3Racing Tamiya TT02 Gear Differential Review

The TT-02 is a popular first time racer for many, one of the things that it is missing for those who are tuning the chassis at the race ...

The TT-02 is a popular first time racer for many, one of the things that it is missing for those who are tuning the chassis at the race track is a sealed gear differential. Recently I noticed that 3Racing had released a gear differential for the TT-02. I have some plans for racing the TT02 type S this year in some classes, so I thought I would take a closer look.

What version of Differential do I need?

Before ordering one for your Tamiya. 3Racing make two different versions of the gear differential. 
  • Part no TT02-10 is made for Standard TT02 with the fat plastic drive shafts (Std TT02's)
  • Part no TT02-09 is for anyone that runs the metal drive shafts or univesals (Including TT02R and TT02 Type S) *Note you will need drive shaft cushions for the dogbones. 
For this article I am building the differential for my TT-02 TypeS so I ordered part no TT02-09.

Building the Differential.

Looking in the packet all of the parts seem to be very well made. 

The plastic is chunky and the differential joints seem to be made from spring steel.

The first differential joint is mounted though the 39t main TT02 gear. I doused the 5mm o-ring with some shock oil to ensure it doesn't snag. 

Once through you can add the large shim and the retaining pin.

Now its time to do the other side, same procedure as before, it helps to have a pair of tweezers to insert the pin

Now fit the 18t bevel gear. They are a chunky 0.8 pitch but make sure you trim any excess off the sprue, otherwise they can damage the gears and the diff will not run smoothly. At this stage you want to add some of the oil to ensure that there are no bubbles trapped.

Now its time for the main 10t bevel gears. They are mounted on a plastic cross joint, I know some would rather this be steel or alloy but I think it should be fine with the stock motor that I will be racing with. (13.5 blinky). With the bevels mounted you fit the shims behind them and lower the completed section into the differential.

Now add more of the differential oil (I used 3k oil). You want to do this until the oil covers the centre cross joint, not any more as that will be too much and you will get the differential weeping as it will over filled. 

The next stage involves fitting the gasket. The actual gasket is quite large and I needed to spend a bit of time to prepare it to actually fit well. I took my time to remove the screw holes so I didn't tear it. The gasket is also a little larger than the actual recess that is on the gear, so to make it more seated I inserted the screws to hold it in place and tucked it in with a pair of tweezers. 

Now you just need to fit the two halves of the differential together. The kit screws have 2.6mm width screws with 1.5mm hex heads, this normally wouldn't be much of an issue but the plastic is very hard so you will find it a pain to assemble, a dab of grease helped but it was a pain. Again make sure the two halves are straight and attach the screws in a cross pattern to ensure that they go together nice and straight. 

The final diff was assembled and it actually felt pretty good, a little stiffer than what I would expect for 3K but I am sure that it will be fine after a gentle run in. I must also mention that the differential comes with a spare gear for the prop shaft. I decided to use this as even though it is the same as the Tamiya one, 3Racing may have a slightly different tooth profile on their bevels so it made more sense to use that. 

The final differential with oil weighs just 23.1g that is only around 2g more than a stock TT02 differential, and 17g lighter than the fat old TT02 differential.

Track test

I've given the TT02 type S a few runs now and the gear differential has been spot on.  The handling of the chassis is much more consistent than the stock differential with AW grease. Head to head with the ball differential it is also better as there is more bite from the gear differential. 

Post racing I have also noticed that there is no leakages from the unit. I swapped out to 5k as I wanted more on power steering and the effect was immediate. 


For those who are trying to get a little more serious with racing their TT02 chassis this is a great hop up. After around 12 runs the differential still feels smooth and I haven't had any failures. It is much easier to tune than any of the other alternatives out there.

Note it should also fit in a TT01 chassis as the TT02 and TT01 differentials are interchangeable. 
TT02 6104072446131980986

Post a Comment

  1. do you recommend a tt02 or gt12 as a first rc car? not racing but the prices are similar. I'm in the UK.

    1. Hi Nick

      the GT12 kits are made for smooth carpet tracks. They are not suitable to be used anywhere else. (Also they require a brushless motor and electrics to compete in GT12 classes).

      The TT02 kits are much more versatile. Also the kits also include a motor and an electronic speed controller (the Gt12 kits contain no electronics). A TT02 can be used on the street, also if you set it to rally settings (The kits allow you to swap the wheel fittings which raises the car a little more). They you will also have a car that is able to tackle short grass and packed dirt. Fitting drift tyres and you can have fun drifting. Also if you want to race there are quite a few clubs here in the UK that have a Tamiya silver can class.

      There are also lots of spares and hop ups (Custom parts) for the TT02 available and Tamiya parts availability is very good.

      There are a lot of versions of the TT02, most are similar other than the body shell but there are some variations (Some come with more goodies in the box). Feel free to send me any more details or questions before your purchase and I will try to help. (Use the contact form link for private emails).

  2. Yes it should be compatible. (TT01 ball diff works in TT02 etc) so hopefully this will also work. I have not tried it myself.

  3. 1. Part no TT02-10 can it be used for the TT01E?
    2. If I used Part no TT02-10 with a Yeah Alum Conv KT, would I need other parts to make it work?
    3. What are your thoughts on the Tamiya TT02 Gear G Parts 51531
    4. The TT02 comes with Gear G Parts, but RCMart sell Tamiya TT02 Gear G Parts 51531 for $4.50 which part is better?
    Thank you for your time.



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