Interesting transmission shim discovery for 1st gens

[dingy]

Came across an interesting tidbit on the VMax side today. At some point, Yamaha started putting a shim in the rear transmission shaft that is associated with the 83-85 gear problem. This shim does not show up in the service manual or the Venture parts fiche. It is however in at least the 88-93 VMax parts fiche in 3 different sizes.

 

Part #'s:

90201-256K5-00 Washer, Plate UN $3.21

90201-256K6-00 Washer, Plate UN $3.11

90201-256K7-00 Washer, Plate UN $3.21

 

One of the most respected guys there that builds VMaxs routinely for people said it is a little known part. He said there is no guidelines on using shim, but he puts largest one in that will fit to take slop out of shaft. Shim pushes gears on shaft towards the thrust washer that is known to fail.

 

The VMax's are prone to developing a gear issue similar to early Ventures, probably due to harder shift points.

 

I am going to get a set of these and see how they work out. Under $10 bucks for a set, so it can't hurt.

 

Picture attached of the 93 VMax fiche for the transmission, it is part #25

 

http://www.vmaxforum.net/showthread.php?t=27263

 

Gary

Edited February 27, 2013 by dingy

[Yammer Dan]

Kind of gives the gears a push togather?? I'm thinking of Randy's repair and replacing washer.Adding shim??

[Venturous Randy]

Dingy, if you want to do some more research in the transmission, find out if Yamaha reduced the spring stiffness on the large spring on that shaft. I am thinking that was done to reduce some of the pressure on the thrush washer.

RandyA

[djh3]

To some extent the leat amount of "slop" between the gear clusters when assymbled is best. You have to have a little freeplay so they will move some to reduce heat and some other stuff. But if free play is excessive it allows to much deflection and then you get not correct contact points. Not that I have particualr knowledge of this transmission, just going with experience on sequenchel gearboxs in general. The heat normaly associated with the motorcycle is going to take some of it out as the gears will expand.

[dingy]

Dingy, if you want to do some more research in the transmission, find out if Yamaha reduced the spring stiffness on the large spring on that shaft. I am thinking that was done to reduce some of the pressure on the thrush washer.

RandyA

 

Same part number from 1983 1st gen through to 2007 last VMax 1st gen, and also through the 2012 RSV's.

 

Gary

[Flyinfool]

I don't know if Yamaha does it also, but on the machines built where I work, if a part is changed to improve function but is still fully interchangeable with older equipment, the part number does not change. So in our case if we had reduced spring pressure to fix an issue and that same fix would help older machines we would not change the number but might put out a bulletin recommending that that part be replaced with a new part if any service was ever done in that area.

[dingy]

I don't know if Yamaha does it also, but on the machines built where I work, if a part is changed to improve function but is still fully interchangeable with older equipment, the part number does not change. So in our case if we had reduced spring pressure to fix an issue and that same fix would help older machines we would not change the number but might put out a bulletin recommending that that part be replaced with a new part if any service was ever done in that area.

 

That is not a good engineering practice. Fit, Form & Function should always drive part numbering. In this case the Function part has been altered since the spring compression rate is rumored to have changed.

 

If this is not followed it would create confusion with part suppliers that have an older part in stock, but there is an upgraded version available. How would they differentiate between the very similar parts that carried the same number.

 

Yamaha uses a three part numbering system most of the time. XXXXX-YYYYY-ZZ. It appears the ZZ component is used by them to track incremental revisions to parts. Don't know this for sure though.

 

Gary

[Flyinfool]

I don't make the rules, I don't have to agree with the rules, I just have to follow them. I'm just saying that it is done by some companies, 2 that I have worked for over the years, especially when they are trying to not call attention to a change, I do not know if Yamaha is one of them.

[bongobobny]

Great info Gary!! Add it to the list for the great engine rebuild for next year...

[jasonm.]

you are assuning the Vmax and Venture trannys are essentially the same. YES BUT the tooth count on gears are just one of the differences. Maybe the gears are just a "bit wider" here and there on a Venture. I had to open my engine up years ago. And a well known Vmax drag racer gave me specs' for the play you are speaking of. Mine fell right into the spec for the "end play" he would call it. I honestly do not remember the exact number...but .010" comes to mind w/o using any washers on my '87. I believe, The 1200s use different gears and I believe use this "washer". 1300 86-93 do not

Edited March 3, 2013 by jasonm.