Alternator Clutch

[Uncle Krusty]

Here's a link explaining why an alternator clutch-decoupler is used and how to replace one on a non-Jeep, and what they look like.

http://www.renntech.org/forums/index.php?showtopic=22520&hl=pulley

Ok, so the "free wheeling" alt clutch is used by Porsche on the manual transmission models only. I can see that manual up/down shifting could put more drastic rev changes on the drive belts than your typical "slush box" would.

I'd have to go look, but I think my '06 automatic has a direct drive pulley as well. I just changed belt & idler pulleys, and don't remember anything "funky" about the alternator.

 

[kb0nly]

Ok, so the "free wheeling" alt clutch is used by Porsche on the manual transmission models only. I can see that manual up/down shifting could put more drastic rev changes on the drive belts than your typical "slush box" would.

I'd have to go look, but I think my '06 automatic has a direct drive pulley as well. I just changed belt & idler pulleys, and don't remember anything "funky" about the alternator.

It looks like mainly the CRD KJ had the special alternator pulley...

 

[Powerslave]

I have an 06, it is direct drive, you can see it RIGHT THERE in the engine bay...

The DIESEL model, the CRD, had them. Dunno why certain persons want to insist that 3 or 4 million other liberties have them, they don't. Maybe 3-4 million diesel models, but are there THAT many?

I would install one on this jeep, if it frees up some more HP when throttling, since it Is clutched? You do lose HP turning accessories, that would be nice for a little more HP to the wheels with a clutched pulley.

 

[kb0nly]

I have an 06, it is direct drive, you can see it RIGHT THERE in the engine bay...

The DIESEL model, the CRD, had them. Dunno why certain persons want to insist that 3 or 4 million other liberties have them, they don't. Maybe 3-4 million diesel models, but are there THAT many?

I would install one on this jeep, if it frees up some more HP when throttling, since it Is clutched? You do lose HP turning accessories, that would be nice for a little more HP to the wheels with a clutched pulley.

It's not really a clutch, its a one way bearing, so it wouldn't help to free up horsepower.

It just lets the alternator spin faster than the belt or freewheel when the engine drops speed when you take your foot off the gas or shut the engine off.

I have seen this on large diesel engines on the farm, i didn't know they did it on passenger vehicles running a diesel engine as well but it makes sense. I know on the John Deere's i ran if you shut off the engine you could see the alternator continue to spin down after the belt stops, rather than being brought to an abrupt stop with the belt. If that helps explain it any better. But as long as the engine speed is equal to or faster than the alternator's spinning speed then its pulling it along anyway, so not like a clutch and it won't help eliminate accessories drag.

Think of a pull starter on a lawn mower, similar concept although its done with a different mechanism rather than a bearing, pull on the rope and the shaft will spin, but if you stop pulling on the rope the shaft can still continue to spin. Same thing with these alternators.

 

[Powerslave]

Sure, but that other one, the decoupler:

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Would be neat if it were like a centripetal (centrifugal) clutch, like a clutched fan, to allow the accessory pulleys to "catch up" so the wheels can get the Max HP when stomping on the gas. Might be easier than an under-drive crank pulley, and keeps everything at the same revolutions once they catch up.

 

[ThunderbirdJunkie]

That wouldn't make sense. Engine spends more time at a steady speed or accelerating than it does slowing down.

At any rate...it was 3-4 million CHRYSLER vehicles ThunderbirdJunkie said, including KJs, not JUST Libertys.

And another aside, it's not all 05+ Libertys...but the vast majority of non-performance-oriented 04-on Mopars have the "decoupler" after a little research. Sorry 'bout that