Does anyone reuse these bolts?
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 7,625
Likes: 4
From: Director of Bands
St. Jude Donor '08
Does anyone reuse these bolts?
When changing the rotors on one of these cars, you're supposed to discard the two bolts that secure the caliper bracket to the knuckle, as per Helms. Those bolts are damn near $6 a piece at my local GM dealer! 
8 bolts (two at each corner)... that could get expensive and Mrs. eschoendorff might start asking questions. 
Does anyone reuse them? Maybe with some blue loctite?
8 bolts (two at each corner)... that could get expensive and Mrs. eschoendorff might start asking questions. Does anyone reuse them? Maybe with some blue loctite?
Pro
Joined: Feb 2005
Posts: 658
Likes: 1
From: Centerville OH
I've reused them in the past with no issues. Just clean 'em up and put loctite on them, and you should be fine.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
Elite Torch Red Member
Joined: Sep 1999
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
CI-II Burnout & Drag Champ
St. Jude Donor '03-'04-'05-'06-'07
I've reused them, but last time out I bought all new ones.
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 7,625
Likes: 4
From: Director of Bands
St. Jude Donor '08
Originally Posted by Z51L9889
I've reused them in the past with no issues. Just clean 'em up and put loctite on them, and you should be fine.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
I figured that GM had its reasons.... but at $6 a bolt, I had to raise the question.BTW... I didn't realize that my bolts lactate. Should I massage them gently before I remove them?
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
I bet it's CYA for GM due to the locktite. Better to charge more for bolts from Taiwan with locktite preapplied than to trust a service tech to do it right.
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Race Director
Joined: Aug 2003
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From: Lake Mary Florida
Its hard to say, then again they could be single torque bolts too. And considering its only that one bolt that secures the entire rear caliper, that tends to make it fairly important.
I figure they must have had good reason to state that in the service manual, so on those types of warnings I listen to them. Besides its not that much money. When I did mine, I install new pins, circlips and rear bolts. I think all the pieces where well under twenty bucks.
I figure they must have had good reason to state that in the service manual, so on those types of warnings I listen to them. Besides its not that much money. When I did mine, I install new pins, circlips and rear bolts. I think all the pieces where well under twenty bucks.
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
You should be able to re-use the bracket bolts two or three times then toss them. As mentioned, chase and the threads and apply BLUE locktite and torque to spec. If you were going thru lots of rotors for track days, I would replace them every other use.
Given the torque spec for the front bracket bolts, the bolt head may get rounded off quicker than the bolt itself will stretch or the threads get messed up. Definitely use a 6-point socket on them.
Given the torque spec for the front bracket bolts, the bolt head may get rounded off quicker than the bolt itself will stretch or the threads get messed up. Definitely use a 6-point socket on them.
Pro
Joined: Feb 2005
Posts: 658
Likes: 1
From: Centerville OH
Originally Posted by CentralCoaster
I bet it's CYA for GM due to the locktite. Better to charge more for bolts from Taiwan with locktite preapplied than to trust a service tech to do it right.
I used to work for GM. That's EXACTLY the mentality that they use. The other reason is liability. What happens if someone forgets to apply loctite, the bolts back out, the brakes come off, and someone dies? I know this sounds really silly, but I've actually seen GM get sued for reasons that were at least this stupid.
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
I've reused them without any problems on every car I've owned. I think the Pins are more important since once they're corroded, the caliper can hang up, but I usually just buff those up too and then reinstall them.
Race Director
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From: SCMR Rat Pack'r Charter Member..Great Bend KS
Originally Posted by Z51L9889
Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
Larry
code5coupe
Race Director
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From: Lake Mary Florida
Originally Posted by Z51L9889
I used to work for GM. That's EXACTLY the mentality that they use. The other reason is liability. What happens if someone forgets to apply loctite, the bolts back out, the brakes come off, and someone dies? I know this sounds really silly, but I've actually seen GM get sued for reasons that were at least this stupid.I mean that is probably a no-brainer to a good mechanic, especially if the understand the system and know that only one small bolt holds this assembly together. It should be torqued and locktite applied.
It would be an engineering process specification. During development they probably noted that the bolt was backing out over time and wrote a process spec to deal with it. I use to see this alot with aircraft systems, except on many of those critical fasteners, they wire tie them after torqueing them.
Le Mans Master
Joined: Feb 2002
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Originally Posted by c4cruiser
You should be able to re-use the bracket bolts two or three times then toss them. As mentioned, chase and the threads and apply BLUE locktite and torque to spec. If you were going thru lots of rotors for track days, I would replace them every other use.
Given the torque spec for the front bracket bolts, the bolt head may get rounded off quicker than the bolt itself will stretch or the threads get messed up. Definitely use a 6-point socket on them.
Given the torque spec for the front bracket bolts, the bolt head may get rounded off quicker than the bolt itself will stretch or the threads get messed up. Definitely use a 6-point socket on them.
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
Originally Posted by Z51L9889
I've reused them in the past with no issues. Just clean 'em up and put loctite on them, and you should be fine.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
Depending on how the bolts are used, some one-use bolts are "torque to yield", which means you actually deform the bolt slightly when you install it. It has much lower strength if you try to re-use it. Other types of bolts are defined as one use because they have threadlocker pre-applied. That's the case for the caliper bracket bolts.
These bolts just might be "torque to yield". Have you noticed in the service manual the torque spec is 166 lbs.ft.!
Then I noticed in the back of the 5B2 section (rear brakes) it lists Bracket Mounting Bolt as 70 lbs.ft. which seems more reasonable for a bolt of this size. 
I torque mine to 100 lbs.ft. with red locktite and never had a problem.
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Originally Posted by Lone Ranger
I thought you were supposed to use red thread lock formula (loctite) on stud bolts?
As far as bolt torque, the rear caliper mounting bracket bolts are torqued to a lesser amount (70 ft-lbs) while the front bolts are torqued to 165 (+/- 15) ft-lbs. 84-87 cars use a slightly lesser value on the front bolts.
1st Gear
Joined: Aug 2004
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If you follow GM's service manual for a '91 Vette and torque the front caliper bracket bolts to 166 ft. lbs. you'll snap the bolt! I just did. Chilton's and others recommend 133 ft. lbs. which is more reasonable for an aluminun bolt.