Accessory belt jumping
Thread Starter
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Accessory belt jumping OK, not strictly speaking FI, but obviously my car is blown, and I recall others mention this problem here a while back, but couldnt find it in a search...
It seems that lately, my accessory belt keeps jumping off a rib when revved hard ( say 6000rpm + )
My blower drive is totally seperate from my accessory drive, which aside from a different crank pulley to facilitate the blower drive, is stock.
Ive replaced the belt a couple of times first with cheapy crap, and more lately Gates ( which did last longer before it happened )
I orignally changed as the factory belt I had been using, was stretched near the end of the tensioners travel ( 2001mm belt )
Tensioner feels strong, and I am still using the stock plastic idler.
New belt I fitted was a 6 rib 1988mm long ( so shorter than the previous 2001mm belt that had originally been fitted to my engine ) with the hope it would fit tighter and hence be more secure from jumping.
My accessory drive is based on a GTO, not a Camaro, but only the power steering pump is slightly different. So essentially they are the same.
Anyone any thoughts as to why the belt would do this ? and a possible fix
I think I'll be ordering a new alloy idler for the tensioner if nothing else.
It seems that lately, my accessory belt keeps jumping off a rib when revved hard ( say 6000rpm + )
My blower drive is totally seperate from my accessory drive, which aside from a different crank pulley to facilitate the blower drive, is stock.
Ive replaced the belt a couple of times first with cheapy crap, and more lately Gates ( which did last longer before it happened )
I orignally changed as the factory belt I had been using, was stretched near the end of the tensioners travel ( 2001mm belt )
Tensioner feels strong, and I am still using the stock plastic idler.
New belt I fitted was a 6 rib 1988mm long ( so shorter than the previous 2001mm belt that had originally been fitted to my engine ) with the hope it would fit tighter and hence be more secure from jumping.
My accessory drive is based on a GTO, not a Camaro, but only the power steering pump is slightly different. So essentially they are the same.
Anyone any thoughts as to why the belt would do this ? and a possible fix
I think I'll be ordering a new alloy idler for the tensioner if nothing else.
Back 5-6 years ago we'd swap over to high sided idler pulleys because the belts would walk off above 6500 rpms. We called it the Larry pulley, maybe Thunder or ASP sells it.
Thread Starter
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Ive emailed ASP, although prob wont get a response til late Monday...
Thunder list an alloy tensioner ( manual as opposed to automatic ?? ) bracket for the stock idler.
I also see Thunder list an MBA pulley, with a machined centre, but it doesnt look like the sidewalls are any different than a normal pulley. Just looks like a bit of bling rather than a functional item...
Thunder list an alloy tensioner ( manual as opposed to automatic ?? ) bracket for the stock idler.
I also see Thunder list an MBA pulley, with a machined centre, but it doesnt look like the sidewalls are any different than a normal pulley. Just looks like a bit of bling rather than a functional item...
I had the same problem after my blower install. Would come off at the upper end of the rpm range. Found that when tensioner was tensioning it would twist to either one directionforward or aft.
Simple fix for me ended up putting a washer between the bracket and the pump, on the inner bolt boss-mount. Can see it in the picture if you look close.
http://i3.photobucket.com/albums/y65...uelrail159.jpg
http://i3.photobucket.com/albums/y65...uelrail165.jpg
Been going strong ever sense, with not one lost belt. Had a buddy with the same problem but if I recall his was walking off the pulley the other way. So he needed to shim the lower boos-mount.
I think I only used about a .040-.060 thick washer, did not take much.
Simple fix for me ended up putting a washer between the bracket and the pump, on the inner bolt boss-mount. Can see it in the picture if you look close.
http://i3.photobucket.com/albums/y65...uelrail159.jpg
http://i3.photobucket.com/albums/y65...uelrail165.jpg
Been going strong ever sense, with not one lost belt. Had a buddy with the same problem but if I recall his was walking off the pulley the other way. So he needed to shim the lower boos-mount.
I think I only used about a .040-.060 thick washer, did not take much.
