Rev drop and roll

[glengine]

With all of the d&r's that i've done on the rev's you keep the center to center on the clutches the same so that you can run the same stock belt.

 

[Modman]

I already have an extension kit to make it a 151" skid so basically I'm just taking a 151" and sliding it back to take up the slack of the 156" track.

I also already have a set of drop brackets for the rear which are a copy of ones that another guy I know in Washington has already put on a few sleds. Tricky part will be the measuring to relocate the front holes but looking at his, it's about a 1.5" drop and 1.5" back. I think the best way to do this is to use the rear drop plates and mark the holes on the tunnel at the front so it gets dropped and moved back the same amount. This way, the suspension geometry should still be somewhat close to stock-just lower and farther back.

I think I would use an 8 tooth if I was doing a roll of the chaincase as well, which would give the track a bit better attack angle and less rolling resistance around the drivers, but I want to see how just the drop works this winter first. Most guys I talk to say it will be fine.

Yes it will be fine. The skid setback is a great mod, sometimes people have trouble because it takes some getting used to, you will have to change the spring settings and realize that the setback moves more weight to the front of the sled, so the ski pressure is greater. You need to drop the front suspension arm down a little more to compensate for it so that the track sits level at static ride height. Too shallow of an angle in the rear and lots of clearance up front is float really well but will put all the weight on the back half of the track and on the skis, and this is where most people run into issues because the sled steers heavy and rides poorly, because its balanced on the back arm and the skis, not distributing the weight onto the track.

Even with the skid setback you will still have to adjust the transfer on the skid so that it takes the weight off the skis, otherwise there is too much ski pressure.

 

[LBZ]

........... You need to drop the front suspension arm down a little more to compensate for it so that the track sits level at static ride height. Too shallow of an angle in the rear and lots of clearance up front is float really well but will put all the weight on the back half of the track and on the skis, and this is where most people run into issues because the sled steers heavy and rides poorly, because its balanced on the back arm and the skis, not distributing the weight onto the track.

Even with the skid setback you will still have to adjust the transfer on the skid so that it takes the weight off the skis, otherwise there is too much ski pressure.

Attached is a rough not to scale pic of the side of the tunnel I quickly drew to show what I am planning to do. The blue circles mark where the new holes will be for the suspension arms. My plan is to keep it as close to the stock angle on the skid as possible-maybe a little higher at the front than the rear but not much to keep ski to skid pressure somewhat even.
Hopefully this will work out for me.

 

[Modman]

Attached is a rough not to scale pic of the side of the tunnel I quickly drew to show what I am planning to do. The blue circles mark where the new holes will be for the suspension arms. My plan is to keep it as close to the stock angle on the skid as possible-maybe a little higher at the front than the rear but not much to keep ski to skid pressure somewhat even.
Hopefully this will work out for me.

I would add slightly more drop to the front because since you are dropping it out, the skis will now take more pressure since the back is now "higher". The higher rear forces more pressure on the skis and the skis and the rear arm end up taking the majority of the load, which makes the steering heavy.

It's hard to explain because you are also moving the suspension backwards as well and that will affect your weight transitioning since the pivot is now moved further back, but the setup that I see there means the attack angle is nice but the front of the track will be just barely touching the ground, which means the sled is being supported by the rear arm and the skis. If you drop the front arm a bit more, you can always use the front limiter straps to suck it back up to get the right amount of ski pressure and weight transition, but if you don't drop it enough you can't lengthen the straps to drop it down unless you go with longer straps and a longer shock, which will affect suspension geometry. This is the common mistake people make when moving skids because they move the transition point back, but they don't realize that affects how much more drop it needs to act like the fulcrum on the pivot point.

None of this makes sense on the internet probably. It's easier to show in real life with a working suspension.

 

[LBZ]

Good point. I'll keep that in mind. Like you say, it's easier to tighten the strap as opposed to changing to longer shocks/straps etc.....

Like I said, that pic wasn't exactly to scale. The guy I got the drop brackets from did the same to his sled. I believe his front bolts were either even or a little lower than the rear.