melted jack shaft

S

saythey

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Mar 13, 2008
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CANADA
I am guessing that the bearing went on the clutch side and got hot. It looks like the jack shaft melted and broke. Now I have to replace the jackshaft and secondary because it cracked when the saft broke. My question is when I replace the bearing, jackshat and secondary do I have to realign the clutches and if so how?
 
2000 700 SXR The shaft did not have a clean break. It looks like it got hot and spun and melted in half
 
I've seen something similar years ago on a gravely tractor. I brought it into work and let our failure analysis engineers look at it. The melted look was from galling of the metal as it spun and the consensus was that the shaft had an internal defect when new that caused a stress concentration at that point within the shaft. The break was conical in shape.
 
Saythey - no one really answered your question so yes, you are going to hav to re-align your clutches once you have everything back together IF you just unbolt everything without either measuring from the bearing journel (housing that the bearing is in) to other parts of your sled or by tracing around the journel with a sharp object to that you get it back in the exact same place. If you have already taken everything apart then you are going to have to re-align the clutches. All of the spec for clutch alignment should be listed in the tech page undet "Stock Yamaha Snowmobile Spec" and then under "Sheave Ctr to Ctr" and "Sheave offset" for the model and year of your sled.
Measure center to center by measuring from the center of the bolt holding the primary clutch to the crank shaft to the center of the bolt holding the secondary clutch to the jack shaft. However the measurement device you use needs to be parallel to the face of the primary clutch. You measure offset by finding the centerline between the sheaves on each clutch and then measuring the distance between the two centerlines. A clutch alignment tool from Dennis Kirk is your best bet for getting everything measured right.
Hope this helps.
Mills
 
If the bulkhead where the bearing went out isnt chewed up it should align exactly as before. The jackshaft is tightened down by the gear in the chaincase so you shouldnt have to align anything. it might be a good idea to take a look at it but in theory nothing should change. tighten down the gear in the chaincase then tighten up your bearing collar and set your set screws (with locktite) on the bearing and you should be good to go. I never melted one but Ive blown a few bearings and had the set screws come out once and the bearing wore halfway through the shaft. good luck
 
i have had my track balloon enough where my studs grabbed the tunnel an it snapped clean off an thru me over the bars grass draggin
 
jackshaft

BBlueSRX said:
If the bulkhead where the bearing went out isnt chewed up it should align exactly as before. The jackshaft is tightened down by the gear in the chaincase so you shouldnt have to align anything. it might be a good idea to take a look at it but in theory nothing should change. tighten down the gear in the chaincase then tighten up your bearing collar and set your set screws (with locktite) on the bearing and you should be good to go. I never melted one but Ive blown a few bearings and had the set screws come out once and the bearing wore halfway through the shaft. good luck
Click to expand...
X2 ,checked alignment it was right on.
 
Snapped a jackshaft right behind the brg.The Sec. just fell off and didn't hurt a thing but the belt.Stuck in a used shaft and drove it.That was about 3 years ago.Still driving it with no problems.
 
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