Axle flex w large motors?

Hobby87

New member
I am running a cr250 on a 2011 badmax, the axle is .187wall (stock axle), no 3rd bearing, using 520 chain setup, curious how much axle flex I will have and should I be worried about loosing the chain?

Also, does chain length affect axle flex at all?

Matt
 

Trackchampion

New member
I run the same set up except on a prowler, 520 chain, cr250, no third bearing, you will have no problems, don't let anybody tell you different, it will work fine.
 

PBR Allstar

New member
Yeah, don't worry about it with the 520 chain. Look at outlaw karts, 500's with no third bearing. If you we're running small chain on a jack shaft, then I'd say yes, run one. In your case, let it be and stand on it!
 

ABR #69

Member
Are most outlaws running 1-1/4 axle or 40mm?

My axle is flexing, but I'm running a 450 four stroke. Just curious, I'm currently looking into putting 40mm axle with no third bearing.
 
I keep my gear as close to the bearing as possible. One of my karts the gear mounts on the outside of the frame rail. The other I modified the mount to be able to get it closer to the bearing.jmo
 

Hobby87

New member
ABR, we have alot of 250/500 open winged karts at our tracks, they are running 1-1/4 axles, but they are alittle thicker than the .187 that my badmax has, the QRC's are usually .250 wall, either way, i'll try it as is this weekend and hope the chain stays on! Brian, I have my rear gear as close to the RR bearing as I can get, thanks for the advice!

-Matt
 

OFG

New member
I run .190 chrome moly wall axle on my 450. It does flex without a doubt, but I have never lost a chain. Next year im gonna go with a .250 chrome moly axle. Reikens racing has a couple of them listed. D
 

GeorgeHenry

New member
Just go with the 40mm stiff axle and add another bearing close to the gear hub and be done with it. That is what I do on the Honda and Ktm 450 for my customers that there 1 1/4 axle flexes .They are worry about losing a chain in a race. If I could find out how to post pic's I will show them on this site.
 
I run .190 chrome moly wall axle on my 450. It does flex without a doubt, but I have never lost a chain. Next year im gonna go with a .250 chrome moly axle. Reikens racing has a couple of them listed. D
Did you know the stiffness squares with the diameter but is linear with the wall thickness.
Pete Muller may have something on this at his web site.
And as far as the type of steel is concerned, all steel is about the same stiffness. Chrome moly will bend farther before taking a permanent bend.
Comments, Complements, Criticisms and Questions are always welcome.
 

ABR #69

Member
I'm not worried about losing the chain, I'm more concerned that my brake rotor is rubbing my caliper. There is aluminum transfer on the center spacers. The rotor spacer rubs the spacer in the caliper and the center sections gall together; both being aluminum.

Ps, I have the super wave rotor from Chris Seay.
 

Attachments

ABR #69

Member
Since I apparently can only attach one per post?!? Here is the other.

You can see the dips in the spacer between the rotors, that was even or maybe slightly above the steel rotor.
The transfer is much less now that it's worn that much and I've ground it down.
 

Attachments

Logan

New member
With no third bearing my 450 would flex the axle a good inch forward. With the bearing I have alot less sprocket wear. Never threw a chain from the flex tho. But I did melt the aluminum out of my super brake before the bearing
 

Hobby87

New member
Have you guys considered running a solid steel vented rotor verses one with the aluminum spacer,seems the spacer is expanding more due to heat and contacting your caliper. I posted a tread under the Uas tab because of your very issue and found a couple places with the solid steel, vented rotor.

Matt
 

Logan

New member
Have you replaced the spacer, and it no longer "melts" or contacts the caliper spacer?
Yeah had to replace spacer. And after adding third bearing it no longer glows. My third bearing is centered between other 2 bearings and is connected with a hiem joint. It allows up and down axle flex but doesn't let the axle flex forward towards the drive gear.
 
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