E Revo Center Diff questions and Opinions - Page 4 - RC-Monster Forums

simplechamp · 09.03.2009, 04:57 PM

Not sure what I want to do next, maybe cut and drill the Traxxas output shafts. Thinking of sourcing a local machine shop to drill and tap the holes in the cap because I don't want to screw it up and bust off a tap in the hardened steel.

shaunjohnson · 09.03.2009, 05:33 PM

are the spurs made from hardened or high speed steel?
cause i could use the lathe instead.

simplechamp · 09.03.2009, 06:05 PM

The Thunder Tiger spur used in mistercrashes revised design is hardened steel, which is what I am using. I'm not sure what type of steel is used in sjcrss' original Hyper 7 version.

sjcrss · 09.03.2009, 06:55 PM

I think it's hardened steel as well,....thats what my machinist told me at least...

mistercrash · 09.03.2009, 11:51 PM

I am pretty sure that all good diffs and center diffs like Ofna, Thunder Tiger, Losi, Mugen and so on use hardened steel spurs and ring gears. That CD is starting to look good simplechamp, if that lip is still too thick and you run into fitness problems in the tranny, you can take off a little more and I'm sure you won't have any problem. The lip I left on my CDs are like half a millimeter thick, it's just there to center the piece on the diff case.

mistercrash · 09.04.2009, 11:13 AM

I wish someone could make these gears for $5 each

simplechamp · 06:34 PM

Nice mistercrash! I was actually planning on trying out just the two mounting screws instead of four, we'll see how well it holds up, my main reason was to have less holes to drill and tap. Also was debating countersinking the holes where the mounting screws go, but not sure if the material is thick enough.

You pretty much read my mind on that drawing!

EDIT: Can I get some advice on drilling the pin holes in the cut-down output shafts? What size bit is used? (I have a bunch of SAE bits, not so many metric) How do you drill the holes exactly on-center? How far from the end should they be drilled?

mistercrash · 09.04.2009, 11:07 PM

This is how I do it.

If you're going to have a machinist make the holes in the spur gear and thread them, maybe he/she can make the holes in your shafts also.

simplechamp · 09.05.2009, 01:21 AM

That's something that had crossed my mind. Probably would be the best. Do you have a measurement for how far from the end of the shaft the hole needs to be?

Modded the plastic spur tonight and it turned out well. All I have left to do is cut down the output shafts and then after the long weekend I'll call around to a few shops to see what they'll charge to do the drilling and tapping. Unfortunately I have a feeling this is going to turn into a $90 center diff, but no turning back now!

sjcrss · 09.05.2009, 07:29 AM

It will be worth it, trust me....you will notice a difference

mistercrash · 09.05.2009, 08:39 AM

You are so right scjrss, the 8th scale diff in the ERevo is so efficient, tough and so tunable. According to my my calculations, the center of the hole in the shafts are 0.229'' from the tip.

sjcrss · 09.05.2009, 11:39 AM

Mc, any updates on the aluminum slipper disk?

mistercrash · 05:15 PM

yep! I'm still running the same disk I made, it wore down by about 1/2 of a millimeter. I had to readjust it a couple times when it started slipping too much. It is still working awsome and I love it.
remember that Losi center diff I made with the three aluminum posts, I plugged two of the holes in the diff cap with JB Weld and made a new hole to install the TRA3985X output gear with only two posts like the last CDs I made. Now I have two CDs made with the heavy duty Losi LST XXL diffs. I will see if the JB Weld plugs hold up. I have been running this last Losi heavy duty CD with the two aluminum posts and TRA3985X output gear every day since I made it and it's working really really well. I'm happy about it.

sjcrss · 09.05.2009, 05:54 PM

thats great news, hopefully everything will continue to hold up well. Mine is still holding on strong, and no leakage that i can tell, but after the summer ends, im due for a complete teardown anyways

simplechamp · 06:55 PM

Just need to contact a machine shop now to have them do the drilling and tapping. Once that's done I'll drill the two holes in the plastic spur and assemble it all. Slid the shafts into the spur/case just to test alignment and everything lines up perfectly. I bored out the center of the plastic spur and then also counter-bored a larger section to allow the metal cap to sit flush on the spur.