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Discussion Starter #1
The theory of the underdrive pulley is simple. They underdrive or spin your engines accessories slower so as to free up some rotating mass from your engine. In most cases they are much lighter than the stock pulley.

Some of the more common underdrive pulley kits you will see out on the market are:

Esslinger
Ford racing
Focus central
Focussport
AFX
AEM

The ford racing and esslinger UDP’s are the same, they are made for Ford racing by esslinger.

The focus central UDP kit also includes a water pump pulley that is color matched and made of the same lighter weight aluminum.

The AFX UDP is said to be smaller than all the rest therefore underriving the accessories a bit more.

One is no better than another per se. The prices run in range from $ 89 - $ 125

If you have a question about one of these parts or another related exhaust part, feel free to PM me or e-mail me at [email protected]
 

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it is bigger to make up for the size of the smaller crank pully
 

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thanks captain obious! [:)~] j/k

im just sayin its probably not lighter as one would assume from readin that first post. just dont want anyone coming here thinking if they put on just the water pump pulley that they will make powerrrrrrrr
 

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Discussion Starter #5
No they will not make power with a water pump pulley, it is just functional so as to keep the stock belt.
 

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I just received my AFX UDP......what should I expect as far as my every day drivebility......Like: heating/cooling air, cd player and others?........am I going to sacrifice something compared to the OEM?......

It's late...I know it's a stupid question........

Peace........
 

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Discussion Starter #7
You shouldn't really sacrifice anything, I hvae had mine on for 35k miles and never had any issues with it.
 

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Cool.....I just installed it and I have couple questions:

  • The engine now seems to be doing kind of an up and down noise....which is probably due to the new pully but did you feel the same difference at first?.....compared to the OEM one....

    I had to change my idle with the screw because of the new lag...it seemed the engine was like "coughing" at idle......Is this ok too?

    Now, it seems that when I pull the car up to 4000 or 5000 rpm....and then shift gears......they're a sound of like something still spinning on the side where the udp is......That one normal too?
Since I left it to a professional wanted some feedback to see if everything was cool...........

Peace..........
 

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Discussion Starter #9
First off, did he shave the cover behind the crank pulley? The plastic cover needs to be shaved or it will rub.

If you unplug your battery there should be no idle change.

You should not touch the idle screw.
 

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Discussion Starter #11
Well that cover needs to be shaved or you will have problems very soon.

You can still go out and disconnect your battery.
 

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for one, its causing drag, eating up the belt....remove the bottom cover, when its off you will see like a half circle, that needs to be shaved for the cover to fit.
 

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Discussion Starter #14
When you take off the crank pulley there is a plastic cover that goes over the crankshaft. It needs to be removed and then the part that sticks out needs to be shaved down.

Didn't you get instructions?
 

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No sir......got the AFX udp and did not come with instructions.......so this is bad.....I gonna have to go to the shop again then........damn....

Thanks very much for the info........

Peace.........
 

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yeah u shouldnt be having any idle problems i have the afx and my car runs smooth and everything now, smoother than it did with the FC to be honest. sucks u ran into problems man keep us updated
 

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I haven't shaved the cover. I guess I better shave it. I've run for like 5k miles and the belt hasn't broken but I guess I better buy one. How much longer do you think the belt will last and how much do belts cost? I looked under there to see if anything would rub and it didn't seem like the cover was touching anything but I'll do it anyway.
 

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the cover may have been grinded away by the belt after all the rubbing. id take the belt off and check it out, wouldnt be a bad idea for a new one. im sure u can see on the cover when u take it off what the belt was rubbin on
 

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Yeah, I'll do that over the weekend. I'm glad the belt hasn't snapped or anything yet. I'll just go buy a gatorback but I don't know the size. Oh well, I'll just take the old belt in and try to compare by just looking.
 
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