Traxxion Dynamics AK20

[catonsvilleguy]

FWIW, I will throw in some anecdotal observations that may or may not be helpful.

I weigh about 185 and have an '07. I found the rear shock to be painfully harsh on any type of sharp impact, even very small ones. To get close on sag, I had to run full preload so the spring must have been light for me but even backing off on preload didn't keep it from killing my already rickety spine on bumps.

I sprung for an Ohlins from LDH and the rear was transformed. Much more compliant over any and all road irregularities but taut feeling at the same time - magic. Some other shock may have been good also but replacing the stock rear is the best suspension mod you can do on a 919, IMO.

For the front, stock felt just way too soft. Too much dive on the brakes and I could not get proper sag numbers no matter what. RaceTach 0.9 g springs and fresh Honda racing oil (stock weight) has me smiling for something like $125 in the front. I'm sure Ohlins or other aftermarket internals would be noticeably better but for now, until my skills get a lot closer to the bike's capabilities, I could not be happier with my current setup. I may upgrade again at some point but what I have now was such a huge improvement, I'm in no hurry to do any more right now.

If money was no object, I probably would go for the Ohlins fork internals.

[AllanB]

Originally Posted by catonsvilleguy

For the front, stock felt just way too soft. Too much dive on the brakes and I could not get proper sag numbers no matter what. RaceTach 0.9 g springs and fresh Honda racing oil (stock weight) has me smiling for something like $125 in the front.

Excellent! Only a bit heavier than me and the same spring rate I got off their site (Well .89 or something came up in the calculator).

I'm presuming the RaceTech springs are a direct replacement for the stock Honda ones? I've emailed them for shipping etc to my end of the world and await a reply. Nothing decent is cheap down here for bikes so I expect to save bucks buying offshore.

Question - how do their fork springs compare $ wise to Ohlins?

Actually the Ohlins USA site did not list springs for the 919 post 03

[mcromo44]

Originally Posted by rmb

But I like my 919...

I love my 919, and it hustles around the track rather nicely now.

[mcromo44]

Originally Posted by arctic954

Damn.....wish I would have jumped into this sooner.

I too had issues (alright LDH....don't slam Penske ).

Penske's rear shock showed up with a 900 spring......I'm 190-195 w/ full gear. The squat from the 9er was ridiculous and causing it to run wide while powering out of corners.

We swapped it out for a 1000 and it's absolutely perfect. You absolutely need to compensate for the 9ers squat characteristics......even for a 160lb guy.



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Oooohhhhhhhhhh, I'm feeling vindicated tonight !

[mcromo44]

Originally Posted by AllanB

I'm presuming the RaceTech springs are a direct replacement for the stock Honda ones?

Yes, in the sense that they fit in without mods.
BUT
You will have to make up your spacers, which is a piece of cake and the spacer material comes with the springs. It's light wall SS tubing. I use a tubing cutter to do the cuts, easy work and you get a perfectly square cut that needs very little cleanup.

[arctic954]

I'm going to open up a can of worms....... here we go. I've been wondering this question ever since I bought the Penske and have been dialing in my front to rear weight bias.


---- Correct me if I'm wrong.......

The stock rear spring on the older bikes was hella, stiff.......right? 1200..... and for me there was zero free sag and the back end topped out on itself. AND, at the time with the stock rear spring.....the bike had pretty quick steering.

So --- If I replace that rear shock with a shock that is for my weight......and proper SAG. The bike will actually drop more in the rear than it did before.....This NOTICEABLY slows down the steering.

With the Penske (that has a ride height adjuster) --- I was able to dial in more ride height to compensate for this..... to get my quick steering back. Trust me.... I did a ride in its 'normal' position and the steering was so slow I about ran off a corner on my favorite twisty road. The 'normal' position BTW on the Penske is in fact the stock length of the OEM rear shock... I measured.

soooo....... how the heck does the OHLINS rear shock work..... if it doens't have a ride height adjuster???

------ Fire away........

[mcromo44]

Originally Posted by arctic954

I'm going to open up a can of worms....... here we go. I've been wondering this question ever since I bought the Penske and have been dialing in my front to rear weight bias.


---- Correct me if I'm wrong.......

The stock rear spring on the older bikes was hella, stiff.......right? 1200..... and for me there was zero free sag it the back end topped out on itself.

So --- If I replace that rear shock with a shock that is for my weight......and proper SAG. The bike will actually drop more in the rear that it did before.....

The back end of the bike dropped farther than before ---- NOTICEABLY slows down the steering.

With the Penske (that has a ride height adjuster) --- I was able to dial in more ride height to compensate for this..... to get my quick steering back. Trust me.... I did a ride in its 'normal' position and the steering was so slow I about ran off a corner on my favorite twisty road.

soooo....... how the heck does the OHLINS rear shock work..... if it doens't have a ride height adjuster?????

Is it longer than the stock shock to compensate? or are you damned with slower steering.



------ Fire away........

Nice post.
I'm watching !

[AllanB]

Now that is a bloody good question.

They do claim to be the worlds best!

[rmb]

[zaq123]

just curious, how much of the ride height did you have to compensate for?

I will try to answer this question how I understand it. Please correct me if I'm wrong.

Penske shocks do not have an internal top out spring, therefore shock's rod length will not grow with the preload of the spring, you will have to dial it in manually to increase the rod length=ride height

Ohlins has a top out spring which will compress and increase the rod length with the application of the preload on the main spring.

Ohlins shock's internals, including this top out spring are rated for the curtain range of the main spring rates. In other words Ohlins are more customized than Penske for a particular set-up.

a couple of pics to give you guys an idea:

[jay313]

Originally Posted by mcromo44

Yes, in the sense that they fit in without mods.
BUT
You will have to make up your spacers, which is a piece of cake and the spacer material comes with the springs. It's light wall SS tubing. I use a tubing cutter to do the cuts, easy work and you get a perfectly square cut that needs very little cleanup.

I didn't have a tubing cutter, so I just used a cheap miter box and hack saw to make a square cut. Cleaned up the edge a bit with a file. No big deal.

In case you've never pulled springs & etc. out of your forks before, your stock spring does not run the length of the fork all the way up to the top. On top of your stock spring, there is also a spacer that is exactly as mcromo described. After you pull the spring and spacer out of your forks, what you will do is lay down the stock spring with the stock spacer on top of it and measure the overall length of the two together. Then measure the new Racetech spring and calculate how long your spacer needs to be to equal the measurement of stock spring and spacer. Or, you can do as I did and just lay the stock spring and spacer on the garage floor, line up the new spring and spacer next to it, and mark where the new spacer should be cut to make it equal to the length of the stock stuff. Easy.

I know nothing about aftermarket shocks, although I am learning quickly from you guys. However, it seems to me that if your rear end squats too much and you lost a little quickness in the steering, all you need to do is slide the forks a little higher in the triples to regain the quickness that you lost. Doesn't pertain to the question at hand, but it could prove useful to a heavy guy with stock suspension and springs if he's sagging too much in the rear. (Let the jokes commence.)

[mcromo44]

Originally Posted by jay313

I didn't have a tubing cutter, so I just used a cheap miter box and hack saw to make a square cut. Cleaned up the edge a bit with a file. No big deal.

In case you've never pulled springs & etc. out of your forks before, your stock spring does not run the length of the fork all the way up to the top. On top of your stock spring, there is also a spacer that is exactly as mcromo described. After you pull the spring and spacer out of your forks, what you will do is lay down the stock spring with the stock spacer on top of it and measure the overall length of the two together. Then measure the new Racetech spring and calculate how long your spacer needs to be to equal the measurement of stock spring and spacer. Or, you can do as I did and just lay the stock spring and spacer on the garage floor, line up the new spring and spacer next to it, and mark where the new spacer should be cut to make it equal to the length of the stock stuff. Easy.

I know nothing about aftermarket shocks, although I am learning quickly from you guys. However, it seems to me that if your rear end squats too much and you lost a little quickness in the steering, all you need to do is slide the forks a little higher in the triples to regain the quickness that you lost. Doesn't pertain to the question at hand, but it could prove useful to a heavy guy with stock suspension and springs if he's sagging too much in the rear. (Let the jokes commence.)

Simply cutting the new spacer for the same overall length as the stock spring + spacer, is not the best way to go. You won't know how much preload you will have, which is an important setting. Use the Race Tech instructions to determine the spacer length, and use the 15 mm stated therein and nothing more. Also, do the required measurement with the preload (ride height ! ) adjusters fully backed out, not midway.

[arctic954]

Originally Posted by zaq123

just curious, how much of the ride height did you have to compensate for?

I will try to answer this question how I understand it. Please correct me if I'm wrong.

Penske shocks do not have an internal top out spring, therefore shock's rod length will not grow with the preload of the spring, you will have to dial it in manually to increase the rod length=ride height

Ohlins has a top out spring which will compress and increase the rod length with the application of the preload on the main spring.

Ohlins shock's internals, including this top out spring are rated for the curtain range of the main spring rates. In other words Ohlins are more customized than Penske for a particular set-up.

a couple of pics to give you guys an idea:

If this is true......it then makes perfect sense.

Good explanation.


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[AllanB]

My RaceTech USA enquiry was forwarded to the RT agent in New Zealand. Now he is renown as the suspension guru here and the NZ Ohlins, RaceTech etc agent. Turns out he can get me Ohlins springs for the front end cheaper than RT ones! Apparently they are a direct drop in with the spring spaces being set by the Big O factory.

Interestingly he has ordered a slightly lighter spring rate than the .90 due to the bumpy, pot-holed condition of the things we call roads. The good thing is that he stands by his products 100%.

Once they arrive I'll have no excuse not to pop them in!

The problem is - if they are sweet then the rear end will nag at me and I cannot afford a Ohlins for that end!

[mcromo44]

Originally Posted by zaq123

just curious, how much of the ride height did you have to compensate for?

I will try to answer this question how I understand it. Please correct me if I'm wrong.

Penske shocks do not have an internal top out spring, therefore shock's rod length will not grow with the preload of the spring, you will have to dial it in manually to increase the rod length=ride height

Ohlins has a top out spring which will compress and increase the rod length with the application of the preload on the main spring.

Ohlins shock's internals, including this top out spring are rated for the curtain range of the main spring rates. In other words Ohlins are more customized than Penske for a particular set-up.

a couple of pics to give you guys an idea:

I am not going to say you are wrong, but I will say I see it another way and here goes.

I've been pondering this, and done some digging beyond what's already hard wired in my head.

1
I went to the Ohlins site, and scrounged as best I could for tech and manuals. Out of that I found only one reference to altering shock length, and that was by the adjustable eye that their better units have. No other method was express or implied.

2
Every single book and article I have all clearly state eye to eye length change tuning is by an adjustable eye - as long as one it out to effect change without altering spring rate or preload.

3
Top out springs, a.k.a negative springs, are designed to soften the effective spring at the end of extension travel. This is to improve grip when the rear wheel is lightly loaded, from hard braking in particular. The Ohlins design is clearly superior in this respect, in the sense that at least some of the Ohlins have top out springs, while the Penske's don't. I think this is why sharp chassis tuners tell Penske users to use a very "soft" Free Sag dimension in the 10-11 mm zone. The light preload serves to make up for the lack of a top out spring, and increase compliance (reduced spring force) near full extension. Of course, when such soft Free Sags are used, the Rider Sag will be too great, assuming the correct spring rate that is, but one easily compensates for that by lengthening the shock. (I had to add 6 mm of vertical ride height to get my Rider Rear Chassis Ride Height where it needed to be as a baseline, with a 1100 #/inch spring and 10.5 mm Free Sag that is.)

4
Adding preload to the correct spring rate to gain ride height is a terrible thing to do. Near extension, lightly loaded with excessive spring force dialled in = poor compliance = poor grip = bad news. Even in one allows that some eye to eye growth could be gained by preloading against a top out near full extension, the internal spring is going to be so weak in relation, that you still end up with excessive spring force at or near full extension.

5
Aside from the internal top out spring, I don't see the Penske as being less customized than an Ohlins. Different, yes. Better, um, for the level we're all at, I don't think so. Penske has a very wide range of damping force curve shapes and magnitudes available, as well as the full range of damping and springing adjustments, to say nothing of the eye adjustment feature.



In conclusion, I don't see what you have suggested as being viable.
4 above is really the nailer on this point.

[touring919]

I'm with MC on this one. Shock length is adjusted from the spherical rod ends on one end of the shock. Its totaly independant of what is going on with the spring, and damping insdie. Ohlins shocks have this as well as penske.

[catonsvilleguy]

Originally Posted by mcromo44

Yes, in the sense that they fit in without mods.
BUT
You will have to make up your spacers, which is a piece of cake and the spacer material comes with the springs. It's light wall SS tubing. I use a tubing cutter to do the cuts, easy work and you get a perfectly square cut that needs very little cleanup.

My RT springs came with aluminum spacer material which I think is the norm. I was able to cut it on a miter saw using a typical woodworking carbide-tipped blade (not a good idea with SS).

A lot of people use PVC pipe for spacer material which works as well as anything else.

[mcromo44]

Originally Posted by catonsvilleguy

My RT springs came with aluminum spacer material which I think is the norm. I was able to cut it on a miter saw using a typical woodworking carbide-tipped blade (not a good idea with SS).

A lot of people use PVC pipe for spacer material which works as well as anything else.

I have egg on me today.
Yes, the tubing is aluminum. The last time I looked at it was 4 years ago and my recollection was an SS ASTM #. Me Wrong. Just went to the box and looked.
It's seamless aluminum thinwall tubing. 1.375 in. OD about 0.055 wall thickness
A friend of mine used the orange coloured underground sprinkler hose and told me it was easy to use, fit well, and held up well.
I don't know if that is a PVC grade or not, but I've heard from others that PVC works real well.

[jay313]

Originally Posted by mcromo44

Simply cutting the new spacer for the same overall length as the stock spring + spacer, is not the best way to go. You won't know how much preload you will have, which is an important setting. Use the Race Tech instructions to determine the spacer length, and use the 15 mm stated therein and nothing more. Also, do the required measurement with the preload (ride height ! ) adjusters fully backed out, not midway.

Ah, well, I purchased a used set of springs that came without instructions. I did it the same length as stock and then measured sag (as best I could) to set front end preload. Primitive, but the ride is better than before and well within my tolerance for error. But I can tolerate a lot more error than some can. Lol.

[mcromo44]

Originally Posted by jay313

Ah, well, I purchased a used set of springs that came without instructions. I did it the same length as stock and then measured sag (as best I could) to set front end preload. Primitive, but the ride is better than before and well within my tolerance for error. But I can tolerate a lot more error than some can. Lol.

Ahhhh, but is sooooo easy to remedy whenever you want to.
That is, pick the preload you want, and dimension the spacer accordingly.
By the way, 90 mm of spacer with Race Tech springs nets you 14 mm of preload in a 04 or later with external adjusters, on the basis of the preload (more correctly - ride height) adjusters being fully backed out. With those numbers, one can correct at will depending upon what it is they are after, be it more or less preload, or doing the spacer length on the basis of a mid point ride height adjuster position.

[mcromo44]

Originally Posted by zaq123

just curious, how much of the ride height did you have to compensate for?

zaq, I began by adding 6 mm of ride height to recover the ride height I lost from use a soft 10.5 mm Free Sag.
Next I added 5 more mm of ride height in an effort to alter the swing arm angle and raise up the C of G re roll initiation and rate leverage.
I got stuck there as I ran out of front end elevation range, having already run in the ride height adjusters all the way and dropping the tubes in the clamps a wee bit.
I'm looking at tall caps for the forks.
I'll try for more height, likely within another 5 mm.
Short story in terms of your question re how much, is what I'd call "lots".

[mcromo44]

Originally Posted by mcromo44

Thanks for pointing this out.
I went back and looked at my RaceTech G2-R instructions, and their computer generated custom output for stack and set up specifics.
The diagram of the time does not show a drilling position.
A Note 6 refers to a drilling, on the basis of "if specified" ( on the custom output).
There was no such call up for drilling on the custom output.
So in retrospect, I'm half right and half wrong.
What would be correct to say though, is a G2-r install for a 919 does not call for nor include any low speed compression drilling instructions.

This is for beefsalad.

[mcromo44]

Originally Posted by zaq123

It is in RT gold valve instructions about drilling



but

Ohlins are the way to go. UES kit is all you can possibly need on 919.
However majority of 919 user can benefit greatly by just reshimming stock valves and getting correct springs

this is for beefsalad

[beefsalad]

I already have a hole in the valve body!

[mcromo44]

Originally Posted by beefsalad

I already have a hole in the valve body!

Keep in mind I have not seen inside to this level.

That hole looks quite big, at least 1/16th of an inch.

That hole looks to be in a steel jam nut, and unless the hole is aligned with a hole in the shaft, it can't flow anything.

The location and size does not look right to me, but I could be very wrong.

[zaq123]

Originally Posted by rmb

Anyone have the Traxxion Dynamics AK20 cartridge kit for the 919? How do you like it? I know..., it's alot of $$, but I'm looking for something to match the quality and performance of the Ohlins shock.

Did you start your install yet? This is the time for the project.
My project this winter: installing big bore and new cams on my DRZ to match my FCR carb. All I need is more free time now

[hornet641]

High/Low speed damping? Are you guys talking in terms of road speed or the speed of the deflection of the suspension?
As I understand it low speed damping is the deflection that occurs from small surface imperfections, ripples & undulations. High speed damping takes care of sudden high high impact deflections such as hitting a hole in the asphalt, or a step where different surfaces meet etc. LDH? Anybody?

[mcromo44]

Originally Posted by hornet641

High/Low speed damping? Are you guys talking in terms of road speed or the speed of the deflection of the suspension?
As I understand it low speed damping is the deflection that occurs from small surface imperfections, ripples & undulations. High speed damping takes care of sudden high high impact deflections such as hitting a hole in the asphalt, or a step where different surfaces meet etc. LDH? Anybody?

Low speed and hi speed refer to both the acceleration rate and final velocity of the suspension unit.
So, anything that causes a high acceleration rate of the unit and yields a high suspension unit stroke velocity, gets dealt with by the so called hi speed circuits.
Compression when compressing, then rebound once the suspension unit shifts into that mode.

A raised pavement seam across the line of your travel would initially be handled by the high speed compression circuit.
A sharp ripple would too.
A crown would initially be handled by the low speed compression circuit.
A dip would initially be handled by the low speed rebound circuit.

Another thing to keep in perspective, is overall suspension energy management.
When in the state of compression, the suspension unit is receiving energy.
When in the state of rebound, the suspension unit is changing the energy received (wheel's inertial mass and the stored energy in the spring) into a form of energy that will not disrupt the chassis.
The damping circuits do this by consuming the energy in the form of hydraulics type frictional losses, as well as some heat gain. There will be some mechanical losses from shim deflection as well as some undetectable vibratrion, again, all be forms of energy transformation.

[PAULIBIKER]

The FZ1 guys swear by these.

Would love to hear from someone that has them in their 919.