Stillen supercharger belt slipage
 

I've been trying to figure this problem slowly out for a few months now... my belt slips at high rpm. I tried different belts (same length) then tried the extra pulley for grip with the longer belt. Same thing.

I sprayed CRC, didn't help even though I could tell belt became sticky.

I replaced my belt tensioner with a new one, no difference.

I feel like I am out of options.

I am running stock pulley sizes, stock impeller that came from stillen. Nothing modified there.


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Check out Topgunz Air-to-Air thread, there is a lot of discussion on belt slip and some pretty good solutions.

Should I add also that both belt tensioners show that each belt I tried is too loose.


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I did. I followed all of them I think. Thanks though


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Have you tried the "high traction" pulleys from Vortech?

I'm using the "high traction" pulleys on the SC and the serp side but not the jackshaft pulley, but using a larger jackshaft idler pulley (due to smaller 3.0" SC pulley). I'm also using the extra idler pulley for more wrap on the serp side. I don't believe I'm getting any slippage. :driving:

Also I've read that CRC will make things worse in the end.

I have not tried those pulleys. I'll consider it.

Do you know if it's possible to adjust the tension of the short belt on the supercharger side without taking the whole supercharger out? I have a hard time seeing wrench size needed because it's kind of tight there


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Gates has new green series belts out now. Supposeded to be really good.

Yes from underneath. Two long 3/8 extensions, a wobble and a 14mm shallow socket. The bolt on the idler itself should be a 19mm wrench. Back it off just a little and then go beneath and increase the tension a little. Tighten the pulley back up.

Keep an eye on the pulley as the adjuster setup puts all the tension on the inside and the pulley can ride askew, potentially causing belt to ride off the rib or put lateral pressure on the bearings. I used a larger, thicker washer behind that 19mm nut so it will sit true when tightened back up.

Don't try and tighten the tensioner from below too much at once. It is really easy to over tighten. Better doing it a couple times instead of getting aggressive with it from the start.

There is a possibility the main bracket itself is flexing under load which will cause slack on the sc belt and slip. However, with the light load setup you have on there it is more unlikely to happen. Unless for some reason you have a bracket that has been weakened somehow.

The price that guy is charging for those brackets is rediculous. I had mine made for $100 and it is way better than that.

Stillen supercharger belt slipage
 

I put on another Gates brand new belt and this one even though "same size" even comparing outside of the engine was a tad bit shorter. The belt tensioner shows the belt properly tensioned now. BUT I still get belt slip just as bad.

And when I compared by hand, the tension on that belt to the SC side belt. The SC side belt was looser. I will tighten that and if it doesn't work, I might take off the supercharger cause I'm done dealing with this hahaha

Topgunz- Yeah, I have the lowest power setup on the stillen. I shouldn't be getting any movement.

And I agree that bracket is way too expensive.


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You can also access it from above with a crow's foot and a ~8" extension. Which way to turn it, gets confusing since it's all upside down, but just keep track of the turns and see if you're going in the right direction. It sounds silly, but it's easy to lose track of it all when you have to keep removing and re-seating the wrench every 1/3 turn. It's clunky, but you only have to do it once.

I'm curious about why you think the belt is slipping. Low boost? Rubber dust coming off the belt? Noise? What are the symptoms?

I found out that I had a belt slip issue by using a IR heat detector and measuring the SC pulleys. They should all be about the same temperature unless they are slipping and then you will see a higher temperature.

IR heat guns are around $25 and are quite handy to have around when chasing any heat problem. https://www.amazon.com/Etekcity-Lase...rmometer&psc=1

Some things I've learned about industrial belt-drive systems over the years. Should apply to SC drives. Hopefully, it will help. Maybe not.

The belt itself is seldom the problem. (Assuming what you are using is reasonably close to original specs and it's not worn out.)

Pulley material/construction is just as important as with the belt. If the pulley doesn't provide some grip for the belt, you're going to have slippage. Get a belt/pulley combo with sufficient stiction and you can get a little sloppy in other areas.

Everything else being the same, pulley contact area will have the greatest effect. Contact area can be increased by having the belt wrap around more of the pulley. Contact area will be decreased if the belt doesn't run flat on the pulley.

Flexing of brackets and other mounting hardware should be kept to a minimum. Flexing causes loss of tension and misalignment of the belt and pulley. This was the cause of many problems I ran into.

Belts will naturally vibrate but if they start to flop, you need more tension or an idler.

Tension is important, but y'all already knew that. :)

I get a loud belt squeal along with loss in boost exactly when the squeal happens. Only at high rpm.

Also, my belt tensioner reads that every single one of the 3 brand new belts I tried is not tight enough.

I tightened the SC side little belt and it didn't help.


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You may need my added idler pulley kit. It gives a lot of wrap around the jackshaft pulley.

Stillen supercharger belt slipage
 

I have your added idler pulley with your special spacer! :)

It's something else that's causing the belt to not be tensioned...

Previous to the SC build I had lightweight underdrive pulley at the crank and overdrive at the alternator, I had those removed for the SC build.

The shop had to remove the alternator to install the pulley for it. Is it possible that the alternator had brackets that let it be moved by 1 or 2mm? Maybe they didn't position it perfectly, which didn't cause problems when the car was NA




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I'm not sure why there would be a tensioning problem unless a wrong diameter pulley was installed somewhere. Dumb question: have you made certain that the belt is routed correctly?

Are you using the standard K081088 belt or the HD version?

Everything is routed correctly. I used everything from NAPA belt to the Gates Racing belt. Not the HD belt though. All belts are not tensioned correctly.

If I had a correctly tensioned belt and it would slip I'm sure that the HD belt would be the answer. But my belt is not tensioned correctly.

I want to look into the alternator but before I do I would want to confirm that in fact it can be installed a few millimeters off


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Here is a picture of my tensioner with the HD belt.

The alternator does use a mounting bracket so you may be onto something.

Stillen supercharger belt slipage
 

Your tension looks perfect Tbatt. Mine has never been like that.

I'll try it and if doesn't work then I'll order the HD belt. At that point last thing I'll be able to think off as a reason is that that my belts stretch. But that seems extraordinary.

I'll check in two weeks after I'm back from vacation :)

I need to be ready for ZdayZ!!!


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I need to back the nut off mine and give it a bit more tension when I swap the new pulley and belt on. Not because of the pulley and belt, because it needs it anyways. Easy enough to do obviously but pretty sure I'll have to grab a second pair of hands to do it.

Yours is too tight?


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Mine is sitting something like this right now. Just a little towards the drivers side past those three bars. Not at home to take a pic.

Mine is the same exact spot. This means the belt is lose and the tensioner is pulling it too hard. I tried to adjust it with the bolt and could not. If you figure it out let me know!


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Has to be adjustable that way. Mine is where it is because I was trying to adjust it with the bolt when there was no belt in and it went to far - I just haven't adjusted it back yet.

When I get Tbatt's kit I'll address it then and report back if 'resetting' the idler position by that bolt worked or not, thing I'm confused fident it will.