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ATF in KDX Gearbox....

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Sep 3, 2003
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#1
Well i used to experience the clutch drag that you guys talked about in the
"kdx clutch questions" thread. Well there is a remedy without tearing
apart your bike to put better clutch springs in or a spacer in. Just use
some Dextron/Mercon Type III Automatic Transmission Fluid. It works
wonders. I was using regular 10-30 Motor Oil in it and i had to adjust the
clutch lever adjusted all the way out to get engagement without it
lurching. Once i did it without the clutch adjusted out and when i popped
it in first gear the clutch dragged so bad it moved 3 feet before it quit.
And when i tried to start it back up in gear it would move the whole bike
when the kick started went down. When i put the ATF in I adjusted the clutch all the way back in and it doesn't lurch like it used too!
I have heard many things about using ATF. They say it causes knotchy shifting...it doesn't. The 2-stroke gearbox is set up like an automatic cars gearbox which allows you to use ATF in it. If you do decide to put it in your gearbox, put a whole quart in, not what the manual recommends. If
you have any questions you can e-mail me at
mvcjr@localnet.com THANKS!
 
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#3
What are the types of ATF you don't want to use? ie; synthetic, with additives, etc
 

G. Gearloose

Pigment of ur imagination
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Jul 24, 2000
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#4
Originally posted by KDXRyder200
The 2-stroke gearbox is set up like an automatic cars gearbox
Uh, no....

The straight-cut gears in a motorcycle gearbox don't look anything like the constant-mesh planetaries in a slushbox, and see higher impact and sheer loading.
Also, the slushbox's BAND clutches see momentary action with short duty cycle. A motorcycle disk clutch can see extended abuse and long duty cycle.
A slushbox has pressure lubrication, a motorcycle gearbox is splash lubricated.

I admire your enthusiasm and I'm not saying some ATFs won't 'work' , but your premise is very false, and better shifting doesn't neccessarily equate to whats best for the hardware.
 
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Dec 14, 2002
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#5
Has anyone had a negative experiance with ATF in the gearbox? What formula or brands are used by those who use ATF and why did you chose that product?
 
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Feb 21, 2003
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#6
I use Type-F ATF in my '89 KDX and have had no problems whatsoever. It definitely shifts better than it did with the 10-30 in it when I bought the bike. The previous owner was VERY easy on it, so the tranny is in good shape. As for which type to use, Type-F is supposed to be the best. I buy mine at wally world for $1.25. I don't bother with synthetic as it is more pricey and I like to change mine every 3-4 long rides.
 
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Dec 27, 2002
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#7
While I voice my ignorance on the subject, I will say that all of the threads I've ever read on this topic recommend using Type F. Does anyone know what the problem is with using Dextron/Mercon??

Jeff
 
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Mar 23, 2000
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#8
I use a 50/50 ATF type F and 0-30 Mobil syntec.
I also put in aftermarket springs, as well as replacing the stock KDX clutch plates with stock XR250 plates.
Here's a picture of a KDX plate sitting on an XR250 plate to show the larger contact area.
http://community.webshots.com/photo/74476185/77652250yQubRE
Oh yeah, a Hinson clutch basket, too.
 
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#9
I just picked up what our local mechanics had which was regular Valvoline Dextron/
Mercon ATF fluid. As for the Type-F that is what they use in Hydrostatic transmissions.
You can use it..i would just stick with the Dextron/Mercon. As for how the 2-stroke
gear box setup i might be wrong but i was talking about a cars automatic transmission
not a hydrostatic transmission found on a lawn tractor or a combine.
 
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#12
IMHO I have found type F to be very knotchy at shifting in my 98 200 and I kept hitting neutral between 1st and 2nd, but have had no problems with 10w30. That being said it seems to have the opposite effects on most peoples KDX's here. So you decide for yourself...BTW both the type F ATF and 10w30 are made by Valvoline.
 

G. Gearloose

Pigment of ur imagination
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#13
Originally posted by KDXRyder200
As for the Type-F that is what they use in Hydrostatic transmissions.
And in older 'F'ords and Toyotas. 1968-1977 thereabouts. Maybe they got the idea from Tractor Magazine. ;)

Search the forums, there are years of discussion avail on the ATF thang. It is of course still not settled, and perhaps doesn't matter much.
 
Last edited:

Wolf

doooode
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Jul 31, 2000
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#14
I have used ATF type F for over one season in my KDX and had good success with it. Before that I used to run Mobil red cap. When I switched it seemed that the shifting has gotten a little smoother, could just be my imagination, though. I switched because I figured if it works its even cheaper.
I used the Walmart brand and occasionally I use castrol type F. To me, one is as good as the other.
I have run the Dexron/Mercon stuff in my son's Husky 50...based on a recommendation. No complaints there either....