UDP Help

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expy916

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I have a 94 MTX and I have an ASP UDP. I already searched, but no definitive answers. What belts do I need?

4 rib 49 inch?
6 rib 44 inch?
 

expy916

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I found it at the jy. The alt and wp were gone. They might have been laying around, but I didnt look very hard.
 

expy916

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I dont think its the older design. The car looked like the owner knew what they were doing.
 

antz

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its still a 2 piece crank pulley its held in with a large c-clip, I wasnt to fond of it and opted to get rid of it and buy the sho source one.
 

shopartsnw

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its still a 2 piece crank pulley its held in with a large c-clip, I wasnt to fond of it and opted to get rid of it and buy the sho source one.

For what its worth, I also have two 2 piece crank pullies on my shelf with the large C-clip. Both were spinning and separated. Both have been replaced with our SHO Source UDPs for the same reason. If you have an old UDP crank pulley with the c-clip, check it well, as it is only a matter of time before it starts slipping. You might hear noise, or you might actually feel is slipping (almost feels like a momentary slip in the clutch).

Mike
 

expy916

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CIMG1663


Mike, could you please measure the two pullies to see if they are the same size, and if they are, could you please tell me the correct belt length for a 94 MTX?
 

gmorrell

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I just have the crank. Thanks anyway for the link.

Mike, could you please measure the two pullies to see if they are the same size, and if they are, could you please tell me the correct belt length for a 94 MTX?

Because you don't have the smaller alternator pulley that went with the ASP set, Mike may not be able to help you. Here's what I suggest, and what I do when I need a wacky serpentine belt length.

Go to the sewing store and get thee a cloth sewing tape. Take the existing belts off the engine and install your ASP crank pulley. Now, wrap the sewing tape around the pulleys for each belt path and measure the length, but you have to do it twice with the belt tensioner pulley at each extreme of its travel. Now you know the range of belt length you need; minimum and maximum length, and you'd like to get something in the middle of this range.

Serpentine belt part numbers are coded for length and number of ribs. For example, 445K6 is 44.5" long and has 6 ribs, sometimes this same belt will be 5060445. ('89 MTX SHO ALT/AC belt)

5040500 or 500K4 is a 50.0" long belt with 4 ribs. ('89 MTX SHO PS/WP belt)

The parts store counterman isn't going to be much help here, because they can only look up belt lengths for OEM applications. You're going to have to do some searching to see what belt lengths are close to what you need. Tell the counterman what you're up to, and ask if you can go back into the shelves, look at all their belts, and pick out something close to what you need.

I have one of the original ASP crank UDP's with the flat head screws and ring, and many years ago the outer and inner sections slipped out of phase, and I stopped using it. Frankly, the "newer" ASP pulley with the large internal snap ring will eventually do the same thing, and might even separate like the pics shown earlier in the thread. As much as I don't personally care for solid (non-dampened) crank pulleys, if you just must have one, the SHOSource UDP crank pulley is the best thing going.
 
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shopartsnw

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Use Gary's technique for measuring the belt (thanks Gary)

Do be aware that your UDP is the same type I have on the shelf (quantity 2) that have failed by slipping the inner and outer portions of the UDP. I personally do not recommend you use that UDP, as it is probably just a matter of time before it too starts slipping.

Just my $.02

Mike
 

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