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TR2/3/3A TR-3A Ring Gear Bolts

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Tinkerman

Tinkerman

Darth Vader
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I'm replacing my ring gear and after pulling the bolts and checking them over I decided new ones would be in order. I odered some from Moss, not even close. HOWEVER I just found a Fastinall shop here my small town in the boonies of Central TN. Yea! went there and bought some grade 8 bolts of the proper size but they do not have a shoulder, they are threaded the full tength. The ones that came off the flywheel have an 11/16" shoulder. Is this going to be a problem or can I use them as is? Is the shoulder there for a reason?
Any comments would be greatly appreciated.
Thanks, Tinkerman
 
Do not know for sure. IMO - If the bolt has a shoulder then a shouldered bolt should be replaced. I think you would be using a bolt with less potential strength in relation to the spin of the flywheel if it is threaded all the way to the head. Ok, come on you bolt experts out there tell me why I'm wrong.
 
You absolutely need the shoulder on those ring gear bolts.

They are designed to be loaded in shear as the pinion tries to spin the ring gear it will cause the ring gear to shift slightly and put those bolts into shear. Without the full daimter shoulder they will see that shear loading in the threads and sooner or later fail by fatigue in the threads right where they come out of the carrier.
There is reason for those bolts to have a shoulder. Ring gear bolts and flywheel bolts are a couple of the toughest applications out there from a fastening standpoint. This is what I do for a living (design bolted joints and other threaded assemblies) and I would never think of using a full thread bolt in that application.
One thing that might work is to see if you can find longer bolts that are only threaded part way and try to match up the length of the shoulder. Then you can cut off the extra thread length using a cut-off wheel. One thing to remember is that trying to cut off grade 8 (or higher) bolts with a hacksaw is a good way to go crazy. They are too hard to cut without ruining blades in a real hurry. If you have to cut them, use a cut-off wheel and then grinder to create a smooth end a chamfer on the end.
 
Thanks to both of you for the info. I kind of figured that the shoulder was there for the purpose that you described. Of have some on order from a vendor, but of course they are back ordered. So I will use the ones I have and go ahead with the assembly. I will change them out when the right ones come in.
Regards, Tinkerman
 
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