Tekin Builds EP. 30 – Tamiya TT-02 Subaru Impreza Rally

The TT-02 is a budget kit from Tamiya and in this episode, we are going to modify and upgrade a basic $125 kit and try to make it more suitable for some rally driving. I picked this kit up a few months back to be built as a shelf model, but after some thought I’ve decided to go further by upgrading it a bit and seeing how it performs!

UPGRADES

In stock form, the TT-02 leaves a lot to be desired. Bushings are provided instead of bearings so the drivetrain is a real drag, pun intended. The “shocks” are just friction dampers, similar to those of a box store bought RC toy. The diffs are gear style, but don’t hold any oil. The drive shafts are all plastic and are dog bone style. The suspension links are all plastic and solid, meaning no adjustability whatsoever. And lastly the screws are JIS, which is sort of like a Phillips but just enough different that a Phillips screwdriver doesn’t fit well. Even in stock form, I can’t help but like this kit for some reason.

The shocks are probably the biggest improvement to the chassis. Having oil and adjustable ride height is going to improve handling immensely, so I went with a set of 60MM Yeah Racing Big Bores. They are a bit longer than stock, which is good since I wanted more travel and ground clearance.

I wanted oil filled differentials so I can tune with different weight silicone oil. I have no idea what this car will need oil-wise, so I went 7K/5K for now and we will see how it works. The Yeah Racing diff kits are pretty decent, the gears are composite inside and seal up nicely.

Bearings are a definite necessity here. The kit-included plastic and brass bushings just won’t cut it and put lots of extra drag on and already draggy drivetrain, so in with the Fast Eddy Bearings TFE411 rubber sealed kit. Fun fact, there are only 16 bearings in the TT-02 chassis.

I upgraded all the driveshafts both for strength and to free up the drivetrain more. The kit plastic center shaft wobbles and can twist over time and the shafts out to each wheel are plastic dog bones, which limit steering and suspension travel big time. The Yeah Racing Universal shaft kits come pre-assembled and are an easy, gotta-have-it upgrade for the rally Impreza.


The center shaft from Option No.1 is Aluminum, as are the prop shafts into each diff housing. It seems decent, however it is quite a bit short and this is bad as it let the front prop shaft fall out of the gear in the diff housing. I simply cut two pieces of fuel tubing and put them in each prop shaft cup, problem solved.

Steering links are a good addition as being able to adjust the front toe is important. The kit links are solid plastic and offer no adjustment, so they ended up in the scrap pile. It may be a good idea to grab adjustable upper front arms as well for setting camber.

The chassis cover not only looks cool, but it should help keep debris out. We definitely don’t need any rocks getting lodged in the center driveshaft. I’ll check the temps on the motor and ESC, but I don’t foresee any heat issues as this 13.5T RS GEN3 system won’t be working too hard pushing this car around.

ELECTRONICS

It may be overkill, but I live for overkill. The RS GEN3 is a capable little ESC and fully programmable via HotWire. It’s small, making it ideal for installs like the TT-02 where there isn’t much room available and it is rated at 120A which is plenty for an application like this.
The 13.5T Eliminator is a souped-up 13.5T. Lower resistance and a torque rotor give this more power than a standard 13.5T.
The T-130 is lightning fast, actually too fast and I tuned the speed down a bit in the HotWire. Full metal gears and a o-ring sealed housing mean it is tough and doesn’t care about getting a little wet.
The 2S 8400 Power Cell battery should provide tons of run time in this car and 120C is more than enough to handled the demands of a boosted 13.5T setup.

PARTS USED

Tamiya
TT-02 Subaru Impreza WRC99 Kit
TT-02 Chassis Cover
Rally Cockpit Set

Tekin
RS GEN3
13.5T Eliminator
T-130 Servo
2S 8400 LiPo

Fast Eddy Bearings
TT-02 Bearing Kit

Yeah Racing
60mm Big Bore Shocks
Oil Differentials
Drive Shafts
Motor Mount

Option No. 1
TT-02 Center Shaft

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