H.F.B.

I'd like to upgrade my 944/968 altenator pulley to a freewheel alternator pulley (OAP or OAD).
http://www.eurekamagazine.co.uk/desi...-engine/39568/

Does anyone know, which one is PnP on a 944/968 alternator?
TIA

marc abrams

Looks like something that would have minimal benefit and prone to failure much like the dual mass clutch. Not worth the effort IMO.

H.F.B.

It's certainly a wear part, but I like the idea. Apart from that, meanwhile I don't drive my 944 and 968 that much, that I will need many pulleys in the foreseeable future.
But at first I have to find a suitable.

odonnell

I have a pulley from my 951's alternator sitting around. I can take measurements if that would be helpful.

V2Rocket

Think I've heard of people putting a simple switch on the field wire to deactivate the alternator and make it like a freewheeling pulley.

no real hardware changes required.

that said a 944 alternator at 100% output might consume 1.5hp (115 amp @ 14 volts, 80% efficiency)

H.F.B.

I doubt that the switch will decouple the alternator mass from the accessory drive.
Contrary to a rigid wheel the overrunning alternator pulley opens in overhauling direction. In addition, the overrunning alternator pulley decouples the alternator's inertial torque during a significant engine speed deceleration such as changing gears. The engine doesn't have to accelerate/deccelarate the alternator after the gear change. I like this idea.
Imagine a drag race, just rev up and let the clutch go, no need to accelerate the alternator again, when you shift up.

H.F.B.

This freewheel pulley will fit:

A simple Volkswagen/Audi/Skoda alternator freewheel pulley

V2Rocket

re-read the link, so basically it only engages the alternator under fairly steady-state conditions (cruising) rather than acceleration?

H.F.B.

The crankshaft does never rotate at the same speed (rotational irregularities). So the OAP allows the alternator to freewheel when the belt speed (crankshaft speed) drops. It only transfers the accelerating proportion of the crankshaft forces to the alternator.

Nathan J.

H.F.B.

Thanks for introducing this topic. I love the idea of upgrading my car to newer technology, and it seems that there are some nice benefits to using a more advanced pulley like this. You mentioned a part number in a later post, 234569, I can see in PET catalogs for 944 that there are two Porsche part numbers listed overt the years for 944 pulleys:

Early
944 603 121 06
Late
944 603 021 01

Do you happen to know whether the 234569 part number matches one or both of these Porsche part numbers? I am actually interested in a replacement for the pulley on my 968, which is yet a third part number ( 928 603 021 01) so I am most interested in finding out if there is a freewheeling pulley that will be a match for this part number.

Thanks and Best Regards

Nathan

V2Rocket

very interesting.
could you direct me to the catalog where you found that pulley pictured above, i would like to see if there is possibly a v-belt option of this technology available (doubtful, but worth a look).

H.F.B.

Here you go --> heavy 127MB PDF-file or go to https://hc-cargo.co.uk/downloads then navigate to HC-Cargo Catalogues and HC-Cargo Starter & Alternators or HC-Cargo Alternator Components.
There is much more interesting stuff to find.

Ish_944

Very interesting indeed.

So do we know which 944 model years this pulley will fit? I'd be interested in one for an early car.
Approximate price?

Edit: Found the price to be around 50 euros!

H.F.B.

The 234569 is the same as the very common LUK or INA 535006010 pulley
Above is what I got today and it fits on my 968 alternator nicely.

It won't fit on an early alternator. The early pulley got 5 grooves and Dim./1.goove is 7.00mm. So I think for an early alternator the pulley with the Cargo #230304 could fit. But I don't really know. -->Here is a reference list

MAGK944