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lower pulley issue after switching from stock

5K views 65 replies 12 participants last post by  lilzilla08 
#1 ·
I swapped my stock lower to a metco interchangeable set up and now the belt jumps off toward the rear of the pulley by 2 ribs. I didnt have any issues with the stock lower. Im assuming something is up with my metco lower as it never did this before but it spins true (from what I can tell) to the crank. Im starting to lean to maybe a bad idler pulley as one idler pulley is running where it always has and the other one is running more towards the rear. Any ideas on what my problem could be? I am new to modding lightnings so any help would be appreciated!
 
#2 ·
what year is your L?
there is a difference in the pulley for 99-00 vs 01-04
 
#8 ·
I’ll double check it this afternoon, thanks! I have looked before and it appeared the crank pulley is out further than the others but also you can see on the idler pulley where the belt ran before and now it’s running further back. I’ll get pictures this afternoon and show what I am talking about
 
#14 ·
From what I see...
The idlers show that a 6 rib belt has been used on the supercharger.
Accessory belt is 6 rib, should be 8 rib.
Missing idler on accessory belt.

My question...
When running, does the lower pulley run true?
Stock heads? Trick Flow use 8mm studs vs the OEM 10mm.
Is the 10mm spacer under the bridge? drivers side lower stud (see Picture)
Whats the tensioner look like?
With the belt off, do the idlers spin free?

542415
 
#15 ·
From what I see...
The idlers show that a 6 rib belt has been used on the supercharger.
Accessory belt is 6 rib, should be 8 rib.
Missing idler on accessory belt.

My question...
When running, does the lower pulley run true?
Stock heads? Trick Flow use 8mm studs vs the OEM 10mm.
Is the 10mm spacer under the bridge? drivers side lower stud (see Picture)
Whats the tensioner look like?
With the belt off, do the idlers spin free?

View attachment 542415
Damn it really is missing an idler! Never noticed that before. I thought that accessory belt might be wrong. I’ll change that ASAP and get the idler for it. Any reason for that to be gone or previous owner installed the wrong size belt?

From what I can see it does run true. I can get a video of it running if that would help.

Stock heads are being used. Truck was all stock up to when I got it. Only mods are jlt cai and catch can along with the 4lb lower now. Tensioner has a very very tiny amount of play. Idlers spin freely with no issues but I haven’t taken them off yet and tried spinning them to see if the bearings are making any noise or grinding

Attached is a picture of the bridge. It has a nut behind it from what it looks like. Not a spacer as pictured.
 

Attachments

#19 ·
From what I see, everything looks correct.
Check the hub, make sure it's seated in the balancer correctly.
It was rubbing on the inner bore a little when installing. I took a wheel and shaved just a hair around the entire middle and it sat a little better from the way it felt. I’ll undo it tomorrow and try resetting it again. I did notice on the inside where the bolt head sits against the pulley that one wasn’t quite sitting right. I made a very small relief for the bolt head to sit flush.
 
#23 ·
Update:

I checked to make sure the pulley was centered and all a few more times and it’s still the same issue as mentioned before. Took some measurements and it’s not possible to mount the pulley on the other side (noted for anyone considering it).

Removed both idlers and the one on the bridge by the tensioner is definitely bad and the other is dragging a little. Not sure if that would move the belt that much off the bottom pulley but I’m going to replace them and see.
 
#40 ·
My tensioner is pretty damn tight. If it should be any tighter than that then ill need more than what I have to install a belt lol. I rechecked it all again to make sure and this time I used a straight edge to check from the tensioner to the 4lb lower and it is definitely off a hair. The 4lb lower is out about 3/16". I have someone that is going to machine it down just a little and ill try again after the new tensioner pulleys go on
 
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