JHM Lightweight Pulley issues

A6 All/ S6 All
#1

After installng the JHM pulley I’m having a recurring issue that the alternator belt keeps running on the edge of the pulley. It goes back out of place after adjusting and the belt now slipped off altogether. I asked the shop I use to take a look at it, and they told me everything looks fine but the part itself has 2mm different alignment compared to the OEM pulley according to their measurement. The measurement was taken from the installation surface to the belt groove. I find it hard to believe unless it’s a manufacturing defect of some kind, so I’m wondering if there’s anything that I’m missing. I asked them to take photos if they can before putting the bumper back on, and am waiting for a reply.

Edit: Talking about the S6 V10

#2

I’d find that odd to believe. This is a pretty solid mod and helps make the S6 motor quite a bit more free to spin up as you already know.

Are you destroying the belts? Or are they slipping off? It sucks with you not doing the install as you’re subject to install issues or part issues? I’d have them not put the bumper on, start the car and video the belt path. Without being there it’s hard but it can be more possible to be the tensioner.

#3

Yeah there’s no way I could be doing this myself as I simply lack the skills :frowning: The belt does get destroyed over time as the pulley’s edge digs into it. But it slipped off before breaking. The shop said the actual pulleys measure different, so I was mainly concerned if there’s something simple that I’m missing? Like are there different pulleys in different model years or is there supposed to be a shim?

#5

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Here are the pulleys side by side. There’s a 2mm difference in the offset of the pulleys. So what gives?

Here is how the belt starts running on the edge of the pulley:

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#6

I think may have had the same issue where two belts were destroyed in a short period of time years ago. But unfortunately, I’m not mechanically inclined and don’t know what the shop did differently for the belt to not break a third time. Also not 100% sure it was because of the LWCP since the shop never mentioned that as a potential culprit. Wish you the best of luck. Godspeed.

1 Like
#7

I had 'em put the OEM one back for now… too bad I can feel a difference in the engine characteristics with the heavier weight. At least it does make a difference. I may put the LWCP back at some point and just accept that I have to keep changing the belts… I sent an email to JHM but we’re still in conversation.

#8

I just bought a JHM crank pulley last week. Your post has spiked my curiosity. I’ll take some measurements this weekend and see if I can provide any further info. Curious what JHM’s reply will be.

#9

Please do. At this point I’m not sure if the measurements are different on purpose or if my part is somehow defective. The shop didn’t have other ideas than to put the OEM one back. Two of the pulley’s bolts were also snapped so someone has been messing with the pulley before my ownership.

#10

So I pulled my JHM out of the packaging and set it up on my workbench next to the stock one. I set them both on identical axle nuts to elevate them up by the contact point in the center. The ribbing looks off as you described. Anyone else have issues? I’ll also reach out to JHM.

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1 Like
#11

I have been running a JHM LWP for 3 years without issue.
So maybe this new batch is defective.

2 Likes
#12

Yes this is a better picture than mine. The belt would keep climbing on the very edge of the pulley, causing the pulley’s edge to dig into the belt eventually breaking it. Let me know what their response to you is. Currently I’m still exchanging e-mails with them.

#13

Did you end up putting the part in? How’s it working?

#14

My engine is still on a stand, but it installed fine. I reached out to JHM and they said were looking at it but have had no issues in their years of production. The tone I got was its nothing to worry about. I do plan on running a ribbed idler pulley in hopes it will help with belt alignment.

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#15

From my experience I’ve installed several and all of them have not only fit well but it’s impact is notable and improved the cars power for the better.

#16

Interesting. I have been using this part since 2017 and no issues whatsoever. Has to be an assemble issue.

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#17

I had two different shops look at it, both highly reputable. The first who installed it and the second who tried to diagnose the problem. They found nothing else than the pulleys having different offsets. What can I tell them to look for? With the OEM pulley the belt stays on fine.

#18

Why you not send it back to JHM for review, maybe one piece was made with issue :grimacing:
Or just somewhere manufacture a spacer plate?