43mm forks with different OEM damper rods

[RamTec]

I'm seeing different (apparently both OEM) damper rod set ups on two pairs of 43mm forks. On the left of photo is an older set (with aftermarket progressive springs - not Maxton btw) with OEM damper rods that appear identical to those depicted in my workshop manual. On the right is a younger set from my 2007 Canadian spec (Japanese full power) model (registered 2008).

The two different types of damper rods are secured by different sized bolts, so they're not interchangeable, not least because the lower fork legs have different sized apertures. I've also measured significant differences in damping rod oil hole sizes.

I'm not seeing alternative part numbers on the official parts list.

1. Any idea when the spec changed and Yamaha's intention, other than reducing unsprung weight?

2. Did Yamaha change the spring rate at the same time, because my OEM 2007 springs seem to perform very well (with the assistance of 7psi)?

Suspension travel data (Fr + Rr) comparisons gathered during sports riding.

Please stay relevant to the thread

 

[Vinmax]

I believe they did the fork change in 2001. My bike (a 2001 model) has the forks like you show in the picture on the right side with the outside tube having a location for the fork tube protectors (those little plastic pieces that hug the lower fork tube and extend up 2" or so to protect the bare chrome slider tube from rocks, etc.
I believe they made that change in 2001 (and the internals changed as well as you show in your pictures).

Vinnie

 

[Equanish]

I'm seeing different (apparently both OEM) damper rod set ups on two pairs of 43mm forks. On the left of photo is an older set (with aftermarket progressive springs - not Maxton btw) with OEM damper rods that appear identical to those depicted in my workshop manual. On the right is a younger set from my 2007 Canadian spec (Japanese full power) model (registered 2008).

The two different types of damper rods are secured by different sized bolts, so they're not interchangeable, not least because the lower fork legs have different sized apertures. I've also measured significant differences in damping rod oil hole sizes.

I'm not seeing alternative part numbers on the official parts list.

1. Any idea when the spec changed and Yamaha's intention, other than reducing unsprung weight?

2. Did Yamaha change the spring rate at the same time, because my OEM 2007 springs seem to perform very well (with the assistance of 7psi)?

Suspension travel data (Fr + Rr) comparisons gathered during sports riding.

Please stay relevant to the thread

I used 1 Racetec .9 for 200lb plus rider. On left fork and a Factory Progressive rate .38 spring on the right. And 14 lbs of air or 1 Bar equal to the low altitude Barometric pressure. I haven't blown the seals in thousands of miles. Can you explain using half a Bar? Cuz I read that and did that before.

 

[Drifter2406]

My 2004 has the same as the ones on the right, not 100% sure it is UK model

 

[one2dmax]

Here's a comparison note I made a few years ago. I think the inner steel tubes are also changed within those same ranges. I do not think the springs changed enough to matter.

 

[Drifter2406]

Here's a comparison note I made a few years ago. I think the inner steel tubes are also changed within those same ranges. I do not think the springs changed enough to matter.

My 2004 is like the one you have marked up as 2007 but mine does not have the 3mm hole at the top, I know this as I have just rebuilt them in the last few weeks using Racetech Springs and Emulators and for the Emulators you need to drill out the existing holes and add a two more..