2 speed in CR?

[Gunngee]

I'm curious if anyone has tried this and if so what transmission did you use and how hard was the install?

I've been thinking it would be nice to have this option as a number of guys in my rc club are getting into ultra4 racing and I can't afford a sensored brushless system or the upgrades I would have to make so that I wasn't breaking something everytime I hit the throttle.

[OSRC]

I've never seen one done. That would be tricky I'd think. I'm sure you'd have to remove the secondary radio plate for a shift servo. I'd be concerned about the driveshaft angles - the rear is tight as it is. Having said that, the outputs on the stock trans are pretty long. Imagine a wraith trans could be made to work, so the AX2 from RC4WD could probably be shoehorned in there. My shorter WB rig is running an axial trans currently - the stock trans was too long.

What are you breaking? I've beefed up my driveline on the cheap, and so far it's holding up very well. Running a Holmes Revolver and some very grippy, heavy tires. Axle wear is my main concern, the pins on my driveshaft are looking awfully thin.

On a side note, I've picked up a 17.5 sensored motor and ESC from hobbyking for $50 (US) and so far it's been working perfect in another rig. Looking into a second system. Should be a good match for the CR's planetary trans.

[Gunngee]

One thing I should have added is I have lengthened the wheel base by 1.5 inches. As far as breaking stuff, not much just the odd stub axle when I get to heavy on the throttle sometimes. Which I thought was weird because I thought the plastic driveshaft would have broken first. I have looked at the AX2 online and it looks pretty cool but I was also wondering about the tranny in the traxxass summits...

[OSRC]

Ah, you should be good then. Especially if you've lengthened it in the rear.

Yes, the stub axles are a bit weak. Tamiya makes hardened ones, and some HPI units fit as well. I have some older RS4 Steel axles here for fitting when mine let go. Look like they'll work, time will tell.

AX2 would be a drop in compared to the Summit. It is physically bigger (I think), has no bolt on mechanism for the shift servo, and different outputs. Physically, I believe it would fit. Would definitely be more of a challenge. Just happened to have one sitting here I can test fit for you if you want some confirmation.

[AC_Crawler]

Also if you drop the frame it helps with the geometry of the drive shafts so they aren't at such extreme angles. You guys have broke stuff? I've been running mine hard for almost 3 years without breaking anything *knocks on wood*. We will see how strong my other cr01 is though after I finish the buggy build on it and leave big tires on. Though I am using 27T motors lol.

[Gunngee]

I just found somebody in my club with a summit, he's gonna let me come over and have a look at it so I can compare dimensions etc to see how difficult it will be. I would love to get the ax2 but the summit tranny is pretty cheap.

[OSRC]

Have an AX2 on the way currently, if the summit trans does not work out, I can get some comparo pics of that as well.

[Gunngee]

Originally Posted by OSRC

Have an AX2 on the way currently, if the summit trans does not work out, I can get some comparo pics of that as well.

Thanks! that would be great!!!
I have to do some trouble shooting though I just put in a new stub axle and spit the same one out the same day I put it in. Broke an ear right off and destroyed the bearing. I think there's something going on with my inner axle...

[OSRC]

Sounds like the axle is bent. Bent a WK axle right at the ball end and it did the same thing. I've beefed up my diffs quite a bit, but the axles concern me.

Let me see what I can do, trans should be here Friday.

[Gunngee]

Well I went and had a look at the tranny from a summit. Definitely to big, it's to long, even though I've lengthened my wheelbase, I would still have to shorten my driveshafts. Looks like I'm stuck with the AX-2 but from what I hear they are a good tranny. As for the problem with my CR axle, it was the cross pin. It was so chewed up that it was destroying the stub axles. I managed to drill out the old one and now I just have to put in a new one.

OSRC, if you wouldn't mind some comparison pics of the two tranny's that would be great!!!

[OSRC]

Got the trans in, just by eyeballing it, it's a fit no problem between the rails. Outputs are fine, shorter than stock. Might be some clearance issues with the upper links, not sure yet.

I'll see what I can do to get pics up for you.

[Gunngee]

That would be great, Sounds like this is the route I'm gonna go. Would love to see some pics for sure!

[J.Peart]

Originally Posted by OSRC

Got the trans in, just by eyeballing it, it's a fit no problem between the rails. Outputs are fine, shorter than stock. Might be some clearance issues with the upper links, not sure yet.

I'll see what I can do to get pics up for you.

Curious to see how you did this cause i looked at an ax-2 and it didn't seem to fit. mind you i had the battery tray in mine still. maybe that's the difference.

[OSRC]

Sorry, by "got it in" i meant it arrived, not installed.

Better than never... here are some pics. Sorry they are not the greatest. Width-wise it's no problem. Height-wise, you'd have to do something about the battery tray. The secondary radio tray would have to
go as well (I never install them) and the spur fits there ok. Run an Axial trans in one of my other rigs in the same configuration pretty much.

The servo plate would definitely interfere with the stock battery tray though.

From the top..it fits, the camera angle does't show it though:


From the side, about level with the skid.

[Gunngee]

Is that the stock can motor?

[OSRC]

No, thats s 550 can

[Gunngee]

So if that's a 550 does that mean 55t? I'm curious to see what motor is going to work best with this tranny. I'm currently running a 35t lathe motor.

[OSRC]

550 is the length of the motor can, it's longer than a 540. Nothing to do with the turns. 35T motor would be an excellent choice for this trans.