Fighting Belt Slip (Pics Inside) - Any Gates RPM Belt/GripTec Vendors?

I logged a 3rd & 4th gear pull, and I could feel the car losing power ever so slightly as my speed was increasing.

Data is from a Gen 2 Whipple 2.9 Crusher w/ 2.75" pulley, stock lower.
Based on the timestamp it held peak boost for about 1.5 seconds and then progressively dropped off. 4th gear only saw 24lbs and started dropping...



This was with a 2.75" factory style Whipple pulley. No additional modifications for anti-slip measures were done to the pulley. Just a smooth 8 rib. I also am running a Gates Green belt w/ a Thump RRR tensioner. During some research, I found out that with the size belt I'm running the tensioner is at 25-30% of it's travel before it's 0% (tensioner unloaded no belt). Which from my understanding is what is recommended when running a Gates RPM belt. If I order a RPM belt, I already have the proper tension part covered.

So, I'm looking to upgrade to an RPM Belt & a GripTec pulley to solve my belt slip woes. If anyone is a vendor that can get me a deal on these products that would be great.

Anyone here have experience with either of these products?

Why not try next smaller belt and see if any improvement?

I'm pretty sure I've seen the whipple guys say anything below a 3.0 pulley is going to slip maybe it was even a 3.25 pulley.

these green belts stretch like hell. On my procharged car I almost lose a finger tip putting a new belt one. 2 weeks later its not even a struggle. I wish they made an RPM belt for me

DSG2003Mach1 said:

these green belts stretch like hell. On my procharged car I almost lose a finger tip putting a new belt one. 2 weeks later its not even a struggle. I wish they made an RPM belt for me

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Same here man. My plan is to go manual brakes and steering and delete that pump all together it’s going to shed a ton of belt length and I should be able to get into the rpm belt line then. I’m running a 115.3” now! Lol

98 Saleen Cobra said:

Same here man. My plan is to go manual brakes and steering and delete that pump all together it’s going to shed a ton of belt length and I should be able to get into the rpm belt line then. I’m running a 115.3” now! Lol

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I think im running a K081092. Im not deleting anything. I'll either re-pully with an Fseries or say **** it and go twins

Damn! That's some serious boost you're trying to wrap with a small upper only combo!

I got my RPM from rockauto about 3 years ago.....got to my door fast. Still on the car! Has worked awesome. I had that green belt maybe circa 2012~2013 absolutely hated it, never worked worth a damn for me. Was ugly as sin against torch red, chirped like crazy....stretched very quickly. I went with a gatorback (conti) and served admirably until I went with the RPM in 2017. The only gates I can recommend is the RPM....if they don't make a size someone needs....I'd go conti.

DSG2003Mach1 said:

I think im running a K081092. Im not deleting anything. I'll either re-pully with an Fseries or say **** it and go twins

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For sure, my car isn't a street car really though.. So I don't mind.. But a 88mm turbo is looking really good these days for my car.

I run a 2.9rr upper on my 2.9. Standard idler setup with snub, stock tensioner, stock lower. Builds boost til redline although I’m only around 19/20.

Been like this for like 2.5 yrs same belt.


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MG0h3 said:

I run a 2.9rr upper on my 2.9. Standard idler setup with snub, stock tensioner, stock lower. Builds boost til redline although I’m only around 19/20.

Been like this for like 2.5 yrs same belt.


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Nice! Those RRs are good.

I think trying to wrap 28psi....I'd contemplate a plunge with a lower of some sorts. And a larger upper. That's giggity levels of boost lol

c6zhombre said:

Damn! That's some serious boost you're trying to wrap with a small upper only combo!

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I have yet to even feel it. It’s been slipping this entire time while I’ve been working out small odds and ends that keep holding me up lol. Only difference is I actually logged it and now I have proof I’m not going insane thinking my car is slow haha.

I’ve been building this car way too long dammit haha! Can’t wait to feel what a proper 3rd & 4th pull feels with 28psi!

BLOWN9646 said:

Why not try next smaller belt and see if any improvement?

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I’m pretty I’m just about there. The way I remove the belt is by unbolting the supercharger pulley, then pull the pulley along with the belt from the snout about at the same time. I install that way too.

DSG2003Mach1 said:

these green belts stretch like hell. On my procharged car I almost lose a finger tip putting a new belt one. 2 weeks later its not even a struggle. I wish they made an RPM belt for me

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Yeah I did notice that they do stretch a lot. In this picture to the left of the stop screw you can see indent marks from the stop screw hitting tensioners swing arm stop. Which in my opinion is not good. That’s when I knew it was time for an RPM belt.

MG0h3 said:

I run a 2.9rr upper on my 2.9. Standard idler setup with snub, stock tensioner, stock lower. Builds boost til redline although I’m only around 19/20.

Been like this for like 2.5 yrs same belt.


Sent from my iPhone using svtperformance.com

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Yeah I have a 3.0RR and pretty sure I don’t have slip, but it’s hard to tell sometimes from the gauge because they’re lagging indicators.

Once I logged the boost, the signal reading was clear as day.

Using a coated pulley by chance? I spent the $100 and said goodbye to slip. My 3.4 was slipping down to 18psi but after getting the pulley coated soared back up to 25/26psi. This was on a 3.3" pulley for me.

I don't think the belt is the issue here. The way I would approach this is either with a better pulley, either griptec or another coating. Or I'd get a lower and a bigger upper, 4lb lower and 3.25 upper will net the same boost.
Personally I'd opt for a 4lb lower with a 3.25 griptec upper
I run a 4lb lower, Whipple 3.5 upper, roush tensioner, gates green belt and a 4pc metro idler set. The belt is actually loose right now, it was sized when I was running the 3.625 upper, and I have no belt slip

94slowbra1 said:

I don't think the belt is the issue here. The way I would approach this is either with a better pulley, either griptec or another coating. Or I'd get a lower and a bigger upper, 4lb lower and 3.25 upper will net the same boost.
Personally I'd opt for a 4lb lower with a 3.25 griptec upper
I run a 4lb lower, Whipple 3.5 upper, roush tensioner, gates green belt and a 4pc metro idler set. The belt is actually loose right now, it was sized when I was running the 3.625 upper, and I have no belt slip

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Wow! That's interesting....I'm shocked it's working so well on that setup you have....especially considering you swapped pulleys and it's still not slipping! Great results

It just never worked well on mine. It kept chirping like crazy at startup and seemed to slip WOT upper rpm. I gave up

04MystiCobra said:

Using a coated pulley by chance? I spent the $100 and said goodbye to slip. My 3.4 was slipping down to 18psi but after getting the pulley coated soared back up to 25/26psi. This was on a 3.3" pulley for me.

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Curious, when you say coated do you mean carbinite coated? I had my 2.76" Billetflow pulley carbinite coated for my KB 2.2...and that was a mistake. I don't know anout you, but there is no amount of additional grip it 'might' provide that can make up for how brutal it is on belts. As it cuts into the belt and literally destroys it, it also leaves a nice black coating of vaporized rubber all over everything. Maybe your experience was better than mine, idk. But I went back to a std non coated pulley. I just didn't see the benefit unless it was for a race specific application.

Yes. That or GripTec. I observed similar results in dust but never saw slip. For my application, changing belts, whether from slipping, chirping or shredding is a fact of life it seems but in all cases I hated boost dropping off.

I've read very good things about griptec but no first hand experience. They apparently don't produce the belt dust like Carbonite coating does. Maybe @jwcobra03 can chime in, I believe he has one.
Here is my belt wrap with my current set up. I'll eventually get the correct belt length, just haven't had the need yet

also Whipple makes a very nice tensioner that gets great reviews by the folks that own it. Again I don't have the issue so I'm not looking to fix it. Plus I like the way the metco looks compared to the Whipple piece

Griptec pulley is the way to go. As far as pulley coatings would go. It does produce a tad bit more belt dust but the belt ribs aren't torn up. I don't find the belt dust to be excessive but you will notice it over a normal pulley.

I run a 2.6 upper with carbonite coating, along with a thump tensioner and a whipple sliding pulley. Works well, but a lot of belt dust.

I recently bought a 4lb lower which I might try at some point.

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