I would suggest taking the stock diffs apart and checking for any debris or damage. I recently found a broken tooth on a plastic diff gear on the used TT02 I've been rebuilding. These are plastic parts that can wear out over time.

Tamiya 54875 TT-02 oil filled gear diffs do come with metal gears inside the diff housing, but still use plastic gears on the outside ring and pinion gears.

Hello everyone. I picked up Tamiya's Mustang GT4 kit and recreated the Volt Racing Mustang GT4 from 2018. I'm still working on the paint and livery but I also have questions about drivetrain options as well.

Most of the information I've researched online about drivetrains is about getting top speed and power out of their car. Personally, I just want it a little bit quicker and faster than stock. With that in mind I went with Tamiya's 17.5T brushless, along with Tamiya's high speed gear set #54500. I THINK it's faster than the torque tuned motor that originally came with the car, but im not sure. What do you folks recommend to make this car a little quicker and faster than stock?

Again im not trying to break any speed records. I'm still running the stock TBLE 02 ESC. Other mods are the tamiya aluminum driveshaft, propeller joints, oil filled shocks. I'm also running a Venom 2S 5K lipo battery. Thanks in advance...

If you want to go faster, you need to shift into higher gear. Same thing as with your 1:1 car.
If you take a look into the high speed Gear Set manual, you will see a choice of different final drive ratios. The lower the ratio, the higher your top speed.
With the Tamiya 17.5t brushless motor you can easily choose the lowest ratio shown. I think it is 64:29 ( spur gear : pinion).
64 t spur gear: Tamiya # 51536
29t pinion: Tamiya # 54229
With a bit of luck and fully loaded battery you can reach 25mph (40km/h) with this set up. If this is still not enough there are other ways to optimize the TT-02 's final drive ratio for even more top speed.

And just like the 1:1 car I have to decide if I want more top end or better acceleration. If I wanted better acceleration, then installing the high speed gear set was a mistake, correct? Since the stock spur was a 70t and the spur in the high speed set is a 68t? Thanks again...

Correct, for acceleration a 72 spur or a smaller pinion gear would've worked.

Not that the spur gear alone makes that much of difference. With the standard 70t spur gear and the max. 25t pinion, your max. FDR is still limited to 7.28 - which is very short (unless you were planning to put a modified motor into that car - which I would not advise). The speed spur gear set has the advantage, that it allows a wider range of standard spur gears (even non-Tamiya) to be mounted, so that was a very good option part to get and install.

Ok then. Thinking about how the car is used, its mostly in parking lots that don't have a lot of room to get up to speed, so I'm thinking about being geared more toward acceleration...I think. How low of a pinion should I try? Or is this when trial and error comes into play? Also, should I be looking at another ESC? I read that the TBLE 02 isn't all that great. How about the motor? Maybe I should've gone with the 15.5T Tamiya?

The 17.5 brushless does have a lot of torque, that allows you to choose a longer final drive ratio for top speed AND acceleration.
You can have final driive ratios of about 4.0 (or even less) and the Tamiya 17.5 still produces a decent acceleration.
I am strongly recommending the 64:29 gearing as a starting point!
​​​​​​

Ok ill give that a shot. Can I just keep the 68 spur and go with a 31t pinion to get that 2.2 FDR?

68 and 31 will give you 5.7 (internal ratio is 2.6). To gain full flexibility with spurs and pinions you also need the Yeah Racing motor mount.

Front left wheel nut came loose today. Stopped driving right away but front end was scraping a good distance before the car stopped rolling. Bottom screw head got grinded down pretty good.

The threads on the Tamiya universal shafts are a couple mm too short for M4 lock nut to thread fully through the nylon insert.

Of all the cars I own this tto2 is my absolute favorite it is so fun to drive so easy to drive I just rebuilt the whole car replace the diffs put ceramic bearings in it and can't wait to tear it up in usgt I've run this car in just about every class and takes a licking and keeps on ticking this chassis is I think around 12 years old and still going strong if you're thinking about getting one don't think it's awesome this started out as a tto2r and all I did was add a set of yeah racing aluminum shocks to it the yeah racing adjustable aluminum motor mount... three racing differentials front and rear and the three racing spool and this thing still kicks ass....

I can be more competitive with my high dollar x-ray but I have way more fun with my tto2... And by more competitive I mean instead of finishing fifth I can finish in the top three out of 10 racers the tto2 can definitely hold its own if you have one just keep practicing and enjoy it the number one upgrade you can do is the three racing diffs and the yeah racing 50 mm shock set.... that will get your car dialed good luck guys...

Thanks for the reminder of the mount. Meanwhile, here's a picture of my Volt Racing Mustang. I'm still finishing up the decals and some painting:

Got another question: I'm still waiting on my XT60 connectors to come in so I can solder it to my ESC's tamiya battery connector, so I've been using a tamiya to XT60 adapter just to test the car until I can solder the XT60 in. I read somewhere that using the tamiya connector is hampering the efficiency of the battery to the ESC?