Questions about Revo 3.3 to electric conversion

[corneileous]

Hey guys, I have an old Revo 3.3 that I’m currently doing an electric conversion on. I pretty much decided I was going to use the hobbywing max8 ESC/motor combo but with their smaller 2500 kV motor and even though I started out planning on going 4S Lipo, do you guys think it would be better to go down to 3S instead? I’m assuming that 14.8V 4S 70C would be OK and even though I do plan to upgrade the front and rear ring and pinion gear to the machined version for greater strength, and that someday down the road, I may upgrade to metal gears in my transmission, but I wondered that, because the Revo 3.3 might not be designed for that much power, if I should reconsider and just power it from 3S instead. What my goal is, is to have it about the same power and performance as my virtually stock Traxxas Maxx that has the factory ESC and motor that I run it from a Traxxas 4S, 25C, 5000 mAh 14.8 V battery.

What are you guys think? Thanks.

 

[Greywolf74]

Hey guys, I have an old Revo 3.3 that I’m currently doing an electric conversion on. I pretty much decided I was going to use the hobbywing max8 ESC/motor combo but with their smaller 2500 kV motor and even though I started out planning on going 4S Lipo, do you guys think it would be better to go down to 3S instead? I’m assuming that 14.8V 4S 70C would be OK and even though I do plan to upgrade the front and rear ring and pinion gear to the machined version for greater strength, and that someday down the road, I may upgrade to metal gears in my transmission, but I wondered that, because the Revo 3.3 might not be designed for that much power, if I should reconsider and just power it from 3S instead. What my goal is, is to have it about the same power and performance as my virtually stock Traxxas Maxx that has the factory ESC and motor that I run it from a Traxxas 4S, 25C, 5000 mAh 14.8 V battery.

What are you guys think? Thanks.

I think you should fully mod it and run it on 6S

 

[Tunedfrog]

Hopefully I'm dong the same thing. I have to wait for word from my nephew first.
He brought over 3 Revo 3.3s and I got two of them running for him and I sent him a text if he will
let me convert it to electric. No word yet but I'm sure he will be fine with it.

 

[corneileous]

I think you should fully mod it and run it on 6S

Well, that could be doable but I really only want to make room for just one battery….lol. I think I can fit a typical 4S Lipo over on the right side where the fuel tank and the electronics box was but I have no idea where I’d put two batteries to make it 6S. But besides, what would I have to do to reinforce it enough to make it handle that kind of power being that it’s really only meant for nitro power??

Hopefully I'm dong the same thing. I have to wait for word from my nephew first.
He brought over 3 Revo 3.3s and I got two of them running for him and I sent him a text if he will
let me convert it to electric. No word yet but I'm sure he will be fine with it.

What do you plan to run it on? Would 4S be fine and not cause it to be a constant fix-to-make-it-better, ongoing project?

I’m not looking to make this be equivalent to the 10th scale E Revo 2.0 with 70+ mph speeds. Lol. I do good as it is with the 50+ mph out of my Maxx and it still has stock gearing.

 

[Greywolf74]

Well, that could be doable but I really only want to make room for just one battery….lol. I think I can fit a typical 4S Lipo over on the right side where the fuel tank and the electronics box was but I have no idea where I’d put two batteries to make it 6S. But besides, what would I have to do to reinforce it enough to make it handle that kind of power being that it’s really only meant for nitro power??

What do you plan to run it on? Would 4S be fine and not cause it to be a constant fix-to-make-it-better, ongoing project?

I’m not looking to make this be equivalent to the 10th scale E Revo 2.0 with 70+ mph speeds. Lol. I do good as it is with the 50+ mph out of my Maxx and it still has stock gearing.

They make single 6S packs or you can just velcro two 3S packs together. I can't speak to exactly what needs to be done to pull off the conversion though as I've never done it to a REVO. I've done it to a few other kits but not that one.

 

[corneileous]

They make single 6S packs or you can just velcro two 3S packs together. I can't speak to exactly what needs to be done to pull off the conversion though as I've never done it to a REVO. I've done it to a few other kits but not that one.

I guess I’ll just have to find out as time goes by. Treat it like a custom rock-hoppin’ Jeep where anything that breaks is just a sign that needs to be made stronger.

 

[corneileous]

Being that this is a discussion about converting a Revo 3.3 to 4S Lipo, what’s the best way to determine which tooth spur gear and pinion gears to use?

Being that my Revo is one of the old older Revos that still had the old-school 27 MHz receiver and radio with the 3 or 4 foot telescoping antenna, it also came originally with the smaller 14 mm hubs and, I’m not sure about the spur gear but I do know the clutch bell is one tooth different from what the current Revo 3.3‘s are that you can buy brand new and when my Revo was still nitro and because I upgraded it to 17 mm hubs and started running the taller 6.4 inch Traxxas Talon EXT‘s, I upgraded the clutch bell to match what the new Revo‘s are brand new but again, being that I’m converting this truck to 4S Lipo, what tooth spur gear and pinion gear should I start with?

 

[Greywolf74]

I would just start with something like a 2.5:1 gear ratio and then just tune it from there based on motor & ESC temps.

 

[corneileous]

I would just start with something like a 2.5:1 gear ratio and then just tune it from there based on motor & ESC temps.

I watched a video on this a little earlier today about gear ratios so if I understand this correctly, you’re saying between the motor pinion gear and the transmission spur gear, I can go with whatever I want as long whatever I go with, the pinion gear makes 2 and a half revolutions to one complete rotation of the spur gear, correct?

 

[olds97_lss]

I say stick with the max8 system you were going for, run it on 4S and just drop the punch on the esc. Then at least you won't be overweighting the electronics.

 

[SpareParts]

I converted 2 recently and I have been keeping it to 3s to avoid breaking stuff. I don't need crazy speeds or jumps, 3s is plenty for blasting around in the backyard. I initially used the Hobbywing max10 g2 2400kv and it was great, it never even got warm. I ended up putting that system in my Rock Rey and now have a hobbywing axe r2 3300kv in the revo and it is also great. I'll probably get another max10 for it because it is more appropriate, but the axe has plenty of power and it never overheated in the rock rey (also a large "1/10 scale" truck with giant tires). I have the punch turned all the way down and I still need to be careful to avoid wheelies.

I am currently running a 10t pinion and 38t spur. Transmission is locked in 2nd with I believe the close ratio gearing. I am using an ancient set of rock hard talons that I had laying around.

With a 3s 5200 mah I am around 9.5 lbs ready to run which is pretty good. Bigger motor, batteries, tires, etc will just mean more weight, more heat and more broken parts. I think the G2 max10(and max8) are very efficient so you can get away with using the smaller system. I haven't actually hit lvc yet but I have been getting at least 20 min run times. In the summer I may need to add fans to the esc and motor but for now they are only warm to the touch.

The 2nd revo I converted into a trail truck with slayer arms and a brushed crawler system. Not really relevant to what you want, but I am using a 550 brushed motor, a tiny esc and small 3s batteries. It is geared lower of course but it gets around just fine at full speed, probably 15 mph, with no heat.

I think with the smaller diffs and weaker transmission on these nitro models, you want to stay light and keep the punch down. Otherwise you'll be fixing diffs.
Here are some pics of my abominations.

 

[corneileous]

I converted 2 recently and I have been keeping it to 3s to avoid breaking stuff. I don't need crazy speeds or jumps, 3s is plenty for blasting around in the backyard. I initially used the Hobbywing max10 g2 2400kv and it was great, it never even got warm. I ended up putting that system in my Rock Rey and now have a hobbywing axe r2 3300kv in the revo and it is also great. I'll probably get another max10 for it because it is more appropriate, but the axe has plenty of power and it never overheated in the rock rey (also a large "1/10 scale" truck with giant tires). I have the punch turned all the way down and I still need to be careful to avoid wheelies.

I am currently running a 10t pinion and 38t spur. Transmission is locked in 2nd with I believe the close ratio gearing. I am using an ancient set of rock hard talons that I had laying around.

With a 3s 5200 mah I am around 9.5 lbs ready to run which is pretty good. Bigger motor, batteries, tires, etc will just mean more weight, more heat and more broken parts. I think the G2 max10(and max8) are very efficient so you can get away with using the smaller system. I haven't actually hit lvc yet but I have been getting at least 20 min run times. In the summer I may need to add fans to the esc and motor but for now they are only warm to the touch.

The 2nd revo I converted into a trail truck with slayer arms and a brushed crawler system. Not really relevant to what you want, but I am using a 550 brushed motor, a tiny esc and small 3s batteries. It is geared lower of course but it gets around just fine at full speed, probably 15 mph, with no heat.

I think with the smaller diffs and weaker transmission on these nitro models, you want to stay light and keep the punch down. Otherwise you'll be fixing diffs.

So being that I’m still fairly new to all this electric stuff, what is the difference between the max 10, the max 8 the max 6 how do I decide which one to go with? I can’t really say it’s about personal preference because I really don’t even know what my personal preference would be, if that makes any sense.

But OK, I realize that the nitro motor in the Revo 3.3 right out of the box probably doesn’t come close to the amount of electric power out there these days and I realize even my Traxxas max has a lot beefier drivetrain components than my Revo does but when you say the front and rear differentials and the transmission are the weak points, if I was to put the upgraded ring and pinion gear in both my front rear differential that’s made out of machined steel and not that cast iron crap like the factory ones are, would 4S power still be OK?

And as far as the transmission, where exactly is the weak point? Are we just talking about a steel gear upgrade or is it the transmission housing or what? I know I’ve seen an aluminum transmission case so, is that what I would probably have to think about later on? FYI, I have done the forward, only conversion, and I used this to delete and lock the 2nd gear.

Also, what about the Traxxas Revo 3.3 center diff? I bought one of those as well being that with the extra power, I figured I’d probably need one of those as well just to help with traction and to just help in reducing the abuse to either the front or rear differential, primarily the back one.

I don’t know if you’re familiar with the Traxxas Maxx but that’s pretty much what I’m after in this build, is to make it like that. I have a version one that for the most part is pretty stock being that it’s got the stock ESC and motor and I run it off 14.8V 4S Lipo.

 

[WickedFog]

So being that I’m still fairly new to all this electric stuff, what is the difference between the max 10, the max 8 the max 6 how do I decide which one to go with? I can’t really say it’s about personal preference because I really don’t even know what my personal preference would be, if that makes any sense.

But OK, I realize that the nitro motor in the Revo 3.3 right out of the box probably doesn’t come close to the amount of electric power out there these days and I realize even my Traxxas max has a lot beefier drivetrain components than my Revo does but when you say the front and rear differentials and the transmission are the weak points, if I was to put the upgraded ring and pinion gear in both my front rear differential that’s made out of machined steel and not that cast iron crap like the factory ones are, would 4S power still be OK?

And as far as the transmission, where exactly is the weak point? Are we just talking about a steel gear upgrade or is it the transmission housing or what? I know I’ve seen an aluminum transmission case so, is that what I would probably have to think about later on? FYI, I have done the forward, only conversion, and I used this to delete and lock the 2nd gear.

Also, what about the Traxxas Revo 3.3 center diff? I bought one of those as well being that with the extra power, I figured I’d probably need one of those as well just to help with traction and to just help in reducing the abuse to either the front or rear differential, primarily the back one.

I don’t know if you’re familiar with the Traxxas Maxx but that’s pretty much what I’m after in this build, is to make it like that. I have a version one that for the most part is pretty stock being that it’s got the stock ESC and motor and I run it off 14.8V 4S Lipo.

The number in the HW Max ESC represents the scale of the RC they are designed for. 8 for 1/8th scale, 10 for 10th, etc. But weight of the RC is going to have more of an impact on stressimg an ESC than the size of the RC. So if you're building a heavy 10th scale RC for example, you might opt for the Max8, just for the additional headroom in the amperage handling ability of the bigger ESC.

 

[SpareParts]

I don't have a Maxx, but looking at the parts breakdown it has a much beefier driveline than the nitro revo. When it comes to the diffs, the Maxx diffs are physically larger, larger gears, more space in the diff cup for more fluid, etc.. They look pretty similar to the diffs that are in the erevo 2.0 which were a considerable upgrade from the erevo v1. If you want to do more research I would recommend looking at forum posts about the first generation erevo as that had the same diffs as the nitro revo. There were a lot of complaints.

For some perspective maybe, the nitro revo has the same diffs that went into the slash/stampede/rally 4x4s. Those are quite a bit smaller and lighter, I think my slash 4x4 with some metal bits and a 3s battery is more in the 6.5 lb range. It also has much smaller tires.

Now that isn't to say these things are crap and will break immediately, but the Maxx is dramatically more durable. You can't expect a nitro revo to take 6s power and land big jumps on full throttle repeatedly without breaking stuff. If you drive with some mechanical sympathy you will be fine. I have been having more fun than I expected with my 3s revo. I can't help but smile while driving it as it is just so absurd. It handles great, takes (normal) jumps just fine and the suspension just soaks up anything. I think it would be fun to try to get it even lighter with some titanium but I doubt I could knock even a half a pound off.

Regarding the nitro motor to electric power comparison, it isn't necessarily fair to say a nitro motor is weaker; they just don't pump out 100% torque from 0 rpm. Between the torque curve and the clutch, they are effectively much more gentle on the driveline.

Looks like the weight difference from the Max10 3665 system to the Max8 4268 system is around 120g which is probably negligible if you're not racing. Max8 would certainly mean you don't need to worry about heat at all.

 

[corneileous]

The number in the HW Max ESC represents the scale of the RC they are designed for. 8 for 1/8th scale, 10 for 10th, etc. But weight of the RC is going to have more of an impact on stressimg an ESC than the size of the RC. So if you're building a heavy 10th scale RC for example, you might opt for the Max8, just for the additional headroom in the amperage handling ability of the bigger ESC.

Oh ok. I never knew that about the number. Thanks for explaining that.

But just to refresh my memory, whether I go with the max 10, Max6 or Max8, they’ll all handle at least 3S to 4S, right? In other words, the S rating doesn’t matter between these except well, the max 6 may handle up to 8S, correct?

 

[SpareParts]

The bigger, 140a max10 esc will go up to 4s. The smaller one will not.

Max6 is probably far too big to consider unless you are looking to use it on a different truck.

With your larger tires, probably best to just get the max8 to be safe.

 

[WickedFog]

Oh ok. I never knew that about the number. Thanks for explaining that.

But just to refresh my memory, whether I go with the max 10, Max6 or Max8, they’ll all handle at least 3S to 4S, right? In other words, the S rating doesn’t matter between these except well, the max 6 may handle up to 8S, correct?

You have no need to go with a Max6. That thing is huge. A max8 would be more than enough, but as @SpareParts said, he is doing just fine with a Max10. If you are just going to stick with 3s, I'd probably just go with the Max10 as well. But I have no experience with the Revo's. SoareParts seems to have given ya some pretty good, firsthand info there.

By the way, welcome to the forum SpareParts.

 

[corneileous]

I don't have a Maxx, but looking at the parts breakdown it has a much beefier driveline than the nitro revo. When it comes to the diffs, the Maxx diffs are physically larger, larger gears, more space in the diff cup for more fluid, etc.. They look pretty similar to the diffs that are in the erevo 2.0 which were a considerable upgrade from the erevo v1. If you want to do more research I would recommend looking at forum posts about the first generation erevo as that had the same diffs as the nitro revo. There were a lot of complaints.

For some perspective maybe, the nitro revo has the same diffs that went into the slash/stampede/rally 4x4s. Those are quite a bit smaller and lighter, I think my slash 4x4 with some metal bits and a 3s battery is more in the 6.5 lb range. It also has much smaller tires.

Now that isn't to say these things are crap and will break immediately, but the Maxx is dramatically more durable. You can't expect a nitro revo to take 6s power and land big jumps on full throttle repeatedly without breaking stuff. If you drive with some mechanical sympathy you will be fine. I have been having more fun than I expected with my 3s revo. I can't help but smile while driving it as it is just so absurd. It handles great, takes (normal) jumps just fine and the suspension just soaks up anything. I think it would be fun to try to get it even lighter with some titanium but I doubt I could knock even a half a pound off.

Regarding the nitro motor to electric power comparison, it isn't necessarily fair to say a nitro motor is weaker; they just don't pump out 100% torque from 0 rpm. Between the torque curve and the clutch, they are effectively much more gentle on the driveline.

Looks like the weight difference from the Max10 3665 system to the Max8 4268 system is around 120g which is probably negligible if you're not racing. Max8 would certainly mean you don't need to worry about heat at all.

That’s interesting what you say about the Revo nitro diffs being the same size as some of the smaller trucks and also being the same ones used in the first generation E Revo and how they had a lot of complaints.

But I take it you run your Revo 3.3 brushless conversion on 3S? Should I reconsider 3S and if you do, with the Maxx8 ESC/motor combo, would that still be OK?

Being that I said, I’d like to have the performance in this build the same as my max, about 50+ miles an hour is all I’m really looking for.

So, regarding your pictures and your second to last post… I see you still have the original throttle/brake servo… even though you have dynamic braking with the electric motor, are you still using the original center brake rotor?

Also, I see you mounted your ESC on top of your transmission. How did you do that? Did you buy/make a special plate that mounts to the transmission using the top trans-half screws?

I also see that it looks like you mounted your non-OEM receiver box over where the right side steering servo was. I think that thought crossed my mind at one point, but depending on your input or unless I decide differently, I think that’s where I’m gonna put my ESC…. Well, maybe not necessarily in that same exact spot but pretty much right in between my battery tray, which is where yours is and where the right side steering servo was. On my build, I built me a little plate out of 8 inch thick aluminum and mounted in my receiver box to that pretty much right beside the left side of the transmission.

Oh and also, what is that blue Traxxas part that pretty much sits right on top of your rear shocks? Where did you get that? And is that just like a chassis brace or what? Thanks.

You have no need to go with a Max6. That thing is huge. A max8 would be more than enough, but as @SpareParts said, he is doing just fine with a Max10. If you are just going to stick with 3s, I'd probably just go with the Max10 as well. But I have no experience with the Revo's. SoareParts seems to have given ya some pretty good, firsthand info there.

By the way, welcome to the forum SpareParts.

Oh yeah, I’m glad he joined the discussion. And yeah, I have no interest in that Max6.

But I don’t know if I’m gonna go with 3S or not because originally I was wanting to go 4S because that’s what my max is but if I can still get almost the same type of quickness, acceleration and about the same top speed on 3S as I can on my Maxx that runs 4S then I got no problem changing my plans to 3S.

But that was one of my questions though, even if I went with the max eight, I could still run 3S if I wanted to, correct?

 

[WickedFog]

But that was one of my questions though, even if I went with the max eight, I could still run 3S if I wanted to, correct?

Yes, and with the Max8, you would have more room to grow, like maybe if you later decided to use it in a heavier rig. But as was mentioned, your drivetrain may not handle 4s, at least without doing some upgrading.

 

[olds97_lss]

I converted 2 recently and I have been keeping it to 3s to avoid breaking stuff. I don't need crazy speeds or jumps, 3s is plenty for blasting around in the backyard. I initially used the Hobbywing max10 g2 2400kv and it was great, it never even got warm. I ended up putting that system in my Rock Rey and now have a hobbywing axe r2 3300kv in the revo and it is also great. I'll probably get another max10 for it because it is more appropriate, but the axe has plenty of power and it never overheated in the rock rey (also a large "1/10 scale" truck with giant tires). I have the punch turned all the way down and I still need to be careful to avoid wheelies.

I am currently running a 10t pinion and 38t spur. Transmission is locked in 2nd with I believe the close ratio gearing. I am using an ancient set of rock hard talons that I had laying around.

With a 3s 5200 mah I am around 9.5 lbs ready to run which is pretty good. Bigger motor, batteries, tires, etc will just mean more weight, more heat and more broken parts. I think the G2 max10(and max8) are very efficient so you can get away with using the smaller system. I haven't actually hit lvc yet but I have been getting at least 20 min run times. In the summer I may need to add fans to the esc and motor but for now they are only warm to the touch.

The 2nd revo I converted into a trail truck with slayer arms and a brushed crawler system. Not really relevant to what you want, but I am using a 550 brushed motor, a tiny esc and small 3s batteries. It is geared lower of course but it gets around just fine at full speed, probably 15 mph, with no heat.

I think with the smaller diffs and weaker transmission on these nitro models, you want to stay light and keep the punch down. Otherwise you'll be fixing diffs.
Here are some pics of my abominations.

I was curious how the max10 g2 system really did. I had the max10 sct/3660sl in my stampede for a while on 3S and the motor ran hot as did the esc. I ended up moving the esc to my eJato with a 3665/3100kv and it does really well in that. I got a slash chassis for the stampede and a mild 1/8th system on 4S in it... and a lot of other upgrades to deal with that. lol!

What motor mount do you use for the conversion? Homemade or something else?

FWIW, the first brushless e-revo had similar diffs to the nitro's, but not fully the same. Similar ring/pinion gear/housing/bearings, but the cup was different as it had steel inserts for the x-pin and the "i-bar" to try and beef it up. They held up well to 4S with the MMv2/1515 2200kv system in the v1 e-revo. Some guys even replaced the input bearings with oillight bushings and ran 6S without issue... long thread on traxxas.com. I'm surprised the internals held up... regardless, when I decided to run 6S, I got a 2.0 roller and move stuff over that I could and never had an issue with the drivetrain with 6S then.