Transmissions

So a couple weeks back this happened:







Short story is too much skinny pedal. Should have broke an axle before the trans but oh well. The bean counters at Polaris denied warranty I already had planned on building a crawler transmission anyway. I found a donor trans from a '18 XPT4 with 300 miles for $1600. I did some digging into Polaris OEM gears and what model uses what gears. It turns out there are numerous gear ratio possibilities. I ordered a combination of ACE & Rangers OEM gears that I will be swapping into the new trans. High & reverse will have a 12% gear reduction and low will get a 51% gear reduction. These are the same gears some companies are selling for 2-3x the price. I have about $350 in four OEM gears. A dimple 2 gear swap netting a 12% cost just $203. If anyone wants to know I'd be happy to detail the assembly or provide info on the possible gear reduction.

While I'm at it the driveshaft will get balanced / phased, new greaseable U-joints, and greaseable carrier bearing.

Yep Polaris warranty sucks. Good luck with the build, it will be cool to see how it does when you are done. keep us posted and take pics as you go along

My dealer quit issuing Polaris warranty's a few years back. They sent out bids to other company's who would not give them any problems. They have a warranty like the first Polaris warranty was. Everything from bearings, ball joints, axles etc... are covered. NO coverage on tires, brakes, belts and hoses though.

holy shit.....!! that's a new machine, that's bearing failure, then it started  braken the teeth off the gears ,, anybody can see that. all them gears are in the top of the trany so if something breaks it will fall to the bottem and not run through the gears. also you want to keep the trans full of fluid so the bearings get proper oil.

Update: I've been a bit busy lately but did manage to get the new trans built. While no expert I have learned a lot about them as of late and what can be done to them.

For time constraints I skipped micro-polishing and heat treating. However, I can see where micro-polishing would be a huge benefit given how rough cut the OEM gears are from the factory. There are also spots where the inside of the trans could use some series deburring, the casting are very rough. Over the winter when I have a bit of time I'll dig back into it and get these done.

There are several subtle internal changes from year to year and between the 2 and 4 seaters. The 18 XPT4 are geared higher than the 2 seaters. The 16/17 XPTs use a one piece input shaft as compared to an assy on the 18+ XPTs. So if you want to change the low gear only on a 16/17 you will need a 18+ input shaft and associated gears. Knowing the slight differences makes multiple gear options available.

I was after the lowest gearing possible in LOW without going to portals. I started with a 18 XPT4 trans that was in excellent shape. Replaced the OEM bearings SKG bearings with the exception of the two on the snorkel gear. These should be submerged in oil 100% of the time and have not been an issue on the XPTs. Backlash was tight and the seals in great shape so I saw no need to change them. However, I would change them on the 1K trans.

Parts:
SKG bearings

OEM parts:
#3235450 48T Stage 2 Gear
#3235451 25T Reverse Gear Shaft

Commonly referred to as the ACE 570 gear set which nets ~12-13% reduction across all gearing.

#3235232 67T Low Gear
#3236132 25T Low Gear

These are from a Ranger 1K and net ~36% in low only.

Combined changing these two gear sets resulted in:

~13% R & H
~57% L
These numbers are from bench testing the trans before and after gear swap. This is crazy low but that what I was looking for in low gear. And the reduction % is only relative to the 18 XPT4 trans. Other models will differ as their starting ratio is different.


Instead of using the Ranger gears if you use 18 XPT gears (2 seater) the result would be ~13% alone or combined with the ACE gears ~26%.


Stock 18 XPT4 gear left vs 67T Ranger on right






Hopefully I have time to put it this week. Had to wait on a few ordered parts the dealer was so kind as to forget to give me back from warranty inspection.

More to follow later....

Great info.  I know I would love some lower gearing.  If for some reason I have to pull the trans i will definitely be changing the gears.

Joe all i can say is, FANTASTIC write up. I know I've, " picked" on you in the past, but that's cause i know you. This is what makes a web forum. Kudos.

Great news Joe, and just in time.  Your tire guy said your new tires are ready for pickup.

Great write up joe,thanks for posting it. Sorry you had the trouble but it sounds like you’re going to come out even better than stock.

crs wrote:

Joe all i can say is, FANTASTIC write up. I know I've, " picked" on you in the past, but that's cause i know you. This is what makes a web forum. Kudos.

It's all good brotha, I think I've pulled that Canned Ham out a time or two

Gimpy wrote:

Great news Joe, and just in time.  Your tire guy said your new tires are ready for pickup.

Those are more suited to Chad's jeep

Joe are you going to be back together in time for the October ride?

hillbuggy wrote:

Joe are you going to be back together in time for the October ride?

All finished! And when I say low is low, I mean LOW. Quick bench test around the property and on jack stands everything works well. The real test will be this weekend at Black Mountain

RZR_Joe wrote:

crs wrote:

Joe all i can say is, FANTASTIC write up. I know I've, " picked" on you in the past, but that's cause i know you. This is what makes a web forum. Kudos.

It's all good brotha, I think I've pulled that Canned Ham out a time or two

Well now next time,,,you'll be able to do it better. Good job, you are now my go to guy when i think,,,,," well, they went this way,,,,what if,".