Precautions when fitting a new AVO front damper.
If the front shock is not installed correctly the rod will flex with EVERY stroke and metal fatigue will set in with eventual rod failure. This is a well known issue that is addressed in the Factory instruction sheet #10
Thanks Martyn. I have just completed a detailed look at front damper alignment. I have asked AVO to include the following info with their new front dampers:
Precautions when fitting a new AVO front damper.
When fitting a new damper that has tighter clearances, any misalignment that was hidden by the sloppy fit of the old damper can become a problem.
To minimise friction and the possibility of a bent damper, the alignment of the new damper should be carefully checked in two ways.
A suggested sequence to check and correct alignment:
- Fit the damper at the bottom only, then with the forks at full compression, check that the damper top D8 accurately aligns with the slot in FF1. This position gives the best indication of errors in the heights of the eyebolts (FF57) as any variation in their heights will tip the damper sideways. Any “fore and aft” error in the eyebolts has less effect in this position.
- With the top of the damper still detached, lower the forks to full extension. Any fore and aft” error now has a bigger effect on damper alignment, but eye bolt height errors are less apparent with the forks in this position. Extend the damper and check the alignment.
- Correct the largest error first, and then recheck the alignment through the full range again. Adjust again if necessary.
- Make sure that the damper is not sliding sideways on the bottom pivot to take up any error still present. This may not be possible when the damper is subjected to working loads, so it should be avoided.
With my Rapide, I found that the eye bolt lengths did not need correction, but both of the eyebolts had been drilled off centre by different amounts and the holes in the bottom link were also slightly out of line. As a result it was impossible to align the damper through its full range of movement by following the instructions in the Vincent manual and only adjusting the eyebolt heights.
I eventually found that by selective assembly of the position and orientation of the eyebolts I could get the errors to cancel out. (For greater checking accuracy, I replaced the damper with a [SUP]5[/SUP]/[SUB]16[/SUB] x ¾ x 12 inch bar with 0.514 long spacers each side, all drilled and reamed to [SUP]5[/SUP]/[SUB]16[/SUB].)
My eyebolts are now stamped to make sure they always go back the same way.
I don’t know how typical my bike is, but I wonder whether alignment problems played a part in the original dampers leaking, and Koni dampers being too stiff when fitted to the front?
Rob Staley 28 Feb. 2013
