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Any experience running a Gates RPM Belt?

6511 Views 6 Replies 4 Participants Last post by  GreenMachine15
I’ve killed two green belts now, each lasting about 500 miles before I get squeal and less boost at wide open throttle. I’ve got an upper and lower on my car, makes 19 psi with a brand new belt. Just installed a Gates RPM belt and was hoping to get feedback before I go try it out. This thing was hard to get, took two months. Side by side comparison is wild, much smaller groove width on the RPM belt, looks like it will have a tight fit. I read up on some past threads on the topic and according to Gates, some of the early RPm belt failures were due to running the tensioner too tight. Apparently these belts do not stretch at all, unlike the green belt, and can snap if under too much load. I also worry about not having any slip at all since I do not have a decoupling pulley. Any thought on where the tensioner is set? Would love to hear your experiences, thoughts, or opinions. Thanks


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I finally took the car out for a spin. It made more boost than it ever has, pulled harder than it ever had, and even made big boost at part throttle instantly. I am very pleased with this belt so far, and no squeal or chirp at all.

The RPM belt must be tensioned different than a green belt or standard black belt. The RPM belts do not stretch hardly much at all (due to aramid core vs polyester core on green belt), so the tensioner must be at 50% or less compared to 85% tight tensioner position for a green belt. If installed at the same tensioner position as a green belt, nearly all the way tight, they will eventually snap when you let off and the tensioner slaps the stop. I actually moved my adjustable idler to a looser position than the pictures above, right at the 50% mark on the tensioner. I couldn’t get it any looser, so I ordered a slightly longer belt just in case this one is too tight and snaps. If you need want more explanation and videos comparing green belt vs rpm belt on a dyno pull, there is a great thread on a mustang forum that’s easy to find with a google search. I had no idea how much a green belt stretch’s at full boost, nearly the entire throw of the tensioner.

I have 20 miles on it so far, I’ll report back if I have any issues. So far, I would highly recommend this belt if you have slip or keep killing green belts. Best part, it’s black. Looks so much better on a white car.
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Sorry for the late reply, had no idea anyone responded to this post.

The tensioner is from Ripatuned, link below, and the catch can is from Billet Technologies, link below. Billet Technologies will take forever to deliver, it was months for me, but the product is great. If you could get them to make the hoses just a bit longer it would work better. They are not designed to work together, but with the right pulley size and belt length there is just enough room to make it work.

The rpm belt is amazing. Put about 300 miles on it so far, no issues, perfect reliable 19 psi of boost, no slip, no squeal, 100% recommend this belt. It took gates two months to make my belt but worth it. I bought it directly from them on Amazon, it was the only place that had the part number/length I needed.

The belt part number I am using is: K100586RPM or 10PK1488, 1-3/8" x 59-1/4"
This fits with a Ripatune idler, Incognito lower pulley, and a 2.57" upper pulley. My advice is to use the fleetrunner belts as guides to get the right part number, then order the RPM and wait wait and wait some more. Make sure the belt tensioner is nearly all the way loose, this belt does not stretch and does not need the tension like the green belts do.

I will admit my setup is not really ideal for a daily driver, especially the horrible mileage on E85. But it's only driven 50-100 miles per month, and it's too fun to go backward. I have my eye on the Hellion Twin Turbo kit as a next step. If so, all the pulleys come off and the supercharger speed will go back to stock. Its going to take a while to save for that kit but I think it will be well worth it.

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