single use bolts

[SS_Dave]

Are the bolts in the rear cradle bushings considered single use? Also, any others in the rear end other than caliper and wheel hub considered single use?

[hesster]

Older file attached with Torque and Angle specs - as are most suspension bolts.

The angle provides the required clamp load.

Endless and almost comical debate on Torque and Angle and Torque to Yield Fasteners, as in "can they safely be reused".

Do you think a Dealer or shop replaces them? (esp like the Strut Clevis Bolts during an alignment).

[SS_Dave]

Perfect! Thanks

[gtstorey]

Originally Posted by hesster

Older file attached but any bolt with Torque and Angle is technically single use.

Based on what?

[KillboyPowerhead]

Whatever 74 + 120° is, you may want to make sure it's at least 165 ft/lbs (https://www.camaro5.com/forums/showt...=474155&page=5). I just did 165 ft/lbs with some blue LocTite and the cradle still hasn't fallen off after 5 years.

Regarding not reusing TTY bolts, found these:
https://www.felpro.com/technical/tec...tty-bolts.html
https://www.camaro5.com/forums/showthread.php?t=509802
https://www.camaro5.com/forums/showthread.php?t=512741

With that said I couldn't find any info on identifying a TTA vs TTY bolt other than by torquing it and seeing if it stretched. Again, I've reused the bolts for the suspension and calipers multiple times with some blue LocTite and torquing them down "gudentite" and nothing has fallen off.

[SS_Dave]

Originally Posted by gtstorey

Based on what?

If it's got an angle specified in addition to torque, you're generally creating some stretch load on it.

[SS_Dave]

Originally Posted by KillboyPowerhead

Whatever 74 + 120° is, you may want to make sure it's at least 165 ft/lbs (https://www.camaro5.com/forums/showt...=474155&page=5). I just did 165 ft/lbs with some blue LocTite and the cradle still hasn't fallen off after 5 years.

Regarding not reusing TTY bolts, found these:
https://www.felpro.com/technical/tec...tty-bolts.html
https://www.camaro5.com/forums/showthread.php?t=509802
https://www.camaro5.com/forums/showthread.php?t=512741

With that said I couldn't find any info on identifying a TTA vs TTY bolt other than by torquing it and seeing if it stretched. Again, I've reused the bolts for the suspension and calipers multiple times with some blue LocTite and torquing them down "gudentite" and nothing has fallen off.

74lbs plus another 120degrees of rotation.

[fz4k98]

Technically, single use is correct if you are going to install using torque plus angle technique. The bolt is still fine as long as it has not been overstressed but will not provide the correct stretch if trying to use the torque plus angle technique.

The end result if reusing on torque plus angle will be overtorqued bolt which will be weaker.

[gtstorey]

Originally Posted by fz4k98

Technically, single use is correct if you are going to install using torque plus angle technique. The bolt is still fine as long as it has not been overstressed but will not provide the correct stretch if trying to use the torque plus angle technique.

The end result if reusing on torque plus angle will be overtorqued bolt which will be weaker.

Torque plus angle may or may not be stretching the bolt.

I think a lot of the service manual stuff saying to use new bolts is because of the factory applied loc-tite on the bolts, plus lawyers.

[CamaroCracka]

I give her about 5+ oogadoogas with a Dewalt mid-torque and a good bit of Loctite, which is a bit more than I give the lug nuts. When I check the lugs with a torque wrench, I rarely have one that is not 135lbft. If you are wondering why I don't just torque the lugs in the first place, I only use the torque wrench on track days.

[fz4k98]

I typically reuse bolts with some loctitie on them in those areas where they use torque plus angle but only use torque on them.

If you want to visualize the difference, the next time you are doing an area that has torque plus angle, use one bolt that is new and the other that is reused and try to achieve the torque plus angle spec. This will show the difference between a new bolt and used.

I did this on my rear calipers and was suprised just how different they acted.

Torque plus angle is one step above torque for accuracy of a bolted joint. It allows better accuracy without spending higher money in the machining and design of parts on critical bolted joints.

Wheel lugnuts are torque only joints as they are removed and reinstalled several times. The bolted joint design to allow this is different.

[Moto-Mojo]

I prefer the old German Torque Spec: Gutentite

[cdb95z28]

Torque to angle (TTA) bolts are not always a torque to yield (TTY) bolts. If GM says a bolt is one time use, it's going to be a TTY bolt. TTY bolts use a torque plus angle tightening procedure just like TTA bolts. Check the service manual to see whether the cradle bolts are TTY.

The yield point of a bolt is the point at which it will permanently deform (stretch). All fasteners should be stretched to a certain point to create the required clamp load, up to the yield point. Once you get past the yield point the clamp load drops. Engineers want a certain clamp load for the bolt so it won't loosen on its own.

IIRC, when I had my Gen5, when I did the AFE solid cradle mounts, I did not replace the bolts.

The Gen6 has a lot more chassis TTY bolts than the Gen5 did.

YMMV on reusing TTY bolts. If you are a bull in a china shop when tightening bolts and forgo any GM procedure, you can easily stretch the bolt past its yield point. One way to know you've yielded a bolt is that it will tighten to a certain point but then the force required planes off. The fastener never gets tighter. Eventually if you keep tightening, the bolt may break. If you have ever seen a yielded bolt, the shank and/or threads (typically), will have an obvious reduced diameter.