Posts
645
Joined
5/30/2017
Location
Tucson, AZ, USA
Edited Date/Time
4/22/2020 10:44am
Just received this bad Larry in the mail today. I haven't seen FC advertise these hard on their website or social media for some reason, as compared to other linkage systems available for these bikes. This system does not require a spring rate change like the others. I'll be testing it out on my 17 FX450 in the next week or so to see how it feels. 
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The Factory Connection linkage is approximately 2.5mm longer than the OEM linkage. Here's the measurements I got for the knuckle.
The FC linkage should drop the rear end slightly, about 2mm, so not much really.
Here are the wheel rate curves for stock, our latest knuckle, the Factory Connection set from your dimensions, and another competitor who I shouldn't name as they sent us their models to quote manufacturing, but never went forward with us (or even bother to respond to my emails
And here's the wheel force curve using the same spring for all knuckles, except for a spring two rates up on our knuckle (as recommended):
So Factory Connection and the unnamed linkages are pretty similar, and they're both less progressive than stock, which I think is an odd choice... Our linkage is a good amount more progressive than stock, so pretty much the opposite. You'll likely need to compensate for the lack of bottoming resistance with valving or a stiffer bump rubber.
You can see that our linkage is pretty much identical to the FC linkage up to 72% shock compression or so, but then shoots up for added bottoming resistance. This allows different valving, which in-turn, allows for better traction earlier in the stroke.
Exact measurements per my calipers for the Factory Connection linkage were:
A 29.32
B 77.33
C 54.55
Progression is the ramping up of the motion ratio at the end of the shock stroke. More progression means that the suspension is stiffer near the end of the stroke whan something with less progression. But it's the whole curve that matters, simply adding more progression at the end won't help if it messes up the motion ratio earlier in the shock stroke.
All three aftermarket motion ratio curves are nearly parallel to each other up to about 55% shock stroke, where they all start getting a bit different. Adjusting the spring rate for each will make them identical force curves up till that 55% spot, as well, which you can see in the second plot. Stock is a bit different from all three aftermarket linkages throughout the stroke.
The FC is less progressive than stock and a lot less progressive than our linkage. This means that the rear suspension is softer at the end on the stroke, which is in-line with FC's instagram post "shock compliance is much improved deep in the stroke", so long as by "improved" they mean "increased".
I'd argue that's not really an improvement, but they may have some valving specific to this linkage that works well with it. The same can be said for our linkage, if you just buy it and put it on with a heavier rate spring, it won't be that great. You need a revalve to see the full potential.
It wasn't as harsh on the braking bumps as it was with the OEM setup, which really helped me set up a little better and get into a particular couple of ruts I previously struggled with on this loop. Turns that had a lot of chop and rollers on the exit felt better when accelerating out, in that the rear end felt like it got better traction and followed the ground a little more.
I did not change any settings from before I put the linkage on. The rear end did feel a little softer than before. There is a decent G out on this loop that I intentionally hit a little faster to see how the rear end held up, and it lightly kissed the bump stop (barely a mark on the fender). I added two clicks of compression for the rest of the ride and it felt good. Looking forward to getting the bike out on the track when this CCP virus bullshit is over, to get a more complete picture of how the bike performs with this linkage set. Again, I'm not a test rider, so I could be full of shit.
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