Well here it is. My attempt at a sticky for the 15’ 900s. As complete and detailed as I can make it, along w much help from this forum and others. Along with RZRWORKS who supplied the parts and help along the way since we both didnt really know dealing w the 2015 and it being an oddball year. So many thanks goes out to Carl at RZRWORKS!!

Machine details:
2015 900 S non eps
No intake or exhaust mods
30” kunati mongrels
Lighter primary clutch spring
Clutch kit w all weights for crawling

Mainly a trial crawler, rocks, some mud but not very often.
We ride mainly Redbird Indiana, done a cpl trips to Interlake IN, Attica badlands, Haspin Acres, and 2017 a 4 day trip to Windrock TN.

When purchased used:
Came w 29.5 outlaw 2’s so I never knew the feeling of stock tires.
Went to lighter primary spring to help with engagement low in the rpms.
Then went clutch kit to keep it tuned more for crawling.
And then the 30” Mongrels

Gear reduction 2017:
Went w info from the web, forum, youtube.
Youtube videos by Mudpuppy and solitude customs.
Ordered Ace 325 gears ($200ish)
PN 3235480 48T stage 2 gear
PN 3235451 25T reverse shaft
Which gives roughly a 27% low reduction.
This was a much welcomed reduction. I went to Windrock TN. The lighter spring, gear reduction, and 30” made crawling much more useful without the constant on/off throttle. It def was an improvement over stock. It made crawling and trails easier to tackle yet still had enough speed in Low to top over 40mph.

*With this I can not comment on High gear since after the reduction It would not engage. I assumed the clip must have come loose and high gear slid over. Upon disassembly, that was not the case. All looked fine. All clips, bearings, gears etc in place. So, not real sure why I didnt have high gear. Simply felt like P, R, N, L, N.
But, with still doing more than 40 in Low, I didnt really need H. Though lower rpms on main trails would have been nice.


Late 2017, I contacted Carl about his reductions. After some talks, it was identified that he in fact had reductions for the 15 n up. But the 15 being a bastard year has a different input shaft in the trans for the secondary. So we discussed it and determined that one may be able to do a 47% reduction but a few things needed to change. And some things were unknown at the time. So heres how it shakes down.

-Parts NEEDED for the reduction:
47% gear reduction kit from RZRWORKS
16’ or newer trans input shaft.
Low and high gear
I went w the wider reverse chain
Kit also came with new input shaft bearing. Federal Mogal (national) PN 206

-Parts also ‘NEEDED’ but not in kit:
16’ Washer PN 7556130
16’ Clutch bolt PN 7519285
16’ Input shaft seal PN 3235495
16’ or newer secondary clutch PN 1323298

2x 15’ Rear output shaft seals PN 3235052
(Replaced while trans was apart, not really ‘needed’ but might as well)

Belt rides motor side slightly.
Used the same belt from before
Gates: C12 #24c4140
Belt to outside of primary is 145ish thousandths. So divide by two to center. So a 50-60 though shim between trans and motor would center it a lil more but as far as pics and videos I took and sent to Carl, we have determined it should not be an issue. I even verified the alignment with a 16’ 1k in the same garage.
Also it was started and ran through the ranges from park to high and all seems to work just fine. (Thank god bc I believe H will come in handy with this much reduction.)

Noticeable differences:

Rpms for max speed

Max speed

My take on the new crawling ratio:

Not fully completed with all the information yet. At work on my phone so Ill get more details and edit as I go. But for now this is the teaser.

Utah RZR Rentals