A thought.... New YZ450 5 speed tranny...


5 replies to this topic
  • odlaw19

Posted January 12, 2006 - 03:53 PM

#1

OK, this is just a thought.

Now that Yamaha have moved back to a 5 speed tranny on the YZ, what makes this transmission different from the YZ426's and are we going to the same problems experienced with this transmission?

I know that the 4 speed gears were wider than the 5 speed. Have Yamaha retained the same size gears and made the tranny "longer" as such?

This may have already been touched on......



Waldo.
YZ426

  • 642MX

Posted January 12, 2006 - 04:53 PM

#2

What problems? I don't really think there where that many problems with the tranny's. A few people blew some gears out, but crap happens.

  • MichiganMXer

Posted January 12, 2006 - 05:09 PM

#3

I've got an 01 yz426 and I havent replaced the clutch or any gears.

And I ride requently.

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  • grayracer513

Posted January 12, 2006 - 07:10 PM

#4

Well, we just don't know yet, mate. We do know that the crankcases are new. Have they been widened to accommodate a stack of 5 beefier gears? Have the same case dimensions been retained (I hope) and the materials upgraded? We'll have to wait to find these things out.

You know, the current WR450 5 speed fits in exactly the same space as the YZ450 4 speed does, an I haven't heard about a great number of troubles with that unit, although there are obviously fewer of them around. But the 4 speed hasn't been totally indestructible, either.

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  • ncmountainman

Posted January 12, 2006 - 08:41 PM

#5

i read (can't remember where) that the cases were widened to accept the 5th gear,if ya do the math :bonk: i'd have to say they're of the bigger sort; but then thats not exactly factual :applause:

  • grayracer513

Posted January 12, 2006 - 10:20 PM

#6

I think I saw what you think you saw, too, but I can't remember where either. I do seem to recall that I discounted it because it either sounded made up, or the source wasn't on my high credibility list. My understanding is that the YFZ quad trans is wider, so maybe they went that way. But it seems to me that most of the failures of the 426 5 speed were in the dogs wearing round so they wouldn't stay in gear, rather than breaking gear teeth because they were narrow.

I remember seeing a picture of the left side of the then new '05 YZ125 engine. Dirt Rider used this picture to suggest that the transmission shafts were stacked vertically to make the engine shorter. The truth was that they had mistaken the bearing boss for the shift cam as the end of the mainshaft, even though it was obviously two inches below the center of the clutch. :applause:

Right now, it's all early info, and I'll wait for the real stuff to come out when it does.





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