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Vibration at Speed?

briancampbell34

briancampbell34

New Member
Messages
10
Age
58
Location
Waterloo, Ontario
Country
Canada
Years Snowmobiling
40
Snowmobile
2019 Indy XC 800
1st post . . . 2016 Pro S 800 LTD, 8100 kilometres or 5000 miles, studded track. Has always vibrated at idle with ski tips shaking but this has never been a prob. Trip to Quebec last week, new belt installed, new 6" single carbides, tightened all studs, tightened loose track to spec tension with 1" drop with 10lb weight 16" front of rear axle. Replaced badly chunked inner idlers that run on the stud backers before trip with stock wheels. 2000km last week and both new inner idlers are chunked again, middle rear axle idler is chunked. I plan to replace with solid wheels as in the XCR.

Initially the sled was better than ever. But then I experienced a bad vibration on Day 6 at the running boards at speeds over 40kph, goes away when you punch the throttle, comes back at high speed when cruising. Threw some cogs off the belt at 160kph plus down a rail line trail, bad vibration ever since and it was likely there before the belt blow up. I did put the old belt back in as a spare. I removed the chunked inner idlers and loosened the track slightly with some improvement, but still bad.

Did not seem to experience a drop of top speed but it felt like something was holding the sled back. Rolling resistance to a stop was very minimal and maybe due to the new Hyfax installed for trip, had to use the brake more than before.

Motor mounts appear fine visually, drive shaft and cogs appear fine, jackshaft and driveshaft bearings appear fine and feel smooth, clutches run smooth and shift smooth with sled on stands, a few idler bearings are rough and due for replacement.

Sled is smooth at low speed. Sled was never as smooth at speed as Cats/Doos I ride with but it is worse now.

Your comments or advice is appreciated. I am hoping it is just the chunked idlers/ idler bearings.

Thanks!
 
Push / hold your track off the upper rear idler wheels and spin. If anything like mine, have a goose egg spot on each, explains why I can't keep bearings in em. Hoping to ride once more this season and will just fire a pair of new bearings in and replace next fall. Also moving towards XCR wheels for the rest.
Second thought, installed the greasable cover from NSP on the driveshaft earlier this season, cup was almost 2/3 full of water when I removed. Possible yours is the same, bearing could be on it's way out.
Another thought, which track do you have? From others I've ridden, the 1.25 is by far the smoothest, especially on harder surfaces / ice.
 
ZR SLEDHEAD said:
Push / hold your track off the upper rear idler wheels and spin. If anything like mine, have a goose egg spot on each, explains why I can't keep bearings in em. Hoping to ride once more this season and will just fire a pair of new bearings in and replace next fall. Also moving towards XCR wheels for the rest.
Second thought, installed the greasable cover from NSP on the driveshaft earlier this season, cup was almost 2/3 full of water when I removed. Possible yours is the same, bearing could be on it's way out.
Another thought, which track do you have? From others I've ridden, the 1.25 is by far the smoothest, especially on harder surfaces / ice.
Click to expand...

Thanks for the comments ZR Sledhead, checked the upper rear idlers and they appear fine, bearings are good. I assume you put the NSP cover on the "clutch" side of the driveshaft? I could check that bearing relatively easy by removing cover behind secondary? Seems fine when spinning the driveshaft though.

I have the 1.25, Woody's stud as installed by the dealer. Vibration was there in hardback and soft snow trails.

Do you think the vibration could be idlers?
 
Being as it improved at least some after you removed chunked wheels, for sure it's at least part of it.
Have you confirmed chain is correctly tensioned? Figured I could check close enough by rocking the secondary n checking for play, felt fine but when I removed cover for gear swap, was waaaaaaaaaaaay too loose.
Be worth having second set of hands to spin track while you watch to confirm driveshaft is not visually bent.
Did you physically get track pressure off upper idlers to fully spin to confirm round?
Back track tension off and remove the driveshaft plate to properly check the bearing would be prudent. Not a chance mine would have survived in the condition I found it.
Have you properly inspected the motor mounts? At that mileage, unless your the easiest rider in the world, can guarantee they are well sacked out. Similar miles here, raised fluted outter edges flattened by approx 1/3.
If you have electric start, also well worth the time to remove primary clutch and check ring gear bolts.
Hoping to head out to Quebec for at least a couple of days next week, if I can drag riding buddies out.
 
image.jpeg

Chain is tensioned to spec, we did spin the track and the driveshaft looks good visually, drive cogs are worn from the studs but otherwise not damaged, rear axle is out for replacement of idlers so track completely loose and upper idlers spin smooth and appear round, photo of clutch side drive bearing here and it looks new and spins smooth, no water in cup, motor mounts do not appear worn much if at all, cannot get the primary bolt to break free and afraid of clutch damage so have delayed the ring gear bolt inspection, new wheels/ bearings in later this week and I hope that fixes the vibration . . . No snow here to allow test. Might snow check an Indy 129 850, dealer is on board.

Ride safe in Quebec, if you get to go.

Thanks again for comments and let me know if I am missing anything.
 
Hey ZRsledhead (or others)
159AA8E5-E3DC-4925-80B8-C00585EBA346.jpeg
FB1DDADD-03F1-4CD1-A470-196DAFFAB2EA.jpeg
see photos of mag side motor mounts, I do get some movement when levering the motor. Good or bad or just replace since I am here?
Thanks!
 
ZRsledhead - Opened up the chaincase and you were right on the tension, way too loose compared to what you would expect to spec. It appears there is a washer with rubber inner seal “in front” of the lock washer, this washer causes the feel of the “finger right” to be distorted, clear when cover is off. I might suggest that Axys owners back off the locknut and washer so that it does not interfere with the feel when tensioning chain to finger tight and backing off 1/4 turn. Any comments on this? Am I correct or is this washer in place to avoid over tightening?
 
Sounds like what I found on my own, sorta po'd I'd missed it and had the chain way too loose. Yes need to back them well off n maybe squirt the threads with a little lube to get a better feel of exact where your at.
 
Agreed, I will replace as I have access now? Looks like Polaris has upgraded the part nums for 16 to match 18 XCR. I understand the mag side goes and can cause belt issues? Any tips on getting the silencer back in and springs on?
 
A long-ish T style spring tool and some patience makes it very straight forward. Worst one is the rear inside, mines been off twice now, no split or bleeding fingers.
 
Anything that cuts down on blood n swearing is money well spent.
 
Hope the new sled is good to you.
Enjoy.
PS, just down the road from you in Scarborough.
 
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