stripped flywheel threads

[96Turbo]

as i went to install my flywheel last night and was torquing down the pressure plate....i discovered that two of the threads are stripped out.

what are my options here? Could i rethread it myself? Or would this throw off the balance too much? Would it be close enough since i'd be taking a little material off, but using a bigger bolt?

Would i hafta have a machine shop to it and rebalance everything?

FYI, it's a Fidanza Aluminum flywheel.

[98s14inaz]

I would imagine all the bolts would have to be the same size and nearly same weight as not to throw off the balance. Probably going to have to do all of them unless you can helicoil or whatever the alternative is for steel.

[96Turbo]

i called up a machine shop and he said he'd put in helicoil inserts. he said there would be no need to rebalance. even though the inserts are steel. i would be inclined to trust the word of an engine builder, but i just wanna get some more opinions

[GSXRJJordan]

Helicoil is your best option, by far. Drill/tap for a bigger bolt (maybe the next SAE size up from your metric size) would work, but does introduce harmonics into the crank bearings, so I'd definitely helicoil first.

[96Turbo]

helicoil is just a threaded insert correct?? Seeing as how it would be steel vs. aluminum....wouldn't it introduce a slight imbalance?? or wouldn't it be significant

[GSXRJJordan]

Flywheel doesn't get hot enough for different expansion curves to matter, and the weight of the helicoil itself is insignificant. Do it, save that flywheel! :)

[96Turbo]

thanks man...i'm taking it in to the engine builder later today

[projectRDM]

Just have it balanced after whatever you decide to do. Done.

[Def]

Just have it balanced after whatever you decide to do. Done.

Word.

As for the question, yes, it'll be a few grams off due to the stainless steel insert vs. aluminum(which is crap when aluminum flywheel manuf. don't use helicoils). It's pretty far out there, so I'd worry about the balance.


All said and done, I'd probably just helicoil ALL of the PP bolts and not worry about the balance after that or stripping the threads out.

[96Turbo]

well i just got back from having it done. of course the guy didn't have any metric helicoils...so i think he used a 5/16" (whatever was closest to what was in there) and i got some matching bolts to use. I ended up having 3 of them done since another one of the threads looked questionable.

I asked him to balance it, but after putting in the inserts he checked it out and he said it didn't need to be balanced.

I would have liked to get them all done seeing as how easy it is to strip out those soft aluminum threads, but it would have been pretty expensive ($11.25 for each insert). I probably should have done that seeing as how i got the FW for only $200, but hopefully it will be good to go and won't cause any problems.

On to removing the pilot bushing!!!...

[babowc]

i stripped mine on the fidanza i had..
i just tapped it again and it worked fine.

[jinesz32]

i stripped my fidanza as well, i drilled it, and put new thread, works perfect.

[babowc]

yyeeah.. those threads are pretty damn soft

[WangonwWarrior]

Helicoil is your best option, by far. Drill/tap for a bigger bolt (maybe the next SAE size up from your metric size) would work, but does introduce harmonics into the crank bearings, so I'd definitely helicoil first.


+1 helicoil is much stronger too

[DJ_Sunrise]

I dunno.. i thought I fucked up threads before.. and just tapping them made them reusable. Go figure.

-Bart

[96Turbo]

well all's good with the flywheel now. got the clutch mounted, T.O. bearing, pilot bushing, and everything else replaced.

btw, grease method FTW for removing a pilot bushing

[adsmithy]

Had this issue myself with one of my threads. What torque are you guys using? I went to 35ft/lbs.

[WISH ONE]

OUch i had this happen to one of my cranks...

[babowc]

what?

we're talking about the ones on the flywheel where the pressure plate bolts to.. not the crank.

[96Turbo]

i also went to 35 ft lbs

oooooh...not the crank, that would be a much bigger problem

[gotta240]

I dunno.. i thought I fucked up threads before.. and just tapping them made them reusable. Go figure.

-Bart


It does make them reusable if its the same size.. Re-tapping with the same size is pointless...infact, thats just called cleaning the threads. These guys are fooling themselves if they think they can just re-tap and its good.

[gotta240]

well all's good with the flywheel now. got the clutch mounted, T.O. bearing, pilot bushing, and everything else replaced.

btw, grease method FTW for removing a pilot bushing


What is the grease method?

[babowc]

pack it with grease until it just comes out.

i personally thing slidehammer is alot easier..

[96Turbo]

pack it with grease until it just comes out.

but you then must force the grease to force out the bushing. by filling up the inside of the PB with grease, and using a tool (i used a backwards socket with an extension in it so the end was flat) to pound the grease into the crank.....the grease forces the bushing out.

it's just relying on hydrostatic properties to pop out the old bushing

pack it with grease until it just comes out.

i personally thing slidehammer is alot easier..

it's probably quicker and easier....but grease is a lot cheaper ;)

[gotta240]

Sweet. Thanks.