how many times can you reuse stock head bolts?

[Michael Yount]

Fasteners that provide their clamping force below the yield point (all ARP fasteners work this way; this thread is inconclusive about which stock Mustang head bolts are non-tty -- at least 4 different opinions have been offered about the year break) can be used more than once. Tightening them to the torque point does not yield them - they simply act like a spring that 'springs' completely back to their original shape once the torque is removed. Measure them before and after torquing, and they are exactly the same length.

Torque to yield bolts are called that because the process of tightening them actually yields the metal - that is it stresses the metal PAST it's yield point. If you were to measure their length before and after torquing them in the proper way, they are longer after they're torqued - they literally are stretched and cannot 'spring' back to their original shape/length. Once yielded, TTY BOLTS CANNNOT BE USED AGAIN SAFELY - they are not capable of providing the clamping force needed to secure the component.

 

[YardSpecial]

SO my Ford book is wrong???????????

 

[351LX]

Not all V-6's use torque to yield bolts.The 2.8 in my Bronco II has re-usable ones.When I put on head gaskets I clean the head and block with brake cleaner so there is no trace of any oil and I put them on dry with no sealants.I have always done this and have never had a problem.

 

[Michael Yount]

Don't know what your Ford book says Mr. C; but I do know that any source that suggests reusing fasteners that have been yielded is doling out harmful information.

 

[IndyBlk5.0]

i beleive 91-93 is torqued to yeild, earlier years were not torqued to yield, check a book

 

[1BAD89GT]

What if someone has already swapped head bolts out of that car before??
why take the chance this really shouldnt even be a discussion buy some new Head Bolts (ARP) And save your self the worry,And time of having to do it all over again if they fail.

"if your going to do something,Do it right the first time!"

 

[Michael Yount]

For those of you that want to learn more, go to the link - an excellent primer on Torque-to-Yield bolts and the mechanics behind them.

http://www.robbos.com.au/myweb/Tech_Bolts.htm

 

[Foxslider]

So i got 5 different answers here. I'll just buy the head bolts. lol.

 

[Hoytster]

So i got 5 different answers here. I'll just buy the head bolts. lol.

You made the right choice

-You DO NOT want to reuse TTY bolts
-From the stock engines I've been in, Ford started using the flanged TTY bolts around 1991-1992. A quick look at Fel-pro's master torque table seems to confirm this:
Fel-Pro Master Torque Table (Page 33)
-Prior to 1992-91, the bolts were standard hex head and could be reused. But I personally never liked to reuse stock head bolts, so I always upgraded to the ARP bolts.

 

[Mustang5L5]

I'll just buy the head bolts. lol.

Probably the best idea

 

[General karthief]

New head bolts are always a good idea. Not that expensive.
and just for the sake of discussion, my 89 assembly manual shows TTY head bolts.

 

[Foxslider]

LOL. 15 yrs later, still getting mixed answers every other time.

 

[General karthief]

I think the consensus is buy new bolts.

 

[Foxslider]

Also for the sake, ill google to see what the different bolts look like. TTY and non TTY.

Ya, i am. Just funny how this one is up in the air. Crazy to get different answers like that from valid sources. Manuals, fel pro etc..

 

[Hoytster]

New head bolts are always a good idea. Not that expensive.
and just for the sake of discussion, my 89 assembly manual shows TTY head bolts.

I've seen so much inconsistency between sources on when the change was made. My 89' came with the standard bolts and my factory service manual for the 89' shows a standard non-tty torque procedure, but I've seen many other manuals that state TTY.

Seems like the best bet is just to replace them.

 

[Infoxicated5.0]

Hey there,

You can reuse any “OE” bolt as much as you’d like give that they are not “Torque-To-Yields”. It is easy to spot a torque to yield bolt as they are fatter OD in the middle of the threads, and when torqued to spec they stretch tight and hold strong. Once removed, you should definitely not reuse them as they will not torque properly.

Make sure you torque in stages of three, wouldn’t be a bad idea to go for new bolts every time, low cost, and ARP obviously makes great stuff. Make sure to clean the bolt hole and threads.
Hope this helps !