1/8 Diffs and Slipperential Gearing?

[jhautz]

I am planning on getting the 1/8 diffs that RCM is working on for the Revo as soon as they come out and im also planning to get the slipperential for the G2R as soon as that is available.

Now just doing some math on this whole thing cuz both the 1/8 diffs and the Slipperential lower the gearing, and combined it really lowers the gearing. To the point that if I want to run a simlar overall gearing setup to what I am currently running with stock diffs and emaxx 2nd gear tranny I will need pinions well over 20T. These arent easy to come by in Mod1, plus it will really limit the gearing options available.

With the stock diffs and emaxx 2nd gear Im running 51/18 or 51/20 dpending on the surface and motor I have in at the time. This is already at the top of the available pinion range so there really isnt an option for going higher. I think Mike can make custom 22T and 24T pinions, but that really limits gearing flexability. But even that doesnt get me all the way there if I run lower profile tires.

Is there an easy solution Im missing here? Are there different diff gears that dont lower the ratio as much but will still work with the Revo 1/8 diffs RCM is working on?

Does anyone have this issue with an emax running 1/8 diffs and the Slipperential? I would think that it would be the same problem.

[BrianG]

You could use larger tires, or motors with a higher max rpm limit, like the LMTs. I know; not very good suggestions. There was another user here (can't remember who) that was trying to get a fast speed with the slipperential and was coming up against the same problem. The gearing was just too low for anything over 40ish mph....

[jhautz]

The slipperential reduces the rgear ratio vs themaxx tranny, but that allone I think I could get by with. But adding into the equasion the 1/8 diffs it really messes things up.

Anyone know if the 36T revo spur gear fits the slipperential? That at least gets me a couple pinion gear teeth back vs the 40T spur.

http://www2.towerhobbies.com/cgi-bin...&I=LXHFR4&P=ML


Also, does anyone know the biggest pionion that will fit on the slipperential?

[MetalMan]

The Slipperential uses the Revo slipper clutch, so yes, the 36t spur works.

If you were to use the buggy diffs (43/13) as opposed to the truggy diffs (43/10), you would have a gear ratio closer to what you are looking for.

With the Slipperential (44/20), buggy diffs (43/13), 36/20 spur/pinion, 6" tall tires (to account for ballooning), and 35,000 RPM, you'd be looking at ~47mph. If you were to factor in 5.5" tall tires that won't balloon, you're still at ~43mph. Dropping down to 30,000 RPM with 5.5" tires would give ~37mph, which in many cases is a good top speed (might even be too fast for some tracks). So it looks like gearing wouldn't be too difficult.

[GorillaMaxx360]

36t should fit i would go with the mamba monster maxx when it comes out the way they are talking about this thing you can easly push your car to 45 maby 50 with this gearing IMO becasuse they said they where getting like 50+ out of a 14 pound maxx so that is pretty good as for now going with a higher rmp motor like brian said like a LMT's. I know though when i was doing the same thing for my maxx awhile back i was trying to go 40mph with slipperential and 1/8 hb diffs. With my maxx and using the speed calculator i came up with 41.82 mph using 1/8 scale Buggy size HB diffs, slipperential, 36t spur, 20t pinion, 14.8v which is 4s, kv or 2148 which is the feiago 7XL rpm, 5.80 tire radius which is the radius of crime fighters, and that is it and i achieved 41.82 which is pretty good with slipperential and 1/8 diffs i hope i helped. (late reply buy 5 min)

[BrianG]

Originally Posted by GorillaMaxx360

... I know though when i was doing the same thing for my maxx awhile back i was trying to go 40mph with slipperential and 1/8 hb diffs. With my maxx and using the speed calculator i came up with 41.82 mph using 1/8 scale Buggy size HB diffs, slipperential, 36t spur, 20t pinion, 14.8v which is 4s, kv or 2148 which is the feiago 7XL rpm, 5.80 tire radius which is the radius of crime fighters, and that is it and i achieved 41.82 which is pretty good with slipperential and 1/8 diffs i hope i helped. (late reply buy 5 min)

Now that you mention it, I thing you were probably the one I was talking about...

[coolhandcountry]

I talked to mike about this on phone. He said thatthe 36 tooth will fit.

[jhautz]

Originally Posted by MetalMan

The Slipperential uses the Revo slipper clutch, so yes, the 36t spur works.

If you were to use the buggy diffs (43/13) as opposed to the truggy diffs (43/10), you would have a gear ratio closer to what you are looking for.

With the Slipperential (44/20), buggy diffs (43/13), 36/20 spur/pinion, 6" tall tires (to account for ballooning), and 35,000 RPM, you'd be looking at ~47mph. If you were to factor in 5.5" tall tires that won't balloon, you're still at ~43mph. Dropping down to 30,000 RPM with 5.5" tires would give ~37mph, which in many cases is a good top speed (might even be too fast for some tracks). So it looks like gearing wouldn't be too difficult.

I was already assuming the buggy 43/13 Buggy diffs. :002: The 43/10 never even entered into the equasion.

Yea, I went through the math, and it should easily be more than fast enough for the track. However I would like to be able to gear it for some light bashing and speed runs also. I do take the revo to the track, but its far from a dedicated track machine for me. Im easily getting 50mph from my setup now and would like to keep it if I can. I'm runnning 5s ~ 50mph for bashing, 4s ~ 40 mph for the track, and 3s ~ 30mph for the small indoor track.

Originally Posted by GorillaMaxx360

36t should fit i would go with the mamba monster maxx when it comes out

Ive already got the electronincs and motor. This is going to be a retrofit to replace the diffs and transmision so I'm kinda locked in using the Quark 125 and the Neu 1512/2.5D(2000kv) on 5s lipo.

Originally Posted by coolhandcountry

I talked to mike about this on phone. He said thatthe 36 tooth will fit.

Cool. Thanks CHC. I was gonna call him if I didnt get an answer here.