Broken Speedometer key, 99 Mountain Max

D

dermestid

New member
Joined
Apr 17, 2008
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6
Age
32
Location
bellevue Michigan
So we bought this sled earlier in the summer from the Dnr up in Escanaba, It is a 1999 Mountain Max tripple 700, I replaced the trailing arms and tie rods as the previous had rusted out, Found out the speedometer was not working, took the flange off from the end of the driveshaft and found the key was broken. I know that this could be a sign that the bearing is going out but I really dont want to tear the track and everything off if I dont have to. is there a sure way to tell if it is bad without actually taking it off? I took it for a little test drive for the first time today but it is hard to tell if it vibrating as there is only 4 inches of snow and it is a little rough with 1 1/4 inch paddles! lol
 
You dont have to remove the track to take the bearing out, just loosen the 2 set screws underneath the tunnel and it comes off the end of the shaft. You can use a small drill bit to get the broken off key out of the shaft
 
Loosen the track and the speedo bearing should come out after removing the TORX head set screws. You can get at the screws between the track and the tunnel with an extension.
 
Why would a broken speedometer key mean the bearing is bad???? The bearing has nothing to do with it. Just replace the key or just ride without a speedometer for a while.
 
I read that the speedometer key is made to break off when the bearing is about to or has gone out. Well I got it out anyway and it was a little play in it so I am going to replace it just to be on the safe side, Also I think I am going to install a grease zert on the hub like Arctic Cat does just to keep the bearing good and lubed. Kinda weird though both of the set screws where missing that hold the bearing in place, now to figure out how to get the half of the key that broke off in the shaft......lol thanks for all the help guys!
 
Yamahasrx700 said:
Why would a broken speedometer key mean the bearing is bad???? The bearing has nothing to do with it. Just replace the key or just ride without a speedometer for a while.
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why it most certainly does!...when the bearing starts going out, it runs oblong, there by, so does the shaft...that puts strain on the key,keyway and cable , not to mention the speed meter(housing) itself...which incidently is what usually breaks first.
 
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Yamahasrx700 said:
The key is made to flex for a reason and the reason is not bearing failure.
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You may want to rethink that. First of all, the space between the end of the drive axle and the speedo housing is very minimal, so the key would only be able to flex very little. Also its not designed to make up the difference between to offset holes(caused by a bad bearing), its designed to flex for two holes that are in line but not perfectly parallel(not in a perfect line)

Also, another problem that will break a speedo key, is bad speedo gears in the housing. They will bind and cause a lot of stress on the key.
 
Heres a rough(VERY ROUGH) illustration of what Im trying to explain. And Im not talking about a bearing that is just getting dry from no grease, Im talking about a bearing that is about to start loosing balls!
 

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DING, DING you are correct. That's it. It is NOT for bearing failure. Its makes up for slight manufacturing tolerance stack ups and process differences... not bearing failure
 
Yamahasrx700 said:
DING, DING you are correct. That's it. It is NOT for bearing failure. Its makes up for slight manufacturing tolerance stack ups and process differences... not bearing failure
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You asked the question why would a broken speedo key mean a bearing failure and then said the bearing has nothing to do with it.

What folks here are trying to tell you is that one of the prominate signs an axle bearing has failed is a broken speedo key. A bearing thats lost or worn down it's balls no longer holds the axle centered in the bearing housing thus the end of the shaft wobbles (excessive run-out) which takes out the speedo key. The key is designed to make up for production tolerances and ease of assembly, not worn bearing rollers.

It isn't the only way to break a speedo key but the bearing is the first thing I look at for root-cause. Once the cover is off, spinning the driven end with the cable attached and looking for speedo movement would confirm whether all is good beyond the housing which in most cases it is. More than likely a bearing that has failed enough to take out the speedo key will show itself once the cover is removed but because of it's location a thorough inspection isn't easy unless it's removed.

I think most here would agree that ignoring an inoperable speedo and just riding without finding out why isn't a wise move. After all, the left side axle bearing is the drivetrain bearing that sees the most severe service and is the one most often overlooked.
 
Yamahasrx700 said:
DING, DING you are correct. That's it. It is NOT for bearing failure. Its makes up for slight manufacturing tolerance stack ups and process differences... not bearing failure
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In this post, you are agreeing that the speedo key is not designed to take up the tolerances of a bad bearing,unlike your first post that states a bearing has nothing to do with a broken key. There for you are agreeing that a bad bearing could cause a speedo key to break? Correct?


Ive had bad bearings break my speedo key on atleast 3 different sleds. Thats been my experience, along with many others on the forum.
Check your bearing,your speedo cable, and also the gearbox for wear.
 
Yamahasrx700 said:
I love the internet. Such good info all the time
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Yepp, and alot of un-usable info also.

Whats your answer as to what breaks a speedo key?
 
Sno-Xr said:
Yepp, and alot of un-usable info also.

Whats your answer as to what breaks a speedo key?
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ooo... oooo.... ooooo!!!!!

I know..... Stress!!!! LOL

sorry I had to....
 
dermestid said:
Kinda weird though both of the set screws where missing that hold the bearing in place,
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If the set screws are gone, the bearing was very likely turning on the shaft and the shaft is worn - which caused play and the key to shear. If so, you will need a new shaft or to have it resurfaced.
 
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