1/8 diff in a pede tranny?

[lincpimp]

Any chance that putting an 1/8 style diff in a pede/rustler tranny could be done? I only ask as I am lunching diff internals on every run. I have tried a rcm steal/alloy diff and the new traxxas steel/plastic diff. Both times I have ripped the teeth off the planetary gears. Never had this problem with my other pedes, but this one is heavier and is running a plett maximum, or a 9l feigao. It would be nice to have a 4 bevel sealed diff, would be alot stronger and diff oil could be used too.

[What's_nitro?]

I'm with you on this one, lincpimp. To my knowledge there are no other options for the rustler/stampede differential. Strange, because everyone putting tons of power into either one HAS to be stripping planetary gears constantly and you would think some manufacturer somewhere would come up with a solution.

Especially where they are both very popular vehicles. It's not like they wouldn't sell any.

I'm waiting for the money to arrive so that I can move the setup from my signature into the truck. I don't know if I should run it 'cause I know it's gonna destroy the differential in just a few runs. Then the teardown begins...

My rustler running 4s lipo on an 8L with maxx size slicks in the back has never broken the diff internals.
Im guessing you guys that keep breaking them are doing it when one wheel lifts and the diff unloads then comes back down? You could try changing your suspension setup to avoid this. Softer rear springs, more weight over the rear, or heavier rear wheels/ tires would all help. Heavy grease in the diff should also help reduce the unloading. Also the slight flex of plastic driveshafts might help the diff survive. I doubt the stock rustler shafts would survive anything that the diff internals wont, but old style maxx driveshafts are a direct fit if you swap to 6x11 hub bearings. The stock 12mm hex can then be drilled out to 6mm, or you can swap to maxx rear hubs and wheels.
Or you could always adjust the slipper so it does its job.

on my rustler, i eventually superglued the stock diff into a spool with CA. don't remember any problems after that mod, with a steel idler and cvd's. hacker 8s, up to 16 cells.

[What's_nitro?]

At this very moment my rustler has the HPI V-Groove tires on RC4WD beadlocks and 100K weight fluid in the differential. The truck is heavy for it's size, 7 lbs. RTR last time checked, but the suspension is relatively soft even with the big Powerstroke shocks. The last time I blew out the diff was wen I ran the LMT XL2800 with 4s doing sprints back and forth down my street. Since then it's been sitting on my shelf waiting a new motor.

[squeeforever]

Try the FLM housing. It solved most peoples problems. It seems as though most of the diff problems come from the housing flexing. That in combination with the metal gears should be damn near bulletproof.

[lincpimp]

I have the flm housing and am still killing the planetary gears. Had a look around and an emaxx diff may fit with some mods. Thinking that I will hollow out the stock vxl steel/plastic diff and use it to replace the ring gear on the emaxx diff cup. The bearing holes on the tranny cases will have to be enlarged to fit the maxx bearings, and I may have to have a ring machined to make up the difference b/t the pede diff and the emaxx diff cup, the diff cup is slightly smaller in diameter. I will try it as i have all the parts sitting around.

It might be easier to mount an 1/8 buggy center diff bulkhead sideways on the back of your rustler, then make a motor mount.

[lincpimp]

Interesting idea, could use a rcm mount and one bulkhead to do it, I will look into this, and see what I can do. Thanks for the idea!

[MetalMan]

Damn, I like that idea too! A fat stubby outrunner with 600-800 kv on 4s Lipo with a pinion of about 12-16t, along with a 1/8 center diff (custom outputs) using a 44t or 46t spur would work awesome! Except for the lack of slipper... But at that point you could use Maxx slider shafts, so that would help.

The biggest problem I can think of is mounting the motor close enough to the diff to gear it reasonably. You wont be able to mount the motor behind the diff like you would on a 1/8 buggy conversion, so the motor can is going to be competing for space with the bulkhead and the diff cup itself. Everything else should be doable, the shock tower could probably be bolted to the upper bulkhead brace, and the FLM arm mounts could be bolted right to the chassis.
Metalman, Im not sure what you mean by the maxx slider shaft comment. Im using shortened maxx sliders on my stock rustler diff, but theyre far from a final solution driveshaft. My rustler chews them up every few runs. Do you mean the 3.3 shafts? They would work Im sure, but you would have problems with the shafts extra diameter hitting the arms.

[What's_nitro?]

I don't think it could be called a Rustler anymore if you replaced the transmission! That's the one piece that really makes it identifiable. Although I agree it's a good idea, it would be better to be able to fit the 1/8 gears in the OEM housing.

[lincpimp]

I was thinking more along the lines of a slipperential type tranny. Use a top shaft with a slipper and 18 tooth gear, put a k type ofna diff with the 51 tooth plastic spur. Then used modded mgt or jato spurs on the slipper and compatible pinion. 2 custom bulks would have to be made, as well as upper and lower mounts. Upper mount would have to tie into the shock tower. This setup would retain a slipper and give gearing choices. Also the use of the 51 tooth diff gear would allow some room for outdrive clearance. I will mock something up and see if it is doable.

[lincpimp]

Heres a pic of the gears mocked up. Looks to me like it would work. I set the gears up so that I would have enough clearance between my plett maximum and the 51 tooth diff gear. Compared to the stock tranny case, it is very similar in size. 51/18 gives 2.8, a little more than the pede 2.72 tranny ratio. That is a 46t mgt spur, and a 12 tooth pinion would give me the right gearing for my maximum on 3s, around 40mph. Plenty of outdrive clearance too.




Heres the BrainG speed calc:

Differential Ratio: 1
Transmission Ratio: 2.8333333
Other Ratio: 1
Spur Tooth Count: 46
Pinion Tooth Count: 12
Total Voltage: 11.1
Motor KV: 3000
Tire Diameter (inches): 4.6
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 3.83 : 1
Total Ratio: 10.86111 : 1
Tire Circumference (inches): 14.45 inches (367.06mm)
Total Motor Speed: 33300 RPM
Vehicle Speed: 41.96 MPH (67.4km/h)
Effective Speed Rate: 3.78mph/V (6.07kmh/V)
Effective KV Value: 3000
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...

[dadnjesse]

http://www.swami-rc.com/ordering/
Did you see the new one that swami sells.
http://www.rc-monster.com/proddetail...edediff&cat=30
Also looks like mike has updated his version to hardened steel!