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Old 02-10-2012, 03:17 PM   #1
cenji OP
out4fun
 
Joined: Nov 2006
Location: Sierra Nevada,CA
Oddometer: 169
G/S swingarm + driveshaft extension 50mm

I am in the process of upgrading my Front-end of a 1981G/S. The new KTM setup will raise the front by two inches. I might be on the wrong track here and ask those to chime in if indeed I am, but I thought too match that rise in the back as well. Bringing things back in balance. There are three options to my knowledge:
1. a custom shock
2. extending the driveshaft and swingarm
3. or combination of shock and swingarm with driveshaft


What I like to accomplish is based on, but might make no sense to some:

A. change the ride characteristics of a stock G/S very little, means tight cornering/handling should be the least effected.
B. I will not race the bike, so a long wheel base for stability in sand etc. is not necessary.
C. easiest maintenance.
D. I want the additional clearance = 2", so shortening the forks is not desired.

My questions are as follows:

Is there an ideal way how to proceed and if there is, please share your thoughts why it is ideal?
Is there a non desired/false/wrong way that should be avoided?
If you have done a similar conversion, what have you found out (does it work well or not, are your happy)?

Does any one have the capability to do a schematic drawing or come up with a formula or might know where one exists, that will explain, what rise I will get in the back with a 50mm extension?

I have a Wilbers shock that is currently on the way to the Beemershop/TED and he will look if a shaft extension can be done to extend the shock to reach a measured 38.75cm, measured from eyelid to eyelid of shock.

I have found two values that explain the shaft-extension ratio to rise under the motorcycle. 1 to 1:6 or 1 to 2.0, that means, that if the shock is extended 2 cm, I will raise the bike either 3.2 or 4 cm.
This shock extension will result in a steeper angle of the shock and require to change the frame cross member above the swingarm, the one that the battery case is mounted too. That can be easily done, by cutting out and re-welding it. No expense for me. It also requires to take some of the inner bell housing off, slight dremel work. I has been done by others and although the angle is steeper for driveshaft, the joints are still fine after 100k. No concern there.


Your help is appreciated. Safe riding.
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cenji screwed with this post 02-10-2012 at 03:25 PM
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