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Part 1



I replaced my OEM Polaris tranny with a DuraClutch and I thought a few of you might like to see what's under that black plastic cover next to your engine. If you have a Polaris Razor, the parts are virtually identical.



Here is the DuraClutch installed but, the OEM transmission looks very similar. The PRIMARY is on the left. It is bolted to the motor output shaft. The pulley on the right is the SECONDARY. It's connected to the transmission input shaft and drives the gearbox which, drives the wheels via the half shafts on the rear and the driveshaft to the front end and the half shafts to the front wheels. Notice, at rest, the belt is low in the primary and high on the secondary. Remember your 10 speed bike or offload bike derailleur: When the chain was all the way out on the rear cog you were in first gear. This is how the transmission gets the most torque to the wheels to get you, mom, and the kids rolling from a dead stop.






Here is the actual OEM primary and secondary on my workbench. The primary throat is open all the way because the sheave is retracted all the way. (More on "sheaves" in a minute.)
The secondary is about to fall apart so the pulley looks bent. I needed a third hand to hold the secondary sheaves closed but, you get the idea.






Here is the primary as veiwed from above. The shiny tube in the bottom of the pulley "valley" is the rolling ring which gives you neutral when you get down to about 10 mph and start "coasting." The belt continues to be driven by the secondary as the wheels turn the transmission but at low RPMs, the primary sheave slides so far back (in this picture, to the left) that the belt falls to the bottom of the valley and just spins around as you coast to a stop. This is also the little devil the belt is riding on when at five mph you decide to accelerate again and suddenly you get a big JERK. The sheave moves over making the valley smaller and the belt gets pinched. With the primary (motor) saying GO NOW! and the secondary engaged on the belt, the result is a jerk as the belt has to get synched. One pulley is going fast (motor) and the secondary is going slower and the belt gets caught in the middle.






Here is the other end of the primary. It's basically a big spring and fly weights that keep the valley as wide as possible (coast or neutral) and as RPM increases, the valley gets squeezed as the moving pulley half (the sheave) makes the valley smaller. The belt will climb up from the bottom of the valley as pressure increases on the sheave, as RPM increases and the counterweights mash the sheave fully closed. That is top gear for your primary.






This is the outside of a Polaris OEM primary. They are fairly robust and can last 5000-8000 mi or more if treated carefully. Except for some rubber dust, after 3000 mi, this one is almost like new and ready for plenty more mileage.



 

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Discussion Starter #2
Part 2


The weak part of the Polaris OEM transmission is the secondary. Mine was starting to squeek and squeal and I decided it was time to swap to the DuraClutch. When I got my secondary off, I was surprised to see it in nearly original shape. If you have experienced the "singing" sound at 5mph this is the culprit. You can tap this secondary with a screwdriver and it rings at that same frequency the squealing is heard at. the squealing is normal when the belt is low in the valley and all the extra metal on the outer pulley halves rings like a wine glass when you wipe your wet finger on the rim.


Here is the secondary as viewed from the side. the upper part in my hand is the mysterious moving half of the pulley, called a "sheave." It pinches or releases pressure on the belt based upon vehicle speed. Wide valley=Low gear (belt riding low). Narrow valley=High gear (belt riding high)...



The secondary falls apart in your hands. Here are the two halves in the bench, belt side up starting with the fixed side, closest to the tranny. Note the radial groove cut deeply into this piece...





This is the sheave half. The little rollers ride up and down on the spiral cut in the fixed piece (above). After 3000 mi, my rollers are a little worn. Notice both parts: Mirror finish on the belt contact surface and hardly any wear on the spiral groove.





Here is my belt (lower one) next to the brand new belt that came with my DuraClutch. Notice my belt with 3000 mi looks hardly worn...





A close up of the belt shows no burn marks or scarring... This belt could probably do another 3000 miles.






My point in identifying the relative health of my OEM transmission is not to say you should get the same wear and mileage I did. My ute spends most of its life in high gear, on my ranch (fairly flat) or blasting to the mailbox or downtown on the street. I occasionally haul a 150 lb grading sled in low to smooth my driveway. All in all, the OEM transmission has held up with the weakest part being the secondary. A nearby friend bought a used 900 XP and it had a loud "TICK-TICK-TICK" as you drove along under power. He discovered his secondary was totally trashed when he pulled them off to install the DuraClutch.



I always wanted to move to the DuraClutch and did so when my ute started mild surging at a constant 15 or 20 mph. I think the secondary sheave may have worn after sliding in and out for 3000 miles and the sheave is not always squeezing together parallel to the other half of the pulley. Could be the plastic roller wear. Anyway, this OEM setup will likely go to someone who wants to replace a worn primary or secondary. These parts sell readily on ebay. A zero-time brand new secondary from Polaris runs about $350.


Hope this helps folks understand how their transmission works. As the tech folks will point out, the actual transmission is the metal gear part bolted to the engine that the secondary connects to. This setup is technically a torque converter (exactly like my 1971 Rupp Enduro had when I was in high school) and the belt serves as the clutch mechanism as the sheaves pinch it and release it under way. Anyway, hope it helps.


I'll do another article on the DuraClutch installation and my experience afterwards...
 

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Great write-up, CCRay! Thanks for taking the time. I'm just going through a new to me '13 Ranger 800 EPS. First thing I did was purchase a service manual and tune-up kit on Ebay. There really is a lot of service to these machines and I suspect many of the problems owners complain about is due to service neglect. The few times I ran it before I read the manual, I would fail to completely stop before shifting out of 4 wheel or from low to high. Now I know why.
Looking forward to your next installment! Thanks again.
Steve
 

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Hi guys I have a polaris ranger 325etx and trying to source a steering rack assembly and 2 front ujs prop shaft joints without going to the dealers (far to dear) any ideas am also on Scotland any help would be great thanks
 

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Hi, Find Polaris UTV parts online. explore our wide collection of Polaris UTV parts to completely transform the look and performance of your UTV.
 
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