YAM182 said:
If you broke an axle was your sled studded?
Do you brake hard and lock up the track often?
Or do you spin the track alot?
Meaning do you stay on the gas over bumps and land with the track spinning faster than before the bump?
Or go over snowbanks and spin the track and throw snow back 30 ft?
Polaris has on their race sled a slip shaft to take some stress off the chaincase/axle.
Doo also has something like this.
I've never broken an axle yet, but guys I ride with have.
We all ride the sleds hard, but I will say the sleds with broken axles are ones with slightly heavier riders (same weight as me) and they do tend to spin their tracks a little more than me. I've also seen them land with the tracks spinning under power. Not wide open at low speeds, but still under a fair bit of throttle and trying to accelerate.
We all brake very hard coming into corners, we all corner hard, and we all accelerate hard, even on rough mogulled trails.
I never used to be much into jumping, but with my 07 RTX I've been doing more and that includes landing with the track at a different speed than the ground (putting sudden torsion loads into the axle). I try to match track speeds reasonably well when I land, but if I'm trying to accelerate I don't match it perfectly (I try to match well enough to not get that loud drivetrain whine that occurs when a track lands under power). I guess we'll see if the axle breaks, but I might change it "just in case".
I think a built in slip clutch would make a lot of sense (if done right), especially with the RTX option. If you're riding at low speeds, take a big jump, and land hard on hard pack with the throttle wide open, the load sent through the drive shaft would be incredibly high. The only thing that can give a little is potential belt slippage, but Yamaha tends to run their clutches with lots of clamping pressure (so there won't be much slippage). This might be a good argument for running a highly tuned clutch kit where the belt clamping is "just right" for optimal acceleration. With just enough belt clamping so it doesn't slip normally, it would slip on a hard landing - saving the drive shaft from the huge torque that the engine's inertia is capable of.
My previous sleds also had clutch kits installed. The guys breaking axles were running stock clutching. My RTX's drivetrain is also 100% stock, including clutching...
