I went riding on Sunday, and about an hour into the trip I noticed a noise at a certain speed. Sounded like a broken pipe spring. It only did it at a certain speed/rpm. We looked and the only thing we saw was the left side universal yoke that goes onto the splined differential shaft had a little play in it. The u-joint is ok, and the roll pin is in, but it wobbles a little. I took the differential out today to check for any problem, and it feels fine. The diff. oil was good, no shavings on the magnet, and no excess backlash or end play on the differential input shaft. The ring gear shaft does have lateral movement, but that seems normal. I have an extra front shaft with a u-joint on it and it did not seem to wobble as much as the one on the quad.

I suspect the noise is from the yoke vibrating on the splined shaft, but am unsure if this is my noise/problem. There is no vibration felt or noticeable with the noise, which makes me think it is not drivetrain related. The noise is only there when under load, not in neutral at any rpm.

Any input from others who have weird noises or from others who can tell me if their front end has the same loose yoke, or heck...I'll listen to anyone who knows something about what could be wrong. I have a Polaris shop manual for reference, and the local dealer knows absolutely zippo, just says,"Bring it in and we'll take a look."

Thanks in advance.

 

I dont know if you tried this or not but have you tried lifting the quad off the ground and running it. Its alot easier to look for stuff like that when your not riding it. Good luck.

 

I ran it with the front and rear elevated, no noticeable noise. I am concerned, but not overly, because we rode really hard and had no problems. The noise was there sometimes, mostly under hard throttle, and only at a certain rpm.
The AWD worked flawlessly, as it usually does, I went right through mud 12"-18" deep no problems, and my buddies on their yz250's couldn't believe it. The Sc400 is really an awesome quad. I got my Ritter kit today, stage 1, split brake and reed cage, got the quad apart, just gotta start popping on the parts.

 

Mine does it to it wolblesaround after racing a warrior around the track ang i got sideways and that tire tire a rock and it poped and i looked down there and everything was still attacted. So i keep goon and it was makin a noise it was comin from down there and what u explained happened is goin to with mine to.

 

Check the bearings in the wheel