Loose shift lever repair

[skymasteres]

Arnie understands and in fact taught us a lot about the talk rating of the gear lever assembly at the 2012 Aussie Rally. In fact he was an award recipient as a result of his efforts. He may chime in, but I have an idea he would dispute the yield strength requirement...     

Well, here you get into the nuances of what different engineers are willing to accept.

I make no claims to being smarter than anyone here. That's why I always post everything so that people can make their own determination.
I actually relish learning new things. So if anyone else has input on my perception of what the strength requirements are, do chime in. 

You're right about my "requirement" for yield strength being on the high side.
When a metal yields it goes through a hardening process. This is why when you look at stress and strain graphs you see a characteristic vertical rise until you get to the yield point (Or elastic limit if you prefer). Then there is a slight drop in stress as the material yields followed by another slanted rise as the metal hardens before it reaches it's ultimate strength. The curve will flatten out when the ultimate strength is met and the strain continues to increase before the metal fails.



A couple factors that influence the shape of this curve are ductility and strength of the material.

I only wanted to stay out of the yielding zone because it would require re-torquing of the pivot bolt after the material yields. (Well that and I don't have a lot of "feel" for how the metal well behave in that range)

Heck, it might still be necessary if a large transient load is experienced. (Like standing on the footpegs. Hence the need for some testing) 

[skymasteres]

On a side note, for the other penny pinchers like myself, an acceptable solution for eliminating a great deal
of play in the shifter pivot is to use aluminum foil to make up the difference. Make sure you clean the bolt
with acetone first then take a 3/4" wide x 2-3" strip of aluminum foil, spray the back with some contact
adhesive, wait for it to dry, and roll it carefully around the pivot bolt counter clockwise. Burnish it well and
grease before reinstalling the shifter.



It's lasted a week so far, but I doubt it's a long term solution. But it did serve to demonstrate exactly how
much improvement there was to be had in the mechanism.  (The missing strip was inside the shifter bushing)