F800GS Traxxion Fork Suspension Mods

I recently had Traxxion Dynamics install the AK-20 compression / rebound adjustable cartridges into my F800GS forks. The base spring rate and damping is much better than stock. However, I do not feel the range of adjustability is near sufficient. To be fare, The folks at Traxxion said to send them back for evaluation, and I will. There is just no perceived performance difference from one end of the adjustment range to the other. So, those who have had Traxxion AK-20's installed, can you comment on the range of adjustability. I'm trying to figure out if mine have an issue, or is the design limited and just doesn't meet my expectations. Thanks for your comments/feedback.

Dave
Ann Arbor, MI

You're probably one of the first to get them, so I doubt anyone has any experience.

If it matters, external low speed damping adjustments aren't linear, and their effectiveness (and range of effectiveness) is coupled to the oil weight. Typically you'll find a small range (sometimes as small as half a turn or so) where you really see any difference in damping characteristics, even though the adjustment may be 3 turns or more. It has to do with the way the typical adjuster works...the geometry and physics and stuff. And again, oil weight. I assume you put in what they recommended? And possibly even sent with the kit?

Also remember that external adjustments are almost ALWAYS low speed--the compression adjustment, for instance, won't make much of a difference at all if you're banging around off road. Its more for stuff like settling into corners and fork dive under braking.

Have you tried them set ALL the way in and ALL the way out? If you do a back to back and just bounce on the front end, you really should notice some difference. If you do notice a difference, then you can hone in on where in the adjustment range you actually see some change, and from there you can set off for actual tuning.

Thank you for the insight. I'm used to the range of adjustability of the high speed compression clickers found on most dirt bikes. There is a real difference in feel.....the range is just not there with the low speed only adjustment. Traxxion actually installed kit and set oil level and specified oil wt based upon weight, etc...

The brake diving is so much better, as is the general feedback and the harshness as been smoothed out.

Dave

Nope,
Indy Unlimited (Dan) has them for a while now. He'll check in I'm sure. He's a good guy and knows what he is talking about.

Yeah I ran into the same issue with mine. I got adjustment but it is too high in the spectrum for off road use IMO. The standard oil weight is 7.5W used by Traxxion. Before I send them the forks back to rework the cartrige valves and open up the overall flow I am going to try a 2.5W or 0W fork oil to see if I can get the dampening range moved into the off road spectrum. This cartridge is the best design available on the market and is more tunable then Ohlins or Bitubo. But unfortunately road or street bike settings are way off what we need for off roading. The guys at Traxxion are road suspension specialists. I will be working wth them all summer trying to get close to perfection for this set up. In the meanwhile I would recommend we collaborate any changes with oil weight etc and how it changes the performance. I plan to ride down to their shop and get some direct hands on training on changing the valves and buying any special tools needed.

Even the Racetech product I reviewed is going to be challenging on getting the valve stack right for off road riding. Docking Pilot's buddy is the Racetech guinea pig so we will see his reviews for them soon. The point is once you got these cartridges right they dont go out of adjustment like the gas style cartridges. Be patient and we will all get the front ends working very well.

Hurry up will ya ?


The Race Tech patient goes out Monday btw.

Did they explain that one fork you can adjust compression and the other you adjust rebound.

I got my fork back on Thrus. They are installed asof about an hour ago. I'm riden' tomorrow! first ride in months(snow, hand surgery). I'll let you know. And yes one tube for compression, on tube for rebound, wtf.
Cisco

Thanks for the feedback all. Yes, one side is compression and the other rebound.

If I bounce the front end up and down and take the adjustment knobs from full open to full close, you can feel a difference. But when actually riding, the performance range is not very pronounced.

I think the part that is missing is the high speed circuit. I would like to be able to soften it up for the sharp inputs like when riding washboard roads and then stiffen it back up for larger whoops and aggressive off road riding. Looks like that is not to be for now. I would welcome the chance to work with others on the ADV Forum and Traxxion to get this AK-20 system dialed in with a adjustment range that matches the range of usage of this bike and ADV riders. I will be talking with Traxxion guys next week and I am planning an ride Easter weekend in Nashville area. I will be senting forks back after that for an adjustment if they agreed there is any room in making them better.

Dave

If it matters, most dirt bikes DON'T have high speed external adjustment on the front end. In fact, I don't know of any, but I'm sure there's one or two somewhere.

But that's not necessarily something that you could change even if you had a high speed external circuit. If you really have a problem with suspension action on one or the other of those surfaces, that's really a function of in the tuning of the cartridge itself.

If I understand the folks at Traxxion stated that the cartridges are set up for low speed rather than high speed like a dirt bike. So you are saying the cartridges may be able to be "tuned" more towards the high speed end of the response spectrum like a dirt bike? That would be cool
thanks
Dave

It's a bit more fundamental than that. Suspension isn't high OR low speed, there are just different ways suspension reacts when it's traveling at different speeds, and in fact completely different parts of the fork that contol the motion at low and high speeds.

They can tune the damping characteristics to whatever they/you choose. It just sounds like that they didn't get it right for you the first time around. Based on the fact that their bread and butter is sportbike suspension with half the travel of a GS, it's not all that suprising.

Any updates on how the AK-20 is working for you folks?

Funny you should ask. I just sent forks back to traxxion for another adjustment. They were very receptive to making adjustments to satisfy my concerns. I have two issues. One - the increased spring rate and damping fixed front end dive while braking, but came at the expense of harshness over washboard type roads. Two - range of compression adjustability is limited. With the work they have done with Docking Pilot and my concerns, Dan feels he can fix both by reducing spring rate and changing taper on compression needle. Additionally, they have added a preload adjustment in the range of 14 mm that should provide additional adjustment. I'll report back as soon as I re-install and ride on a variety of surfaces.

Here is the latest set up that works great with the Traxxion Dynamics AK-20 Kit:

Preload spacer length 225 mm
Oil level 110 mm using 5 wt fork oil
Springs 0.60 kg/mm x 310 mm long
Range of adjusters is 4.5 turns
Cartridge valves set at C 3 R 3
Machine stock fork caps: Compression adjustment on one fork cap, Rebound adjustment on the other fork cap
Or get the new caps with compression and rebound on each fork and air bleeders.

Spec all that when sending your forks in to Dan Anderson at Traxxion Dynamcs.

Also Dan has been working on new fork caps to replace the modified stockers with full rebound and compression adjustments on each cap. I just spoke with him today and they made a boat load of fork caps and they are out for anodizing and will be available in 3 weeks.

Docking Pilot should post in soon with ride results he has had on this set up for the last 2 months now.

The front forks are now world class.

Any update on the Traxxion solution?

I need to do something about the suspension for even the most mild of offroad adventures....

Here's from an e-mail thread (09/21/2010) I've been having with Dan at Traxxion on this very topic.

question from jscottyk

...curious where things stand with the latest fork caps that allow
for compression and rebound adjustments on both fork legs? ​

answer from Dan

We do have the fork caps ready. With the new caps, one fork is adjustablefor rebound, and one fork is adjustable for compression, and both are preload adjustable. Note that this setup differs from the setup on some of the OEM forks on bike like some new Triumphs and the new FZ1, which literally have a rebound piston only in one fork, and a compression piston only in the other. This is our normal AK20 cartridge, with a rebound AND compression piston in each fork. ​

follow up question from jscottyk

One follow up question, what's the reasoning behind rebound and compression damping in both fork legs, but adjustability for one/another in each? Is this a limitation of the fork cap?​

answer from Dan

It is a limitation of the fork cap. Most compression adjustable forks have an adjuster in the bottom of the fork, and rebound at the cap. There is no easy way to add compression adjustability at the bottom. And there is no easy way to have both C+R in the cap in a fork with a standard cartridge. Generally, our compression/rebound at the cap will provide more than sufficient adjustment range if the forks are valved properly. The rebound only in one leg comp only in the other setup does not have enough piston area for proper tuning. It is hard to get the firm low speed, softer high speed for bump absorption with a single small piston. The Showa Big Piston Forks (rebound one leg, comp other) work like that, but they have BIG PISTONS, hence the name. ​

follow up question jscottyk

So for the rebound or compression valving that is in the non-adjustable leg, is it set in the middle of it's range?​

answer from Dan

Yes. It’s set to what would be the middle of adjustment. The compression leg is pretty interesting. It was one where the tech actually had a dream about the fork and came up with the idea in his sleep. He was unhappy with the single piston setup but wanted fully adjustable forks for his SV650 racing buddies.​

Looks like the Traxxion site is down for maint. so how much do these go for? I'm a noob but I'm starting to notice the front suspension diving a lot. Wouldn't mind an upgrade.


Never mind, got on their site. $1100, bit much.....but needed.

If on a set of forks everything seems fine, except the high speed compression which is too stiff, is it right to assume that going to a lighter oil will improve things? I suppose that the low speed actions can be compensated by stiffening the compression and rebound clickers.

Lighter oil will only help to a degree. Shim type high speed compression valves are less affected by viscosity than the fixed orifice low speed circuits. So really the valving should be modified if there's a high speed problem.