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Are Gates belts inferior for supercharged Whipples?


springer

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Here are some pics from the install of my new 100mm Thump RRR pulley. I got it on tonight and it works like a champ. The pulley flange is 2mm away from rubbing the Whipple adjusting bracket, but it clears just fine. If you notice in the first photo, my belt no longer rides at the edge of the pulley like it did on my original pulley. The belt now rides 1/4" closer to the center of the pulley.

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  • 2 weeks later...

Here are some pics from the install of my new 100mm Thump RRR pulley. I got it on tonight and it works like a champ. The pulley flange is 2mm away from rubbing the Whipple adjusting bracket, but it clears just fine. If you notice in the first photo, my belt no longer rides at the edge of the pulley like it did on my original pulley. The belt now rides 1/4" closer to the center of the pulley.

 

 

pm sent

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  • 1 month later...

They are on the website with some grooved pulleys

 

 

Here is the part number for the Thump RRR Racing flanged 100mm pulley from ThumpRRR. PM-20100-DF 100 mm Billet Aluminum Rib idler Pulley with Flange $129

 

Web site address: http://www.thumpracing.com/idler_pulleys.htm

 

 

Here is the part number for the Thump RRR Racing 87mm grooved idler pulley that is directly below the 100mm idler pulley. PM-2087-G 87mm Billet Aluminum Grooved Pulley $79

 

Wed site address: http://www.thumpracing.com/grooved_pulleys.htm

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  • 1 year later...

I too had the shredding issue on the belt.

 

Several factors seem to make it a perfect storm for the problem. As others, I put the 100mm Thump Dual Bearing idler on the car and the problem was fixed. (for now)

 

Curiosity drove me to dig a little deeper to find the problem.

 

1. Once an aluminum casting is machined (idler mount diameter) you will eliminate the hard skin of the casting and the surface is softer and more porous.

 

2. The inside diameter of the Whipple supplied 100mm bearing is longer than the idler shaft on the casting.

 

3. There is an air gap between the end of the cast mount and the end of the bearing surface from front to back. Didn’t measure it but guessing its 3-5mm.

 

4. Since there is no bearing surface at the front of the bearing it can wobble depending on machine tolerances on both the bearing and bearing mount. Reach in there, grab it and if it moves you may have a problem.

 

5. Any slop will be exaggerated over time and temperature.

 

6. The change in HP and torque will exagerate the mis-match over time and use as well.

 

 

My Whipple Supplied bearing had 5-10 degrees play while installed and the bolt was torqued to 32 ft/lbs. The bearing in the pulley was good but it fit loose on the on the bearing shaft.

 

Because the Thump 100mm came with a step washer/bushing it is solid with no movement what so ever. I called and eventually talked to Art Whipple at WI and reviewed the issues. Good guys and they eventually sent me some Stepped washers and a belt for my troubles. I used the stepped washer and put it on the 90mm that had been moved from the driver’s side.

 

In summary, depending on the setup and QC from all involved there can be enough play in the Pulley standoff and the bushing so that it will deflect enough for the belt to ride off the back of the 100mm idler and shred the belt. My suggestion would be to call WI and ask them to send you the step washer for the 100mm idler if you’re having the problem. It may or may not fix your problem, but it’s the most cost effective start and you still have more options.

 

Good Luck!

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Great info, but I was confused after reading your post. If you used the Thump RRR flanged, twin bearing 100MM idler pulley on the driver's side, which replaces the Whipple/Ford supplied 100MM pulley, the belt can't come off the backside of the pulley anymore. The other problem with the Whipple/Ford supplied 100mm idler pulley was that it did not fit close enough to the timing chain cover so when I designed the 100MM idler pulley with Thump RRR, it was milled so that it would fit closer to the timing chain cover which centered the belt much better on the pulley.

 

The only other problem I had was with the Thumper RRR single-bearing tensioner arm pulley - the bearing went out and the squeaking was killing me at start-up. I ended up modifying a Thump RRR twin bearing pulley to fit my Thump RRR tensioner arm and have not had a squeak or any issues since I installed this pulley. Although the tensioner pulley was not flanged, I believe Thumper RRR has one now, or were in the process of making one last tome I talked to them.

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Yes and thanks. I had put about 1000 miles on the Whipple supplied 100mm pulley and had no issues. Once it got to a 100 Degrees here in Austin the belt must have streched and it rolled off the back of the whipple 100mm pulley. That's when I went ahead and ordered the Thump flanged dual bearing 100mm because I noticed the play/wobble in the whipple pulley. I was just curious as to what caused the fit issue and hence the rest of the info above was discovered. The Thump 100mm did indead fix the problem and I added the new whipple step washer on the 90mm on the passenger side to avoid any issues with that one just in case.

 

The information is just for some Whipple owners that think they might have the same problem and can quickly check the 100mm for fit issues before the belt gets shredded.

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I don't think you had belt stretch issues after 100 miles. The tensioners will take-up the millimeters in stretch that the belt will eventually have.

 

My guess is if the belt came off the back of the 100 idler pulley because the belt wasn't centered very well on this pulley and when you put your foot to the floor, the belt walked-off the backside of the pulley. With the flanged 100mm pulley, the belt is centered better on the pulley as well as the addition of the flanges to keep the belt from flying off the backside under load. Sounds like you had the same problem I had. Glad the pulley worked for you.

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Well, I'm pretty sure I've never put the peddle on the floor..... Maybe once on a closed track somewhere here in texas. Anyway I'm happy with the outcome and am just trying give options to the Shelby SGT/SC Freaks in here some opitions. ;)

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There is another thread somewhere where a heavy duty 7 rib belt gets 1 rib cut off and works fine. I got one and have it laying in the trunk just in case. Anyone remember the specs on this one? I got the upgraded Shelby tensioner also. TASCA did my install. Very nice job! As they say about Jamaica "Once you go you know". You cannot imagine the power increase.

 

Found the belt info - Gates K071247HD

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  • 3 years later...

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