Are Heli Coils safe in a Flywheel???

I have seen some marons who taped a 5/16-18 hole to install a 1/4-20 Helio-Coil and didn't understand what went wrong. Maybe that happens more than I thought

 

Well, that would be too logical perhaps - if he was building a race car, but since he isn't that isn't even warranted either. Regardless, if he was, check comment #7, covered.

 

No, but it'll make your obdula oblongata hairy... And you'll go blind.... And to Hell...

 

Kinda reminds me of a budget meeting I went to once. The 10Gs for office supplies was debated for an hour and a half. The 3 mill for various acquisitions was approved in less than 2 minutes. Everybody knows about 10g but 3 mill is kind of a nebulous figure that nobody is sure what it is. Same thing with Helicoils.

 

Psssst! P*** it on to your fellow "Jet Doc", OK?

 

the debate over helicoils versus solid metal inserts is being played out on every auto, truck, motorcycle, aircraft, marine and industrial board online as we speak, its not going to stop any time soon.

 

if you want run a grade 8 bolt a quarter inch longer and nut it/lock***e it. i would do it on mine but maybe not for a friend or one of my childrens' cars. merry Christmas

 

Proper OEM and ARP pressure plate bolts have a little step between the head and the threads. This step fits snugly into the bolt hole in the clutch cover. If you look at the flywheel there is a small counterbore before the threads start. All of this is to keep the clutch cover from shifting around as it can with hardware store "Thread to Head" bolts. To install a pressure plate properly you should invest in "Pressure Plate Bolts"

 

I just skimmed over some of the replys and may have missed one, but how many cast flwheels are out there? How many of us have NDT inspected them before installation? What about the re-surfaced ones, were they done correctly?

It just seems like a lot of nay sayers on helicoils, I use them, but there are many other things to be concerned about when it comes to flywheels.

 

Wow,I read all 7 pages and in the end it was mentioned that pressure plate bolts are unique shouldersd bolts.
Helicoil,new arp hardware,and breakout the torque wrench,you will be better than new.
As mentioned earlier in the post,This board IS full of pros of all types.
A great place for information,and some amu*****t from time to time also.

 

Ditto! Bad feedback!!!!

 

Part of what I was trying to say ,but guess it came out wrong,,anyway I'm headed to Wawa,,anybody need coffee

 

as long as the coffe pot aint been heli-coiled could be bad and generate another 7 pages off pros n cons
Ken

 

I agree that heli-coils are perfectly fine and yes, I to used them on aircraft while in the Air Force. I think that point is moot at this time. I just wanted to respond to the why did they helicoil all of the holes. I think it was probably to try and maintain balance. I can't speak for anyone else, but I have no idea what the weight difference would be between two grades or alloys of steel. I am sure it would be very minimal for the amount of material removed, but with the centrifugal force applied at the outer rim of a flywheel at even a modest 2,5000 rpm I for one would heli-coil every damn hole to make sure things were close.

 

Spent 24 years in an airline maintenance base machine shop, and 16 years prior to that in other machine shops. Plus wrenching on cars, trucks, hot rods, and race cars since about '53. Heli coils were and stlii are a good, safe repair on damaged threads. If the FAA authorized repair on critical parts on commercial airliners flying at 35.000 -45,000 ft al***ude carrying a couple hundred people includes heli coil use, then as far as I'm concerned, they are a safe repair. We even had "twinserts" for holes that were too far gone for a conventional heli coil. You first installed a large heli coil and then installed the regular one inside it. This allowed going to a larger diameter hole and stlll use the same bolt size.
IIRC, some aftermarket aluminum flywheels actually came from the factory with heli coils already installed to make the hole more durable. I think this whole thread is "much ado about nothing".
Dave

 

The quality of the bolts you use is probably way more important than whether the holes were helicoiled or not.

I bet a pro installed them just to have a more durable thread for some application where they have to ***emble/dis***emble it over and over. It just doesn't seem likely that someone would replace all six of them unless it was for a good reason.

If you use it though, you should probably have it magnefluxed and buy some new correct bolts with the same type of shoulder and torque it to specs carefully.

 

The truly safe alterntative would be to ditch the flywheel alltogether... flywheels and flexplates are dangerous by their very nature, and should not be used....