There are several changes that you can make to your truck that will make it easier to drive. The first thing is to get the steering sorted, this is the subject of a separate article linked here How do I adjust my steering .
Other steps that you can take are varied, some are mechanical and some electronic. Mechanical changes include replacing the bronze bushes with bearings, Replacing the motor, either locking the Tamiya gearbox in first or replacing it entirely, making speed adjustments on your transmitter and setting the failsafe on your radio.
Motor
The motor(s) supplied by Tamiya are either 27 or 35 turn mabuchi style 540s. These run far faster that the truck needs and provide unrealistic scale speeds. A scale 60mph is nowhere near as fast as you think. We recommend replacing with something closer to 80 turns. The Carson Poison motor is popular, it is a sealed can 80 turn 540 motor and still has bushes for bearings. You can replace with a rebuildable motor with ball bearings and replaceable brushes e.g. from Surpass, These will give a smoother output.
Bearings
Replacing the bronze bushes with bearings is best done at build time. It will make a noticeable difference to the smooth running of the truck and reduce the drive train friction. There are some bushes in the gearbox that slide rather than rotate, these should not be replaced.
Bearings come in several varieties but there are sets for trucks out there and they are generally offered as metal or rubber shields. Rubber shields are better at keeping very fine dust and carpet fibres out but wear faster than metal shields. They are not suitable for over 50,000 rpm but we come nowhere near that! Metal shields have less rotational resistance but by their nature are more prone to collecting dust and fine fibres.
Gearbox
The Tamiya gearbox has three gear choices but honestly you only really need first gear (or maybe second depending on the motor). It is a simple matter to "lock" the gearbox in a specific gear using the setup spacers from the kit. Once installed you will no longer need the servo. Moving the spacers to select second gear as opposed to first is a simple matter of moving spacers around.
You can replace the Tamiya motor/gearbox with an inline version, this will save space and open up some options. I use a 19:1 gearbox with a Surpass 27-35 turn 550 3 pole motor (yes 550 the rotor is 10mm longer), Bothe are available online from e.g. Aliexpress but there are also prebuilt versions from e.g. Servonaut.
Failsafes
A failsafe is designed to leave the model in a safe state if the radio fails. There are a few different versions out there. The simplest takes the output settings at bind time and uses those as failsafes. This can be problematic, for example if you are using a speed controller with cruise control then this failsafe type will not stop the truck.
Similarly if you are using a speed controller that has direction change and fwds(or reverse) neutral and brake, then the truck may continue rolling. In both these cases a different failsafe is needed. Either a setting that applies the brake or if the speed control has its own built in failsafe then a no signal output.
Some transmitters allow you to set individual failsafes and allow you to independently set the failsafe at any time and to any value.
Some transmitters allow you to choose hold value as the failsafe, I use this on my width adjustable trailers as I do not want the servos trying tyo change the width with a load sat on them.
Check your radios manual for what failsafe types are available.
Endpoint adjustment
The last stop for this article is end point adjustment. Not available on very low end transmitters but if it is available, it provides a very quick way to reduce the models speed. This is very useful to limit top speeds for learners and children. One point though, this does reduce the speed controller output (and servos for that matter), and it is always better to adjust the full throw effect (less throw on the servo arm, larger gear ratio for the gearbox) than to limit it using the transmitter endpoint adjustment.
Thats it for now, any questions please do ask.