RC4WD R2 Dig Install In R1 Chassis

[supermoturd]

This is my first crawler build (actually my first RC build aside from a heli I built in college) so I have no idea what I'm doing. I'm attempting to install the R2D tranny in my R1 tuber chassis. I've seen bikerzee's install thread for the Stealth chassis and, as he noted, the Stealth chassis is a bit roomier. I ordered the R2D tranny before I even got the R1 Rock Buggy kit and have chewed my nails down to the quick as I've calculated and researched, wondering things like if the R1 chassis even had the width to accommodate the R2D transmission. I'm happy to report that it can and does. The other problem that I anticipated was interference between the rod end of the rear, upper, right suspension link and the endbell of the motor. As you will see, If I'd gone with anything longer in the can than the 55T Integy Lathe Motor, things would not have worked out.

I installed the transmission as far forward as possible on the delrin skid plate. Due to proximity to the preexisting mounting hole, I was forced to go with only 3 screws.




Doesn't get any closer than this! Rod-end barely touches the endbell! (rear, right, upper-link rod-end shot from above)


Same thing, but shot from below.


Front lower links have sufficient clearance.


Here's a shot of the rear from below and aft.


And the front.


I'm doing cytogen's battery tray mod, but I've had to trim the tray to accommodate the savox SC-1251MG that will be used to drive the disconnect. In this shot, you can see what I have to work with space-wise in the cockpit. I'm going to mount my receiver on the radio tray that I have moved to the rear of the cockpit (where the battery tray was.)


So. There it is. Assuming that I can shoe-horn the servo and mounting kit into the space between the tranny and the ESC tray, it is possible to cram an RC4WD R2D tranny into the stock R1 chassis.

I forgot to mention that I had to trim 12mm of of the front and rear drive-shafts.

[supermoturd]

I have found myself worrying about whether or not the U-Joint on the rear drive shaft will interfere with the collar that will be attached to the rod that drives the shifting fork for the dig. Upon receiving the sideways servo mount steering kit from RC4WD, I was discouraged to find that the U-Joint does, in fact, interfere with the collar. RC4WD's solution is to install the provided shaft extension so that the U-Joint can be connected further aft, thus clearing the collar. Unfortunately, this would push the U-Joint back far enough to interfere with the rod end of the upper right suspension linkage. The only option that I had was to grind enough material off of the collar to facilitate clearance for the U-Joint. It works; as can be seen in the image.


I am a bit disappointed with RC4WD. The steering kit was very poorly assembled. It almost seemed like more of a grab-bag of hardware. The kit was missing a rod end and included two 20mm long socket head cap screws instead of the required 25mm long socket head cap screw. Fortunately I had a 25mm long screw left over from my RCScrewz kit (which I HIGHLY RECOMMEND to those who are considering the Gmade R1.) As for the rod-end, looks like this build will be on hold until RC4WD can get one shipped to me.

[supermoturd]

Finally finished assembling, tuning, and installing the RC4WD R2D transmission. As you can see in the photos, you really need to use a low-profile servo to actuate the dig. I don't have the funds to purchase a Savox SC1251MG right now so I used an old Hitec HS-311 that delivers a meager 51 oz-in of torque at 6V, which is well below RC4WD's recommended 60 oz-in minimum torque for the dig servo. I was able to fit the HS-311 by mounting it on the wrong side of the mount. And I had to carefully trim channel 3 and adjust the EPAs to enable the servo to shift into each of the 3 positions without humming. This was very easy to do with my hacked GT3B (thanks to Overkill RC!) Of course, you have to apply a bit of throttle in order to enable the dig mechanism to engage; but once engaged, the servo does not hum at all.

I went for a test drive around the living room and am happy to report that I am thrilled with the performance of the RC4WD R2D transmission. The steering on the R1 is so pathetic that driving the R1 without dig is painful.

[bikerzee24]

Well done on the build, I am glad you were able to get the tranny fitted in there for use.

[supermoturd]

Originally Posted by bikerzee24

Well done on the build, I am glad you were able to get the tranny fitted in there for use.

Thanks! Your build thread was very helpful. I am very happy with the R2D transmission.

[Androtaz]

Slick. Nice shoehorning job!. I just went through this same thing with a trail stomper chassis and a dna dig. Tight quarters sucks but its worth all the effort when it works.

[supermoturd]

Originally Posted by Androtaz

Slick. Nice shoehorning job!. I just went through this same thing with a trail stomper chassis and a dna dig. Tight quarters sucks but its worth all the effort when it works.

Thanks! It is challenging but oh so rewarding. I've been obsessed with RC crawling for over 5 years now. It was not until recently that I was able to afford to indulge this obsession. With most obsessions the anticipation is far more exciting than the realization. Not so with this hobby. Crawling and working on the rig, for all of the frustration and dawnting challenges they present, are so richly rewarding. It takes a special kind of brilliance and ingenuity to even get an RC crawler rolling. I salute and celebrate with everyone who has accomplished this amazing feat. This is such a great community to be a part of. I do hope that my small contribution proves useful to others.

[Niels]

Thanks for sharing! Good to know that its possible to cram the R2 in there

I tried the R1 dig unit from Junfac but it didnt work out very well. Ended up with an Axial tranny + VP dig:



VERY tight fit, but it works great!

[supermoturd]

Nice! I would prefer the axial tranny but the R2 was $39.99. What is the gear reduction ratio on that transmission? The reduction on the R2 is 30:1, which I feel like is too short. The stock R1 tranny has a ~40:1 reduction. But with my 55T motor, the R2 seems to have plenty of torque.

[Niels]

Great price for a complete tranny! I paid $80ish just for the DIG I love the Hurtz DIG though, very solid and it doesnt abuse the servo as much as other DIGs I have tried. I think you can even use a mini servo like the HS-225MG.

The axial tranny is very flexible. By varying the spur and pinion you can gear it from 15:1 to 74:1. I have roughly the same gearing as the R1 trans now

[supermoturd]

Originally Posted by Niels

Great price for a complete tranny! I paid $80ish just for the DIG I love the Hurtz DIG though, very solid and it doesnt abuse the servo as much as other DIGs I have tried. I think you can even use a mini servo like the HS-225MG.

The axial tranny is very flexible. By varying the spur and pinion you can gear it from 15:1 to 74:1. I have roughly the same gearing as the R1 trans now

Yeah. The R2 is tough on servos. I think that down the road when I have the money, I will do what you have done. One question: will that tranny go in an SCX10?

[Niels]

Originally Posted by supermoturd

will that tranny go in an SCX10?

Yes, it is an SCX10 tranny I think its more or less the same tranny in the Wraith too - they just added a spur gear cover and the casing is a bit larger to house the optional dig.

[supermoturd]

I tore the R2 transmission down to inspect it after putting about 2 hours of run-time on it. The teeth on the spur gear on the output shaft were badly worn to the extent that they were hook-shaped. Not sure if this is due to inadequate lubrication or if it is due to overly tight mesh between the gears. Any body have recommendations for lube for metal gears? The lube recommended by RC4WD is out of stock (big surprise there).

Also, with the 12-Tooth pinion, the reduction on the R2 transmission is 20:1. I'm pretty happy with this ratio. The rig has plenty of torque. And truthfully, I'd rather have it stall than shear an axle off or strip gears.

[supermoturd]

I rebuilt my R2D transmission again tonight and inspected it to see if the gear on the output shaft had sustained any additional wear after being properly lubricated. Inspection revealed no additional wear so the stickier grease seems to be working. Regardless, I took the opportunity to apply an even stickier grease, viz., Lucas Oil Red and Tacky #2.

I've included the following images just in case others might want to use them as a reference for reassembling the R2D transmission.

[supermoturd]

After putting about 15 hours of crawling on the R2D, I regret to say that I don't like it and will be replacing it. My main problem with the unit is that it cannot be shifted from 4WD to neutral or from the locked position to neutral while the throttle is being applied. I have a low-profile Savox with what should be plenty of torque. Regardless, when I try to shift to neutral during a climb to disengage my rear wheels and keep them from flipping the rig over backwards, the dig shaft simply will not disengage from the transmission output unless I come completely off of the throttle. When I do so, the rig slides backwards and surrenders hard-won progress. It really defeats the purpose. Furthermore, when the dig is engaged, I have to apply a bit of reverse throttle before the dig can be disengaged. This is not such a big deal, but it is still a pain.

I've ordered an Axial transmission and the Vanquish Products Hurtz dig.

[Nzmaximus]

I find it odd that you are wearing out the spur gear on your r2, i have not had these problems (touch wood) perhaps it was a production fault. I have noticed a very small amount of metal in the grease, but nothing seems particularly bad. I have not got the dig actually working, i have it locked with an elastic band. It was second hand in the crawler i bought, and it didnt have the linkage or mount. If i had enough money, a steering-size servo wouldnt fit in my chassis, the plate above the trans is pretty much touching. I think i would have enough space to put a smaller size servo in but you say it wouldnt work? Also, i am confused at how the collar stays on the digs shifter shaft, it is smooth. Does it have a grub/set screw or what? I was thinking of welding a bolt on the end of the shaft to provide more options for a custom linkage. Thanks

[Nzmaximus]

Perhaps the wear was from a different pinion? Slightly incorrect teeth size? Sounds like you used a different one, the stock is 8 tooth, not 12. Good luck with the axial trans, anyway.