pulley replacement

[shopo27]

I want to change to a smaller head pulley for my sn93, How is this done? Any special tools needed? Thank you

[Michael]

There's generally no special tools needed to remove the pulley from the head unit. However, that depends on the type of pulley.

Generally, most SN superchargers came with pulley held in place with a single bolt/washer that threads into the end of the input shaft. Loosening this bolt should be all that's required to remove the pulley. However, these pulleys also use a key (be careful not to lose that) so a pulley puller may also be required.

The SN89 I have came with a morris taper style pulley. Fairly rare - I've only seen them on kits sold/installed by Blowerworks. You can identify this type of pulley as it doesn't have a large hexagonal bolt head on the end, instead it just has a flat face. This type of pulley uses three pieces of metal inside the pulley itself which are held in place by three small socket head cap screws. Tightening these screws causes the pieces of metal to simultaneously tighten against the input shaft and the pulley. The clamping force is incredible! So much so that loosening the socket head cap screws won't loosen the pulley from the blower's input shaft. There are three different holes in the pulley into which you thread the socket head cap screws which push the pieces of metal out of the pulley and releasing their grip on the input shaft.

If you look in my photo album on the site here, you'll see photos of this morris-taper style pulley.

Hope that helps.