Planning Revo V2, to use stock tranny, C. diff and RCM motor mount
 

I am looking to start a V2 revo conversion using after doing an Emaxx tranny conversion last year. After a few little tweaks to the tranny, the setup has been pretty bullet-proof and I've been extremely happy with it. The area for improvement I'm looking for is the addition of a center diff. The 8Xl motor I have now just puts out too much TQ (esp on 5S) to put all that power down. While I'm at it, I'm aiming for manual brakes at the expense of reverse. I've also gone entirely to lipos now, so I don't need to fit all those NIMH cells on both sides, so going to a single batt tray will keep things easy. Plus the new RCM 1/8th Diffs are calling, so I'm looking at setting up one nice truck. :)

Before I get started I'd like to gather some information and opinions here.

Biggest question is what all is needed to get the stock Revo tranny ready? I still have the 2.5 tranny from the last conversion, so that will be the start. I will be adding the centerdiff, FOC, rear brakes, and prob the wide ratio kit w/ buggy diffs to get the gearing right (thanks to Brian's calc, swapping the gearing around to find ~previous ratio was easy.)

My understanding is that locking the oneway bearing should not be an issue since I am not going to have reverse nor engine braking, yes? Basically the BL motor will be a "direct" replacement for the nitro motor.

It seems the stock tranny is very tough and smooth, so no metal gears are needed. Is this the experience of those that have used the stocker (either BL or a Big Block nitro or equiv.)?

Lastly, how is the clearance w/ the rear arms using the RCM mount and an XL motor. should be tight but ok?

Sounds like a plan! Do you still want the two speed tranny? Because unless you lock it, it will still shift. You could adjust the shift point until it is basically locked into first or second, but not as solid IMO. As a plus, if you remove first gear, it lightens up the tranny a little, and if you decide to later use reverse and/or motor braking, the tranny will be already capable of it.

The stock tranny is pretty tough and can stand up to BL quite well. The only thing I have broken is one of the little pins securing a gear to the shaft (the intermediate gear in front of second gear).

The end of an XL can does clear the arms, but you'll have to orient the motor so the wires will clear. If you look at my revo pics ("My BL Conversions" link in my sig), you can see how my wires sit. I also mounted a little L bracket to support the wires coming out of the motor. It was mounted using the same screw that holds the rear rocker arm in place, so no big deal there.

If you go with a center diff, you are going to want some pretty thick fluid. I don't know what weight is currently in mine (it's a custom 8th scale diff I got from Squee) but it diffs out easily. I'm thinking somewhere around 300-500k.

2spd? No! Who needs a stinking 2spd w/ BL power? :) 1st will go going out too. The only advantage I see of keeping the 2spd is to be able to overgear a bit for some top end, but I don't think it will be needed, plus I'd rather trade off that for better reliability.

Did you do anything to upgrade that pin, or is it just an expected casualty?

I did see pics of the motors mounted, and I did notice the wires on the top. I couldn't tell from the pics is if the arms would touch the wires when the suspension was fully compressed. Looks like it will clear, so that is good.

So now goes the long process of ordering parts, waiting for backordered stuff, and getting stuff in. Good thing is 1.) I have a truck to play with in the meantime, 2. I should be able to get most of everything from Mike. :)

I think I used the stub axle pin from a Jato (the one that holds the driveshaft to the stub axle). IIRC, it's black instead of chrome so I thought it might be a little stronger. No problems thus far, but even with the old style pin, it took several days' worth of running before it snapped.

And yup, the arms do clear even at max suspension compression.

i would go with 500k, i have one in my erevo and its got 300k and it still diffs out badly with a hvmaxx 4.5, so go for the thick stuff, imo

Plans are still alive! I've been busy acquiring the parts. I have the tranny w/ CD and rear brake and a revo roller to go along with it. I decided to go with a 3.3 instead of the 2.5 chassis that came with the roller and I'll pick that up Mon from the LHS. Recent news of the pending release of the MMM has got me excited. I would really like to go 6S lipo and ~12XL motor. Should be powerful, smooth and cool running. Now how to fit everything is a different matter... We'll have to see what the dimensions are.

Pics of Mike's pretty mount in the chassis to keep things interesting in the meantime:

http://i7.photobucket.com/albums/y25...4/7f708e46.jpg
http://i7.photobucket.com/albums/y25...4/a7183308.jpg
http://i7.photobucket.com/albums/y25...4/eb359538.jpg
http://i7.photobucket.com/albums/y25...4/772cab12.jpg
http://i7.photobucket.com/albums/y25...4/ca80a509.jpg

Cool project Finnster.

You can have Mike make you a batterytray machined from some plastic.!

Is that going to be in the store? I just made a polycarbonate one and I don't really like how it came out.

It would't surprise me if Mike puts them in store sooner or later!

Finnster, I am going to be attempting a similiar conversion on a used revo I recently bought.

I have been struggling with how to set up the tranny though and wonder how you plan to be able to use a single channel on the reciever to make your esc work when you pull the throttle trigger back and yet make it controll the servo for mechanical brakes when you push the trigger forward? I can't figure out how to make that work and I can't seem to find any info on it or even a different way to do it.

I would really like to retain the mechanical reverse and brakes on my revo tranny so that I can keep the two speed functional but I am stuck on the issue I asked about previously, how do you controll two different items with a single channel on the reciever?

Welcome to the forum.

Quite a familiar username you picked.

You use a Y cable on channel two to make it happen; on 1 side you hook up the esc, and on the other the braking servo.

thanks:) yeah I figured I would try my question here since this forum seems to have a lot more folks that have done the revo conversions.

My problem with a y harness is that I'm using a hvmaxx 6.5 setup for it and there is no way to defeat the motor braking on the hvmaxx esc (that I can find anyway) so if I did the y harness it would apply the motor brake and the mechanical brakes at the same time.

Now that I think about it though, would that even be a problem?.....I read somewhere in here that the two speed in the revo tranny has a one way bearing so does that mean that even though the motor is braking it would only stop the rotor on the motor while the tranny would continue spinning freely allowing the mechanical brake to do all the work? Is that how it would work? if so is there any harm to the motor in doing it that way?

Yeppers, in addition you want to make sure you have the reverse disabled on the esc obviously. :)

Now the (mechanical) reverse is a diff story. You will need a 3rd channel for that, but they are notoriously weak and heavy, so most do the FOC (forward only.) There is not a way to have motor reverse and mech brakes either, unless you tried brakes on a 3rd channel.

I am curious how much the transmission would weight with the FOC? got a scale Finnster?

I have a very fine digi scale. :) I actually have two trannies, one stock 2.5 and a CD/rear brake (which includes FOC by default.) I'll get some weights tonite. IIRC, after I got done with my Emaxx SS tranny on V1, I think I got it down to 180g. I'll find my notes or reweigh it when I pull it out for a little service. The Revo I think will be more, but the brakes do make up some weight, 20g maybe? We'll see.

I have most of my parts now. Its just a mtter of putting everything together. The roller I got was a used nitro, and its dirty and smelly, so I'm taking my time going thru it, getting as much as the oil and grime off, going thru all the bearings, re-oiling, and basically doing a whole tear-down. My V1 was a truck that was bascially a new 2.5. Guy had the motor frag during break-in, got pissed and sold it. Got a barely used truck for 1/2 price :) What a difference in cleanliness. V1 has barely seen nitro, so no dirt sticks, the V2 roller is lightly/mod used w/ nitro and there is sticky oil all over every surface. What a pain. Yuk.

Since I have a Revo to play with, I'm taking my time on this one. I'm actually going to be Chester NY on memorial day, so was hoping to make it to the Barn, but I don't see that happening. :( I could bring my v1, but its very much setup as a basher, and since I've never raced, it would be pretty ugly. I don't even have good racing tires. Is there a RCM bash this year? I'd really like to make it to there. Hopefully either the Tekin MT or MMM will be out by then as well.