damaged threads in flywheel
 

Hi all,

Putting my engine back together and it's gone astray. I was torquing down the bolts that attach the pressure plate to my Supermiata flywheel with a 1/2in torque wrench and I screwed up and took some thread material out. This is an expensive flywheel that's on backorder, so I'd like to repair it. Usually I'd toss a helicoil in there but I'm concerned it might throw off the harmonics of the flywheel and cause damage to the crank and mains. Are my worries substantiated or will an extra ounce or two not do anything?

When installing a helicoil you remove material and replace it with the insert. Ounces, I think you mean grams or .002oz. Maybe you should have been using a 3/8 drive torque wrench. I believe the pressure plate fasteners torque specs are 13-19ft-lbs.

Is there enough material to tap the holes deeper and use longer screws? I recently had to do this on the aluminum flywheel I use in my car.

I wouldn't worry about helicoiling only one, but if you're worried about it just helicoils all of them.

For balance do two, one opposite the other.

Properly installed Heli coil will work. Timesert is stronger and a better option for high torque and vibration.
Balance is not a problem as your removing then adding pretty much same amount of material.
Get a different torque wrench.
Ask the 949 guys what they recommend.

seems my reply a few days ago never made it through

I ordered a helicoil style thread repair set, should be here tomorrow. Definitely going to use my 3/8s or even 1/4 inch next time. Live and learn.

The repair kit I got is a pretty cheap helical style. Highking brand. Hopefully it holds up. Timesert for M8 x 1.0 is nearly $100!

Timeserts are honestly way over rated. I install helicoils on power plant steam turbines and they see built stretch loads of over 50,000 psi and run over 700° f. Quality helicoils are stronger than the oversized threads they get inserted in to.