chriswh86

New Alternator Pulley - Decoupling pulley

10 posts in this topic

Well, my Fortwo suffered from the dreaded alternator belt slip since I purchased it. I couldnt wait long listenening to it every time id fire the car up. I learnt early that a new pulley was tough to find and usually resulted in purchasing a new alternator. Really not practical when one small component needed to be swapped.

 

 I was tempted to make a new pulley on the Lathe but opted for a quicker alternative. I did some searching and came across a post made by @tolsen on the use of a decoupling pulley. I wasn't able to find the exact pulley used but after some more researching I was able to source a pulley from a 2000 Volvo S70 2.3L L5 Turbo. Below is the stock pulley

 

IMG_20190626_1643334.jpg

 

As you can see, the aluminum pulley is showing horrible signs of wear. Each tip has multiple grooves in it. I do like that its lightweight but its not made to last a long time and should be a readily available part at a good price but it is not.

 

IMG_20190626_1643195.jpg

 

And the new Volvo de-coupling pulley beside the old setup. You will notice the new pulley is a lot more involved. In simplest terms the pulley will engage/lock when on the throttle and the belt speed is higher than the current rpm of the alternator pulley. As soon as the belt speed decreases below the pulley rpms the pulley begins to free-wheel. This decreases load on the belt and, in turn, the engine and apparently it will reduce up-shift time. I did not time the upshifts before fixing the pulley but it might have increased slightly.

 

IMG_20190626_1805532.jpg

 

As noticed above the pulley wasn't a perfect fit out of the box. For one, its a 6 rib belt, not a huge deal as you can pick either the top 5 ribs or the bottom 5 ribs to use your belt on. The main concern is that none of the ribs lined up. I was able to easily press the inner race and shift it slightly to align the ribs perfectly.

 

IMG_20190626_1809373.jpg

 

Much better alignment. The photo shows it being off but from my measurements at the time it was perfect.

 

IMG_20190626_1815386.jpg

 

Beautiful new pulley installed and ready to go. I was lucky to grab this pulley off RockAuto for only 50 bucks Canadian! You'll notice it comes with a top cap or outer cap, this is to help protect the bearing.

 

IMG_20190626_1941401.jpg

 

And finally installed back in the car. I've been running this setup for a good few weeks now without issue. The belt is running great. Very happy with the results and the price of the pulley. Has anyone else ran a de-coupling pulley?

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I too have one here and will be installed when the engine goes back into the sub frame and back under the car....good to hear others are sourcing this pulley.  There is also another member who is waiting for one to be installed.

 

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@Willys @stickman007 Are you both going to be running de-coupling pulleys and what vehicles did you find them on? I wish I had of timed the up-shifts before swapping.

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Mine was the exact one Tolsen recommended.

It was mounted to many many vehicles in England/europe

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4 minutes ago, Willys said:

Mine was the exact one Tolsen recommended.

It was mounted to many many vehicles in England/europe

 

Ahh yah, here it was tough for me to find the exact one. But i was able to find measurements and one that was similar in the Volvo.

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Yes Volvo Peugeo, Fiat, Ford i think....The lists of common vehicles was long!   I had them sent to me from England.

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