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Interesting recommendation for fork oil

14K views 42 replies 18 participants last post by  spacetiger 
#1 ·
I just received my Traxxion Dynamics drop-in kit to spiff up my front suspension. It contains: Springs, modified damper rods, modified Gold Valve emulators, and spacers. As I'm going through the install instructions I noticed a rather strange recommendation for fork oil replacement. They recommend using Maxima 20wt for the LEFT fork and 30wt for the RIGHT fork. They seem to have worked things out for specific bikes, but before I order the fluids (local guy doesn't have it), can someone explain the science between using two different weights?

 
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#2 ·
I would like to know the logic behind different weight oils for LHS and RHS fork. I just did my racetech emulator, spring and oil change yesterday and Racetech recommended 15wt oil for both sides with 130ml oil level.

What was the cost of the Traxxion Dynamics drop-in kit set up?
 
#3 ·
Same here, I am about to finally put my emulators in that have been sitting on my workbench and Racetech told me 15W as well. I know that a few people here have went with 20W, which they have been running with successfully, so that seems fine as well. Never heard of different weights in each fork though, especially that high. They don't even sell 30W at any of my local shops, nor have I seen it on my travels to Cycle Gear. That's a new one to me too.
 
#4 ·
It was $300, which was $50 less than when I first discovered it.

Yeah, I don't know. I also found it interesting that they gave me .90kg springs, when the online calculators generally suggest .80kg on my light days, and .85kg on my fat days. I told Traxxion to go with a 150lb rider. I found a discussion on some forum that mentioned that they tend to run heavier springs in their setups, and they do some modification to the emulators, but they were also more favorable to the end result vs. Racetech's results. I've found it's generally better to go with what the experts recommend, rather than second guessing and going my own way when I don't fully understand why. I think I'll shoot them an email before ordering the fork oil.
 
#5 ·
Yes, please let us know what there reasoning is for the different oils used.

I weigh 90KG without gear and the racetech website calculated .85 springs.

I have tested my bike today for the first time since doing the upgrade. Will have to agree with most of the people here that have already made that upgrade, what an improvement....Between the GSXR750 rear shock and emulators, springs and fork oil replacement, the bike feels like a completely different bike. The bike is so much more pleasurable to ride now. The $500.00 investment is well worth it.

Still need a little tweaking here and there but straight out of the box it feels fantastic.
 
#6 · (Edited)
I have to admit I do not know how they came to this conclusion on two different recommended fluids , but I can imagine a few theories behind.
In general it might not be a bad thing. It is a widespread practice to have different controls in different legs. e.g. on a Versys one leg has a spring only the other has a cartridge type compression and rebound damping. Separating compression in one and rebound in the other leg is very common nowdays both with track and mx bikes.
so the theories
1, They had modified the damping rods to better separate compression and rebound and need different viscosity to perfectly tune it
2, The emulators set to provide slow and mid speed compression damping in separete legs so they implement a two step damping curve with the two different weights.
3, which is the most unlikely they wanted 25w damping but it was not available.
4, they are compensating for the slightly different forces under braking with the single disc of the CB.

I think number 2 is the most likely. It would mean that in certain parts of the travel only one or the other leg tuned to operate and the rebound damping holes are sligthly enlarged to accommodate the substantially heavier fluids recommended.
Would be interesting to see a comparison shot of the original and modified damping rods.
 
#30 ·
I have to admit I do not know how they came to this conclusion on two different recommended fluids , but I can imagine a few theories behind.
In general it might not be a bad thing. It is a widespread practice to have different controls in different legs. e.g. on a Versys one leg has a spring only the other has a cartridge type compression and rebound damping. Separating compression in one and rebound in the other leg is very common nowdays both with track and mx bikes.
so the theories
1, They had modified the damping rods to better separate compression and rebound and need different viscosity to perfectly tune it
2, The emulators set to provide slow and mid speed compression damping in separete legs so they implement a two step damping curve with the two different weights.
3, which is the most unlikely they wanted 25w damping but it was not available.
4, they are compensating for the slightly different forces under braking with the single disc of the CB.

I think number 2 is the most likely. It would mean that in certain parts of the travel only one or the other leg tuned to operate and the rebound damping holes are sligthly enlarged to accommodate the substantially heavier fluids recommended.
Would be interesting to see a comparison shot of the original and modified damping rods.
I wonder did you mean #3 as a joke or not? I figured if they wanted to get 25 they would ask you to mix them both and get a 25. am I missing something?
Just got off the phone with Traxxion Dynamics, and he was very helpful. I won't be able to remember every detail, but I'll share the basic points here to help others.

You can't compare their recommendations for a given bike/rider with the recommendations from another company because it isn't an apples-to-apples comparison. Their damper rods are different than drilled-out OEM rods, and even some of the spring dimensions are different, thus oil displacement is different, etc. I think he was also saying I'd get some of the advantages of a stiffer spring, but other factors cause the system to also react as if they aren't as stiff (my words).

Also, whoever mentioned using 20 & 30wt oil was because they don't make 25wt was actually right. Traxxion said you probably could mix them, but it's just easier this way. I was concerned this might cause uneven stress on the fork legs, but he assured me it's all good, is commonly done, some forks are designed with spring on one side and damper on other, etc. (like someone else here mentioned).

To be clear, don't use Racetechs spring-rate calculator to figure out springs from other companies. Check it out with them before ordering if you are buying their springs. Also, if you buy the kit I got you just enter your weight and bike, and they do the calculations.

Hope I relayed the info clearly, but I feel much better about moving forward with the install now. :)
I'm not sure what "BS" statement you are referring to. Traxxion never said that mixing 20wt & 30wt will give you 25wt. You seem to think that's what they said and therefore, you will never buy anything from them because they are "clueless" and "take advantage of people".

To me that's overreacting.

I sent an email to them because I was curious. They immediately got back to me and based on what they said it's clear they know what they're talking about. What they came up with is based on actual experience and testing and finding out what works in real use.
See above! That's what all my replies have been to.

I also didn't say that their stuff doesn't work. I said I don't know know much about them, and that I personally would stick to what I know works.

My spiel was about the viscosity mixing deal. Again...not over-reacting, just trying to provide info, as useful or useless as it may be to some.
 
#15 ·
LOL viscosity doesn't work like that. Mixing 20 with 30 at 50/50 ratios does not necessarily yield 25. Viscosity scales are generally logarithmic, not linear. Of course I'm not sure what 20 or 30 actually is, because that's not a real unit of measuring viscosity, like Poise, centiPoise, etc.
 
#8 ·
Not exactly a joke, but as I wrote quite unlikely this would be the case.
Just a sidenote - it happened to me more tyan once to mix two different viscosity fork fluids to get the desired result but I allways use the same type and manufacture from both. BTW I've yet came across a 25w fork oil. 20w is a less used standard viscosity fork oil and 30w oils are also available but again I haven't seen these two from the same made - but it might be only me.
 
#9 ·
I remember reading about racers using two different wts in each leg but I don't remember why.
 
#10 ·
Maybe it's not a good idea to mix the oils?

That would be the logical conclusion if they recommend 20 here and 30 there.

Maybe the innards of each leg are different, too?
 
#11 · (Edited)
I wouldn't mix them. I don't have them in front of me, but I believe the innards are the same L & R. Also, notice most of the bikes listed are only using one weight of oil. I must be how they worked it out for the CBR500. Will update if I hear anything official.

EDIT: I just called Traxxion, but the guy to talk to was on another line and I had a meeting to get to myself, so I'll call tomorrow. My initial contact was very pleasant, and the women gave me his direct number. Stay tuned (no pun intended)....
 
#12 ·
Just got off the phone with Traxxion Dynamics, and he was very helpful. I won't be able to remember every detail, but I'll share the basic points here to help others.

You can't compare their recommendations for a given bike/rider with the recommendations from another company because it isn't an apples-to-apples comparison. Their damper rods are different than drilled-out OEM rods, and even some of the spring dimensions are different, thus oil displacement is different, etc. I think he was also saying I'd get some of the advantages of a stiffer spring, but other factors cause the system to also react as if they aren't as stiff (my words).

Also, whoever mentioned using 20 & 30wt oil was because they don't make 25wt was actually right. Traxxion said you probably could mix them, but it's just easier this way. I was concerned this might cause uneven stress on the fork legs, but he assured me it's all good, is commonly done, some forks are designed with spring on one side and damper on other, etc. (like someone else here mentioned).

To be clear, don't use Racetechs spring-rate calculator to figure out springs from other companies. Check it out with them before ordering if you are buying their springs. Also, if you buy the kit I got you just enter your weight and bike, and they do the calculations.

Hope I relayed the info clearly, but I feel much better about moving forward with the install now. :)
 
#16 ·
Also, whoever mentioned using 20 & 30wt oil was because they don't make 25wt was actually right. Traxxion said you probably could mix them, but it's just easier this way. I was concerned this might cause uneven stress on the fork legs, but he assured me it's all good, is commonly done, some forks are designed with spring on one side and damper on other, etc. (like someone else here mentioned).
Seriously??? That's what they said?? Wow! Good to know not to ever buy anything from Traxxion as they are clearly clueless in fluid mechanics if they think that.
 
#13 ·
Thanks for the update. Let us know what the ride comfort is like after install.

My only concern would be that if the springs are on the stiffer side you may find it difficult to tune the forks for road / touring riding. Stiffer springs feel fantastic on smooth road surfaces but can be a little harsh over bumpier roads.

Best of luck.
 
#14 ·
If I remember correctly what I read was some racers were running it like that and then depending on conditions at the track they could replace the oil in just one fork if need be. That way they could have 20, 25, or 30 by only having to replace the oil in one fork.
 
#20 ·
I too have RaceTech emulators in my CB500X and I used 15wt oil...Traxxion knows what they are doing and they have shock simulators where they can test the response. With emulators you can easily "tune" the high speed compression response by either changing the little spring that sits on top of the emulator or by changing the preload on the spring so I doubt that Traxxion wants you to have different set-ups per fork just to be able to get compression right. Since using emulators the rebound response is NOT adjustable and is fixed by the size of the factory re-fill hole drilled into the damping rod it is ONLY adjustable in response by changing the weight of the fork oil. Apparently in their testing they found this odd combo gave the best rebound response. I can tell you that in my set-up using 15wt fork oil that my rebound is on the "light" side and I could use a little more rebound. Putting 30wt in one fork tube just might be the sweet spot. Don't discount Traxxion...I have bought several sets of their drop in AK-20 cartridge units and they have all been "spot-on" as instructed.
 
#21 ·
Yeah, I was just going to comment that regardless of the science, I'm following their recommendation because it's what they came up with as the best performer. It's what they do for a living, so I'll give them the benefit of the doubt. I just ride bikes to work and talk to angry soccer moms all day.
 
#22 ·
You bought their product so it makes sense to follow their recommendations. Some BMW's had compression damping in one fork and rebound in the other. The ST1100's had a cartridge in one leg and conventional damping tube in the other. I can't see a slightly different oil viscosity in one fork tube than the other, being a big deal. Showa has "bending valve" technology now, and we may see it next year. An inexpensive system to make budget forks perform like cartridge forks. There may soon be an end to harshness in budget forks.
 
#24 ·
I went on the Traxxion website and read their engineering philosophy. They state that the damping tubes they make, reduce the oil viscosity required to achieve good results. They also mention that companies like Racetech use too thick an oil, which does not result in consistent damping. Well, 30wt. oil is as thick as it gets, and they don't list that grade on their site. That all seems a bit odd.
 
#25 ·
My bike came with Racetech springs, emulators and preload adjusters, and so far the front end seems pretty good (though I still don't have that much time spent on it), and since this was a cheap bike I don't want to put thousands of dollars into it, so I won't change anything anytime soon, but typically with bikes I tend to stick to what I trust and what I know works, and #1 on that list is Ohlins. I'm not sure that Ohlins makes any forks for this bike though, so my next option would be the other thing that I know has been well proven, which is Andreani fork cartridges. That's what all the 500s use in the European Junior Cup, so if it works for all those guys that are better riders than me, then it sure as **** will work for me. Racetech is a good cheap alternative to make your forks better because of their emulators, so that's not a bad way to go either. Although I've heard of Traxxion before, I've never used any of their stuff, and after some of the posts here, I'm starting to doubt their credibility, so like I said....I'll stick to what I know works.
 
#32 ·
Yes, I'm sure my comment was confusing. These were my words meant only to articulate how I understood it, and never attributed directly to TD. There has been some clarification in the background, and I can confidently say they never actually said to mix fluids. An easy misinterpretation for those not part of the original conversation with TD. Glad this is settled and behind us now.

I'm looking forward to the install and sharing what I anticipate being a much better performing bike.

Yeah, I don't know about the rear shock. Adjusting preload made a huge difference for mine, but it still leaves a lot to be desired. Unless a relatively easy/inexpensive mod comes along, I'm going to wait for my next bike to improve suspension any further. I'm at the point now where it just doesn't make since to continue putting upgrade money into the CBR500r.
 
#33 ·
I am still trying to figure out how to adjust the preload in the forks. It is interesting that my owners manual and the Honda shop service manual do not tell you how to setup your suspension? The service manual explains how the suspension come apart and goes together, but not how to adjust it.
 
#34 ·
The front is not adjustable from 2013-2015. You have to buy preload adjusters to replace the fork caps. OR you could just throw shims on top of the spacers, but I'd always go with adjusters if an option. Ebay will be your cheapest bet.
 
#38 ·
It looks like the '16 does come with adjustable preload. Take a flat head screw driver and turn the silver stud.



I would go all the way out first, and then all the way in and make a note of how many revolutions it can go, so that you know what the full range of adjustability is. Then you can set it wherever you want based on how it feels for you. Best thing to do is to set your sag like in the video posted above.
 
#37 ·
Thanks, I will check this one out. I saw another one on You Tube and I know you can use the kickstand to tilt the bike on to get the forks off the ground into full extension. Instead of getting it totally set up with measuring sag, for now I just want to know which way do I turn the adjustment to make the forks firmer.

My service manual only goes to 2015 as the 2016 was not available now. Clymer and others will take a few years. These Honda manuals do not even show you how to adjust the rear suspension either.
 
#41 ·
There is a chart somewhere on the internet where a whole bunch of fork oils were tested for their actual viscosity. I saw it when I rebuilt the forks on a sportbike I had.
If anybody is interested I'll try and find it.
All I can say is this..the weight listed on the label has almost nothing to do do with the actual tested weight. It is off by quite a bit.
 
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