426 tranny..


3 replies to this topic
  • yogist

Posted May 14, 2006 - 11:43 AM

#1

Ive read a few posts about people losing gears on their 426s...

I found a chip of metal on my magnetic drain plug last oil change, has me concerned..

Why are the gears crapping out on these bikes, and are the new ones prone to this, Or are the replacements, Harder, more reliable...?? I thought I read somewhere the the new gears were shotpeened more to firm them up..

Has anybody had a rebuilt tranny fail again..??


Ran the bike today ..Ran great, Ill check the plug here soon to see if theres any more metal..

  • 2wheels-drz

Posted May 14, 2006 - 02:15 PM

#2

what size was the chip? if its small then its just normal wear.

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  • grayracer513

Posted May 14, 2006 - 02:56 PM

#3

Most of the failures I'm aware of are basically a wear problem on the locking lugs on the sides of the gears. They are built with a slight undercut, or dovetail, so that they hold into each other under a load. Over time, the lugs wear, chip and round over to the point where the undercut is reversed and they pop away from each other under a load. Usually, they re-engage immediately, because the shift fork has not moved, and you get a jerking, harsh, slip/grab feel in the offending gear under hard acceleration. This is hard on shift forks, and usually bends and wears them excessively, which makes matters worse, of course. The bent shift fork can sometimes be the root cause, but it's always one of those chicken/egg questions. Some gears break one or several teeth off, but IMO, it still probably started as a popping out/in problem, and the resulting beating broke the gear.

I don't know for certain whether the replacement parts have been improved or not, but know good machinist would ever advise shot peening a finished part. You'd have to refinish it afterward.

  • yogist

Posted May 14, 2006 - 03:47 PM

#4

what size was the chip? if its small then its just normal wear.


It was a thin chip about .125 long .062 wide...Just 1 chip..

Thanx gray for your answer....


I really like this bike, but these expensive repair Horror stories almost make me want to sell it....Ive never had issues like this with my old cr 250....
I beat the hell out of that bike too....


I make aircraft gears, and there shotpeened in several areas before being finished...Shot peening the teeth would be a no no..


Im gonna pull the clutch assembly and look at that, next oil change, I havent been in there yet..

I just replaced the cam chain...sprocket on the crank was a little worn...
Some small burring..





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