I just had my 19% pulley installed a week ago. I took my MCS for a drive yester (120 miles) and was hard on it the for just the last 20 miles, but I still didn't rev it past 6500rpms. When I inspected the belt it was badly damaged, I have only used the car 4 times since I had the pulley installed. All in all I only have 650 miles with the 19% pulley on.

A rib was missing on the outer most part of the belt and the outer surface of the belt was badly damaged. The ply of the belt was already showing on the side where the rib got torn off and the only portion that looked good was the center. By the way, I was still using the original belt since I forgot to bring the shorter belt to the shop. I had a mechanic change my belt to the shorter one yesterday, drove it for 120 miles again and so far it still looks good.

Is it this easy to blow a belt with the 19%? Or do you think something might be wrong with the alignment of my pulley, etc. I'll post pics of the belt once I get my cam charged.

 

You have to change the belt when using the 19% pulley. You will damage the stock belt because it is too large.

I would be interested in hearing whether anyone has damaged their shorter belt? I know that all of them were damaged at the Ultimate Mini Challenge, but I think that was mostly due to the fact that everyone was reving well above the limits of the supercharger.

 

JohnD,

Which type of pulley did you install? Many like those from Helix align themselves during installation. Not much to to wrong.

For the 19% reduction pulley you MUST use the smaller belt. Now you know why. For some MCS owners with 17% pulley upgrades they have also installed the smaller belt but it is not needed for the 15% upgrade. So far over the last 6 months in my area there have been not problems with belts with that strategy.

So no it is not "easy" to blow a belt if you choose the correct sized belt for your pulley upgrade.

 

I have the helix self aligning pulley. If I remember correctly, I read a post here in NAM that someone was using the stock belt with the 19% and havn't had any problems with it despite bringing it to the track. I think it was in the post regarding the water to air intercooler by FMD, the 1st post.

I was hesitant to use the NAPA belt too since they say that it didn't last very long because it stretched after a while.

 

the NAPA 060539 has proven to be the best choice for smaller pulley's to date - at least with mine and Randy Webb's experience

 

I am using a Helix 17% pulley with the Goodyear Gator back belt. The belt tensioner is in the same location as it was with OEM pulley and belt. After 500 miles I can still read the part number's on back of the belt, yes the pulley has seen a test or three. Here's the part number and spec. for other option"s.

17/19% pulley Goodyear part# 4060537, part# 6PK1365, 6 rib effective
Lenght 53.75", outside Length 54.5"

 

The stock belt should not be used with the 19% pulley. The installer should not have let it go like that IMO.
The Goodyear belt will run cooler because of the segmented ribs. Less flex = less heat.

 

I have 21k+ miles on a NAPA belt and a 19% pulley. As far as I can tell (which isn't much) the belt looks as good as new. I'll have Helix check it tomorrow while I'm there though.

 

So the reason why my belt failed was due to the orignal belt being too long, that's good to hear. At least I don't have to worry about anything else, but I might have the shop check it just to make sure.

Currently, I am running the NAPA 060535, I'll just keep on observing it untill maybe 1000 miles. So far I've used it for 120 miles and the part number can still be read on the outer surface. What's the difference between the 060535 and the 060536?

By the way, where can I find the goodyear belt? And why are there 2 part numbers for this belt?

 

" By the way, where can I find the goodyear belt? And why are there 2 part numbers for this belt?"

part# 6PK1365= the discription, 6 rib, 1365 millimeters

Use the first part number, Goodyear part# 4060537

Summit sells them at: http://store.summitracing.com/default.asp?target=main.asp&l=GTR or

http://www.hotrodlane.cc/PRODUCTS/goodyearbelts.htm

GATES sponsors Schumacher race team

Gates is another maker of good belts. here is one, one size down, they don't make a 53.7" / 1365 millimeters belt.
Gates cross match with goodyear part # 4060537 for 17/19% pulley
Product ID 85520232Part # K060535 =
Product Description
K060535 MICRO-V BELT
UPC 072053049299

GATES http://www.gates.com/index.cfm