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1:18 Ruckus Differential Problems and Upgrades Discussion

mikel81

Well-Known Member
Messages
111
As many come to find out, the diffs in the mini ruckus don't stand up to much hard use. Within a few runs of the stock nimh pack I already had a 2wd truck. I ordered a new one for a quick fix and went looking for an upgrade. I shimmed the new one and it lasted longer but it still rounded the gear at the outdrive. Another thread mentioned mini 8ight diffs working but the axles didn't reach. And someone else had modded duratrax gears and outdrives to work. (which I believe are still holding up) There were a few other suggestions, like mini quake ball diff works if you replace the bearings with 6x12x4. I currently have 3racing ball diffs for a kyosho mini inferno in my ruckus. The bearings for the ruckus diff slip over the outdrives and make a perfect fit.

DSC01082.jpg

The only thing now is to get axles that reach.

Hot racing cvd axles work but I had to use the wheel bushings that came with the truck and sanded one to about half thickness and used it as a shim between the axle and the bearing. I left enough so the axle could ride on the bearing.

This worked great but did eventually pop out on me with some hard bashing.


DSC01221.jpg

Another option is ECX Smash stub axles #ECX8320

The center of the plastic hub needs sanded a little so the pin and wheel hex aren't too tight at the outside. The problem I had after doing that was the axles I found (swk4064) were now just short enough to pop out. They would need to be about 56mm and the only one that length I found has bigger balls.

DSC01222.jpg


So my current setup is a bigger diameter stub-axle. It fits like it was meant to be, and the wheel wobble is nearly gone. http://hpiracing.world/en/part/a557 It needs a larger wheel nut but fits the stock wheel holes.

And longer axles, sportwerks swk4064

The cup is bigger than the axle's ball but I have been running it with no noticeable wear. I have the axles meant for it and was going to dremel one ball smaller to fit the diff if I needed to but it's holding up.

DSC01223.jpg





And I know it can handle some power because this is what's at the other end now.

DSC01112.jpg

I don't abuse it but I also don't take it easy on this truck. I let my kids drive it. Skate parks. My sons ramming it with their Amps. I am pretty happy with it now but I know my frankenaxles are hardly a perfect solution... And that's why I'm posting. Hopefully help get some more ideas flowing here. I must thank everyone in the rctech thread that have shared info and made this possible. Hopefully I can get them over here too.
 

Hellfish

Member
Messages
8
I am very happy you found a hop up/replacement solution for this. Unfortunately the required Axles/Hubs are hard to get in Germany. Wouldnt it be possible to drill a small hole through the outdrives, so the original Axles (Balljoints) will fit? This would be a awesome, since you only need to buy the Diff Assembly to get it going. Would the original Balljoint fit into the diffs outdrive?
 
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mikel81

Well-Known Member
Messages
111
I really wish I had a solution to use the stock telescoping axles. That would have solved the axle length problem. Another guy, VICIOUSxVENTU is using duratrax gears with stock axles but they require a bit of modification. The part number of the gears is DTXC7412. There is a picture he posted here of them next to the stock gear and outdrive, and on the next page describes what needs done to make it fit.

I just stripped my gear at the main driveshaft where it contacts the diff ring gear. I suspect my incorrectly sized axles bound up and caused it but it may have just been the nearly two months of hard runs on brushless power. So I will be revisiting this for a better solution when I have time.
 

Hellfish

Member
Messages
8
I just ordered 2 MIF-048/BU from HK, giving me enough time (ETA May 20) to think about a good axle solution. Meanwhile i found what seems to be a very nice hotfix for the standard gears. Instead of shimming the outdrive planetary gear on the rear left like stated on rctechs thread, i just put canopy rubber grommets from my good old T-Rex 450 in the gaps between the two telescopic parts of all axles, and they fit just perfectly. For me it seems to work even better then the shimming method since it obviously gives more advantages and is far more easy to install.

  • not have to search for the right shims, cheap, easy to get
  • not have to completely disassamble the diff
  • everyone can install it less then 2 minutes, no additional tools required (like loctite, very small screwdrivers,diff grease)
  • stiff enough to completely removing the In/out play on the axles AND the outdrive planetary gears.
  • flexible enough to compensate axle length changes due to variable riding height/Bumper action.
  • in combination with ball bearings tire wobble is nearly completely gone.
  • in addition i loosened the slipper to the point that if you push the car to ground and hit the gas it starts to slip on half throttle.

I am running on Stock 380 with bearings and grommets and now had 5 2200mAh/Lipo rides on grass, dirt and on the road since install of grommets and about 10 on LiPo - even had some hard crashes - and the rear diff runs like butter. Before "grommeting" it often stuttered and had a slight grinding noise. The whole car feels much more stable and responsive now.

I'm quite sure (at least hope) this mod will keep the original diff alive until the final solution is there.
 

MakeARuckus

Member
Messages
5
Hey guys,

I've been following this thread for quite some time. I would like to thank @mikel81 for pointing out that the inferno ball diffs is a possible solution. It seems that the only part of the puzzle yet to be solved is getting an axle that reaches, correct? I noted that you mentioned that the axle needs to be about 56mm, I had a look at my ruckus and can say that it does seem about right.

If that is the case, could we not look at the HPI WR8 axle
hpiracing.world/en/part/107874? A 5mm stub axle (also from the WR8) can be coupled with it.
 

mikel81

Well-Known Member
Messages
111
Hey guys,

I've been following this thread for quite some time. I would like to thank @mikel81 for pointing out that the inferno ball diffs is a possible solution. It seems that the only part of the puzzle yet to be solved is getting an axle that reaches, correct? I noted that you mentioned that the axle needs to be about 56mm, I had a look at my ruckus and can say that it does seem about right.

If that is the case, could we not look at the HPI WR8 axle
hpiracing.world/en/part/107874? A 5mm stub axle (also from the WR8) can be coupled with it.

I tried these http://hpiracing.world/en/part/86036 which are 54mm from pin to pin by my measurements. The ball is a larger diameter and would need ground down. The shaft diameter is 3.7mm on the 107874 and 3.3mm on the 86036 so I assume they will have the same problem. The 86036 was too long to use the stub axle they are meant for http://hpiracing.world/en/part/a557 because it sticks out from the hub further (top in the pic).

STs1L2n.jpg

I don't know what I am going to do with it now because I damaged the diff gear and would need a new ecx diff. I think my problem was I used the smaller balled axle with the larger diameter stub and it got bound up in there and locked the axle up. It worked for a while and only really failed after I raised the truck height back up which increased the axle angle.
 

mikel81

Well-Known Member
Messages
111
It looks like I can no longer edit the first post but wanted to add this. To use the a557 stub, in addition to the larger wheel nut I used traxxas slash pins and ecx amp hexes that I had spares of. So it needs 1:10 hardware all around basically.
 

Hellfish

Member
Messages
8
Wow! That seems to be the perfect solution. So you used the bone from this kit? Can you tell the exact sizes, so i may search for bones that fit that are sold single? For this solution the ball diameter/pin-length seems to be most important.
Keep up the great work!
Meanwhile i had another 6 runs with my grommet-mod, and diffs still running fine. Even if they hold up well i will change to ball diffs since they may be adjustable (are they?) and sound way better ;)
 

MakeARuckus

Member
Messages
5
This just might be what we were looking for!!! I have already ordered my mini inferno ball diff!! Also Hellfish, I don't really understand how you have installed the T-rex 450 grommets. Could you maybe show us a photo of your current set up?
 

mikel81

Well-Known Member
Messages
111
That is the one but I just tried to fit it in the truck and it is too long. I measured it at 46mm pin to pin (not centered but outside of the pins). It would need to be almost 10mm shorter. That is the shortest axles I have but in theory they don't need to be a perfect length any more since they are adjustable.

And yes @Hellfish the ball diffs are adjustable which is nice.
 

slick2500

Well-Known Member
Messages
186
Location
Rapid City SD
I just ordered 2 MIF-048/BU from HK, giving me enough time (ETA May 20) to think about a good axle solution. Meanwhile i found what seems to be a very nice hotfix for the standard gears. Instead of shimming the outdrive planetary gear on the rear left like stated on rctechs thread, i just put canopy rubber grommets from my good old T-Rex 450 in the gaps between the two telescopic parts of all axles, and they fit just perfectly. For me it seems to work even better then the shimming method since it obviously gives more advantages and is far more easy to install.

  • not have to search for the right shims, cheap, easy to get
  • not have to completely disassamble the diff
  • everyone can install it less then 2 minutes, no additional tools required (like loctite, very small screwdrivers,diff grease)
  • stiff enough to completely removing the In/out play on the axles AND the outdrive planetary gears.
  • flexible enough to compensate axle length changes due to variable riding height/Bumper action.
  • in combination with ball bearings tire wobble is nearly completely gone.
  • in addition i loosened the slipper to the point that if you push the car to ground and hit the gas it starts to slip on half throttle.

I am running on Stock 380 with bearings and grommets and now had 5 2200mAh/LiPo rides on grass, dirt and on the road since install of grommets and about 10 on LiPo - even had some hard crashes - and the rear diff runs like butter. Before "grommeting" it often stuttered and had a slight grinding noise. The whole car feels much more stable and responsive now.

I'm quite sure (at least hope) this mod will keep the original diff alive until the final solution is there.
Does this look like the correct groomet? http://www.ebay.com/itm/10Pcs-Rubber-Canopy-Grommet-Nuts-for-Trex-450-500-Helicopter-/141429070387
 

Hellfish

Member
Messages
8
Here are some pics of my grommet mod install.
You don't necessarily need canopy grommets. Depending on the size of the gap servo grommets, a couple of o-rings or a wrapped around rubber band will do.
Actually i used servo grommets for the back and canopy grommets for the front axles. Just make sure the gap between the two telescopic axle parts is filled completely providing a slight pressure to both sides.
I recommend to install ball bearings because otherwise the original bushings may be eaten up faster due to the pressure applied.

step-1.jpg
step-2.jpg
step-3.jpg
ready.jpg

@mikel81: yes, length doesn't really matter any more ;) But the ball diameter and the pin (that goes through the ball) length and diameter. Last problem to be solved seems to keep this assembly centered. I can imagine if installed like that it would go of center and eventually hook up somewhere, destroying something. Maybe some epoxy might help or o-rings put in the axle.

Dog Bones for Tamiya TT01/TT02 Gear Box Joint & Wheel Axle seem to have 35mm length, not sure about the ball size and pin length.
 
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MakeARuckus

Member
Messages
5
I am yet to receive my 3racing kyosho mini inferno diff. International deliveries from HK to Australia take ages :(

Just thinking out loud here, is there no way that we can modify the existing ruckus drive shafts to fit the inferno ball diffs? Like dremel the ends, maybe insert small rod? Any ideas?
 

slick2500

Well-Known Member
Messages
186
Location
Rapid City SD
I am yet to receive my 3racing kyosho mini inferno diff. International deliveries from HK to Australia take ages :(

Just thinking out loud here, is there no way that we can modify the existing ruckus drive shafts to fit the inferno ball diffs? Like dremel the ends, maybe insert small rod? Any ideas?
Or Ecx should just make a metal diff gear upgrade.
 

mikel81

Well-Known Member
Messages
111
Got a set of axles for .99c and went to town with the dremel so they fit in the axle. The ball was tight and I had to dremel the anodizing off the inside of the diff cup so they would slide in and out but it seems like they'll work. Before I did, the suspension would stick on the rebound.

PiZPqnd.jpg

Still far from what I'd like but my truck is running again for a buck. I am sure there are better axles but these were cheap and I wanted to try it. Similar length with a smaller than 6mm ball would be ideal. I would not recommend the ones I got unless you want to fit them.


 

Hellfish

Member
Messages
8
Good Job! This looks good enough for me to try it too. Lucky that my ball diffs arrived yesterday way before ETA. Funny thing that my order from HK arrived earlier then my Mini 8ight wheels/shocks ordered in a local shop a day later. Lucky too that HPI parts a widely available in germany. I just placed my order to get some A172 for cheap.
So recently i got this dremel thingy as a gift, the first in my live, and i am not sure which of the many tooltips to use to get the remove anodizing job done well. Can you give me some advice or show a photo of the tooltips used?
 

mikel81

Well-Known Member
Messages
111
So recently i got this dremel thingy as a gift, the first in my live, and i am not sure which of the many tooltips to use to get the remove anodizing job done well. Can you give me some advice or show a photo of the tooltips used?
I used a ball shaped diamond tipped attachment for in the diff cup, very lightly don't remove much. And a cutoff wheel to shape the axle. Use low speed for working the aluminum. When it gets hot I think it melts into the grinder bits and ruins them.
 
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