RX-1 121 to 155 Opinions

[winginit]

I've been wanting to extend my 05 RX-1 121 and make it into a crossover sled of sorts. Its not my primary sled, its just a project. I'm in the northeast so facts are that it will still spend most of its time on trails, but want some off trail capability. As I understand it, in its stock configuration it has a 121 x 15 x 1.25 track with 2.52 pitch and 9 tooth driver. I'm considering the following combination:

155 x 15 x 1.6 Ice Cobra 1.6 at 2.86 pitch
155" skid from a 2017 Polaris RMK AXYS
7 tooth 2.86 driver

I'm thinking the smaller diameter driver should give me the clearance I need up front for the deeper lug, and effectively lower gearing to turn the bigger track. I realize the speedo will be off but other than that not sure I would need to change sprockets, no intention of any more lake running with it. I believe that would change driver diameter from 7.219" to 6.373", giving me 0.423" more clearance.

Anyone have any thoughts on pitfalls or challenges (installation or performance) this combination might present?

Thanks!

 

[maim]

sounds like you are headed in the right direction. just make sure that you have all the mounting point info from the donor sled for the skid. i was told to measure from a flat on the drive axle or from its centre to each mount point bolt centre and include the top of the tunnel down to it as well.

brother is going to be running a 2.52x15"x151"x1.5" talon track in a 03/04 rx franken sled on 8 tooth exroverts. had it previous incarnation on a 1-1/4" ripsaw before he wrecked sled and toasted track but still had clearance for the 1.5" to go in there.

doing one on a 1990 sprint atm installing a phazer II skid witch is 1/2" narrower than the polaris skid that came out.

 

[winginit]

Thanks maim...Unfortunately I won't have a donor sled from which to measure since I'd get the skid on eBay. Been looking around to find same sled for sale in the area so I could go do some measuring. Question though...you said to measure the mounting points with respect to top of tunnel, and I get that it is a point of reference and you need to ensure you have enough clearance for travel...but, should the skid mounting points be established as distance down from top of tunnel, or from distance down from center of driver shaft? In other words, the driver shaft distance down from top of tunnel can differ between donor sled and target sled. I'd think the desired placement would be relative to driver shaft. Yay or nay?

 

[maim]

Yes tha is the desired result. In my case the sprint I am doing has 6 tooth drivers and the phazer has 8 tooth. Both shafts are mounted at different heights as well with the sprint at 9mm and the phazer at 14.5mm. I figure I will have to raise the mounting points 5.5mm ish to compensate for the different shaft heights.