Pas Belt Turning Inside Out / Coming Off?

[Chris Wilson]

RB26 engine with a sequential box turning only to an 8500 RPM limiter. I am 99% sure the PAS pump, pulley and bracket are correct and compatible, and they are all OE, the crank damper is new and stock. On the road I have no issues, but on track I get the belt either turning inside out or coming off broken. I have heard this can be an issue, especially with sequential dog boxes and un-damped clutches, which is my set up. I use the car for track work. I have made a pulley to run on the outside of the none tension side of the PAS belt, as it seems a long run, to hopefully dampen any oscillations. It seemed to ripple when revving and coming off the throttle. Pulleys seem perfectly in line. Has anyone else had issues? I haven't yet tried it on track to test my theory. Thanks.

[zebra]

This happend to both Paul (swiper the fox) and giant, it was the p/s pump not being far enoungh forward. and they had to space it out a smidge.

[R31Nismoid]

^ I was going to say the same thing.

OEM belts by are large are the best. I know there was some issues with Daikin (or something similar) "replacement" bands that were cheaper than Nissan OEM, thing was though they just shredded far too easily. Happened to me

Back to OEM and it was fine there after. Not exactly the same situation, more so evidence that it shouldn't be the belt...

[Chris Wilson]

^ I was going to say the same thing.

OEM belts by are large are the best. I know there was some issues with Daikin (or something similar) "replacement" bands that were cheaper than Nissan OEM, thing was though they just shredded far too easily. Happened to me

Back to OEM and it was fine there after. Not exactly the same situation, more so evidence that it shouldn't be the belt...

I double checked pulley alignment, even borrowing a Gates laser pulley alignment tool. All was spot on. I got a reply from a UK forum suggesting the hard shifting of the sequential dog box may have caused belt oscillation on the long un-driven run. This made sense, for example Toyota Supras in manual form have a damper (shock absorber) on the auxiliary belt tensioner that's not fitted on automatics. I made a simple bracket to mount a cam belt idler pulley for some engine or other (4-AGE Toyota I think) to run on the back of the PAS belt. This has cured it completely, and it ran maybe 80 laps of a fairly long UK race circuit at race type speeds, with race type gear shifting. Thought I'd share in case someone comes upon this in a search. Two UK drag racers using RB26 engines have had this same issue, similarly cured. Thanks.