My e-revo brushless edition build

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8th SCALE CENTER DIFF

The 8th scale center diff in a Revo all started with a guy naming himself ‘’CowboyRay’’. He made an 8th scale CD using a Thunder Tiger TTR S3 buggy center differential. His design required extensive machining to be done and was financially out of reach of many. Some people tried to take over this design and tried to market this CD but the financial aspect was a problem again. It was just very expensive to produce and the sale price was high. Cowboy made and sold a few hundreds of them and then stopped when Traxxas came out with their own version of a center differential with rear brake. Then I saw on the RC Monster forum a guy named ‘’sjcrss’’ made an 8th scale center differential with parts of an Ofna Hyper 7 buggy CD that did not require the help of a machinist or machining equipment. Having at least a drill press or access to one helps a lot though. The hardest part of making this CD is definitely making M3X.5 threads in hardened steel.
So I went with sjcrss’ idea of using the hardened steel spur gear as the diff cap and CowboyRay’s idea of using Thunder Tiger parts. I modified the ERBE’s output gear TRA3984X and I modified these two parts, TRA5415 and TRA5416. They are the output shafts for the Revo 3.3 center diff.

The Thunder Tiger spur gear PD1893

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The Traxxas TRA3984X output gear


The Traxxas TRA5415 and TRA5416 output shafts



The Thuder tiger diff parts, diff case PD1897, diff gear set PD1895



The modification done to the Thunder Tiger PD1897 diff case



The final product

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ZERO SLOP 17 MM OFNA ADAPTERS

The Ofna adapters are tough and cheap. The Traxxas adapters are very similar except for the splines. Both of them have slop that gets worse with time because they get grinded by the threads of the stub axles. There are other systems out there that require the use of 8 mm stub axles or stub axles with no threads but they end up being expensive, although they are very good. Also there are cheaper styles that work great but I started with Ofna before any other systems came out and with the modifications I did, they have been working so well that I don’t see why I should change anything.

GETTING RID OF THE SLOP

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GETTING RID OF THE LOCKTITE

Here's a couple things I do to stop the need for Locktite. Some slots Dremeled in the nuts, they bite in the wheel's plastic and they don't come of by themselves and a groove around the adapter for an O ring to keep the set screw from backing out. This has been race and bash tested for a long time. It works.



I mount the adapter on a spare stub axle so that I can chuck it in the drill press. I make it turn at medium speed and with a cut off wheel on my Dremel, I can make a clean groove for the O ring.

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SPECIAL TOOL

I made a simple tool to screw in or out the little tubes I made. It works great and doesn't damage the part like a flat head screw driver can.

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ALUMINUM SLIPPER DISK

Nitro vehicles use aluminum clutch shoes inside hardened steel clutch bells so there's the hardened steel slipper disk already on the ERBE, why not use an aluminum slipper pad. So that's the route I decided to take. I have been extensively testing this slipper for the past month and it is holding up to just about any kind of abuse I give it. I tried a carbon fiber slipper disk before that and it held up for a while but failed once it got the abuse of racing at the track.



This is how the disk looks after more than 25 cycles of 4, 5 and 6S runs at the track and bashing. The middle disk is the test one, the left one is new and to the right is the slipper steel plate.



Here are the measurements to make one out of a piece of aluminum anywhere between 2 and 3 mm thick. I tried to be as accurate as I could with the measurements.



BULKHEADS

I have a tendency to over tighten screws sometimes. Especially with the plastic bulkheads. I feel these need to be sitting as tight as possible against the chassis but I often stripped the threads in the plastic trying to do so. I installed some Dubro brass inserts to deal with this problem. Now I can torque those screws very tight and I believe that this helps make the bulkheads sit very snuggly against the chassis adding to the overall structural strength.
I used the 4-40 inserts for the screws that go through the shock towers and 6-32 inserts for the rest on the screws.



ROCKER POSTS

I don't know about you but when I want to take the rockers arms and this happens, it annoys me.



The P2 progressive rockers will be used but this is a small modification I like to do to the rocker posts. I take out the M4 button head screw, I make sure the rocker post is firmly screwed to the bulkhead. Then I take an M4X.7X16 mm set screw and screw it firmly in the rocker post with red Locktite. I then use an M4 Nylok nut to secure the rockers. Whenever I need to take a rocker out, the post stays in the bulkhead.



REAR BODY POST

There’s not much to say about the rear body post but I just wanted to show what I did to it. The body post used on the ERBE is the same as the 3.3 Revo with Easy Start so it has this orifice in it for the Easy Start plug. It is not used for the ERBE so I sanded it off with a sanding drum.



AXLE CARRIERS

This is something I always do with the axle carriers. I use a longer screw and a lock nut.

Hi, I've been scrolling thru your notes here. Im new on this forum or to any I should say. I have to tell ya! You opened my eyes to a whole new way of looking at my revo! Ive been bac into RC for about a year and searching this dam computer for fix's, how to this, how much that, I dont have a big support network built up, but Its looks to me like, You just have to try it, break it, build it, tweak it. Like your style! The Ofna hub thing is slick. Anyway I bought aluminum outer dif cases for a revo and Im about to put em together,Im having a hard time deciding oil wt for the F +R. I want to have a crossover revo if u kno what I mean. hardcore offroad/street? is it possible?

Hi, I've been scrolling thru your notes here. Im new on this forum or to any I should say. I have to tell ya! You opened my eyes to a whole new way of looking at my revo! Ive been bac into RC for about a year and searching this dam computer for fix's, how to this, how much that, I dont have a big support network built up, but Its looks to me like, You just have to try it, break it, build it, tweak it. Like your style! The Ofna hub thing is slick. Anyway I bought aluminum outer dif cases for a revo and Im about to put em together,Im having a hard time deciding oil wt for the F +R. I want to have a crossover revo if u kno what I mean. hardcore offroad/street? is it possible?

Hi, I've been scrolling thru your notes here. Im new on this forum or to any I should say. I have to tell ya! You opened my eyes to a whole new way of looking at my revo! Ive been bac into RC for about a year and searching this dam computer for fix's, how to this, how much that, I dont have a big support network built up, but Its looks to me like, You just have to try it, break it, build it, tweak it. Like your style! The Ofna hub thing is slick. Anyway I bought aluminum outer dif cases for a revo and Im about to put em together,Im having a hard time deciding oil wt for the F +R. I want to have a crossover revo if u kno what I mean. hardcore offroad/street? is it possible?