couple of thousand as "cheap" insurance, as insurance goes, this is cheaper still.
The observation that the major stress is to shear the bolt as opposed to trying to pull appart may very well explain why there hasn't been any/many failures of these bolts. The brain trust at GM put them there, and recommend replacing them, there must be a reason.
IMHO, I would install the new bolts ASAP. After all, no one minds dumping $35 worth of oil after a couple of thousand as "cheap" insurance, as insurance goes, this is cheaper still.