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Discussion Starter · #1 ·
Hello!

My brother recently bought a Summit 800 Etec 2013, sled has approx 4500km, i'm new to those machines but learning quickly. I notice it vibrates alot at idle, so much you see the enging shakind and primary clutch kinda bouncing around. But as soon as you give some gas, lets say go to 1500-2000 rpm it runs smooth it's unbeleivable! Nothing like my GTX 550F which runs really smooth.. It seems to be "normal" for those machines from what i've read on forums in the last days.

I got a shop manual with specs for crankshaft measurements, but i did not have time to check with the clutch removed (had a day do a "tuneup"), i used a dial gauge to check the crankshaft runout, but on the outer part of the clutch (lets say top drum) and got .030" which i consider alot, but could not find any specs with the clutch, only on the crankshaft itself.

Anybody got measures, or at least do you guys think we can finish up the month 1/2 of riding season without blowing anything? (mostly trails, some lake fun and woods exploration, nothing too crazy lol)

Thanks!
 

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You need to remove the primary clutch and measure the run out on the center of the crank taper.

My guess is your primary clutch has not been indexed properly to the crank.

And the torque stop on the front left side of engine mount...needs to be set up tight.
 

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Engine spport(s) might be kaput.

You also mentionned reving to 1500rpm, what is the idle speed of the sled ? Sound low to me if you have to rev it to 1500
 

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Most do at low rpm...resonant frequency vs excessive runout are 2 different things. if it gets better with RPM it is likely fine. If it got worse with RPM that is a bad sign. Worth checking PTO runout with that many km's just for peace of mind. A worn clutch will also show more shake at low RPM, or possibly sacked out motor-mounts.
 

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Most do at low rpm...resonant frequency vs excessive runout are 2 different things. if it gets better with RPM it is likely fine. If it got worse with RPM that is a bad sign. Worth checking PTO runout with that many km's just for peace of mind. A worn clutch will also show more shake at low RPM, or possibly sacked out motor-mounts.
I agree with the clutch wear

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0.030" runout on anything is an obvious problem. It doesn't even fall in the grey area. Keep plugging away at it and you'll find the cause.
 

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Discussion Starter · #7 ·
Thank you guys! I'll see how to get the primary off to correctly check crank runout when time allows,

Will also check motor mounts that i can access in the field since the sled is now gone from my garage. From memory warm idle seems like 1250RPM, when it really vibrates, then with some more speed it runs smoother than my 550F lol

Clutch will probably be redone before next season, will buy some speciality tools for those machines and my atv's ..
 

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Took my 15 to the dealer for the same issue when it only had 400km on it & still had warranty as all my buddies XM's didn't do it. They pulled my primary & put it on a different sled & it was smooth & the new primary wobbled like me after a case of beer! The result was Crank Runout & they got approval from BRP (surprisingly) to change the Crank. Here's the catch...BRP said that the runout has to exceed the allowable amount of runout which I cant remember what it was but it was high, or I would be on the hook for the labour which was 4 hours at $140 p/hr plus tax to do the test. They then told me that none of the previous complaints were bad enough for approval so I opted out & now have 3000km problem free so far.
 

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Took my 15 to the dealer for the same issue when it only had 400km on it & still had warranty as all my buddies XM's didn't do it. They pulled my primary & put it on a different sled & it was smooth & the new primary wobbled like me after a case of beer! The result was Crank Runout & they got approval from BRP (surprisingly) to change the Crank. Here's the catch...BRP said that the runout has to exceed the allowable amount of runout which I cant remember what it was but it was high, or I would be on the hook for the labour which was 4 hours at $140 p/hr plus tax to do the test. They then told me that none of the previous complaints were bad enough for approval so I opted out & now have 3000km problem free so far.
Good story! In the last several months or so, someone did mentioned the maximum allowable runout which was surprisingly high and much higher than what is shown in the Shop Manual.

I got lucky and managed to Google the thread I was thinking of. The two things that came out of it was 5 thou was still acceptable, one owner had his crank replaced @ 12 thou, and by the end of the 2018 season BRP was changing the maximum allowable runout and 9 thou was refused. I am beginning to wonder if 10 thou has become acceptable under warranty.

https://www.dootalk.com/forums/topic/1544863-crank-runout-800-etec/
 

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I had a Polaris with 0.011" runout. PTO rod pin was visibly walking out of the crank wheel when I pulled it down. Imminent failure there, though it still ran fine, just put your hands to sleep.

My '13 Doo stayed steady around 0.003" until about 5k miles, when it climbed up to over 0.005" and had noticeable shake. With a reman trued crank and balanced clutch, it was crazy smooth, measured within 0.001"
Just checked last night after about 2k more miles, it's back up around 0.0035" runout, still super smooth though.

Edited to add: when the g4 clutches were first discovered to have that crazy runout built into the fixed sheave, I measured my fixed sheave runout out of curiosity. It was 0.005" near the outer diameter (about 4k miles at the time), same for the 2016 m8000 sitting next to it with 1600 miles. Neither sled has ever grenaded a belt. 0.030" sounds pretty bad..
 
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