Crank Pulley Lightening

[Ferrino]

Out of curiosity, how much weight can be dropped off a 3.2 crank pulley by machining off the outer A/C pulley? Seems like a cheap way to shave perhaps 1 lb. of rotational mass?

[AskewRSR]

I bought a very light pulley from Dzug. I am very happy with it. Check out his site.

[911pcars]

Rothsport Racing also sells an aluminum crank pulley, available from our host or direct.

Sherwood

[Ferrino]

Thanks. I'm aware of the aftermarket items - was wondering if I could do a poor man's alternative :-)

[911pcars]

Originally Posted by Ferrino

Thanks. I'm aware of the aftermarket items - was wondering if I could do a poor man's alternative :-)

Depends on the cost to delete the unneeded second pulley section. A machine shop can estimate. Weigh cost vs benefit. The "poor man's alternative" might be more costly to produce. In addition, the modified factory pulley will still be heavier than an aluminum version (if that's a concern).

Sherwood

[G50911]

is there a noticeable diff when switching to a lightweight aluminum one?

[911pcars]

Originally Posted by G50911

is there a noticeable diff when switching to a lightweight aluminum one?

The engine is incrementally lighter. Seat of the pants comparison; aluminum single pulley is <1/2 weight of the factory steel double pulley. If weight is not an issue, then weigh the cost of machining the steel pulley vs. cost of aftermarket pulley.

Sherwood

[Jeff Jagusch]

IMHO, you would not be able to notice any difference
It's a small amount of weight and realatively small diameter

Jeff

[joefrantz]

I saved just about 1 full pound by switching from a double pulley to a single lightweight from Clewett.

Oddly enough, I've since picked up a used single factory pulley that is a couple of ounces lighter than the Clewett.

It would be a good idea to check around for used single pulley's in whatever size you need.

[911pcars]

Originally Posted by joefrantz

I saved just about 1 full pound by switching from a double pulley to a single lightweight from Clewett.

Oddly enough, I've since picked up a used single factory pulley that is a couple of ounces lighter than the Clewett.

It would be a good idea to check around for used single pulley's in whatever size you need.

Not sure how a steel single crank pulley can be lighter than a single al. crank pulley (assuming equal diameters).

If so, I'd say Clewett should delete the term, "lightweight" from their product description.

Sherwood

[joefrantz]

I checked my old weights on these and , in fact, I did have it backwards.
The Clewett is lighter that the factory single unit, but only by .85oz.

Factory double pulley - 30.9 oz.
Clewett Single - 15.8 oz.
Factory Single - 16.65 oz.

Still not a bad trade-off considering the Clewett cost $144 and the factory used one was about $30.

It would be interesting to see weights of other aftermarket brands if anyone has them.

Gratuitous Pictures:

It's not hard to see why the double pulley is so heavy.