Mag powers belt shredded

Tony8470

Registered User
Anyone else have these problems? I got the new dayco steel pulley 89016, and clocked the tensioner to add pressure to the belt.

I saw 2 ribs of the belt were off the idler pulley when I first installed everything, but I didn't think they would shred off in less than 10 miles. The belt is rubbing against itself now too.
 

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Anyone else have these problems? I got the new dayco steel pulley 89016, and clocked the tensioner to add pressure to the belt.

I saw 2 ribs of the belt were off the idler pulley when I first installed everything, but I didn't think they would shred off in less than 10 miles. The belt is rubbing against itself now too.

I think I read something about having to cut two of the ribs down on the belt.
 
It's not the belt so much as it is the pulley. You must have 10% or more blower pulley on there, right? You are going to have to create a longer path for the belt. Raising the blower is the easiest thing to do. If you have an aftermarket hood, I'd raise the blower 1/4-1/2" up. You'll have to raise the return plenum too. You'll need a spacer for that. You have to find a way to achieve at least 3/4" gap between the belt. Of course, that belt might be damaged/stretched too. I'm thinking it may have jammed against itself and that caused several other random bad things to happen.
 
The belt is whatever came with the pulley set. I don't have the part number near me but I want to say 20400. It was originally 12 ribs, I cut 2 off. Now it's more of an 8 rib after the others tore off.

The pulleys are the 20% set that Charles offers. I really think the idler pulley is too skinny. Those 10 miles I punched it pretty good, and I'll bet the 2 ribs that were not contained by the pulley just sheared off. I'll have to find a different idler that is wider.

I read a thread about the various belt sizes available and I believe this is the shortest one of the 12 rib variety. I'll have to see if I can find it.

I'm going to call around and see if there is a way to get a smaller custom belt made. My hood is stock height. And if I put my cervinis hood on then I'll have to get it painted. Which isn't ideal for me right now, as the paint job I want will be $$$.
 
Well, you can't get a shorter belt, so forget that idea. Custom isn't an option either.

I'm not sure what exact language Charles uses to sell the 20% kit, but the fact is there is no belt that will fit. You will have to make accommodations.

One possibility would be to get two stock belts and cut them both down to 5 ribs, then run them together. That's what they did in the olden days. ;)
 
[QUOTE

One possibility would be to get two stock belts and cut them both down to 5 ribs, then run them together. That's what they did in the olden days. ;)[/QUOTE]

That is not a good idea at all an 8 rib will still work better than two 5. It doest take a lot of shim to "make the belt shorter" . I think shimming up the blower is a better way
 
[QUOTE

One possibility would be to get two stock belts and cut them both down to 5 ribs, then run them together. That's what they did in the olden days. ;)

That is not a good idea at all an 8 rib will still work better than two 5. It doest take a lot of shim to "make the belt shorter" . I think shimming up the blower is a better way[/QUOTE]

I kind of like that idea. What's wrong with that option Kevin? I never had much belt dust in the engine bay when I was running 15% 8-rib. Actually none at all. So I have little reason to believe that the extra 2 ribs will have enough significance.
 
That is not a good idea at all an 8 rib will still work better than two 5. It doest take a lot of shim to "make the belt shorter" . I think shimming up the blower is a better way

I kind of like that idea. What's wrong with that option Kevin? I never had much belt dust in the engine bay when I was running 15% 8-rib. Actually none at all. So I have little reason to believe that the extra 2 ribs will have enough significance.[/QUOTE]

Both belts are not going to be identical. So basically one 5 will be doing the work. While the other will be just be riding along. . All I am saying is that 2 5 ribs will cause more belt slip than an 8 rib. If you don't want to raise the blower you could move the bracket that holds the jackshaft down and to the right a little. There is a bunch of play to begin with. Maybe just loosening the bolts and try getting as much movement as possible.

Back to the 2 five ribs. Even at idle they start to move in relation to each other.
 
I had a similar setup to yours, though I had the 5% jackshaft, I would like to know the diameter of your jackshaft pulley on the blower belt side. I never had an issue that required me to raise my blower, it was an mpx. As for your tensioner pulley concern, my pulley was too skinney for that belt also but mine road in the center of the belt, where yourse seems to ride the edge hard. Make sure your tensioner isn't separating away from the mounting bracket. I still have the factory tensioner pulley also, maybe that makes a difference also.

Chris
 
[QUOTE

One possibility would be to get two stock belts and cut them both down to 5 ribs, then run them together. That's what they did in the olden days. ;)

That is not a good idea at all an 8 rib will still work better than two 5. It doest take a lot of shim to "make the belt shorter" . I think shimming up the blower is a better way[/QUOTE]

I just want to make sure I am following this thread properly. You really aren't making the belt shorter by elevating the SC. You are making the path that the belt travels longer as Dave suggested, correct?
 
That is not a good idea at all an 8 rib will still work better than two 5. It doest take a lot of shim to "make the belt shorter" . I think shimming up the blower is a better way

I just want to make sure I am following this thread properly. You really aren't making the belt shorter by elevating the SC. You are making the path that the belt travels longer as Dave suggested, correct?[/QUOTE]

Yes. There is no way to make a belt shorter!
 
I found the part number of the belt. 25 120400 with the 25 in small print. I believe the part numbers are coded for length/width.
 
I found the part number of the belt. 25 120400 with the 25 in small print. I believe the part numbers are coded for length/width.

The 12 is number of ribs. 0400 is 40 inches. stock is 080393. Or 8 ribs 39.3 inches

I just noticed I missed the #3 in the stock belt size
 
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The belt is whatever came with the pulley set. I don't have the part number near me but I want to say 20400. It was originally 12 ribs, I cut 2 off. Now it's more of an 8 rib after the others tore off.

The pulleys are the 20% set that Charles offers. I really think the idler pulley is too skinny. Those 10 miles I punched it pretty good, and I'll bet the 2 ribs that were not contained by the pulley just sheared off. I'll have to find a different idler that is wider.

I read a thread about the various belt sizes available and I believe this is the shortest one of the 12 rib variety. I'll have to see if I can find it.

I'm going to call around and see if there is a way to get a smaller custom belt made. My hood is stock height. And if I put my cervinis hood on then I'll have to get it painted. Which isn't ideal for me right now, as the paint job I want will be $$$.

The idler pulley being too skinny for the belt is not what caused the damage, the belt rubbing against itself is the problem. I tried using a pair of 5 rib belts with an MP3 many years ago and it slipped like crazy because they are not matched sets. If you not interested in shimming up the blower height, just do like Kevin suggested and get an 8 rib blower belt about 39" long, and put it on the ribs that line up best with your tensioner pulley.

David
 
The idler pulley being too skinny for the belt is not what caused the damage, the belt rubbing against itself is the problem. I tried using a pair of 5 rib belts with an MP3 many years ago and it slipped like crazy because they are not matched sets. If you not interested in shimming up the blower height, just do like Kevin suggested and get an 8 rib blower belt about 39" long, and put it on the ribs that line up best with your tensioner pulley.

David

For now that's what the plan is. Maybe if I get bored enough when it's warm out, I'll look into shimming it. Right now I'm focused on getting the griffin radiator in. I would have never checked it as soon as I did, had I not planned on installing the radiator.
 
I wanted to update. I got a gates K120390 belt. Cut the large peg off the tensioner. And drilled a new hole clockwise, and next to the small peg hole, on the accesory bracket. Clocking the tensioner loose just enough. The belt works, but doesn't wrap around the pullies as far.
 
I didn't read all the other post so sorry if already said but mine was doing something similar I figured out my tensioner was tightly fitted and alouded play not at the pulley but at the bolt that holds the whole tensioner on. Which alouded the whole tensioner to shift and let the pulley edge cut the belt I tore up like 3 belts before I figured it out, mine started with a small line in the belt like I was lightly cutting it was a blade

This all started to happen after doing my mp springs. I can't remember but I think I temp fixed it with some washer to hold that front plate on harder and then changed the tensioner, it's been a whie
 
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