Ball Differential for WR02 Wheelie?

[Kev187 19]

I have a WR02 Wild Willy 2000.

Is there a ball differential available for this kit? I seem to remember that the M03 Ball Diff fit in the Wr02, but I cannot seem to find anything to back this up on the internet? Would like to give a bit more grip on the rear wheels without locking the diffs!

Thank you in advance everyone :-D

[Nobbi1977 1793]

No idea about ball diffs but many use heavy grease. I use Tamiya diff putty to slow the action without total locking it

[waterbok 1282]

Try the antiwear grease, that works nicely. Clean out the old grease first.

[XV Pilot 1936]

The M-03 ball diff won't fit the WR-02. The M-03 uses the smaller diff casing held together with 2mm screws as seen in the TL-01 whereas the WR-02 uses the bigger diff casing held together by 3mm screws as seen in the Wild Dagger.

Perhaps the DT-02 ball diff would fit? It uses a larger casing...

[Kev187 19]

Thanks everyone, so just some heavier grease. Was worth a shot

[Nobbi1977 1793]

The M-03 ball diff won't fit the WR-02. The M-03 uses the smaller diff casing held together with 2mm screws as seen in the TL-01 whereas the WR-02 uses the bigger diff casing held together by 3mm screws as seen in the Wild Dagger.

Perhaps the DT-02 ball diff would fit? It uses a larger casing...

I have a DT-02 one kicking about so I am sure I would have fitted it if it looked remotely like it would. I am stuck in a hotel for 5 nights so I cannot check :-(

[Nitomor 2122]

Can confirm it doesn't

I would love a ball diff for the WT01/WR02!!

Come on Tamiya!!

 

[kontemax 1725]

A ball diff without a slippery clutch will be probably an issue.

 

Max

[Nitomor 2122]

From the design of this ball diff, it looks like it could inadvertently act as a slipper...

[kontemax 1725]

It shouldn't.

 

Max

[Nitomor 2122]

I guess it depends how tight it is but the balls in the gear body grip the plates either side, if the wheels are jammed then the gear could potentially spin, no? It would probably damage the pates/balls with overheating if it span too much I'd imagine, but surely that would give ultimately if it wasn't set so tight as to be fully locked.

[kontemax 1725]

Without a slippery clutch you have these two scenarios:

1) Ball diff is not tight: it will slip, you will square the balls and grind the plates, will loose acceleration and you will have a ball diff rough that works like a normal gear diff.

2) Ball diff is tight: it will not slip but you will have a solid rear axle and the model will totally understeer.

 

Max

[Nitomor 2122]

I've just fitted the DT02 diff to my DT03T, it's a tamiya recommended hop up and that model has no slipper. Surely if setup correctly it will allow a small amount of slip to the tyre with least resistance, but not so much that it will spin the diff up generating too much heat and wearing the balls. It must be able to cope with some slip, isn't that he point of a variable tension adjustable diff? I can't really comment because I have limited experience with ball diffs, my TA03 pro has one and that has no slipper either. A slipper will only be effective in preventing the ball diff from spinning up if it spins first which would have it slipping all the time and defeating the object of having a ball diff. 

 

[Darat76 265]

A ball diff without a slipper clutch is just waiting to be damaged if running it in a heavy vehicle, or an over powered one. And if taken to extremes, a ball diff can generate enough heat to warp a gearbox.

[Nitomor 2122]

That sounds logical, but this is in an offroad vehicle, I would expect wheelspin to protect things way before anything else needs to slip. Perhaps beadlocks would be a bad idea with a ball diff.

The point being that a limited slip diff should keep power going to the loaded wheel in a situation where all this power would have been diverted to the unloaded wheel therefore converting the squandered power into traction and forward motion which would be its normal function. Rather than a wheel being jammed forcing the diff to spin which of course is undesirable, but in reality that would be quite an unlikely scenario in real use unless in an impact causing jamming or something. Unless running really sticky tyres and beadlocks is the above not more theory than anything else. Surely there should be a correct balance point between Max's scenario 1 and 2 above? The DT02 ball diff is adjustable in situ which helps things from an adjustability perspective.

[TurnipJF 9192]

I suspect people are using the term "slip" in two different ways here, which may be leading to some confusion. "Slip" as applied to diff action means something quite different to "slip" as applied to clutch action.

 

 

[Darat76 265]

if your motor can produce more power faster than your ball diff can transfer, it will slip in a bad way regardless of the surface the car is on, if there is a slipper clutch installed and setup correctly it will take the excess power from the motor and deliver it to the diff when the diff is able to transfer it effectively.

Basicly you don't want your ball diff to slip, you want it to spin with differing degrees of resistance to recreate different thickness of oils and putties.

and a limited slip diff has clutches not to transfer power to the wheel with grip, but to force both wheels to match in rotational speed, regardless of if your doing a burnout, or just trying to do a full throttle start

[Nitomor 2122]

Ok, so if the power of the motor is too much for the diff, you fit a slipper, but if the slipper is absorbing that power then it's pointless having that much power surely? (I shall be fitting a slipper to my Bruiser runner with beadlocks but from what I've read, others that have fitted it can't even climb a hill which makes it pretty useless in my book unless they just haven't set it up well enough.) I can't see any of this being an issue with a silvercan but if going brushless then I guess that would be a different story and you'd be best matching the BL punch characteristics to suit the drivetrain rather than masking that issue with a slipper.

I don't want to sound hard headed, but I'm finding it difficult to see how not having a slipper is the end of the world for the ball diff, why would Tamiya offer ball diffs on so many cars without slippers, TA03Pro, Vajra, DT03 just as examples of a few I have. For the diff to slip from a slipper clutch perspective would surely require a massive resistance to block the wheels, surely the car flipping over, wheelspin, or tyre spinning on the wheel would all occur first before damage to a diff could occur in this manner unless it was setup poorly/badly worn.

Time will tell, then I'll no doubt come crawling back here after burning out my diff lol!

 

[TurnipJF 9192]

The way I understand it, slipper clutches were first introduced to help absorb the shock to the drivetrain that occurs when a RC lands a jump. It is therefore typically omitted from touring car chassis and buggies derived from them. It is also omitted from entry level offroaders that instead rely on coarse pitch gears to survive landing shocks. 

 

The ball diff on the other hand was developed to give a smooth and easily adjustable differential action. This is equally useful on road and off, hence the inclusion of ball diffs in models that were never intended to see a jump.

 

Using slipper clutches to protect drivetrains from heavy-handed use of overpowered brushless setups is a far more recent phenomenon, and one that I am not totally comfortable with. To my mind, if the motor has enough power to shred the drivetrain, you either have too much motor for the car, or a drivetrain that needs upgrading. It may be just me, but I see a slipper as a band-aid in such situations, not a proper fix.

[Darat76 265]

slipper clutches aren't the end of the world for ball diffs, they just save you from consistently spending money on new balls and plates for the diff, and rebuilding the diff all the time. A slipper clutch doesn't bleed power all the time, it just bleeds power until the speed of the gears past the clutch match the speed of the gears before the clutch. A well setup slipper clutch will actually save the whole drive train in a car from damage.

Given how adjustable a slipper clutch is, the problem they are having is it's not set tight enough. In that setting, it will take a lot of adjusting to get the slipper set to provide the most amount of power to climb, whilst bleeding off the power that would cause damage to the drive train.

 

[Nitomor 2122]

Thanks chaps, useful perspectives. I hadn't considered shocks from jump landings at all. Hopefully broad and numerous gears as in the WT01 help with that aspect. I appreciate what you are saying regarding the slipper. It'll be interesting to see how often it'll need attention and whether the juice will be worth the squeeze as it were!

Cheers

[kontemax 1725]

The slippery clutch protects all transmission and geartrain from the excessive torque, included the main shaft, the belt, the wheel axles, everything.

The slippery clutch also helps to moderate the spinning of the wheels on soft dusty surfaces.

 

Max