F800GS Traxxion Fork Suspension Mods

[Gumbeaux]

Any update on the Traxxion solution?

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

[jscottyk]

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.

[bodhizafa]

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.

[mousitsas]

Originally Posted by bxr140

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.

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.

[bxr140]

Originally Posted by mousitsas

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.

[mousitsas]

Originally Posted by bxr140

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.

Thanks!

[seaswood]

Originally Posted by Indy Unlimited

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.

Mike from Traxxion did say they (which we do not do any more) use the stock caps I believe.
With the Traxxion Caps the numbers are slightly different because of the cap length but they all equal out. The bleeders would not eliminate the preload adjustment. The caps would have Spring Preload on both sides, Rebound on the right and Compression on the left. Both caps would have the bleeder valve as well.
Preload Spacer – 215mm
Oil Level – 115mm (125/150 7wt Maxima Oil)
Compression Valve – 2 turns out (3 total Turns)
Rebound Valve – 2 Turns out (3 total turns)
Preload set – 7 turns in (15 total turns)


Price 1249.99 $ 1299 for bleeders.
Pricey but it is a proper fix

.
You can install yourself or they will do it for 150$

[tileman]

Ok, heres a query. If you were to use a dirt bike fork on a dual sport bike (f800 etc), change the travel (possible), change the spring length and rate (possible) what about damping? As said earlier I think dirt bikes (high speed) road ish bikes (low speed) damping. If the valves are set for high speed what happens when oil weight for a road ish bike is added? Is there a problem with the oil flowing through other parts of the fork?

[bxr140]

Originally Posted by tileman

Ok, heres a query. If you were to use a dirt bike fork on a dual sport bike (f800 etc), change the travel (possible), change the spring length and rate (possible) what about damping?

Those are all pieces of the suspension pie, not individual components. When setting up suspension you have to consider everything, and how it all effects everything else. If you were to install a dirt bike fork on the 800 (as some people have), you would modify the valving to work with the characteristics of the 800. To not do so would pretty much completely defeat the purpose of swapping forks, not to mention you could very well end up with worse suspension.

Originally Posted by tileman

As said earlier I think dirt bikes (high speed) road ish bikes (low speed) damping. If the valves are set for high speed what happens when oil weight for a road ish bike is added? Is there a problem with the oil flowing through other parts of the fork?

Bike type does not dictate oil weight. Most suspension tuners have one or two off the shelf oil weights that they'll put in all of the standard customer forks they do, from stiff track bikes to squishy trail bikes. Typically only for very low tech kit or for very high performance race machines is a different oil weight considered, and even then its usually not that different.

One thing to understand is that, while the high speed damping is stiffer on a road bike (that sees less big hits and has less travel) than a dirt bike, there's nothing inherently different between the internals of a street and dirt suspension--its just the specific tuning that's different. Different shim sizes and shapes, different shim stack profiles, sometimes different piston orifices/geometry...but that's about it. You could tune a sportbike to be as plush as a dirtbike off road (up until it bottomed out its 4" of travel), and you could tune a dirtbike to be as stiff and controlled as a track bike (but you would use a fraction of its 12" of travel).

[itsatdm]

If you are looking for the best set up for a bike for both street and dirt, the best you are going to get is a compromise.

Cartridge forks are typically set up with certain terrain, weight and rider skill in mind. To achieve that, a spring rate is determined and a particular valve shim pac is chosen that will work best with a limited range of oil viscosity.

Most good cartridge forks have adjustments that the rider can change to slow or allow more flow through the valves on both compression or rebound, some even allow separate adjustment for low and high speed flow. Changing the viscosity has minimal good effect, it may even be detrimental causing the opposite of what you are trying to achieve. A small change may extend the range of adjustment available to the rider.

Once the internal parts are chosen, you are limited to the external adjustment for compression and rebound with some forks having more than others. I think most riders find that sufficient, because if you are starting with a dual sport bike, suspension is not going to make it competitive with a race bike anyway.


Bxr140 you are too quick for me tonight. See anything that contradicts you?

[The Griz]

bxr140 you are too quick for me tonight. See anything that contradicts you?

[bxr140]

Originally Posted by itsatdm

Bxr140 you are too quick for me tonight. See anything that contradicts you?

Nope. Spot on.

[Oso Blanco]

I spend almost that much on my Shiver 45 swap and I'm still not 100% with them. If I were to do it again, I'd just get an off the shelf solution.

[The Griz]

Originally Posted by Oso Blanco

I spend almost that much on my Shiver 45 swap and I'm still not 100% with them. If I were to do it again, I'd just get an off the shelf solution.

Good info.

[johngil]

Bitubos still kicking ass. Just sayin'...

Rebuilt only once and about 13,000 miles on them now.