ARP Flywheel Bolts

[PFM]

Does anyone here have any feedback positive or negative on the ARP flywheel bolts for Porsche?

I know I looked into them a few years back and they did not offer them in the early Porsche size, it looks like things have changed.

[jgparker]

I have the same question. I checked with ARP's tech support and they verified that they are non-stretch bolts and can be reused unlike the OEM flywheel bolts. 200,000 PSI and appear to be less expensive than the OEM bolts. I wish Pelican carried ARP, but they don't and I'm sure they have their reasons. Anyone tried them yet?

[Walt Fricke]

I'm a guy who is willing to live dangerously. I don't believe that the 12mm 6 bolt flywheel bolts are stretch bolts. Stretch bolts, to me, are defined as bolts which are tensioned beyond their elastic limit, but not past their plastic limit (i.e., their yield point). So when relaxed they are longer than they were to start with, but more importantly are, at least somewhere, thinner. And thus not as strong.

It makes sense that a bolt which has stretched more than an awfully small amount is not going to do as good a job if reused. Rod bolts will get a permanent stretch (because you can measure them easily and stretch instead of torque them when installing, you can accumulate data without making an experiment out of it).

Long ago I talked with a local mechanic, whose work was meticulous and who had an engineering degree. He said that for stock motors he just reused the flywheel bolts, and never had a problem.

When Bruce Anderson told me to torque my race motor's bolts to 150 lbs/ft (to stop shaking the flywheel off when shifting at 8,000 rpm), I wondered if I would be breaking bolts. Well, I never have had one give the feeling you get when you have overtorqued a fastener and can feel it yielding. Much less had one snap off.

Maryland Metric's chart rates these 12.9 bolts at about (from memory) 130 lbs/ft max torque. Which is rather more than what Porsche specifies (110).

Fact is, I have started reusing (once) these bolts from my race motor also, after accumulating a drawer of them from using new ones at rebuild time. So far with no ill effects.

So it makes sense to me that a bolt made out of stronger steel could certainly be reused in this application. ARP's engineers are going to know all about this stuff.

I didn't know that ARP made these bolts, so once again I've learned something useful here.

[YTNUKLR]

Walt, between you, Frank Barrett, and Grady, Colorado is home to some true 'old-school know-how'

And I just learned about the ARP bolts too. Sounds great, I will have to try them .

[tadd]

I'm in the market. Any more on the ARP stuff?

t