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Discussion Starter #1
I just did the TSB 98-23-14 dual tensioner mod on my truck. However, I used Gates parts instead of Motorcraft:
  • 38191 Dual Tensioner
  • K081223HD Belt (8 ribs, 122 3/8" long)
  • 38022 Smooth Idler Pulley (not part of the mod, but it needed to be replaced)
After putting everything together, I found that the belt was considerably too short. After threading the belt, I couldn't get it closer than about 5/8" from going around the smooth idler pulley on top.

So I headed to my Ford dealer and bought (for $95!!!) the Motorcraft JK81227 belt -- half an inch longer at 122 7/8" -- but I still can't get it on.

I can think of two possibilities
  • I've heard about Motorcraft belt length inconsistency. Maybe I got a short one, and if I exchanged it for another, it would be long enough.
  • Perhaps the Gates tensioner isn't exactly a match of the Ford part. With this tight of a fit, it wouldn't take much variation to go from a fit to not-fit.
I see in the TSB that Ford calls for an "8 PVKx3132mm" belt. Since there are 25.4mm/inch, this would be 123.31" belt. Rounding the the nearest 1/8", it would be 123 3/8", half an inch longer yet than the Motorcraft JK81227 belt I bought. I think I could make this belt work, but apparently it's no longer available. The next bigger size belt I could find that is actually on the market is a Goodyear Gatorback 4081252, which is 125 2/8" long. This is 1 7/8" longer than the 123 3/8" belt called for in the TSB, which is the smallest belt I think I could make fit. I think the tensioner could probably take up that much slack, but I'd have to try it to be sure. This belt isn't available locally; I would have to order it, wait a week to get it, and then deal with hassle & shipping expense to return it. Since my truck is not my daily driver anymore, this is possible. There is also a Dayco 5081254 at 125 4/8", but that's even longer, and it's also special order.

So I see three options:
  1. Order the longer Gatorback 4081252 belt and try it out.
  2. Buy a genuine Motorcraft tensioner and compare it to the Gates. If they are different, install the Motorcraft tensioner and see if that works with the Motorcraft belt.
  3. See if I can find a smaller smooth idler pulley.
Any words of wisdom?
 

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Discussion Starter #3
That's a good link, Billy. Thanks!

The summary of that thread is
  • Try a different Motorcraft JK81227 belt; 1 in 5 is too short
  • Install a SD water pump pulley, which is slightly smaller than the OBS one
  • Install a smaller alternator pulley, but some were worried that the smaller pulley could overspeed the alternator
Also, the OP on that thread was concerned that, even though he got a belt to fit, the tensioner is up against the stop and unable to float on the tensioner spring. I'm also concerned about that, as well.

I'd still love to hear if anyone has tried the Goodyear or Dayco 125" belts.
 

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Discussion Starter #5
Since nobody has tried the 125" belts yet, I'll put my money on the line and order one. I'll post results when I get the belt (probably about a week).
 

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Discussion Starter #7
I would return the Motorcraft belt and try another one.
Yes, that's probably the most expedient answer. But I'm still concerned that the tensioner would be on the stop and not "floating" on the spring, even if I can get a Motorcraft belt that fits. I could also play around with pulley sizes and probably get the float I want.

But I'm curious whether the 125" belt will work or not, and I don't mind donating $40 (the cost of the Goodyear belt on Amazon) to the cause, if need be. I also don't need my truck running in the next week. So I'll try it and have some fun with it. Besides, the Motorcraft belt was $95 at the stealer, whereas all the other belts I've looked at are in the $35-45 range online. I can get a Motorcraft belt for that price online as well, but if I get another short one, I would have to ship it back rather than return it locally.
 

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The dealer charged you full retail on that belt. Rock Auto sells that belt for $42.xx.

If a place charges me retail on anything, they can keep the part and will loose the sale. There are plenty of other places that want to make a sale.

The tensioner has gauge/window on it showing the tension/belt stretch.

Billy T.
[email protected]
 

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Discussion Starter #9
Yes, I only paid retail because I wanted to try that belt Saturday with the ability to return it easily if I wanted to. You live in a huge metro area -- I bet you can buy the belt locally at the discount price. In Colorado Springs, there's only one Ford dealer (with two locations), so they can charge whatever they want.
 

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Hey, Dan is all I have to add.
 

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Yes, I only paid retail because I wanted to try that belt Saturday with the ability to return it easily if I wanted to. You live in a huge metro area -- I bet you can buy the belt locally at the discount price. In Colorado Springs, there's only one Ford dealer (with two locations), so they can charge whatever they want.
In that situation I get the lower price off line from another ford dealer, print it out and ask them for the lower price. It's worked more then once for me.
 

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Discussion Starter #12

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One poster found that only one pulley would pivot on his aftermarket dual pulley tensioner and the JK-1227 belt was way too tight along with several other brands of belts. (This problem also occured for several other posters).

Finally talked him into buying a genuine Motorcraft BT-50 with both pulleys pivoting and that cured his problem using the JK-1227 Motorcraft belt. In the catalog pictures the Motorcraft and aftermarket dual tensioners appear the same but only the Motorcraft has both pulleys pivoting.

The Ford dual pulley tensioners also work correctly (Van F8UZ-6B209-CA or SD F8TZ-6B209-BA) with the JK-1227 belt. I have used all three part number dual pulley tensioners; they are identical.

One key to identifying the bad aftermarket tensioners may be that some would fit WITHOUT notching the alternator bracket for tensioner housing clearance. The BT-50 housing has a bulge on the housing that needs the notch to fit into the bracket and so do the Fords.

The Motorcraft belt and dual tensioner are way cheaper online at http://Rockauto.com and sponsors like Sunrise Ford. $77 for the tensioner at Rockauto and you can get a 5% discount code from http://Retailmenot.com

So, the JK-1227 works if you use the Motorcraft BT-50 dual pulley tensioner and not with some aftermarket tensioners. Have no idea if all aftermarket tensioners are the same but its not worth taking the chance.

Dual Pulley Tensioners:
Motorcraft BT-50
Ford Van F8UZ-6B209-CA
Ford SD F8TZ-6B209-BA

Motorcraft Belt JK-1227 1227/8"
Goodyear PolyGator 4081223 122"
Goodyear PolyGator 4081223F 122"

Belt routing decal F8UZ-8B656-AB
 

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Discussion Starter #14
Thanks, Dave -- that's really good info. I trust Gates belts, but I guess their non-rubber parts are not so good. I did notice that only one pulley swivels, and that the notch on the webbing seemed unnecessary.

I will order a genuine BT-50 this evening.
 

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Forgot to say you enter the discount code in the "How did you hear about us" box at checkout.

The dual tensioner is off of a 1999-2003 7.3 and at Rockauto is listed under "belt drive"or enter the part number in the part number search.
 

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Discussion Starter #16
Thanks, Dave -- I found it. Goodyear belt should arrive Fri or Sat; tensioner should arrive early next week.
 

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Discussion Starter #17
OK, solution #1 (Gates tensioner, Goodyear Gatorback 4081252 125 2/8" belt, stock pulleys) does work, but only just. After installing the belt and running the engine for a few minutes, the tensioner is about 1/4" off the "loose" stop. Here's what I mean: the pivoting part of the tensioner has a metal part that limits the motion between two stops on the fixed part of the tensioner. So there's about a 1/4" gap between the stop part on the pivot and the fixed "loose" stop.

This might work for a while, but I'm concerned that over time, belt stretch might allow the tensioner to open to the point where it's riding on the loose stop, reducing tension on the belt. I think before I would be happy with this solution, I'd try to find a larger idler pulley or something that would take up some more belt slack.

Looks like my Motorcraft BT-50 tensioner won't be here until Tuesday. I'll post again after I try it out.
 

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old man dave tells my story perfectly as I was the one he help! Thanks Dave!

Get the part numbers gnxtc2 lists and you will be good. Don't let the parts store tell you theirs is an equivalent...it most likely is not.
 
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