New Revo Owner

[rchippie]

Originally Posted by crazyjr

oh yeah i forgot, but it required too large a gear to be practical, thanks i forgot

I belive you are correct my good man LOL. The BPP truggy had the same problem & they went with a 65t spur.

[Serum]

It depends on the kv of the motor and the used voltage if you need a bigger spur or not.

[MetalMan]

Lately I haven't been doing much to the truck (replacing parts that were broken when I received it), but I've been thinking rather hard about what's next. My original idea for the center "area" was a center diff. I have found that it would be tough to mount the motor and the center diff so that the chassis wouldn't interfere with the mounting of the motor/center diff. Right now I'm thinking I could make my own "slipperential" using the Revo center diff and the Revo slipper clutch. This way I can get the gear ratio lower and won't have to worry about the motor hitting the center diff outdrives and I won't have to worry about the chassis interfering with mounting the motor.

But, this relies on the Revo center diff. Does anyone know what pitch the Revo center diff gear is? I'm hoping it's mod1...

[squeeforever]

I think it is mod1 because if I remember correctly, the pitch of the Revo tranny gears and the Maxx tranny gears are the same, and I think think Maxx is mod1...

[BrianG]

Well, I just took a spare 51T spur (which we all know is Mod1) and ran it through several revolution of a Revo first gear and a Revo input gear and it meshes perfectly. So I would say it is Mod1, unless Traxxas did something silly and made a Mod .9999999999. :)

[MetalMan]

Thanks for the replies, guys. Looks like I'll be using the employee discount at the hobby shop in a few minutes :).

[MetalMan]

Well, that Revo center diff idea didn't work out too well. The 28t gear on it was too small for what I was going to use it for.

So, I created a semi-transmission that has a slipper clutch and a center diff together, for the ultimate in light-weight and tunability. Basically, it's my version of Mike's Slipperential, except I won't call it that because that's his name for it :027:. It mounts where the old tranny went, so it doesn't take up any extra space. The motor is a Feigao 540C 7XL. For gears, there's a Kyosho 44t plastic spur on a Hyper 7 diff, an 18t mod1 pinion on the slipper clutch shaft, a 40t Revo spur gear on the Revo slipper clutch (the slipper shaft is also from a Revo), and a 20t pinion on the motor. Here's a couple pics:
http://img.photobucket.com/albums/v1...o/IMG_4276.jpg
http://img.photobucket.com/albums/v1...o/IMG_4279.jpg

I will have to get an E-Maxx or Revo output shaft and cut it down, so I can modify it and use it as the output for the center diff.
The batteries for this will be 5s2p A123 cells, taken from a Dewalt 36V pack. I will charge the battery as 10s1p on an Astroflight 109 as 9s Lipo at the highest current it will charge the pack at.
So far, I'm not sure how the I will mount the batteries. Either both packs will be on the left side, or they will be split with one on each side. Any opinions on this would be great.
Here is an overall pic:
http://img.photobucket.com/albums/v1...o/IMG_4282.jpg

Sorry about the width of the truck, those are IMEX Romulin offset wheels (17mm Savage X hexes were used for the 17mm wheels). It looks like a square even though it's as long as they get - extended chassis (3Racing) and extended wheelbase arms.

[BrianG]

Very nice! Mike ought to make something like that for the Revo crowd! Are you going to come up with some type of cover for the gears? Probably not needed, but you never know about those stray pebbles/rocks and that's a lot of gear exposed...

By the way, where did that extra chassis piece come from? It's the one in this pic, right under the motor wires...

[Dafni]

Nice slipperential rip-off ;)

When you trim those fins off the slipper plate, you can get the spur closer to your mount, and the revo input shaft deeper into the bearing. Just a thought :010:

Nice dimensions on this revo, Metalman. The wheelbase looks just right!

DAF

[MetalMan]

Originally Posted by BrianG

Very nice! Mike ought to make something like that for the Revo crowd! Are you going to come up with some type of cover for the gears? Probably not needed, but you never know about those stray pebbles/rocks and that's a lot of gear exposed...

By the way, where did that extra chassis piece come from? It's the one in this pic, right under the motor wires...

There will be a cover for the gears, and it most likely will be 1/8" thick (clear) polycarbonate, bent to shape using a flame. There will also be some sort of guard under the diff gear, but I haven't figured that one out yet.

I'm not sure where the "extra" chassis piece came from. I have done very little to the chassis. Maybe it's like that because it's not a Traxxas chassis, but an extended one that came out before the 3.3 chassis?

Originally Posted by Dafni

Nice slipperential rip-off ;)

When you trim those fins off the slipper plate, you can get the spur closer to your mount, and the revo input shaft deeper into the bearing. Just a thought :010:

Nice dimensions on this revo, Metalman. The wheelbase looks just right!

DAF

Technically it's not a ripoff because Mike hasn't made for the stock Revo chassis yet :027:. Maybe if Mike does make one for the stock chassis his will be a ripoff of mine :005:.

Good idea for trimming the fins off of the slipper plate! I never would have thought of that... As it is the input shaft is only in the bearing about 1mm, so this should add another 1mm of shaft into the bearing.

Thanks for the comments, guys! :004:

[BrianG]

Originally Posted by MetalMan

...I'm not sure where the "extra" chassis piece came from. I have done very little to the chassis. Maybe it's like that because it's not a Traxxas chassis, but an extended one that came out before the 3.3 chassis?

Ah, that makes sense then. The stock 2.5 or even the 3.3 don't have that extra piece, just the thin one that would hold the gas tank.

[RC-Monster Mike]

Originally Posted by MetalMan

Technically it's not a ripoff because Mike hasn't made for the stock Revo chassis yet :027:. Maybe if Mike does make one for the stock chassis his will be a ripoff of mine :005:.

Good idea for trimming the fins off of the slipper plate! I never would have thought of that... As it is the input shaft is only in the bearing about 1mm, so this should add another 1mm of shaft into the bearing.

Thanks for the comments, guys! :004:

Well, lets see...Revo slipper/input shaft driving a center diff - sounds like a slipperential ripoff to me - just in a different chassis. :) You said it yourself - ("Basically, it's my version of Mike's Slipperential"). No worries, though. I actually had a few prototypes similar to that last year - I wasn't happy with the relatively few motor/gearing options that were possible - it is a very finite balance between the input gear(on the input shaft) clearing the motor to make the gear mesh and the actual spur gear(Revo slipper in this case) clearing the diff out drives all while trying to maintain a reasonable reduction. There are very few gearing and motor options that will work well with this set-up. It is a nice, compact design, which is why I tried it several different ways, but in the end I simply wasn't happy with the relative lack of overall adjustability related to motor and gearing options.
I know how to get around this snafu, though. Perhaps some day I will finish the thought, but I have many other projects in the works first! Nice looking design, Travis. :)

[MetalMan]

Mike, you're definitely right about the gearing options. I already have an 18t pinion on the input shaft and a 20t pinion on the motor, which is almost the lowest gear ratio I can get on there. I chose the 7XL over the 8XL because I wouldn't really be able to properly gear an 8XL that's running on 5s A123 cells.

Do you happen to have any pictures of your prototypes? I'm interested in what they look like compared to mine. Since you already made one for the stock Revo chassis, I guess that means I truly did rip off your design - but hey, it works :).

[MetalMan]

I just scored a Dewalt 36V pack on Ebay for $101 shipped. Not bad :). Maxamps is selling loose IB4200WCE cells for $10 each, $140 for 14. This Dewalt pack will be reconfigured as 5s2p (16.5v 4600mah) and will have better runtime, lower weight, faster charging, better cycle life, and more voltage under load than those 14 IB4200WCE cells, and for a lower price :).
Unfortunately I didn't realize until after the auction ended that I will have to pay by money order, so it might be a couple weeks before I get the pack.

[BrianG]

Sounds like you scored pretty good! What are you planning to use to charge the M1 cells? The only thing keeping from using them is the charging and the relatively low Ah for the physical size...