Dealer re-using old head bolts
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Joined: Aug 2002
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From: Hartsdale, NY
Dealer re-using old head bolts So I swaped heads a few years ago and the dealer where i got new head bolts says the dealership has re-used the old head bolts on Gen IIIs on dozens of warranty jobs and has never had issues.
They crack-up and say you are only making GM rich.
Is this possible?
They crack-up and say you are only making GM rich.
Is this possible?
They aren't doin it right then. These bolts are torque to yeild, meaning once they have been torqued once they need to be replaced if removed. I wouldn't let them do that to my car unless I had ARP hardware instead of stock GM.
If the dealer re-uses torque-to-yield bolts on a warranty job they are doing it to put money in their own pocket. What does that say about the business practices and ethics of this dealer if they spit in the face of GM engineering and repair practices?
The head, main, and rod bolts are not re-usable, as noted by GM, and is non-negotiable.
The head, main, and rod bolts are not re-usable, as noted by GM, and is non-negotiable.
Thread Starter
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Joined: Aug 2002
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From: Hartsdale, NY
Yeh, I know about T-T-Y bolts. The dealer guys say, ALL bolts stretch, so what!
I checked with a licensed structural engineer who advises NY on highway bridge construction. He concludes all bolts stretch too.
I used new bolts but if I ever ripp the heads off again, I'm not sure I would buy new bolts again???
I checked with a licensed structural engineer who advises NY on highway bridge construction. He concludes all bolts stretch too.
I used new bolts but if I ever ripp the heads off again, I'm not sure I would buy new bolts again???
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It's not about all bolts stretching, they do....it's rather about how, after a bolt has been torqued and stretched out, do you know how much clamping force it provides for your cylinder head. After its been torqued, do you go 90ftlbs, 110ftlbs, etc to get the right clamping. I may re-use a head bolt on my cousin's old POS beater...but not on my baby!
You have to step back and think about what a bolt actual does, mechanically, for your engine. Why do people use rod bolt stretch gauges insead of just torquing to a specific ftlbs rating? Because the torque spec in ftlbs is an approximation of how much force/torque it takes to stretch that bolt so far, which is what what happens when you are providing that clamping force.
Next time, ask a mechanical engineer...this is more up their allies!
You have to step back and think about what a bolt actual does, mechanically, for your engine. Why do people use rod bolt stretch gauges insead of just torquing to a specific ftlbs rating? Because the torque spec in ftlbs is an approximation of how much force/torque it takes to stretch that bolt so far, which is what what happens when you are providing that clamping force.
Next time, ask a mechanical engineer...this is more up their allies!
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From: Hartsdale, NY
OK - you have convinced me to always use new TTY head bolts.
Matt:
I thought a torque wrench would give you a good idea of how much torque a given bolt (new or old) will be applying to the head? I realize TTY bolts are installed without a torque wrench, but is this necessary?
In other words, lets say you used new TTY bolts and wrenched them to 75lbs. Would that get you close to the factory tollerence?
Matt:
I thought a torque wrench would give you a good idea of how much torque a given bolt (new or old) will be applying to the head? I realize TTY bolts are installed without a torque wrench, but is this necessary?
In other words, lets say you used new TTY bolts and wrenched them to 75lbs. Would that get you close to the factory tollerence?
Well, the torque wrench measures the force needed to overcome the resistance there....but once these stock bolts are stretched out, that resistance may not be giving the same clamping force for the head.
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http://www.oliver-rods.com/library/libraryindex.html
That's an article from our friends at Oliver that might help clear some of this up!!
That's an article from our friends at Oliver that might help clear some of this up!!
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TTY means that all bolts are torqued down in sequence, and then tightened a certain degree of rotation
ex ls1 heads require NEW bolts to be torqued in sequence at 37 lb/ft. Then each bolt is tighened an aditional 120º of rotation to add the correct stretch
if a mechanic had to do a head job under warranty, why wouldnt they get the damn bolts, its not like its coming out of the mechanics pocket.
No one at my dealer would ever reuse TTY bolts, Especially under warranty.
ex ls1 heads require NEW bolts to be torqued in sequence at 37 lb/ft. Then each bolt is tighened an aditional 120º of rotation to add the correct stretch
if a mechanic had to do a head job under warranty, why wouldnt they get the damn bolts, its not like its coming out of the mechanics pocket.
No one at my dealer would ever reuse TTY bolts, Especially under warranty.
Originally Posted by CamaroRick
TTY means that all bolts are torqued down in sequence, and then tightened a certain degree of rotation
ex ls1 heads require NEW bolts to be torqued in sequence at 37 lb/ft. Then each bolt is tighened an aditional 120º of rotation to add the correct stretch
if a mechanic had to do a head job under warranty, why wouldnt they get the damn bolts, its not like its coming out of the mechanics pocket.
No one at my dealer would ever reuse TTY bolts, Especially under warranty.
ex ls1 heads require NEW bolts to be torqued in sequence at 37 lb/ft. Then each bolt is tighened an aditional 120º of rotation to add the correct stretch
if a mechanic had to do a head job under warranty, why wouldnt they get the damn bolts, its not like its coming out of the mechanics pocket.
No one at my dealer would ever reuse TTY bolts, Especially under warranty.
we must have some cheap *** service managers in my area. My instructor was a mechanic for7 years. People would come in under warrenty complaining of squeaking brakes.
Break off the squealer. Done.
I think they would reuse bolts SPECIFICALLY if it was under warranty.
Originally Posted by vettenuts
What do they know, they never even crack the service manuals. That's why I work on my own cars 
you also have to remember with bolts you do not get an even amount of torque over the entire bolt. not only does it stretch but it also twists and the torque at the bottom of the bolt will be different than the top. this is why there are studs. studs provide a much more uniform of torque through out the piece.
