Belt drive problems/troubleshooting

[Passelat]

I am reacthing out for some help/tips at troubleshooting on my C3 Syncrodrive.
I have been running the Syncrodrive on my 13 M800 for some years without issues, and this season I decided to switch the Syncrodrive over to my dragsled 12 XF 1100 turbo, and having problems now.

Installed it with a SSI/BDX Titanium jackshaft and new SKF 2206 bearings (sealed and self alignment) in both ends. And new SKF sealed 6009 bearings in both ends of driveshaft.
Did also replaced my motor mounts with some adjustable polyurethane mounts from Hi-tech Engineering, and then adjusted/aligned the engine/clutch parallelism to 1mm.
Machineered a shim behind the hub (top gear) and made sure that the gears was aligned too.

The problem comes when I ride it, when going at steady speed or low resistance the belt is sitting perfect at the gears. BUT as soon as I go harder on the throttle and the resistance/load from the track is rising, the belt is going more and more side ways out on the top gear.
Did have a couple of "holeshot/take offs" and the belt smacked the guide plate so hard that it bent, as you see in the pictures.
I'm very frustrated because I dont see the issue that makes my belt to do that.
I appreciate every help!

 

[IDspud]

I had one doing that earlier this year and finally put a square on my idler block, was warped. Threw on a new one and ran three hundred miles no issues since.

 

[Teth-Air]

Is there any movement in the bearings If that shaft moves at all the belt will follow it.

 

[Passelat]

I had one doing that earlier this year and finally put a square on my idler block, was warped. Threw on a new one and ran three hundred miles no issues since.

I will then take a deeper look into the idler block when I get back home again from work.
I've notice that the idler block/tension wheel is not pushed against the inner chainhousing like it sits now, when was running the Syncrodrive on my M800, the idle block was squeesed between the inner chainhousing and bracket when the torx screw's for the bracket where tensioned.

Is there any movement in the bearings If that shaft moves at all the belt will follow it.

I've not notice any movement. Movement is my first thought that comes to mind when I am having this problem here, either from any of the shafts or motor itself. I can not provoke any unusual slack or movement, it feels actually very thight. Very frustrating with this problem because it looks and feels good wherever I check around on the sled.

 

[IDspud]

My block end was mushroomed out of square just a hair, but it allowed the pulley to lean forward which allowed the belt to slide towards the end of pulley, even made some belt marks on inner wall which weren’t visible until I cleaned it when installing new block. They’d been dusted over by belt dust.
I never would have caught it by assembled visual inspection.

Was minimal enough with square my thought was no way that’s my issue, but it’s the only thing left to troubleshoot. Was definitely the issue for mine.

I’m pretty sure original owner installed new belt way too tight and caused it based of some of my conversations with him.

 

[Teth-Air]

The motor mounting should be independent of this problem. It has to be your jackshaft or driveshaft moving so that only leaves the chassis or the bearings and their retainers.

 

[Passelat]

One thing that comes to mind when talking bearing, is that all my new bearings on both driveshaft and jackshaft do have C3 clearence. I am not quite sure what clearence stock/original Arctic Cat bearings are, but if Cat uses standard clearence, mayyyybeeee that could be something that effect my belt drive???

 

[boondocker97]

Bearing clearance shouldn't be enough to cause this issue. If everything is square with your tensioner I would look next to the Ti jackshaft. Aside from torsional forces along the axis of the shaft there are bending forces present as well (think clutch end being pulled toward the crankshaft and belt drive end being pulled down). Ti has a lot of flex and under heavy load it's going to want to turn the shaft into a "C" shape. Especially with self-aligning bearings at each end there's nothing to help fight the flexing.

 

[summ8rmk]

The motor mounting should be independent of this problem. It has to be your jackshaft or driveshaft moving so that only leaves the chassis or the bearings and their retainers.

Remember, cat has the TCL (the only solid mount for the jack shaft) locking the engine to the jack shaft.
If the engine moves, the jack shaft moves and vice versa.

Sent it

 

[kiliki]

you could have a bad motor mount on the recoil side upper. this would let the motor move as mentioned above^^

 

[Teth-Air]

Remember, cat has the TCL (the only solid mount for the jack shaft) locking the engine to the jack shaft.
If the engine moves, the jack shaft moves and vice versa.

Sent it

Yes you are right, I was thinking of the Polaris design.

 

[Passelat]

Did hold my square angle tool up against the idler block from every angle, and the block is straight and not out of spec.
Then I replaced the TI shaft with a 2012 M800 jackshaft I have laying around, and now the belt stays in place!
Had first some pulls on the jack stand with the brake on and then went out for some short runs at the grass fields (snow is all gone down in the valley now), all the testing were done without the guide plate on the top gear!

Just purchased a heavy duty jackshaft from BDX. Looks like this is the only one with longer splines that will work well together with the belt drive. All others from Taylor, STM and Belanger does use stock lenght at the splines.