Erevo / Emaxx 1/8 center diff

[lincpimp]

So I have begun designing and constructing a center diff for the erevo / new emaxx tranny. Basing my design around a std 1/8 scale diff cup. So it will employ 4 spider gears and 2 output gears. My current diff cup is a HPI al savage cup that has the steel blocks to reinforce the cross shafts. Strongest design I could find. My adapter will also fit any kyosho, OFNA, or hot bodies cup, and any other cup that has the std 4 hole mount pattern.

Some pics:







The al adapter is not complete yet. It still needs to be cut to the correct length and the end tuned down to accept a 8x12 bearing. The black gear also needs to be milled to a certain thickness, as you can see in the 3rd pic it sits too high compared to the input gear. I have done the measurements and should be able to have the machinist finish the adapter on Monday.

Due to the overall thickness of the diff cup and the adapter, and the diameter of both they will contact the idler gear. My only method of fixing this issue is to remove about 1/5 of the thickness of the teeth from the idler for adequate clearance.

This is necessary due to the mounting issues with the stock lower gear to the adapter. If I can have a gear custom made, I can modify the adapter to place the gear closer to the face of the diff cup, although I may never be able to get it close enough to work without some trimming of the idler. Just not enough room inside the stock tranny case.

More info when I get some more progress! All ideas and thoughts welcome...

[Takedown]

Hmmm... Ill be watching this one.

[sjcrss]

Ok, I see how its looking now....couple of ideas or suggestions possibly....
can you machine adapter to be thinner at the attach point to cup....this can bring the gear closer, also how does the gear attach to it, and the output shafts....I see one side is threaded.....are you going to use a modded stock lower shaft?..all in all...looking good and is a good start....

[lincpimp]

Originally Posted by sjcrss

Ok, I see how its looking now....couple of ideas or suggestions possibly....
can you machine adapter to be thinner at the attach point to cup....this can bring the gear closer, also how does the gear attach to it, and the output shafts....I see one side is threaded.....are you going to use a modded stock lower shaft?..all in all...looking good and is a good start....

The lower gear has a .080 think flat area on one end, and I will mount the gear to the adapter thru that. The adapter has to be that thick for the mount screws to have something to screw into. I will use cap head m3x6 screws, just the right length.

[George16]

I'm watching this one too.

[TruckBasher]

Interesting idea Linc....I might build another E-Revo...

[George16]

Do you have one of those tmaxx 2.5 Forward only gears? It's thinner than that but I don't have one on hand to make some measurements.



http://www3.towerhobbies.com/cgi-bin...?&I=LXCNA8&P=7

[lincpimp]

Originally Posted by George16

Do you have one of those tmaxx 2.5 Forward only gears? It's thinner than that but I don't have one on hand to make some measurements.



http://www3.towerhobbies.com/cgi-bin...?&I=LXCNA8&P=7

I think that is a 26t gear, not 33t...

[lincpimp]

I may be able to use the gears, modded a bit. If I can get a set, I may try to use them with the next proto shaft. I will probably do this, as I can run one style setup in each of my trucks and see which one breaks first!

http://www3.towerhobbies.com/cgi-bin...?&I=LXTKP2&P=7

One side of the gear is recessed a bit, and only has those 2 ribs where the dog clutch engages. If I mill them out, I can reduce the diameter of most of the al adapter to fit inside of the gear, bringing the gear closer to the diff cup. I would only need a small amount of the adapter to be the full diameter, maybe .050" thick, it is currently .200" thick. I have a truck with a 2 speed setup in it, so I may have to rob the tranny out of it for testing purposes!

[George16]

Will you have enough space for the screw holes on those emaxx gears? I have a couple of those and was looking at how are you going to mount them.

[lincpimp]

Originally Posted by George16

Will you have enough space for the screw holes on those emaxx gears? I have a couple of those and was looking at how are you going to mount them.

I am sure that I can figure something out. They look more promising than the stock lower gear.

[SnoopMaxx]

I am watching this one

[lincpimp]

More progress. Had the machinist turn the output gear down to the correct width, and shorten the adapter and turn it down for the bearing. My measurements were slightly off, but it is going together ok. Need to drill and tap the mounting holes for the output gear and put the diff internals in properly. Then I can do some testing in the erevo with the 1515!!!

[brushlessboy16]

wow, that looks awesome linc, let us know how it goes

[SnoopMaxx]

Sweet .... Looks good