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Author Topic: Help! Downshift gone bad!  (Read 293 times)

MTchuckles

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Help! Downshift gone bad!
« on: September 04, 2013, 04:56:22 PM »
I was commuting to a meeting today and climbing a hill in 5th. As I lost power and got down to 60 I down shifted to 4th and felt/heard a terrible rattling/wobbling. I immediately went back to 5th.  But now I randomly get this terrible stutter from the drive wheel in any gear.  It feels like I broke the clutch or screwed up the drive chain but I can't see anything external. Any ideas?! I'd like to have this somewhat figured out so I can decide whether its safe to ride home.
« Last Edit: September 04, 2013, 05:04:03 PM by MTchuckles »

mrunderhill1975a

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Re: Help! Downshift gone bad!
« Reply #1 on: September 04, 2013, 05:11:22 PM »
Could be a number of things, but, I had a wheel bearing fail which acted that way, it was the rear wheel sprocket bearing.  It's symtoms were: 1) a "ballsy rumble" noise when the bike on the centerstand and wheel spun, 2) The rear wheel drive spocket had side to side play of about 1/8th inch.

Other things it could be: rear wheel lock nut is loose and tire rubbing on chain stay, or rear wheel out of alignment, or broken brake return spring activating one shoe.

If the clutch has the innermost plate inserted the wrong way, the ball bearings in the clutch basket will pop out and start bouncing around the primary chain case (ask me how I know).

Arizoni

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Re: Help! Downshift gone bad!
« Reply #2 on: September 04, 2013, 10:48:37 PM »
Another thing it might be is a bad "cush drive".

This is a multi-piece rubber insert that is in the rear hub.  It's job is to cushion the drive from the sprocket to the rear wheel hub.

I think it can be checked by placing the bike on the centerstand with the rear tire off the ground.
Placing the transmission into any gear, try rocking the rear wheel forward and backward.
It may move a little but there shouldn't be any noise.  If it gives a "clunk-clunk" sound, remove the rear wheel and visually check the condition of cush-drive rubber pads and the 4 cast webs it rests against.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

MTchuckles

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Re: Help! Downshift gone bad!
« Reply #3 on: October 03, 2013, 11:36:37 PM »
Thanks for the tips guys, and I apologize for the late reply/update.  Luckily I had tools on me, so when I got to town I pulled the rear wheel and realized the chain had indeed become loosened.  I guess the sound was it swinging and hitting the tire, and the popping/jolting was it skipping teeth on the wheel.  Has this ever happened to anyone before? I know chains stretch, but I wouldn't have thought that they would loosen that badly...

On a side note, I have recently discovered a few pinhole leaks in my tank along the welds.  Does anyone have opinions on whether I should buy a sealer epoxy, or whether a full new tank would be worth the gamble.  I took it to a welder in town and he said the metal was just too thin to fix with anything he had.

ace.cafe

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Re: Help! Downshift gone bad!
« Reply #4 on: October 04, 2013, 12:34:47 AM »
Caswell's Plating makes a very good tank sealer that is impervious to the fuel and alcohol too. It's a mixture that you put in the tank and roll the tank around to get the whole interior coated.
We have used it with good success.
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