New Revo Owner
 

It was only a matter of time... I found a good deal from a pretty reputable guy on another forum. It cost me $225, including shipping. It's a roller, and it has the stock tranny and fuel tank, but those will go. This is the description the guy had for it:
The pictures he gave me are attached.

My plans start with removing the fuel tank and tranny, as well as the radio box and engine mounts. I want to use a diff in the center, so as to reduce the weight. For those who have thought about this using a stock chassis, what have you come up with?

Also, I haven't followed the Revo much on this forum. I would appreciate any tips that you guys can give to a first-time Revo owner.

EDIT:
DUH! I forgot to mention that this will be electric... At this point I'm thinking of using my Maxamps 4s 6300mah 15C battery, Mamba Max ESC, and Feigao 540C 8XL. The motors going to have to wait a couple of weeks, though, since I spent all of my cash on the roller.

hm... center diff in the middle of the stock chasiss. that will be interesting. not even sure how to go about that one.

I'm working on an electric revo truggy chasiss right now that uses a center diff. ITs near completion.


Looking forward to how you mount the center diff.

Using the stock chassis, I've done two types; one with the Dafni-style conversion (rcbros has that chassis now), and the current one I'm using now (and having success with).
Pic 1
Pic 2

Metalman, I can tell you that a few parts you have will sell for probably enough to pay for 50% of your motor. The tranny, Tekno R/C throttle servo mount, and motor mount (appears to be 3Racing) will sell decent...

It has a Tekno throttle servo mount? Just goes to show what I know :p. I can also sell the RX/RX pack container thingy, and fuel tank, and maybe get a few bucks.

Some of the other items I want to get are:
-Maximizer 17mm hub adapters (I only have one set of Maxx tires, they are Maxx Mashers on Imex offset 17mm wheels)
-Tekno wing mount

Soon I'll be getting my XTM buggy back which has a Feigao 540C 9L on it. I can try that motor out and see how it fares, but most likely I'll end up getting an 8XL.

BrianG, due to the size of the batteries I have, it shouldn't be too hard to do the conversion Dafni-style. But I will keep your setup in mind.

Rcbros, I have no idea what it will require to do the center diff. But judging from the pictures, I might be able to use a standard buggy center diff setup that will drop halfway below the chassis, with some custom pieces connecting it to the chassis. Or, I'll just make some diff mounts that will fit the original tranny mounting holes, and incorporate a motor mount into that.

At this point, this truck will only be a basher. So if anyone has any tips to strengthen the Revo, I'm open to suggestions.

Well, don't go with the Maximizer adapters...Go with the Ofna's....there alot better and don't use a damn washer like the Maximizers...

Are these them:
http://www2.towerhobbies.com/cgi-bin...?&I=LXHSX7&P=7 ? If not, could you post a link?

Actually, these are.

Metal man there is a thread around here some were that starscream started & he had a center diff on the stock revo chassis.

Thanks, squee. I'll ask Mike if he can get them so I can place just one order and save on shipping.

I think it's this thread:
http://www.rc-monster.com/forum/showthread.php?t=774
Unfortunately the pictures aren't loading :020:.

Metal man what he did was use the hardcore racing titanium skid plate. He mounted a ofna diff to the skid plate. So the cvd's were level with the diffs. He had to notch the chassis a little on each side to clear the ofna 51t spur .

Starscream used a transmission with a center diff. Nice truck Metalman

I'll mount this one to the chassis, just to save on building costs, and it should also be more secure. I'm looking at use the Hyper 7/Kyosho 46t spur gear combo, with a 9t or 10t pinion.

He also made one with a ofna buggy diff on the stock chassis .

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.

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

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...

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...

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. :)

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

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.

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...

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

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?

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:

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.

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. :)

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 :).

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.

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...

For now, I'm not so sure. But I have an idea - let my ICE charge the 5s2p pack as a 10 cell NiMh pack at the full 8 amps. I don't know when the ICE will cut off for the voltage getting too high, but when it does I'll swap the pack over to my Multiplex LN-5014 charger and charge it at the maximum amp rate until it reaches 18v.

Later on (in a couple weeks or so) I'll get an Astroflight 109. Word on the street is that AF is working on a new chip for the 109 that will allow you to charge A123 cells to 3.6v/cell.

As far as low Ah for the physical size, I'm not worried. The way I see it, as long as it's better than NiMh, then it's all good.

Something else you could do to charge those M1 cells is simply use a CC charge until the voltage hits 3.6v/cell and then keep reducing the charge current to keep the voltage at 3.6v/cell. Sounds like a lot of work and wasted time just sitting there watching it, but it'll work (provided your charger lets you change the current on the fly).

Yeah, I'll do that with the ICE if it will allow the voltage to go high enough. If it doesn't, then I won't do it because the LN-5014 doesn't allow you to alter the charge rate during the charging process.

Update! (after a month and a half).

The Revo is operational, and about 96% complete. The other 4% includes minor details, like increasing the strength of the battery hold-downs. It's running 5s2p A123 cells with a Mamba Max and Feigao 540C 7XL with my custom "slipperential" on pre-3.3 extended chassis (aftermarket). So far, it runs very well. I have 30,000wt. oil in the center diff, but unfortunately it is leaking pretty badly (I gotta get a new case and o-rings for it). As it is, it will wheelie, lifting the front tires up a couple inches from a stand-still, and then it quickly sets them down and takes off as the front tires gain traction.

Unfortunately, I was having problems with the Mamba Max thermalling after a few minutes. Part of the reason may have been starting and stopping very quickly with Maxx Mashers in the street (HIGH traction). But that problem has been resolved by mounting a 40mm 5v fan over the heatsink of the MM (a screw threads into the fins of the heatsink). And now, the MM is running at something like 135-140 deg.
As for the motor, it has hit something like 150 at the highest. I would say that's pretty good, considering that the gearing on the Revo right now was an estimate from before I ever ran the truck. The gearing is 20t pinion/40t spur, and then for the "slipperential" it has an 18t pinion on a 44t spur. The estimated speed is at 38.5mph with the battery voltage at 2.8v/cell, and assuming no tire ballooning on 6" tires (they're duct-taped on the inside).

Pics should come soon :).

How dare you post that and supply no pics at the same time! Shame! ;)

J/K. Good job! How much runtime do you get on that setup? I was thinking of going with a 8 or 9XL with 6s2p on my Revo, but still on the fence about it.

The fact that the MM thermals so quick, but then the addition of a simple fan makes it run that much cooler makes think a larger heatsink would do wonders. Too bad the current heatsink wasn't epoxied on the FETs...

At this point I'm not too sure on the runtime, but I think it's about 15mins. The last time I ran the Revo, I was having a small problem that made a bigger problem. There was a loose contact on the UBEC input connector that was causing intermittent power to the receiver. Well, it cut out at one point and allowed the Revo to go into the curb at 25-30mph. At the time there was no front bumper either (just the mounts and the skidplate). The impact caused the 3s2p pack to slip forward, and it hit the receiver on its way forward. This caused the receiver's antenna to rip. Now I'm waiting for funds to get a new radio with (looking at the Nomadio React and an extra receiver).

You should be able to fix the antenna of your current receiver. Just solder it back together and put some heat shrink around it. As long as you dont change to total length of the antenna by alot you should be fine.

Cant wait to see the updated pics. I like this project.

The antenna is fixed, and the receiver worked in my TC4 yesterday (drifting). However, with the Revo I was only getting about 50ft. of range in each direct before the antenna ripped. In the TC4 my range was at least 100-150ft (for me distance is harder to measure as things get further away). I will have to find the cause of this glitching, as it has been affecting my cars (Revo, Rustler, X-Terminator) for years now. It's a MX-3 75mhz FM with a Novak XXL using "genuine" Airtronics crystals.

I think you have the right idea. If your having glitching problems like that just go Nomadio or Spektrum and call it a day. Actually I think Airtronics is comming out with their own version of the 2.4ghz technology. Its supposed to faster that the existing stuff (like thats necessary). They have a 2.4ghz version of the MX3 comming out (or out already not sure).

Nothing more frustrating than radio poblems. Its always a PITA to figure out whats causing the issues.

The React has been top on my list, but now that I think about it, it's more than I need. Then I too remembered the MX-3 2.4ghz version and looked at it on Tower's website:
http://www2.towerhobbies.com/cgi-bin...4&I=LXPNM6&P=K
http://www2.towerhobbies.com/cgi-bin...4&I=LXPNT0&P=K
It's a heck of a lot cheaper, and I know I would like it since I use a MX-3 right now. For the price of the React ($300), I could get the MX-3 2.4ghz and 1 1/2 extra receivers (assuming the prices don't change). I just wish it would come in stock NOW!