Direct Drive to Diff E Revo Build - Page 10 - RC-Monster Forums

johnrobholmes · 11.27.2007, 07:45 PM

done yet? Got an hour of test time too? :D

BL_RV0 · 11.27.2007, 08:04 PM

hurry your ASS up! j/k, take your time and do a good job.

DrKnow65 · 11.28.2007, 10:35 PM

Any thoughts on a centrifical clutch setup for a direct drive brushless? It would have to stay engaged (spelling?)under braking and work at a low rpm. Wouldn't this fix all cogging issues?

I'm picturing a clutch (old old school) that had two weights on levers that would spin out with rpm, pushing (leverage) on a clutch disc. I remember seeing them on elevators for speed brakes and at a power pland to control a turbine flow valve. Hope you know what I'm jabbering about :)

I also saw a modernized version for harley davidsons that used sliding weights that spun between two concave washers to apply force to the clutch. I'll see if I can find a photo to help you all understand.

DrKnow65 · 11.28.2007, 10:44 PM

Here's a link to the harley autoclutch, but I couldn't find any photo's of the internals.
http://www.efmautoclutch.com/

Basically there are two plates with tapered grooves (channels) from the center out (large groove at the center, getting smaller twards the outside). There are balls (weights) that are in the groves, when the rpm's increase the balls are pulled outward by centrifical force, this wedges the balls farther into the grooves and pushes the two plates apart, applying force to the clutch pack.

sikeston34m · 11.28.2007, 11:16 PM

Quote:

Originally Posted by DrKnow65

Here's a link to the harley autoclutch, but I couldn't find any photo's of the internals.
http://www.efmautoclutch.com/

Basically there are two plates with tapered grooves (channels) from the center out (large groove at the center, getting smaller twards the outside). There are balls (weights) that are in the groves, when the rpm's increase the balls are pulled outward by centrifical force, this wedges the balls farther into the grooves and pushes the two plates apart, applying force to the clutch pack.

That's a pretty interesting design. I think there is much improvement to be seen in the "clutch" area of RC. I wish someone would design a clutch for RC that works like that.

Most "slipper" clutches that are used today are designed to "protect" the drive train, but they also hinder acceleration. It's really the fact that it never truly locks up that does this.

I'm almost 100% positive that I have the answer to the cogging. These diffs will change how everything acts. With the Phaltline tires and the 4.3:1 diffs, Rollout is exactly the same as the E maxx outrunner setup in 2nd gear. This is gonna be awesome because this is SOOOOOOO much tougher.

I got the Diffs assembled. They look great inside and out. I also figured out the CVD arrangement. Now I have to split the bulks to install them.

For all you guys taking notes here, the RD Logics CVD's work with the Hotbodies diff cup. The THS Racing cvd's do NOT work with the HB cup.

DrKnow65 · 11.28.2007, 11:23 PM

Keep good notes of this buildup for me OK Sike? I won't be able to do it too soon, but imitation is the most sincere form of flattery :) I think I'll be converting my hyper7 befor I can do the DDR (direct drive revo) but I'd like to do direct in both of them. Eventually....

Matthew_Armeni · 11.28.2007, 11:30 PM

Maybe I'm wrong, but doesn't a Centax clutch work like that? Or is it the balls themselves that apply the direct force on the clutch? I know that it uses balls set in a concave hole so when the flywheel spins the balls are forced outward but the shape of the hole they sit in forces them forward as well. What I don't know is if they touch the bell or touch something else that in turn touches the bell. Any thoughts?

sikeston34m · 11.29.2007, 12:10 AM

Well I got the front end tore apart and the Bulks split. This is my first time tearing down a Revo. I'm impressed with the design. It's a tad more complex than the E maxx.

I took out the front stock diff. There's something wrong with it. It's leaking grease everywhere. When I spin the pinion, it feels like the ring gear inside is warped or something. It spins freely for about 1/3 of turn, then I feel the gear mesh and there's ALOT of drag. Hmmmmmm.........Aaah well, I'm not gonna trouble shoot it right now.

This does point toward the fact that this diff was dragging the setup down though.

The RCM diffs feel sooooooooooo smooth and spin VERY freely.

@Drknow:

Let me get this perfected. I'll show you the EXACT setup to go with and some video's.

lincpimp · 11.29.2007, 01:54 AM

Quote:

Originally Posted by sikeston34m

Well I got the front end tore apart and the Bulks split. This is my first time tearing down a Revo. I'm impressed with the design. It's a tad more complex than the E maxx.

I took out the front stock diff. There's something wrong with it. It's leaking grease everywhere. When I spin the pinion, it feels like the ring gear inside is warped or something. It spins freely for about 1/3 of turn, then I feel the gear mesh and there's ALOT of drag. Hmmmmmm.........Aaah well, I'm not gonna trouble shoot it right now.

This does point toward the fact that this diff was dragging the setup down though.

The RCM diffs feel sooooooooooo smooth and spin VERY freely.

@Drknow:

Let me get this perfected. I'll show you the EXACT setup to go with and some video's.

Sounds like the inside bearing on the pinion let go and the ball bearings are floating around inside the diff. I had the same problem with my tekno revo rear diff. It only had 3 different nitro motors and 1 hour of hard brushless running! Maybe some better bearings, boca avid etc, would be the ticket. They may be expensive, but would sure roll nicely.

its me · 11.29.2007, 02:57 AM

I am also digging this build and dieng to see the end results :)

MetalMan · 11.29.2007, 01:59 PM

This truck has caused me to stop procrastinating on turning my MT2 into a direct-drive outrunner-powered truck. Now I have everything I need, except for the custom shaft that still needs to be made.

Thanks a lot

aqwut · 11.29.2007, 03:52 PM

This build is awesome.!.. my 3rd GST will be direct Outrunner as well..

sikeston34m · 11.29.2007, 06:57 PM

Quote:

Originally Posted by MetalMan

This truck has caused me to stop procrastinating on turning my MT2 into a direct-drive outrunner-powered truck. Now I have everything I need, except for the custom shaft that still needs to be made.

Thanks a lot

The MT2 looks like a pretty awesome truck. Are there aftermarket 1/8th diffs available for it also? I'm gonna check that one out a little more. Only weighs 5 pounds! I like that!

In considering other trucks for direct drive conversion, just remember what we've ran into on the cogging issue. I think that line that you can't cross is somewhere about 4 inches of roll out per turn of the motor. Vehicle weight affects this I'm sure.

But more so, I believe it also has to do mainly with the level of EMF pulses that the ESC MUST get from the motor to start properly. More on this later.

johnrobholmes · 11.29.2007, 07:08 PM

What did you use for your bracket? I am having a hard time sourcing local angle aluminum of good grade and size.

sikeston34m · 11.29.2007, 07:24 PM

Quote:

Originally Posted by johnrobholmes

What did you use for your bracket? I am having a hard time sourcing local angle aluminum of good grade and size.

In the beginning, I thought I wanted a full skid plate under the motor, so from Ebay, I ordered a 4 foot stick of 4" x 4" 1/8" thick angle.

Then I changed my mind and went to Lowes. There I bought a 4 foot stick of 2" x 2" 1/8" thick angle. It's back there by the threaded rod and the steel angle.

Everything is made from the 2" x 2" angle except for the ESC mounting plate. That's 1/8" sheet. And also the little blocks that support everything, those are made from an aluminum sheet that's 3/8" thick.

All the bolts and nuts also came from Lowes. They have a really good selection. In thinking back, I probably should have used aluminum bolts for some weight savings. That probably wouldn't amount for much though.