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Edge Skid Swap

T
Nov 21, 2020
25
10
3
Hi there, time for my first post! I have a 2001 RMK 700 144 that I have swapped an 2004 Edge RMK 151 skid into. At the same time I added 4" rail extensions, a 162x16x2.25 3.0 pitch track and a 2 wheel big wheel kit and set the skid back 1.5". It powers it just fine and rides great. The issue I'm having is that when I ride through a dip so that the sled is only on the skis and the very back of the skid it bottoms out so hard that the track bites the rear cooler. I'm just wondering if anybody else have had an issue with the track contacting anything with an edge skid swap?
 

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BeartoothBaron

Well-known member
Lifetime Membership
Nov 2, 2017
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Roberts, MT
Were you using dimensions for the EDGE skid when you moved the mounts? JB Shocks website had those, but I can't get that to come up now. Makes me wonder if Jerry Butler (whose site it was) has retired. It could be the rear mount needs to be dropped and/or moved back, but blindly moving those around is likely to cause other issues. The short tunnel and the rail extensions are at least part of the problem. Obviously the skid is longer than the tunnel, so you may need to extend the tunnel or raise the points it's hitting out of the way. The quickest solution to the symptom is to drop the rear mount, but if it feels well-balanced, that's likely to upset it. Anyway, these are all pretty typical issues with a skid swap. I'd start by putting the sled on a stand with the track springs out so you can articulate the skid, which will give you an idea of how far you need to go to eliminate the problem. A slight drop of the rear mounts combined with running the torsion springs at their softest setting might be the ticket – just keep trying things until it works!
 
T
Nov 21, 2020
25
10
3
Were you using dimensions for the EDGE skid when you moved the mounts? JB Shocks website had those, but I can't get that to come up now. Makes me wonder if Jerry Butler (whose site it was) has retired. It could be the rear mount needs to be dropped and/or moved back, but blindly moving those around is likely to cause other issues. The short tunnel and the rail extensions are at least part of the problem. Obviously the skid is longer than the tunnel, so you may need to extend the tunnel or raise the points it's hitting out of the way. The quickest solution to the symptom is to drop the rear mount, but if it feels well-balanced, that's likely to upset it. Anyway, these are all pretty typical issues with a skid swap. I'd start by putting the sled on a stand with the track springs out so you can articulate the skid, which will give you an idea of how far you need to go to eliminate the problem. A slight drop of the rear mounts combined with running the torsion springs at their softest setting might be the ticket – just keep trying things until it works!
I used the edge dimensions then I set the skid back 1.5". At least as far as I am aware anyways. Here are the measurements I have:
Driveshaft flat to front torque arm: 8 1/2" back and 4 7/8" down from top of tunnel on the inside
Front arm to rear arm: 30 7/8" and 4 7/8" down from top of tunnel inside.
I don't have the sled that the skid can out of. And if I pull the torsion springs and let it drop onto the track it looks like it contacts the tunnel right where the extension meets the tunnel itself as well. The skid sits relatively flat on the ground as it is and I think moving the rear arm mount down would change that. Or am I wrong? Should I lower the whole skid in the tunnel?
 
T
Nov 21, 2020
25
10
3
Slight correction on my measurements above. The rear arm is mounted 7" down from the top of the tunnel as it sits right now. I think my best option at the moment is to extend the bump stop up to keep the track out of the cooler
 

BeartoothBaron

Well-known member
Lifetime Membership
Nov 2, 2017
1,233
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113
Roberts, MT
Hmmm, not sure how different the tunnels are, but using the same measurements as the EDGE might be throwing things off. There may be numbers out there specific to "'skid X' to 'chassis Y,'" but it's hard to find anything on that, and they're only as good as the person who comes up with them. The templates I was thinking of based everything around a line parallel to the ground with the sled at ride height, centered on the driveshaft, and measure up/down from that line, not the tunnel. If I remember right, the front and rear skid mounts should be level with each other with the sled sitting on level ground.

Anyway, that's all academic without the right measurements. What I was suggesting was to drop the rear mount, which would tend to raise the rear of the sled and make it heavier on the skis. By softening up the rear springs, you might be able to find a spot where it still rides acceptably, but doesn't hit the tunnel anymore. One thing to keep in mind, it may be that the skid is mounted correctly (or close enough) in terms of geometry, but that the additional length is what's getting you. If that's the case, then you're looking at either limiting the rear travel or moving the skid mounts again (which would throw the front/rear balance off). To get that much track to work without trade-offs may take more of a mod approach (extended chaincase and/or drop/roll combined with more height in the front end), but I've never stuffed that big a track under a mid-length sled; maybe someone who has can give you some more specific guidance...
 
T
Nov 21, 2020
25
10
3
Hmmm, not sure how different the tunnels are, but using the same measurements as the EDGE might be throwing things off. There may be numbers out there specific to "'skid X' to 'chassis Y,'" but it's hard to find anything on that, and they're only as good as the person who comes up with them. The templates I was thinking of based everything around a line parallel to the ground with the sled at ride height, centered on the driveshaft, and measure up/down from that line, not the tunnel. If I remember right, the front and rear skid mounts should be level with each other with the sled sitting on level ground.

Anyway, that's all academic without the right measurements. What I was suggesting was to drop the rear mount, which would tend to raise the rear of the sled and make it heavier on the skis. By softening up the rear springs, you might be able to find a spot where it still rides acceptably, but doesn't hit the tunnel anymore. One thing to keep in mind, it may be that the skid is mounted correctly (or close enough) in terms of geometry, but that the additional length is what's getting you. If that's the case, then you're looking at either limiting the rear travel or moving the skid mounts again (which would throw the front/rear balance off). To get that much track to work without trade-offs may take more of a mod approach (extended chaincase and/or drop/roll combined with more height in the front end), but I've never stuffed that big a track under a mid-length sled; maybe someone who has can give you some more specific guidance...
First things first, thanks for the your insight. I know I'm probably doing something that no one has actually done before. The mounting points seem relatively parallel to the ground. I'm currently trying to figure out a design to raise the bump stops, or limit the travel in the rear as you say. Seems like the easiest and fastest solution until I can spend a significant amount of time playing with the geometry. The other option is to lift the entire sled about 3 inches front, middle, and rear. Maybe I'll see if I can find some longer front shocks. The 1.5" set back along with the anti stab kit I installed to clear the 3.0" extroverts should let me get away with a half decent angle of attack. At least I hope... I'll report back when I come up with a solution or if I give up and just limit the travel.
 
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