Where does it say that OEM flywheel bolts are torque to yield (one-time use)?

amodoko · Feb 25, 2013

Just a general question, I'm not trying to debate anything at all, just figure out where some information comes from. I know on the forum, it is advised to never re-use OEM flywheel bolts because they are torque to yield (or one-time use). When ordering some parts for my car and talking to the parts guy at the Toyota dealership, I brought the topic up and he basically said the flywheel bolts are re-usable and they are not torque to yield. I don't take his opinion as fact, obviously parts guys and even the technicians don't know every detail about everything. So then I double checked the service manual, and it also doesn't say the flywheel bolts are torque to yield... implying they are reusable. So then I emailed Toyota (because I'm anal about details... kind of an obsession actually), and asked them whether flywheel bolts can be used again once removed. And this was the response to that question:

"Per the 2000 Celica GT-S repair manual the flywheel bolts may be used if they are in good condition. Please note: Toyota does not market bolts as "torque to yield"."

So I guess my question is, where did fellow Celica owners get the information that the flywheel bolts are one-time use only? Was it just from experience from the bolts breaking when reused? Or was it written somewhere? Or just a general suggestion since it is cheap insurance to buy new OEM flywheel bolts?

I am buying new bolts anyways, but was just wondering this stuff since I'm bored at work right now.

indianboy · Feb 26, 2013

I had to look deep also..........can't do a picture, but I just looked it up. There's a diamond next to the torque specs for the flywheel bolts on the clutch parts explosion. The legend actually says "non-reusable part"

Omnious · Feb 26, 2013

If you value the integrity of your transmission, don't risk it. Get the ARP for the 4A-GE. They are cheaper than OEM and stronger.

From MonkeyWrench:

monkeywrench said:
The stock bolts are torque to yield- you torque to a spec then another 90 degrees which permanently stretches (yields) the bolt. This makes it longer but also weaker. It does its job but if you remove it then try to reuse it it's already been stretched and weakened. That is why it's recommended that you do not reuse torque to yield bolts.

The ARP's have worked great in my experience. That is what we run at 750hp and 9500+ RPM and they stay put as they're supposed to. If any flywheel bolts, ARP or stock, come loose then there is a good chance they'll shear off from the shock loading.

The ARP's are stronger, reusable and are cheaper than stock bolts so I think they are a good value.

amodoko · Feb 26, 2013

That's weird indianboy. I remember looking at the parts diagram too and seeing that diamond, but my legend in my pdf manual was unclear (there was no diamond in the legend, but there was one on the diagram itself - an obvious misprint). Actually, the legend had the number "4" to designate "non-reusable part" while the actual parts diagram itself had a diamond in it (so basically, the "4" in the legend represented the diamond in the diagram... but the "4" in the legend was a misprint since it should have been printed as a diamond and not the number 4). It was definitely a misprint I believe which is why I couldn't find it in my manual. I had bought my pdf manual off of ebay several years back before it was on the internet for free, and I am guessing I had an earlier copy of the manual that had more typos/errors in it.

I just checked another pdf manual for the celica linked via newcelica, and found that it has been corrected in that version and you are right. That version does clearly indicate it is not a reusable part since the legend has a diamond in it, and a diamond in the corresponding diagram. Thank you for looking that up in your manual. If I had known there were other versions of the manual I would have downloaded more copies.

Okay, so that solves that. It is indicated in the newer manual that the flywheel bolts are not reusable. I will definitely be replacing my flywheel bolts with new ones. But I think I will buy the OEM ones this time (for peace of mind) instead of the ARP ones since it seems a few members on newcelica said the ARP ones were too long and actually caused the flywheel to get stuck. I'm assuming that is a rare occurrence, but nonetheless I want to try the OEM ones this time.

Anyways, thanks guys, much appreciated.

Smaay · Feb 26, 2013

the diamond indicates a one time use or replaceable part. but the give away that its torque to yield is that the factory torque of flywheel bolts is 36 lbs and then turn the bolt another 90 degrees. that extra 90 degrees is stretching the bolt therefore it will not have the same strength when re-used.

now with that said, I have gotten away with using them over again. i clean the old locktight off on a wire wheel and then use blue locktight. same torque settings and everything was fine. This was for a near stock application. If you are making big power, get the ARP bolts from MWR

amodoko · Feb 26, 2013

Awesome, great input and explanation, much appreciated

Where does it say that OEM flywheel bolts are torque to yield (one-time use)?

amodoko

indianboy

Omnious

amodoko

Smaay

amodoko

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