BL Revo using Revo Transmission?
 

Just wondering if there was a good BL motor to use with a Revo using a stock transmission with a 40T, standard pitch spur? I'd think the gear ratio would be quite a bit less than using an E-Maxx tranny and would strain the BL motor.

I like the fact that the Revo tranny sits lower and uses stock center shafts and slipper assembly. Creating a motor mount and finding a good spot for the batteries would be a bit of a challenge, but I don't want to start it unless I know if the tranny can even be used.

I've seen someone who has used the stock tranny with a BL motor before, but they used a larger spur and had to cut the chassis to allow for the larger diameter. I really don't want to do that.

anything is possible
i have a friend working on a design so he can use a t-maxx two speed tranny in his emaxx but the tmaxx tranny has a one way bearing in first gear(and i think the revo does to) so that would mean you woudnt have any brakes in first gear

You mean you wouldn't have any engine (motor) braking :)

correct
you would have to come up with an external brake

The beauty of a nitro transmission is having a disc brake. The electric brake on my lehner 2000XL is absolutely hopeless.

I think starscream has a revo tranny in his truck. He has also ran a tmaxx tranny. You may want to search for this.

I have a friend in France who designed an internal part that converts the Revo tranny into an "electric" tranny. It basically locks the tranny up and eliminates the clutch I think(been a while since I looked at it). I have the file for the poart somewhere and I don't think it is terribly difficult to make. I will have a look at it again. I definately know the Revo tranny can be used with the disc brakes, though.

ive been think of doing the same thing with my evo although i would reverse the tranny and use a center diff. the mgt 52 tooth spur would fit if you have concerns about gearing.

let us know if u find it

I think traxxas makes a singlespeed conversion for the Revo tranny

Boss 302: Yeah, I kinda figured it was possible, I was just curious what pinion to use with a 40T spur and a good matching motor for 12 cells.

midnit: Well, I would use the stock disc brake setup. I'd prefer to use that anyway as electronic braking just reduces runtime. I;ve heard of brushed ESCs that actually charge the batts during braking, but not sure if that is available in a brushless ESC.

Mike: Those directions would be handy. That was one aspect that I was wondering about. If you do come across that file, please do post it.

Squee: How would the 52T spur fit without cutting into the chassis? The 40T is pretty close as it is.

carzyjr: actually, depending on how the gearing works, I may just keep the two speed.

I would be doing the FOC, which of course wouldn't really remove reverse as long as I do something with the OWB in the tranny. It would just be really nice and tidy to be able to use almost all stock parts (brake, tranny, center shafts, slipper, etc) except for a fabricated motor mount for the BL motor. Converting a Nitor Revo would be a lot easier that way. Plus, offering an electric production conversion kit would just involve mounting a battery tray and motor mount, not the whole chassis.

i dont think they make a single speed for the revo tranny.

im not sure on the spur clearing the chassis although i know it will fit it.

also, the brushless esc's DO recharge the batteries when you brake. so it would actually increase runtime. it would just be a ever-so-little bit harder on the esc.

im pretty sure that you can lock the revo tranny with some jb weld. i have heard of people doing it to the savage trannys.

Really? I've never seen a BL ESC with the regenerative braking feature listed. Maybe Mike can confirm (not that I don't believe you Squee...). I thought it was only a brushed ESC feature. You are right though; if it did have regenerative braking, it would increase runtime. But, if the ESC simply attempts to lock the rotors when braking, that would definitely decrease runtime.

I just looked at my Nitro Revo with the 40T spur on it and there is about 1/16" clearance between the teeth and the chassis. Maybe shimming the tranny up a tad might gain a little more clearance, but not too much or the center shafts will run into the underneath of the chassis. Normally, I wouldn't care about cutting a little trough into the chassis so a bigger spur will clear, but the cut would be right on the angle and I don't want to do anything that would compromise the structural integrity.

Does anyone know of, or can measure, the diameter of a 51T Mod1 spur? The Trx 40T spur is exactly 42mm in diameter from tip of tooth to tip of tooth. Plus, using the stock spur allows the use of the stock slipper, which seems to hold up well even with larger Nitro engines. Can the 52T spur use the stock slipper assembly?

Speaking of spurs; I am using a 40T spur and a 12T clutch bell (pinion), which equates to a 3.33 ratio. When using a 51T Mod1 spur, using a 15T pinion comes out to the same ratio. If not, 14T or less should be available. Keep in mind that the standard gears of 38T spur and 15T pinion (ratio of 2.533) gives a top speed of approx 45mph at an engine speed of 50k rpm (approx). My Nitro (stock 2.5R engine) with 40T/12T gives about 30mph top speed, which is fine, so I would guess a similar 3.33 ratio would work since that engine rpm is about the same as a BL motor (actually a bit less). Here is the gear ratio chart for a Revo:

http://bgosselin.home.mchsi.com/revo...atio_chart.gif

correction to my last post. I checked and there's no singlespeed conversion for the revoat this time

That's OK as I really want the two speed. First gear speed for more torque at start and slower speeds and then second gear for some high speed passes.

I use the mgt 46t mod1 gear and a 20t/22t pinion with my maxcim setup. I am also using the center diff I got from ebay along with rear brakes :cool:
I'll have to post pics of the rear brakes when I can. Its a simple design really. I also use a micro servo for braking. I've found that rear brakes really don't require a large servo.

I am also using my tmaxx tranny on my G2R. I am working on mounting a center diff in it as well.

46T and 20T?! That's a 2.3:1 ratio. I'd like to see a picture of the spur/slipper assembly if you have one. Are you using the stock slipper, or something else? Also, did you have to cut into the chassis a little for the spur to fit? How do you have your brakes set up since they are disc?

I'm not going to be racing (at least not competitively) so just the stock braking setup will be fine for me.

Hows it running with the Tmaxx tranny? And are you running it the same as the Emaxx you had?:cool:

Transmission Conversion
 

I posted the following at the Traxxas forums, but don't seem to be getting any responses, so I'll see if the good people here have any input:

I'm trying to figure out if it is possible to convert a Revo transmission for use with brushless motors. It might be easier to refer to the transmission exploded view (http://www.traxxas.com/products/nitr...evo_tranny.pdf) while I go through this.

The goal is to have a transmission that will do reverse via the motor, and not by using a shifting servo. To do this, I have to find a way to replace the three one-way bearings with something equivalent (2 x #5121 and 1 x #5393) so the tranny is locked both ways. This would also allow me to use the motor braking feature if I decide not to use a disc brake.

I believe I can replace the two roller bearings (#5121 6x10x8mm) on the output shaft with equivalent regular bearings. The output gear (#3982) would then roll freely on the output shaft, but since it is coupled to the dog gear, which drives the splined part of the shaft, it should work.

However the first speed gear (#5386) is coupled to a special roller bearing (#5393) that is attached to a hex adaptor of some sort. I don't think I can find something to replace that assembly. This isn't a big deal really since I don't need first gear. So, I could simply do away with that gear and special bearing and replace them with some bearings/shims as a spacer. I realize this would create a single speed tranny stuck in second gear all the time. If there is a way to replace this bearing with a non-one-way version, I could keep first gear, but I don't think that's possible.

So, if I remove first gear, I then have to find a way to lock the two-speed clutch (#5390) so it always engages the second speed gear (#5385), which is coupled to the primary gear (#5396) through the shaft.

I think I have the solution planned out, but was hoping for someone else to take a look to see if this sounds right. I'd hate to go through all this and realize I forgot something. :)

There are not three one-ways in a revo tranny. the two needle bearings on the output gears are standard needle bearings

You can either have first or second if you want reverse and no servo's. Anthing else and it will be a grind, literaly

you may be better off using the two speed because first may be too slow and second may not be able to pull the truck

These are my opinions based on what i know from working on my Revo tranny. Starscream has the experience from doing it and i would wait and see what he says, because he might know something I don't

The emaxx tranny is the easiest and most effective way to accomplish the forward and reverse you are looking for.

The Revo tranny is ideal for the automatic 2 speed. Due to the mechanical aspects of the one way bearing design, you will not be able to use a motor for reverse. Locking the Revo tranny in 1st or 2nd gear, with reverse, will be much more complicated and more work than just using the emaxx tranny.

I really like the revo tranny but if you want reverse, use the emaxx tranny.

carzyjr: OK, I assumed the two roller bearings (#5121) were one-ways simply because the exploded view specifically says to orient the writing on the bearing a certain way. That makes things a little easier. So now I can either lock the tranny in second or find some type of replacement for the other hex bearing (#5393).

Starscream: Yeah, I figured it wouldn't be easy, but it's a challenge. As I see it, it's just a matter of replacing that odd hex one-way bearing with a locked one. I can see that being complicated. The rest of it seems simple enough. I think if one person can come up with a solution to allow reversing that uses some easy-to-find parts, it will make for a nice conversion. At the very least, it should be relatively simple to lock it into second gear since that gear is up against the primary gear (which goes to the output gear). I guess I'll just have to pick up a tranny and experiment.

Thanks for the feedback!

OK, I picked up a tranny from Ebay. I then installed a FOC conversion and the wide ratio gear set. I can see where you can't have an autoshifting tranny while locking it so reverse and braking work.

So, I removed the first gear and bearing altogether. Then, I removed the shifting tension screw, spring, and ball from the clutch and put a 4mm screw in its place. I cut the head off so it will fit in the second gear cup. I figure this will give the now locked clutch something else to grab onto instead of just the single clutch arm. I had to file down the threads on the screw a little so both the clutch arm and the screw shaft were against the pins at the same time.

While the clutch arm was held open and positioned on the "grabber" pin, I filled the entire area with plastic epoxy. If that isn't locked, I don't know what is!

http://bgosselin.home.mchsi.com/e-re...evo_tranny.jpg

Looks good. I hope you got a motor that will pull the wide second gear, because it will be high geared. In that instence i would've used the close ratio. Good luck

Actually, in second gear with the wide ratio set, the revo tranny ratio is 2:111 (38T/18T). The e-maxx in second gear is only 1.722 (31T/18T). The ratio for the revo standard ratio set is 2.29 in second gear - so it's even less.

Emaxx: 2.846 diff x 1.722 tranny (gear 2) x 51T/14T spur/pinion = 17.852958:1 total reduction ratio.
Revo: 2.846 diff x 2.111 tranny (gear 2, wide) x 40T/14T spur/pinion = 17.16544:1 total reduction ratio.

So, what does the motor mount look like?
All you need now is a center diff to finish the tranny:027:

Well, I haven't started that yet. :dft001: I'll have to work on that once I get a hold of a BL motor, but I suppose I could use a cheap brushed motor to at least get the design worked out. I have no clue yet as to how I will implement it, but I'm shooting for using parts of the stock Revo motor mount and working from there (because it already has an adjustable mount for changing spurs and pinions). The final version will probably have to be machined for accuracy, and I don't know where I'll get that done.

This started because I was waiting for my tax refund and now for my order from Mike to arrive to finish my current E-Revo, so I started thinking about how to use a Revo tranny to allow braking and reverse. Once my current E-Revo is done and working, I want to build another lighter one of a different design and see which I like better. I also want to use more stock parts (like center shafts) so I can pick up replacements at my LHS instead of trying to order or fabricate something that'll work. The only other part I have right now is a chassis. I should be able to move most of my existing E-Revo parts to the new design and maybe sell the one I don't like as much. The next design might even use Lipos.

I don't plan on ever using a center diff. I don't race so it's not needed IMO. I seem to enjoy building these than driving them, but unfortunately cash is not over abundant in my household.

cool. I don't think that far into my projects

Well, when you're stuck looking at unfinished truck because you're either waiting for parts or cash for some parts, you have time to think. :)

OR you can think of ways to make more money:)

Quick question: I was reading this thread about what "Mod1" pitch meant and it sorta answered my question. I understand it is metric, but is it 1mm? So, does that mean it will work with stock Revo spurs since those are 1.0 metric pitch gears?

BrianG-
Any updates on the Revo tranny project?

me and my friend are using a t-maxx tranny. We are still working on the motor mount. we just havent had time to make it lately.

No, no updates. The tranny is now locked like I said in a previous post, but haven't tried it out in real conditions. I can guarantee it will be fine though - filling the 1/2 speed clutch wil epoxy is very effective and hard as rock.

I'll do more on this project once my currently unfinished BL Revo is finished (waiting for backordered parts from Mike).

I took a stock Revo motor mount and ground down the part that would normally be the throttle arm pivot area so now it is flat. That's as far as I got.


So, nobody has an answer to my question?

I'm 99.9999999999% sure that the Mod1 pinions will work with the revo spurs.

I remember reading about them being the same.

I've used a Revo spur gear on my 1/8 buggy, it's mod1 for sure.

Cool, I kinda figured, but wanted to be sure. I hate it when you think something is gonna work and it doesn't - makes me grumpy.

Thanks.

Guys I ran into the same problem, I am trying to shrink down pics but I have them posted on my website, I will shoot pics of the individual parts this weekend. I can make the individual parts available, too

www.eaglesviewaerial.com/products.html

I just posted this to RCU the other day here is the relevant exerpts...

Since I have a small machine shop (2 cnc mills and a cnc lathe), I set out to build a BOLT ON KIT for the Revo that could be sold for less than 100 dollars in a retail setting, that would allow for a brushless drop in conversion.


To solve the gearing problem, after some messing around and searching, I found a suitable SAE pitch gear that Associated makes, and quite incidentally, it has three molded holes that were almost a perfect match to the 120 degree bolt pattern on the slipper!
So we keep the slipper (good thing), and now I had to just machine an adapter/spacer to get the gear mounted flat, (after 3 or for stripped gears I finally got one machined/sized correctly and now it is solid).

I had to lock the reverse shifter, very simple, a nicely bent piano wire and a bolt took care of it. Getting a good gear ratio (similar to the Emaxx overall G/R on a Novak system) using the stock gear box again, cheap and bolt on requires a lock up device on the second gear stage. I machined an ALU replacment hub for the second gear gearing that replaces the stock one way bearing hub that goes through it. Then you just ditch the first of the two stages of gearing, and use the lock hub so that electronic braking from the motor would work Viola! Works like a Charm!

Problem 2: Motor mounting
So I started with a hybrid motor mount of carbon and aluminum, the carbon gave too much flex and I went to an all aluminum machined two piece motor mount which allows gear ratio and mesh adjustments. (Older carbon verticle mount shown in pictures, I will shoot pics of the newer one this weekend)

Designed some simple and stiff carbon fiber trays that bolt into stock bolt holes on the chassis for the battery and ESC, and its done.

Performance:

Holy cr*p! I ran a 14 cell (cheap 3000mah NiMHs) and 4s2p TP Lipolies and it will wheelie on any surface even easing into the throttle, and is visibly faster than the nitro setup I had on my stock revo. The verticle CG remains very much the same, so the handling of the truck (other than off the line grunt which was not even close in the nitro setup) is very much the same. I went to stiffer springs in the rear to better support the battery weight and keep the ride hieght higher for my personal bashing terrain.

Price: The conversion kit is 74.99 retail, I am offering direct orders on www.eaglesviewaerial.com/products.html The only things you need to complete are BL motor, batteries of your choice, and a 14-19t pinion gear from Traxxas (from the Emaxx line). If you want to buy individual parts such as the lock up hub and gear mount for the associated gear, I can sell those individually, just call me directly.


Compared to well over 600 bucks for a complete gorilla max conversion, this offers a nice relatively cheap alternative.

Ok ok, pics, I can't post em because I took them in high quality format and don't have any of my image tools with me, check the website for detailed pics.

PLEASE NOTE THAT THE CARBON PORTION OF THE MOTOR MOUNT IN THE PICTURE IS NOW ALUMINUM....
(sorry, been out of town, need to shoot pics of the new mount piece).

I will post videos of it shortly, check my website for more details....

If you have any questions, please feel free to call or IM or email...
847-778-0874, (for IMs and email check profile).

BTW if you guys are looking for good sources for gears, I use MOD1 for all the heli engineering I do and sdp-si.com has a great source and catalog of all metric stock drive gears and pulleys etc. THey have tons of 5mm bore mod 1 gears that could replace the stock spur and bolt directly onto the input shaft of the stock revo gearbox (which is 5mm incidentally).

Mod 1 refers to the standard spacing between teeth which is largely greater than 1mm, if you look at the PDF drawings of some of the gears on sdp-si.com you can see the measurements for your self.

Hope that helps...