What length M8 bolts for IS gear?

[Baby]

For the 6-bolt gear, and where do you buy them? Mucho gracias.

[Walt Fricke]

The three IS setups I have are in engines, so I can't measure. And the parts manual doesn't show these as separate parts. Porsche anticipated that a worn out aluminum gear would be replaced with a whole IS, though the two chain wheels are separately available.

But why can't you just measure yours? You can buy them from anyone who sells M8 1.25 8.8 (I think those are the specs) bolts.

[Baby]

Thanks, Walt. The three that survived are too chewed up to measure (or to read the lettering on the heads). They all measure different lengths. It's clear that at least two of them have been ground down, but I'm not sure if the longest one has been ground down as well or how much.

[Walt Fricke]

Well, put your replacement gear in place and use the depth reader of your caliper to measure through the hole. They should be basically flush where they emerge from the IS flange, and I think a thin steel washer is in order. If you get bolts which are a bit too long, install them and grind off what sticks out before you put the chain gears back on.

Surely you have some 8mm bolts around you can use to verify that these are 1.25 pitch. Compared with other issues you may face while reassembling your engine, this ought not to be memorable when you are finally done.

[eastbay]

Just looked at an IS shaft on the shelf and my calibrated eyeball says 10mm thread length (not including the head)

[Baby]

Thanks, all. Good idea about checking the measurement. And the longest one I have (which still suffered some damage at the end), appears to be about 15mm including head--probably about 10mm without. Thanks again!