UmX

I was talking to another member about how i am stretching the 4rib belt that drives the accessories like crazy under load.. I know ECS used to sell cog style crank pulleys/jack shafts.
With in the last 3 days on a brand new belt i have managed to stretch it 3 times to the point i cant tension it any more.. And this was just doing a few highway pulls not even really beating on it..
But what are some of you guys who are running high as HP cars doing? Swapping belts left and right? or have you found a solution to this issue..

Patriot Six

I’ve had my secondary drive kit for two years without any issues. What symptoms are you having from the stretched belt?

UmX

It will stretch and start slipping and squeal like a banshee So the car won't charge until it warms up.

Patriot Six

I had some squeal on the alt belt at startup when I first got it. The 370 belt that came with the kit was too long. Since going to the 365, I have no squeal or issues. I never had issues with the 4 rib belt.

UmX

I went with a smaller pulley on my alternator and went to a smaller belt on there,, but never had any issues with the alternator belt its always the 4rib belt.. what kind of power u making or what set up

Unreal

Direct drives can be tricky. You don't want too much tension, or can stretch belts, not enough and it slips. Also double check all the accessories for their load. See how easy they spin. Things like a smaller alternator pulley are not helping as that is just going to increase the load on the little 4 rib belt. If you can find a RPM belt in that size, they don't stretch, so that is a good place to start.

K040360RPM K04 9/16” x 36 3/4” - Black 4 36.14 918 36.75 933
K040365RPM K04 9/16” x 37 1/8” - Black 4 36.56 929 37.125 943
K040370RPM K04 9/16” x 37 1/2” - Black 4 36.994 940 37.5 953

Patriot Six

I’m making 874whp on a forged LS7 with Ti trim on e85.

UmX

those are overly long for the 4rib.. the 292 is 293/4 ill see if i can find somethign close to that in rpm

Unreal

K040292rpm

UmX

ima hit up oreilys here in a bit.. wonder if i should just replace them all these rpm belts.. seems logical

Unreal

If they make them in the sizes you need, they are by far the best belts made from my experience.

UmX

I was looking for the blower belt.. but doesnt look like they have that size.. i havent really havent had any issues with my K080537HD belt moving.. or "not yet" lol

Unreal

Normal black belt is better than the green HD belt, so if anything go back to the standard black if you can't get the RPM belt.

UmX

Ah ok .. Ya i cant find a 537rpm any where.. if i can at least find a 4rib thats all that matters.. thanks for the help today and last night

gameover4

since going to RPM belt ive had zero issues with belts and the longevity has increased. I get best prices at NAPA on these. RPM blower belts for cheaper than HD belts.

mourat

I daily drive my corvette, and my belt is about 3 years old. Rain, sun and even some snow. Many dyno pulls and was at the track the other day. Reving to 6600 rpm many times. Voltage is stable at 14.5, no issues here. I'm using A&A old kit and the C5 AC bracket. Before the C5 bracket it was terrible. Also, I'm using the gates green 4 rib belt which doesn't stretch like black belts.

Unreal

Green belts still stretch. The RPM belts are the least stretchy. Green belts are made for long life for stuff like diesel truck that see 100k+ a year.

UmX

depends on boost as well.. i never see 14.5v when car is warmed up.. im at 14.5 on start then drops to 13.4 thx mechman alternator smh

fasttz06

Sorry to pull up an old thread. Did anyone try the RPM belt #k040292rpm? Did it solve the issue or did it at least last longer than a regular belt?

gameover4

I only run rpm belts and def last longer and my Napa has them cheaper than the green belts