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Discussion Starter · #1 · (Edited)
In case you are wondering what exactly is going on with the front diff and why a new driveshaft fixes it, this video is the best I have seen that explains the problem.




Notice how little he moves the yoke when he changes the phasing, and how much of a difference it makes


Tim
 

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That's it in a nut shell! Thanks for posting!
 

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Well Cowracer...that was posted about two years ago by yours truly. Its the reason I spent $900 on the CCI Driveline driveshaft set with three CV-Joints and a different carrier bearing.

The video does an excellent job of explaining how "phasing a driveshaft" reduces noise and vibration. Here's the catch tho...it only works in one plane. If you watch the video all he's working with is vertical issues.
Like a 4x4 truck. The rear axle pinion gear is directly behind the output shaft of the transfer case. The front axle pinion is way off to the passenger side so that it lines up with the front output shaft of the transfer case.

If you crawl under your general, with the skid plate off...you will see that the transmission output shaft is pointed down about 10 to 15 degrees. The rearward section of the driveshaft has a U-joint at the transmission and then goes forward and passes through the carrier bearing. But wait...the carrier bearing is not directly in front of the transmission output shaft. So the driveshaft has an offset in the vertical...the tipped down output shaft and a horizontal offset from the output shaft to the carrier bearing. You cannot phase a driveshaft in two planes.

Looking at the forward section of the driveline there is a U-joint where the driveshaft connects to the rearward section, just forward of the carrier bearing. Then it goes even further over horizontally to the Hilliard differential and the pinion shaft is tipped down 10 to 15 degrees. So this shaft has two U-joints one at the carrier bearing and one at the Hilliard differential. No help. The driveshaft has a vertical offset and an even larger horizontal offset. Again, you can't phase a driveshaft in two planes.

How this got lost on the Polaris Engineers is beyond me. This is what led to CCI Driveline, who does all kinds of driveshaft work, to make the set with three CV-Joints. A CV-Joint with either 5 or 7 balls can handle offset at about any angle. So you put three in the driveline and there is no vibration due to the old style with three U-Joints.

So, going to the CV-Joint driveline took out all the noise and vibration from the shafts.

The Hilliard differential can be noisy and vibrate due to large internal clearances. What clearances??? Jeff Robbins at JJandA Racing Products has perfected the blueprinting of the Hilliard differential. Jeff keeps his process proprietary. But he will tell you that he's seen some with clearances as large as .030" to .045" and cuts that to 0.0005" that's right half a thousandth. Where is this clearance?

Since Jeff owns a significant CNC machine shop... I believe that clearance is between the output hubs, the rows of rollers in the cage, and the internal slopes of the ring gear. The output hubs are a good piece of workmanship. Probably pretty close on OD from piece to piece. The Ring gear is a cast piece that is then machined. How accurately machined? I dunno. Then the rollers, produced by the thousands. Accuracy of the OD? who knows. So if Jeff takes measurements and then CNC produces a set of rollers for your differential...then he can achieve that 0.0005" clearance and give you a smooth quiet differential.

Jeff also offers a number of upgrades that also contribute to the smooth working of the differential. A better cage for the rollers, and upgraded armature plate, and upgraded coil...and probably one or two I can't remember off the top of my head. Mine with all the upgrades cost $469. I got my General home on May 20, 2016, backed it off the trailer, pulled the front diff and sent it to Jeff.

He did my 2009 RZR 800 Hilliard differential and the change was amazing. Never hear it engage or disengage, just nice smooth, quiet operation.

So there's a bit more to think about!

Pirate
 

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Discussion Starter · #9 ·
Well Cowracer...that was posted about two years ago by yours truly.

Well congratulations! Go have a half-day off.


Tim
 

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Sorry Tim,

Did not mean to piss anyone off.

Its a good video, there are a number of them on YouTube. But none really talks about what happens if you have offset in more than one plane. So I took a little time to write up what I went through to figure out what was going on, and what could be done about it.

Again, my apologies.

Pirate
 
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