neffets

Did anyone ever replace the inner wheel on the crankwheel to a polybelt one?
I know clewett makes a serpentine belt kit, with a new crankwheel.
But since the 964 crankshaft needs a harmonic balancer I was thinking maybe if one were to replace only the inner part with a poly belt groove, and then bolt it to the harmonic balancer, which I guess is the left one with the rubber insert?

neffets

And is it possible to remove these wheels by removing the 10 bolts instead of the big one in the center?

jpar

I'm not sure about your first question, but yes the pullies comes off by removing the 10 bolts, no need to touch crank bolt.

Duck

I believe from another thread, the section with the rubber insert is for the AC only. It is to help dampen when the AC compressor kicks on.

robt964

^^^ that's what I too originally thought until corrected by people far more knowledgeable on a later thread

Duck

Sorry, Robt964 is correct.

https://rennlist.com/forums/964-foru...ft-pulley.html

Not sure where you would fine an inner polybelt pulley that would match with the outer one.

robt964

Thats interesting, so what exactly does the crank bolt fasten to the crank then? Looking at PET, there isn't even a mention of the smaller 10 bolts.

J richard

You have to remove the center crankshaft bolt to remove the lower pulley (harmonic balancer) there is a porsche tool or a DIY with a 16mm bolt and spacer. it is a one piece dampner that is internally rubber isolated and held together by the 10 bolts. If you take the bolts off and use a puller on the pulley you will pull it apart and distroy it, and then you still have to pull off the rest. Ok if you are replacing it, not so much if reusing.

It is there to balance the harmonics in the crankshaft due the the natural frequency of the engine. You may have issues with vibration that effects things like sensors and electronics if you go to a solid hub, which is common to do on race cars.

neffets

Looking at this picture I don't see why you need to remove the center bolt in order to get the pulleys off.
And if you remove the 10 bolts it should come apart as the first picture in this thread without destroying anything.







So to get back to the original topic, then if the harmonoic balancer is the left part in the first post, then it should't be a problem making a new inner pulley with polyrib threads, and still have the harmonic balancer in place?
Of course you need a new one for the fan, and a tensioner.

J richard

Doh! My bad, I thought you were trying to reuse the pulley sans the inner damper piece...

Yes I think you could graft a second pulley to the outside. The AC pulley is hub centric and nests in the outside pulley. There is a difference the height of the hub flange where the pulleys stack on the hub so you'd need to machine it larger or make a spacer for the bolts to clear. If you're thinking a V rib belt there's not much width in the lower pulley area to be had for a wider belt tho...