Fork Fluid
 

I was going to do a simple post in "What did you do to your RX3 today" but thought I'd start this instead.

Has anyone here changed their fork fluid yet? I did yesterday. Got bored, all three of my Penske Boyz were knocked out of the NASCAR race so I thought no better time to gut the front off the RX3 and do the fluid.

Now....with the TT250, I recorded 320cc's drained from each tube. Makes sense because they're rated at 330cc's and there's always leftovers inside unless you do a complete teardown.

The RX3 forks are supposed to hold the same amount (330cc's), according to the CSC tutorial. Now, just like the TT forks, the RX3 forks worked well enough, but had that harsh little bit at the first "bounce" of travel that you could feel in your wrists and elbows. Nothing big but it was there, nonetheless. Other than that, I was happy with how they handled the rough stuff and twisties.

Well, well.....I was only able to coerce 250cc's from each fork tube....and they're supposed to be holding 330cc's. I understand that there will always be some left inside, lining the tubes, dampening rods, springs, etc...but 80cc's?

Anyway, I refilled with the same amount (250cc's) of Bel Ray 10W (I'm currently 220 lbs) and went out for a burn. That first little harsh bit, gone. The forks now eat up all the little stuff the road feeds them. Even with the odd "lesser amount", they feel just fine.

Anyone else had this experience with the fluid volume? Unless there's some "mystery chambers" that are holding upwards of 80cc's of fluid, they seem to work just fine with the amount I refilled. I surely didn't want to overfill them.

Thanks for the post, 2LZ.

I haven't replaced the fork oil yet, but have been thinking about it.

The front end of my RX3 has a "jittery" up and down motion to it.

I was hoping new fork oil might cure it.

And mote than likely, the new fork oil would be a better quality than the factory oil.

What weight oil did you use? Did you flush out the old oil with ATF fluid?

jb

I've been strung out on Bel Ray 10W since my young MX days. It's all I've ever run. I used to use ATF as a kid but once I got more aggressive, it would foam and blow up the forks. I don't ride like that now but I've never had any bad results with the Bel Ray.
The biggest thing I noticed is now the forks really function in that first 1-2" of travel. Eats up the small stuff now.

I didn't flush them, just let them ooze for a while until they dripped at least 50 times. I flipped them back and forth a couple of times looking for that mystery 80cc's but both forks acted identically.

Typical RX3 though. Compared to the smaller bikes, it's a pain to wrench on. You have to remove the cowl around the ignition just to get to the upper tree bolts and you have to undo all the plastics and pull them away from the tank to access the lower tree bolts. As usual, it's the plastics you spend a bunch of time on, not the actual project.

i know spud man used mobil 1 synthetic atf in his forks there is a thread someplace on the different amounts of oil people were getting in there

2LZ,

Had near enough the same thing a while back,

See here http://www.chinariders.net/showthrea...591#post195591 and my following posts in that thread :)

Thanks katflap! So much for my "search" talents. Sheesh... I must have spelled it "ferk erl" or something like that. ;-)

I see that there is an internal cartridge that holds the mystery 80cc's. Good to know! Still a nice improvement with the new stuff in it, for sure. More forgiving to the elbows and wrists in the light bumps.

2LZ,

I thought measuring the height of the oil in the fork tubes was the traditional way of measuring the correct amount.

Am I missing something?

jb

That's with conventional forks. The RX3 has inverted or sometimes called USD (upside down).

Thanks, haven't had to change fork oil in usd forks before.

jb

Since CSC was kind enough to supply us with a measurement in cc's (and fl oz) in the tutorial, that at least let me know what's "too much".

Generally speaking on USD's, if I'm not completely disassembling them and changing seals, I usually put in what I take out, if they both measure evenly.
Out of all my CB's, only Q (Q Link), the TT250 (Zong) and now the RX3 (Zong) have had the same amount in both forks! Makes it easy guess work.

How do you know if there was the correct amount of fork oil To start with?

I'm currently changing the fork oil in my TW200 (long overdue), and the amount of fork oil was not anywhere near what the manual calls for.

jb

You mean to tell me a Japanese bike didn't come with the recommended amount of fluid in them!? ;-)...either that or your seals are leaking???

Are you gutting them completely and replacing seals and bearings? If so. I'd do the recommended amount. If you're just dumping them and refilling (on normal forks), I'd do the measurement from the top without springs if you have that stat. Then you know it's correct.

No evidence of seal leaks on the TW, just dumping and refilling.

I've done this job on "right side up" forks many times.

Yes, having the wrong amount of fork fluid from the factory is not uncommon on TW's.

What I'm wondering is how do you know if the amount of fork oil in USD forks is correct from the factory if you only replace the amount of oil that comes out?

jb

I have to second this question. When I drained the forks on my Qlink XF (when I had it), I got 330 ml out of each fork just like the specs. said I should have.

Hey I can chime in here. I just changed mine recently. I couldn't find Mobile 1 ATF but I used another well known brand I can't quite recall. But I also used the synthetic ATF. I let my forks drain for a couple of days and got 325 CC's of fluid out of each one. After changing the fluid the sharpness did go away a little. Certainly better than stock.
Hope yours get better as well. Good luck.

Thanks, Moto.

Did you put in the recommended 330 cc or the 325 that came out?

Another question that I should know, but don't.

What is the weight of ATF? Is it all the same? As I recall, there are different types of ATF.

jb

Funny thing is I got 320cc's out of each TT fork on the first drain (spec is 330 also) but the RX3 only gave me the 250. I believe it's due to that cartridge that holds the extra 80, as katflap pointed out.
Possibly if I would have let them drip a few days as Moto mentioned, then it may have given the entire 320-330.
Especially after a couple rides, I feel confident that the correct amount went back in.

Spud, as always, did the homework for us. Check out post 27 here for the info; http://www.chinariders.net/showthrea...t=chart&page=2

Spud's chart is very helpful. Another ATF that Spud has recommended in the past is Valvoline Maxlife ATF, which comes in a little lighter than Mobil 1 Synthetic ATF. Maxlife viscosity@40C cSt is 28.82, whereas Mobil 1 is 34. Both are excellent choices; it depends on your specific needs/preferences.

Good find! Good find, david3921!
Yes....Spud always comes through....wherever he may presently be. We're still currently in a potato famine. ;-)

Like I've said, I've always had spectacular performance from the Bel Ray, even back in my younger MX days when I was far more demanding of my bikes....but I may have to try the Mobile 1 ATF next time around. As Spud pointed out, it's less expensive, easy on the rubber, doesn't foam like the older ATF's I've run, and is readily available many local places....and Lord knows I don't ride like I used to ;-)

I was thinking about this the other day also.

Count me in as I've been pondering this also.

Mobil 1 synthetic atf ! I think I even have some left. 204k on that silverado and have changed a.t. 5 times exclusively with the stuff. First time it took 14 qts to replace all the organic stuff (quiet expensive as I remember) but i believe it made all the difference in keeping my transmission alive.

Thanks, David.

Impressive chart.

But what is a centiStoke?

And how does that translate into terms normal people can understand?

And where the heck is Spud? :hmm:

jb

A centistoke (cSt) is the derived centimeter-gram-second (CGS) unit of kinematic viscosity.
---
I don't care what's inside those fancy fork oil
DEXRON-VI https://en.wikipedia.org/wiki/DEXRON#DEXRON-VI ATF or AW32 Hydraulic fluid from name brands is economic workhorse in bike's forks

Yeah...that didn't help. Take it down to dolphin level for me, please.

He's bi or multi lingual but still not speaking in my language:lmao:

A unit to measure this:
https://www.youtube.com/watch?v=6LNPhWqObao

It gets very complicated. Best to just consider it a mystical unit of measurement. The only way it is handy for folks like us to use is in a chart so we can use it to select something thinner or thicker than what we are currently using.

Product Whoopie Oil 10 rates at 28 cS and we want something a little bit thicker. Product Nifty Oil 15 sounds good, but actually flows at 25 cS. So that's not what we would want to buy.

Weight is a SAE rating for lubeication..
forks/shocks work by flow rates that is the
centistroke "CST" rating at 40*c

I have never seen a CST rating for ATF.. but I have
never looked either.... not something i would put in my forks...

the real prob with useing weight.. Is a 10 weight oil
from one company can be the same as a 15 weight from another
the weight rating is all over the place with no real standard..

For a dirt/trail bike...
used in the dirt stay with a centistroke "CST" rating under 18..

There are CST Centistroke charts on the net that give almost
all fork/shock oil from diffrent companys & bike Manafactures oil
in the centistroke rating..

Google is your freind...



...

summer is short in the potato state lets hope spud is putting another 10.000 miles on his ZONG

Probably another reason I've always stuck with the Bel Ray for decades now. I know what to expect from each weight and its performance.

The 5W was good for Mrs. 2LZ Kingpin. She's lighter and rides less aggressively than I. The 5W gives her good dampening for her needs.
I use the 10W in my dualys and dirt bikes but ran 15W in my massive Vic TC. Between my weight and the bikes weight, it was the correct choice for those forks, loaded up for a camping trip.

I would imagine that it doesn't matter what you choose, sticking with one brand product gives you the consistency to know what to expect in product performance.

Thanks Pete and HB for trying to educate me. I appreciate it.

I know I could do my own googling, but I am in the North Carolina mountains for a couple of months where, even in theses modern times, there are places with no cell phone coverage.

My internet connection is through an intermittent cell phone connection that drops the signal half the time.

Nevertheless, thanks for the assistance.

I'm tempted to try the Mobil 1, but I have a couple of bottles of Yamaha 10w fork oil on the shelf, and will give it a try.

jb

Spud is enjoying his summer; he checks in from time to time, but he's not typically as active on the forum during the summer. All he wants to do is ride.

The chart is useful in a few different ways. You don't really need to know what cSt means, just use the numbers to compare. As an example, 2ZL uses the the BelRay 10w and the chart shows that is has a cSt of 33.5. Spud likes the Mobil 1 @ 34.0. These two will be pretty dang close in performance. The thing is that the Mobil 1 will be readily more available to most of us. Blackbike says that he uses it in his truck's transmission. Also, like 2ZL said, once you find a brand you like (availability, anti-foaming, ect.) you can use the chart to find a higher or lower cSt based on need.

Dang! If it's that close, I'll get the Mobil 1 next time around at Walmart! ;-)
All good info once again.

Edit: I thought I'd price compare to see how much I'd save. I may have another bike joining the "rescue" (as my neighbor calls my garage) and will probably do all the fluids.

On Amazon (my small town Walmart doesn't list it) has the Mobil 1 ATF for 9.50 a qt. Prep Boys is around 9.

I paid 11.33 for a liter of Bel Ray on Amazon with free shipping.
These are priced far closer than I thought they'd be. I thought the "fancy" fork oil would have been quite a bit more. Surprising.

Centistroke rating for most fork oils...
you may have to save it to your computer then zoom in to read it...

http://i1244.photobucket.com/albums/...on%20fluid.jpg





..

Now that's some good Smidt there Pete! Thanks for posting it.