1/16 Mini E-Revo - Top Speed Build
 

Some of you may remember I have been wandering around here lately asking a lot of questions related to brushless motors and getting the most speed from my 1/16 Mini E-Revo. I had upgraded the stock ESC and motor to an EZRun 60A and Neu 1112/2D. This worked fairly well and got me up to 73 MPH. The truck felt pretty unstable at those speeds and I had to strap about 100+ grams of weight to the nose to keep it down. My next step was to go to a larger motor. Like many others, I bought the Tenbol big block mount. While the part seems nice and is very easy to install, I was unhappy with how high the motor sat and still had clearance issues with the motor I chose. At this point I decided to pursue a custom chassis. I wanted more space for a large motor and larger batteries. I also wanted a longer wheelbase for stability and to minimize wheelies.

I wanted to do a top-notch job and decided trying to cut the chassis out with the tools I had was not going to yield the results I was looking for. I downloaded a free CAD software package and taught myself how to use it :yes:. This is the first time I have done something like this, so I took careful measurements of the stock chassis, especially all the mounting hole locations. I then started designing the new chassis in the CAD software. I knew I wanted the wheelbase to be extended 40mm, all between the motor and the rear diff. I just designed what I thought would work well. I printed the design out on paper as I went, so I could see a scale representation of how things would fit. I made multiple revisions before I was happy. The final piece was to send the CAD files off to a place to have them cut on a waterjet. I chose 1/8" 6061-T6 aluminum for the material. In hindsight, this is overkill and I could have gone a bit thinner.

Here are the chassis plates after I received them from the waterjet. I did have to make a few small adjustments manually for things I overlooked. All the bolt holes lined up perfectly, but there were a few areas that needed additional clearance around the tranny and driveshafts. I also did all the countersinking for the bolts. I also did the front chassis "kick-up" and rear "kick-down" with an inexpensive vise metal break I bought.

http://www.nuibe.com/rc/minierevo/20090930/plates.jpg


The top and bottom chassis plates are connected using M3 screws and aluminum threaded standoffs. I am using 20mm standoffs, but can run anything from 15mm to 25+mm, depending on how much battery space I need. Only a couple of the top screws are installed in these photos.

http://www.nuibe.com/rc/minierevo/20090930/chassis1.jpg
http://www.nuibe.com/rc/minierevo/20090930/chassis2.jpg
http://www.nuibe.com/rc/minierevo/20090930/chassis3.jpg

More to come....

Next up was a motor mount. The Tenbol mount was way too high for me, especially now that I had a longer chassis and rear shock interference was not an issue. I designed this mount to be strong and as low as possible. This was not done in CAD or cut on a waterjet. This part was all manual (drill press, hacksaw, files, etc.)

Here we have the transmission plate, motor plate, and a rear brace, all 1/8" 6061-T6 aluminum.

http://www.nuibe.com/rc/minierevo/20...ount_parts.jpg


Here are the parts assembled on the chassis. The rear brace was put there so that the pivoting motor plate is in a "double shear" connection. It also takes all of the load off of the transmission case that normally is presented by the weight of the motor.

http://www.nuibe.com/rc/minierevo/20...anny_plate.jpg
http://www.nuibe.com/rc/minierevo/20090930/mmount1.jpg
http://www.nuibe.com/rc/minierevo/20090930/mmount2.jpg
http://www.nuibe.com/rc/minierevo/20090930/mmount3.jpg


The Mini Revo rear transmission mounts are below the top of the chassis, so I had to make these little mounting tabs that bolt to the chassis and hold the rear of the transmission.

http://www.nuibe.com/rc/minierevo/20...nny_mount1.jpg


More to come...

The next pics are the rolling chassis. The front and rear diffs bolted in with no issues. The "arms" of the bulkheads that reach towards the middle of the truck needed to have small spacers between them and the underside of the chassis. I made small blocks of aluminum to serve as mounts/spacers for the shocks. The servo dropped straight in. You can't see it in the pics, but I made a thin sheetmetal cover for the top of the rear diff. In earlier pictures, you could see the chassis had to be cut out to clear the rear ring gear. This left it exposed, so I made the thin cover to bolt to the top of the chassis to seal it up. I used standoffs to move the rear body mounts forward some. Everything else is stock Mini Revo stuff. I was able to pull the front and rear suspension/differential assemblies from my stock truck and bolt them right on to this chassis.

http://www.nuibe.com/rc/minierevo/20090930/roller1.jpg


The Tekno Neu 1512/2D/F mounted up.

http://www.nuibe.com/rc/minierevo/20090930/roller2.jpg
http://www.nuibe.com/rc/minierevo/20090930/roller3.jpg
http://www.nuibe.com/rc/minierevo/20090930/roller4.jpg


As you can see, there is plenty of motor space now. In fact, this chassis can accomodate a motor up to 3.3 (84mm) in length. So, I guess anything up to a Neu 1521 should bolt up to it. :diablo:

Wow, nice work! This is one of the first truly inspiring things I have seen done with the 1/16 platform, since it's along the lines of something I'd do :party:

When all's said and done, that thing should be a tank... at least the chassis won't break :lol:

Due to the extended chassis and the location of the standoffs, my battery "compartments" are 142mm long and 44mm wide. The height of the compartments is determined by the length of the standoffs used to seperate the chassis plates, in this case 20mm. I chose these batteries, Zippy Rhino 3S 2550mah 40C/50C.

http://www.nuibe.com/rc/minierevo/20090930/batts.jpg


I made covers that bolt onto the chassis to hold the batteries in place securely and provide a bunch of surface area to mount electronics to. They are made from thin aluminum sheetmetal and weight pretty much nothing.

http://www.nuibe.com/rc/minierevo/20...att_cover1.jpg
http://www.nuibe.com/rc/minierevo/20...att_cover2.jpg
http://www.nuibe.com/rc/minierevo/20090930/under.jpg

Almost done :yipi:

OK, so here are some pics that get you caught up to the current state of things. I'm using a Pro-Line Slipstream body that I did some creative trimming on. The idea is to keep it aerodynamic. Not really sure if I achieved that, but it looks cool. The suspension is "tied down" to keep the chassis low. There is still another 1/2" to 3/4" of travel left.

With HPI Super Nitro belted slicks on Super Star wheels...

http://www.nuibe.com/rc/minierevo/20...lick_front.jpg
http://www.nuibe.com/rc/minierevo/20...slick_side.jpg


Here are a few with some custom made foams on stock wheels...

http://www.nuibe.com/rc/minierevo/20...foam_front.jpg
http://www.nuibe.com/rc/minierevo/20.../foam_rear.jpg
http://www.nuibe.com/rc/minierevo/20.../foam_side.jpg

As for the weight...
 

I weighed things as I went through this build. My friend's bone stock Mini E-Revo is sitting here and it weighs 2.95 pounds with 2 stock nimh battery packs. The completed truck in the pics above weighs 3.95 pounds with the big packs pictured, a Ko Propo receiver and EZRUN ESC installed. I will not be using the EZRUN, but itis all I had to get the weight. So, it is 1 pound heavier. The vast majority of that weight is the batteries and motor though. The chassis itself is only 100 grams (3.5 ounces) heavier than the stock chassis/receiver box/skidplate combo. If I were to go to thinner metal (likely 0.100") I could shave another 2 ounces or so. I'm hoping the weight won't be too much of an issue for top speed with the powerplant I am running.

BTW, the ESC I plan to run is the Mamba Max Pro that I am waiting on. I'll be running it on 6S.

Another thing you cannot see in the pics. I have made a flat spot on the tranny input shaft. I am using an RCM 4mm/5mm sleeve to run a pinion gear on there. So, I will be running pinion gears on the motor and the tranny. This was the only way I was able to get the gearing options I want in the space provided. I have tested this pinion-on-pinion arrangement in a stock chassis and it seems to work OK. Not sure if it will present any issues or not. Opinions on that?

Thanks for the kind words. I just hope it goes VERY fast.

A couple more points I just remembered...

Yes, I have Traxxas CVD's on the rear and stock plastic sliders on the front. I split one of the front drive cups and don't feel like dropping $55 on a whole set of CVDs to get that one part right now.

The rear-center driveshaft is made from multiple stock shafts that were combined and glued. One of the joints was left free to plunge like the stock one. I saw this trick here at RCM on an EMaxx I believe :wink:

Lookin good Kazuaki! Cant wait to see this one rip! I spoke with Jenny at Castle today and they're finally sending me back my MM. She said they should be shipping out to the distributors by the end of next week or the week after =)

I like it! It's an inspired build

Can I suggest loosing the rear wing & making/purchasing something with almost zero downforce but with vertical stabilizers...& maybe a splitter with a little downforce at the front

WOW thats awesome! How are the diffs gonna take the news?

Can you show me an example of what you are talking about? First runs will be made with the current setup for sure, but I expect I will be tweaking the aero after that, so I am very open to suggestions.

I think they are gonna be pissed :) Since this is a top speed build, I'm trying to avoid sudden throttle hits and trying to roll into it easy.

I just received an aluminum tranny case with hardened steel gears from Hot Racing. I have not installed it yet as I want to see how the stock one will last.

Looking good. You could try to add a little lip to the front of the body for some downforce. How fast can you remove the batteries?

There are 2 screws holding each of the battery covers, one on each end. It takes a minute to remove them, but not too bad.

Sounds good! And maybe someday somebody will make an upgraded diff.

I didn't know the revo platform had a "downkick" to the rear suspension...

Yeah, I didn't either until I was getting ready to assemble. It is very subtle, but it is there. I have since read that the 1/10 version does as well.

I wonder what the purpose is.?? It kicks down toward the ground right? Pretty sure the Maxx doesn't have this feature.

Yeah, just a little. I'd say half as much as the front, or even less.

That downkick has something to do with the suspsension geometry and optimizing the force that applies the tires to the ground. I can't remember the word exactly...

It gives you what is called "anti-squad" angle, I think.
On 1/8 RCs it's adjustable.

Sweet. For 1/8th scale is it dictated by the rear brace thingy? The brace that connects the top half of the bulkhead to the chassis?

Its dictated by the plate bolted to the front of the REAR diff. The Plate bolted in the rear is for Toe adjustments.

Well damn that's a nice build!

Honestly the 16th's were really kind of boring me reading about until now. This has truly gone from just slap a big motor in there to something of much more inspiration.

I really like the look with the body and wing but agree with PBO on the changes. I think in your case he was saying that stabilization is more important at this point than downforce. As well too much down force on the rear can cause the front to lift as well.

On another note if I was you I would get some more of those chassis made and sell them. I am sure you could turn them over pretty quickly.

As far as the diffs go that will be interesting to watch. Maybe linc will find a way to fit LST2 diffs in the mini revo as well. :whistle:

That would be something to see. The LST2 diffs are the size of the Mini Revo front end... lol

I do agree that they are rather boring. I have one. Its fun to go 50mph down the street. But it does flip rather easy and anything taller than dirt isn't fun to drive in...

My goal for this one is to approach triple-digit speeds. There will be nothing boring about that. I gave it a quick test run with the old EZRUN esc and some small 2S packs I had in series (4S). I made multiple passes at just over 70 mph and the chassis seems very stable so far. It is much more controllable than before. I can even make steering corrections at 70 mph without getting the truck all upset. Also, no issues with unintended wheelies so far. I need the new ESC so I can run this with the big packs on 6S.

Can you fit a MMM in there? or a RX8?

And how's the pinion on pinion holding up?

I believe I can fit an MMM. I'd know for sure if the one I sent to Castle for repair would ever come back :sleep:

I made the mistake of running aluminum on aluminum on the pinions. That did not last long, even on 4S. I have some RCM Mod1 pinions coming in the mail today. I got a 25t, 23t, and 21t. We'll have to see how well they mesh with each other.

Does anybody forsee and issue with using these?

I'm basing the aero theories on my own experience with my Rustler

http://i703.photobucket.com/albums/w...h_P1010038.jpg

http://i703.photobucket.com/albums/w...h_P1010042.jpg

Sorry, I'm being lazy by just posting pics but I think you get the idea. The rear wing is a BRP Super Wing & the forward splitter is a 1/10 TC rear wing...my initial issue was to stop wheelies, then blow overs, then straight line stability. My set up generates a lot of frontal downforce, which solves the first 2 issues & my rear wing is more for extending the cord length of the vehicle which smooths the airflow exit around the transmission & motor & it also provides a mounting position for the vertical stabilizers. These are important to help the vehicle track straight at all times

All that being said, aerodynamics is extremely complex & everyone has their own theories. I'm about to work on my truggy which has similar issues to the 1/16 revo. I'm hoping a small forward splitter with a low downforce rear wing incorporating vertical stabilizers will be a good starting point

looks like a great build


i cant wait to see some videos

That is helpful, thank you. I'll look for a rear wing similar to yours.

Wow I dont know how I missed this thread. Thats a piece of work!

What paint did you use for the body?

Its looking very nice :)

But its not a mini revo anymore though



Nice work with the aluminium.
Me and a friend are also working on the mini revo top speed , we are currently at 83mph

Good luck with your truck, it look sharp! :)

Not sure I agree with that, but OK. Seems like aftermarket chassis have been a standard option for many 1/10 monster trucks for a long time.

Didnt tried to make your work look unfair or anything :)

You are absolutly right i can buy aftermarket chassis for various rc, but i dont see yours for sale anywhere, its a unique design, no one will have a truck like yours.


Im not trying to argue about that, i really wish you good luck with your goal.

It still look sharp to me. :)

Just regular black Lexan paint.

I sent a PM asking specifics, length and weight and shafts

crazyjr,

Chassis is extended 40mm behind the tranny. The front uses the stock center chaft, the rear uses a longer shaft I made by glueing stock shafts together. The chassis weighs 100 grams more than the stock one.

BTW, all of this info is in the first page of this thread :smile:

Thanks, didn't know you had roller weights on the first page, thought it was RTR. I'm wanting to do something similar with maybe adding 3/4"over stock, I think 40mm might be too much for what i'm planning