BL Revo tranny - DIY

I’m in the middle of building a ground-up E. Revo – a “kit build” if you will. :027:
I wanted to use the stock Revo transmission for my conversion for overall simplicity; to retain the stock drive shafts, mechanical brake, chassis mounting locations, etc. I locked the shifting mechanism (eliminating reverse), to use the electric motor’s ability to switch rotation and reverse the entire gear train.

(refer to the exploded view of the Revo tranny for part numbers).
I know others have done this in different way, but my conversion eliminates first gear, and the lower reverse gear. It locks second gear directly to the Primary shaft (5393), by pinning it directly to the aluminum Primary Clutch assembly (5390).

How to:
Disassemble tranny halves and remove the top input shaft (5366) assembly.
Remove the Primary Shaft assembly.
Remove the first gear (5386) that rides on the one-way bearing (OWB) (5393) from the Primary Shaft. Remove the E-clip from the OWB and remove the first gear. Set the OWB aside for now.
Next, to pin the aluminum Primary Clutch assembly to the second gear, it’s easiest to remove them from the Primary shaft.
First, remove the 3x13.75mm screw pin from the white Primary gear, remove primary gear from shaft;
remove Second gear from the Primary clutch, and off the shaft;
push the pin out that holds the Primary Clutch to the shaft and remove the aluminum assembly.
Put the 10x15mm bearing (5119) from second gear back on the Primary Clutch and place it bearing up on the worksurface. Mark and drill a .089 dia. hole (#43 drill bit) through the aluminum Primary clutch, right next to the bearing. Don’t worry about scratching the bearing, it will simply become a spacer.
I also removed the set screw, spring and ball to release the cam in the Primary Clutch, and used a piece of wire to jam the cam open (to increase holding power).
Place the Second gear back on the Primary clutch and turn the clutch until the cam engages one of the pins in the Second gear. Hold it in this position and drill a .089 dia. hole through the previous hole, down into the Second gear. Run a 4-40 tap through the entire assembly to thread the holes.
Place the Primary clutch back on the Primary shaft and pin in place. Place Second gear back on the Primary clutch and turn the clutch until the cam engages one of the pins in the Second gear. Hold it in this position and insert a 4-40 setscrew through both to secure them together (use loctite).
Reassemble the Primary gear with the screw pin; place the OWB back on the Primary shaft as a spacer in place of first gear.

Note: in this section, the Forward gear is closest to the brake end of transmission. It is thinner than the reverse gear.
Outside the tranny, remove the reverse spring linkage (5392) from the reverse yoke shaft; pull the shaft all the way out to engage forward gear. Slide a wheel collar on the shaft to lock it in place.
Inside the tranny, remove the Reverse gear from the Output Shaft (5369) assembly; press the 6x10mm needle roller bearing (NRB) from the reverse gear; place the bearing back on the Output Shaft as a spacer in place of the Reverse gear.
Reassemble the shafts into the transmission – noting the location of all shims (thrust washers).

That’s it!
You now have the advantage of the Revo spur and slipper clutch set-up, the ability to use motor reverse to spin the drivetrain in reverse (if your controller allows), and the ability to use a mechanical brake.

I am working on locking the connection between the drive dog and forward output gear (5395) by pinning or screwing these two together. This would eliminate the drag of the shift yoke in the drive dog, and tighten the drivetrain.
Here's a link to pics:
http://community.webshots.com/album/548981601lQvCMa

Sorry for being long-winded.

[mothman]

Nice write up mate. Im in the process of converting my revo too. This helps alot..Thanks alot!!

[BrianG]

Originally Posted by Cadtech

...I am working on locking the connection between the drive dog and forward output gear (5395) by pinning or screwing these two together. This would eliminate the drag of the shift yoke in the drive dog, and tighten the drivetrain.

Yeah, nice write-up! Couldn't you just get the FOC? Yeah, it has a few other parts you won't need, but contains the important sensor cover, output shaft (lightened), and output gear.

Originally Posted by BrianG

Yeah, nice write-up! Couldn't you just get the FOC? Yeah, it has a few other parts you won't need, but contains the important sensor cover, output shaft (lightened), and output gear.

I could, but what fun would that be?:027:

Actually, the store bought FOC doesn't address the issue of locking the second gear to the Primary clutch. Which means you can't use the motor to reverse the geartrain, correct? (I haven't seen a Revo FOC installed, so I don't know). Do you keep first gear in the tranny with a FOC installed?

My other rationale was to try this as if I had zero budget (there are always folks who save all their pennies for new motors/controllers, and have nothing left for anything else). Usually, this quickly degrades to me building/milling some elaborate piece that costs 50 times what a store bought piece would - but that is one of the most enjoyable parts of this hobby for me...
...building parts!
Fortunately, this is a pretty simple conversion that requires no extra parts to purchase. Wouldn't even need a tap if you were to drill/pin/epoxy the parts together.

[BrianG]

Originally Posted by Cadtech

I could, but what fun would that be?:027:

Actually, the store bought FOC doesn't address the issue of locking the second gear to the Primary clutch. Which means you can't use the motor to reverse the geartrain, correct? (I haven't seen a Revo FOC installed, so I don't know). Do you keep first gear in the tranny with a FOC installed?

My other rationale was to try this as if I had zero budget (there are always folks who save all their pennies for new motors/controllers, and have nothing left for anything else). Usually, this quickly degrades to me building/milling some elaborate piece that costs 50 times what a store bought piece would - but that is one of the most enjoyable parts of this hobby for me...
...building parts!
Fortunately, this is a pretty simple conversion that requires no extra parts to purchase. Wouldn't even need a tap if you were to drill/pin/epoxy the parts together.

Ok, I guess it would be less fun.

The FOC doesn't even touch the first and second gears at all. It removes the sensor gear (the one with the crenellations), reverse idler, dog gear, shift fork, and reverse output gear. The forward output gear is replaced with one that pins directly to the output shaft. Oh, and the output shaft is replaced as well. You get a few other odds/ends like a plug to cover the shifter hole, a cover for the OptiDrive sensor, and a blank cover for the OptiDrive itself. When I did mine, I removed first gear and the associated bearings and added the wide ratio gear set so the final gearing was closer to an E-Maxx. This thread explains exactly what I did and it works well. Posts #23 and #25 are the ones you really want to read.

Hey just an FYI, you don't need the one way back on there as a spacer, I have been running mine for a while now without and it works fine.

This mod works exactly the same as the hub I milled to replace all of this, basically you are locking up the second gear to the shaft instead of the clutch doing it. If you reassemble correctly the gear will be held into place on the shaft and won't slide, the shaft is turned down at the end and won't slide further into the bearing than it is supposed to. You can lock the tranny in either forward or reverse and it will work, I have my locked in reverse and the motor is just setup to go the other way.


Good work around dude!

Originally Posted by BrianG

This thread explains exactly what I did and it works well. Posts #23 and #25 are the ones you really want to read.

Been there, read it. You were the inspiration for me to try this method! I liked the idea of using the Revo, but was skeptical of the durability of the epoxy, especially on the nylon gears. Time will tell if any of our methods have durability issues.

Originally Posted by b0gh0s

Hey just an FYI, you don't need the one way back on there as a spacer, I have been running mine for a while now without and it works fine.

Yep, thanks. I figured that out too, after putting the tranny halves back together for the umteenth time. Was pretty obvious, but obvious is always the first thing ya miss, eh?

Originally Posted by b0gh0s

This mod works exactly the same as the hub I milled to replace all of this, basically you are locking up the second gear to the shaft instead of the clutch doing it.

I like your machined part! Very well done.

And locking up is what this is all about. It basically creates an E-maxx tranny out of the Revo tranny - but allows for all other stock Revo drivetrain parts to be used, and no chassis mods need to be made. Others looking to convert a Revo can use what they have, without buying another trans.

Thanks to you guys for the kind words, and for the information/inspiration!