Reworking Aluminum Rear Suspension Shafts by: garserio
So you let those plastic bushings wear thru to the aluminum... Now What?

Of course you know the importance of going through your rear suspension every 2,000 miles. But, the season is short and you can't waste time wrenching during the precious weekends of a short riding season, right? I, too, let periodic maintenance go by the wayside, especially when the snow is flying and there are trails to be ridden!

To my surprise, the lousy winter we had in 2005 was one my busiest riding seasons. The lack of snow at my typical riding spot of Tug Hill, NY motivated me to extensively travel to other snowy locations like Quebec. All this continuous riding without periodic maintenance took a toll on my 05 Vector's Rear Suspension. Oh yeah, I do religiously grease the skid before every ride...

This fall, I pulled the skid frame out like I supposed to do in the middle of last winter. I was happy to see that Yamaha used aluminum cross shafts to save weight on the Proactive Suspension. The problem with aluminum is that it is soft compared to steel, so when those thin plastic bushings wear out, so does the aluminum!

Here is what I found on the Front Arm Cross Shaft: Almost 0.050" of wear!
By the way, the bushing wall is only 0.040", so the shaft wear was more than the bushing thickness.

Worn Shaft End New vs. Old Bushing

There are 3 solutions to this problem:

  1. 1. Buy a new OEM Shaft... Typically EXPEN$IVE and the problem will most likely reoccur next season
  2. 2. Make a new Shaft, probably steel which kills your weight savings. Ok, you can go with titanium, but I'd rather spend my $$$ at the bar!
  3. 3. Rework your worn shaft with press-fit steel collars. Little weight penalty, long term durability and cheap.

For solution #3, you will need a lathe and some steel stock(or even better stainless steel)

  1. 1. Turn the damaged ends of the shaft down by the maximum amount of wear and length of the bushing surface. (I recommend that you don't reduce the original diameter by more than 80% because the shaft will be weaker in the reduced region, especially at the shoulder.)
  2. 2. Make steel (or stainless) collars with an ID equal to the OD of the turned down end MINUS 0.005". The OD of the collars should be the original shaft diameter PLUS 0.005"
  3. 3. Heat the collars in an oven to 300 deg F. Cool the shaft in a freezer.
  4. 4. Press fit the heated collars onto the cooled shaft and then let everything reach room temp.
  5. 5. Turn down the collars to final OD and blend into the orignal shaft.

In the case of my 05 Vector, the OEM Shaft OD = 0.856". I turned down the ends by 0.060" to an OD = 0.736" x 1.5" Long. I made two stainless steel collars, OD = 0.870", ID = 0.731", Length=1.6". After press-fitting, I turned down and blended everything to the stock shaft.

Here is a picture of my results:

Reworked Shaft End

That's it! Hopefully next year I will find the time to pull my skid frame out before the bushings go junk again. At least now there is a tougher surface for the bushings to ride on, so hopefully the shaft will remain undamaged. See ya' on the trails...

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