Locking the revo in 2nd gear to use motor braking/reverse

[BrianG]

If you get the rc-monster revo motormount, you can either use the mechanical brake or use this to lock it into 2nd gear;

Option 1: Two-speed transmission with stock brake and stock reverse:
You'll need servos for the reverse shifter and the brake. The downside to this is that the reverse stock mechanism is generally pretty weak, especially since you're now using brushless. And you cannot use a center differential because the diff replaces the shift fork, dog gear, and second output gear. You can however still use the Optidrive to help protect against accidental reverse when moving.


Option 2: Two speed transmission with mechanical brake and no reverse (the cheap way):
You'll still need a servo for the brake. Lock the shift fork somehow.


Option 3: Two speed transmission with mechanical brake and no reverse (the right way):
You'll still need a servo for the brake. Install the FOC (forward-only conversion) to eliminate reverse and get rid of the extra weight from the servo, Optidrive, assorted linkages, etc. This option lets you use a center differential if you want.


Option 4: Modify the transmission for single speed (2nd gear):
Lock the centrifugal clutch into second gear. See locking mechanism picture below. You don't have to, but you can also remove first gear altogether for a simpler and lighter tranny. Either way, 1st gear won't be used at all. Locking into second gear is the ONLY option where you can use the brake and/or reverse using the brushless motor.


And here is a method you can use to lock the tranny in second gear should you choose to do so:



To do this:

1. Remove first gear
   
   
2. Install the FOC
   
   
3. Install whatever gear set you want (std, wide, or narrow). Since each of these gear sets just adjusts 2nd gear, you can set a higher or lower ratio right off the bat to possibly allow better spur/pinion selections.
   
   
4. Remove screw, spring, ball bearing, and little grey plastic plug on the centrifugal clutch.
   
   
5. File three half-moon slots in the edge of the clutch lined up with three of the holes in second gear.
   
   
6. Screw three 4mmX10mm pan head screws into second gear so they lock into the half moon cutouts you made on the clutch.

Simple diagram showing the basic parts before and after:



Thanks to Finnster for the following images showing much more detail on how to perform the actual locking modification:








Link to the "pin mod": http://www.rc-monster.com/forum/show...8&postcount=45

[jnev]

You can still lock it into 2nd gear to use motor braking with the wide ratio gear set, right?

oops, nevermind. Stupid me never read the last part. You can delete this post. :o

[Serum]

yes, indeed; that's possible.

[jnev]

I was planning on asking for more help on locking it into 2n gear, but those new diagrams helped so much. Thanks so much for that. :smile with a big thank you:

[BrianG]

lol, no problem. As they say; a picture is worth 1,000 words...

BTW: The scale is a bit off, and the gears are all white-ish...

[jnev]

Quick question, when you file down the 3 slots for the screws, do you file right on the side f the gear so the thread of the screw goes into the gear a little? Or do you file the top of the gear, so the pan head of the screw goes into the top? Let me know, if you want to me to explain it more. It may be a little confusing the way I said it.

Let me know. Thanks.

You file into the centrifugal clutch. There are already holes in the gear that the 4mm screws fit into and the screw top rests against the face of the clutch once installed.

[jnev]

Oh I see. So part of the thread will be in the centrifugal clutch after sanding it down in the three spots?

I bought the screws today. So now I just need to wait for the wide ratio gear set to arrive before I can actually lock it into gear.

[BrianG]

Originally Posted by jnev

So part of the thread will be in the centrifugal clutch after sanding it down in the three spots?

Yup, that's right. Once you have the gear and clutch in your hand, you'll see more easily. The holes in the gear are partially covered by the clutch, so filing half circles uncovers the holes and lets the screw thread in. Three seems to hold very well so far, but you could go crazy and use all of the holes.

Whatever you do, make sure the screws are equally spaced or you'll have balance issues.

[jnev]

Thanks so much for the help. Hopefully the wide ratio gear set will arrive tomorrow so I can get to work. :)

I also heard that you put some Jato pins like these: http://www.buytraxxas.com/product_in...oducts_id=2399 into your center tranny. Can you explain to me where these pin(s) go and are they actually needed? When my bro ran a Picco .26 in the Revo, he had no problems at all, but then again, its not brushless. :)

Thanks again for all the help so far.

[Finnster]

If you don't mind I'll add a couple pics of the clutch for clarity:
[see OP]
The filed holes should line up to to the holes in the 2nd gear. If you have a 4mm tap, its a nice idea to run it thru the plastic gear for a bit more strength and durability. The holes should be in the same place for all the gear sets. As pictured, try to line up the clutch arm right to the drive pin of the 2nd gear so the drive pin is taking most of the force of the acceleration (as its designed to.)

Lastly, don't use longer than 10mm screws or it will stick out the back end into anther gear.


Other notes: I didn't remove the plug on my 1st one. Seems fine. I also switched to button heads later as they are lighter. I also did one clutch w/ just two screws (instead of 3) and it seems strong as well, tho I use manual brakes and no reverse so YMMV. I also removed the set screw that controls shift points to remove the spring pressure pulling the clutch arm in. Do not have to do this, just makes life a bit easier (as found on 1st one.)

Thanks Brian!

[BrianG]

Originally Posted by jnev

I also heard that you put some Jato pins like these: http://www.buytraxxas.com/product_in...oducts_id=2399 into your center tranny. Can you explain to me where these pin(s) go and are they actually needed?

Those pins replace the ones currently in the tranny. There are two places where these go; on the input gears (blue ones in the pic in the first post), and on the output gear that is on the output shaft. These pins secure the gear to the shaft.

The Picco is a strong motor, but doesn't have that instaneous snap that BL has, which can break these pins.

[jnev]

Thank you guys so much for the help. This is exactly the info I really needed.

Sorry for another question, but I want o get it all right the first time, lol. The Jato pins fit right where the stock ones go, correct? Is there any modification like widening the hole a little to get them to fit needed? If there is something needed to do, should the pins fit really tightly, or somewhat loosely?

Thanks again for the help so far.

[BrianG]

Yeah, you're gonna have to drill the shaft hole out a little and it'll be kinda tough since the shafts are steel. Use a vice, NOT your hand to hold the shaft while drilling. A drill size just big enough for the smooth part of the pin, but no slop, is needed. Then, the hole in the gear (where the pin's threads will bite into) need to be widened just a bit too.

[jnev]

Thanks for the help Brian. I feel like an expert now, lol.

LHS was out of the Jato pins :sigh: Looks like rebuilding the tranny will have to weight even longer... I would like to get everything done right the first time, so I don't have to go back later and rebuild the tranny because of some broken pins, that I was told would have a chance of breaking anyway.