Clutched alternator pulley

[dremd]

A4 CLUTCHED ALTERNATOR PULLEY $62 SHIPPED - Parts for all water cooled VW cars specializing in TDI models

dont know anything about it; but WOW.

[Frank Lee]

I didn't know there was such a beast!

My replacement Alternator is fitted with a standard pulley, where the original had a clutch pulley.

The Clutch Alternator Pulley was pioneered by Audi, BMW, Mercedes, Seat and Volkswagen.

The idea of which was to reduce possibility of sudden snatch when coming down from high revs such as motorway driving to a standing stop thus prolonging the life of expensive automatic tensioners.

Unfortunately the pulley design was such that they failed after a relatively short period of time and that they are a costly service item.

QX Components has looked into the fitment of these pulleys in great detail and we now fit a standard non clutch correctly spaced pulley in place of the prone for failing clutch pulley.

This is of no detriment to the performance of the unit and if anything extends the life of a regularly replaced OE item.

http://www.qxcomponents.co.uk/tech.pdf

Sounds like it's a pile of poo.

[dremd]

does sound that way.

My main question is what actuates the clutch?

[Frank Lee]

It's a simple over-running clutch- freewheels in one direction, takes load in the other. Functions like the freewheel on a bicycle, but I'll make no comment on how this thing is put together. No external controls.

BTW I don't know WHAT they're talking about re: "The idea of which was to reduce possibility of sudden snatch when coming down from high revs such as motorway driving to a standing stop thus prolonging the life of expensive automatic tensioners."

The tensioners is what they're worried about? Automatic tensioners are just spring loaded idler pulleys right? (Unless VW has concocted some sort of dumb*** expensive high-tech version for something simple and cheap ) The tensioners I've priced in the past are cheaper than this clutch thingie.

[greasemonkee]

When shifting at 9000 rpm to the next gear and dumping the clutch there is extreme deceleration taking place?


how much parasitic drag could a freewheeling alternator possibly be in the first place if the stator and rotor loads are cut?

[me and my metro]

My daughter's Caravan has a clutch on it's alternator. I think it is easier on the belt and on the armature when you shut the engine off. It also makes a replacement alternator quite expensive.

[bgd73]

sounds backwards to me. coming down is off the throttle, ride that energy for all its worth. Ahh, VW. the people that helped kill the boxer engine. Those silly kid engineers with crayons.

I still can't get over the sideways engine smashing my face off.

[RobertSmalls]

These clutched alternators show up on lots of Chyrsler products. I was disappointed to learn it's not a fuel economy device at all.

I googled it and got this:

Originally Posted by FSM

GENERATOR DECOUPLER PULLEY
DESCRIPTION
The Generator Decoupler is a one way clutch (Fig.
3). It is attached to the generator and replaces the
standard pulley. It is a non-serviceable item and is to
be replaced as an assembly. It is a dry operation (no
grease or lubricants). The operation of it is not temperature
sensitive and has a low sensitivity to electrical
load.
OPERATION
The generator decoupler is a one way clutch and
should be replaced as an assembly. It is designed to
help reduce belt tension fluctuation, reduce fatigue
loads, improve belt life, reduce hubloads on components,
and reduce noise.

[erice1984]

they pioneered these clutched alternator pulleys to reduce the load ont eh crankshaft because they had problems with crankshaft pulley bolts working loose and creating "wobble" and then getting out of time enough to grenade the engine.

Basically the rotational torques and engine decelerating faster than the alternator caused bad stuff to happen. Go physics.

[Frank Lee]

My stuff seems to be doing fine w/o it...