TheRcRacer Tamiya TT02 ARS rear active Toe Control Rear Suspension Guide and tips

As any regular visitor to the site will know, I love tinkering with the Tamiya TT-02.  The TT-02 Toe control Rear Suspension is something that I have experimented with for a while now. So here is I will cover what it is, why it can improve your chassis and how you can install it on your own TT02. 

Background 

One of the best modifications for the Tamiya TT02 is to add some rear toe-in. A stock TT02 will have 0.5° rear Toe-in. This might be ok for casual driving, but  it can drastically reduce the amount of rear end stability when exiting a cornering at speed and on the straight.   

The more rear toe-in a car has it increases the slip angle on the tyre and creates more stability. This gives you more power under-steer because of the added traction. Importantly it also allows you to put the power down more easily onto the straight and keeps the rear more stable on the straight.  

For the Tamiya TT-02 Tamiya provide the following hop-up parts to add rear toe-in.

• Tamiya 54549 Aluminium Rear upright (2.5°)
• Tamiya 54733 Aluminium Rear upright (3.0°)

These parts are great, and they transform the way in which the TT02 will handle on the track. The more rear toe-in your car has, the more stable, but you do lose a little bit of corner entry speed, steering response and straight line speed. At different tracks you so sometimes want to get the best compromise of straight line speed and corner stability, so you do change the rear toe settings. So if you want both of the options above, it could be quite costly.  

One of the features that has been appearing on most manufacturers top end touring cars an adjustable rear toe control suspension set-up. These allow you to not only tune the amount of toe-in you have at the rear, but also allow you to adjust the amount of Toe-in at the rear of the chassis as the car leans into the corner.  This can give you less rear toe on the straight, for more speed on the straight and into the corners, but as the car leans it will add rear toe and makes the rear more stable when at the apex and coming out of the corner. 

As you would expect there is nothing like this for the TT-02. So I thought I would at how to implement this on by using Tamiya parts so it could be legal for most stock TT02 classes 

So let's have a go..

TheRcRacer TT02 Toe Control Rear Suspension Mod

The fundamentals to do this are not too hard. The main time and effort was spent looking at lengths for the link arms, and obviously track testing it.

Parts Required. 

A pair of front arms. (I purchased the A and B Sprues). Instead of buying a P-Parts I used the Tamiya 54559 Low friction suspension balls. 

You need a pair of adjustable link arms. If you want to use the chart included here you need to build them as per the instructions here.  

• Tamiya 50875 5mm ball connectors (You get 8 in a pack, you only need 4)
• Tamiya 53539 5.5mm Aluminium spacers Set (Or just use some Tamiya plastic spacers).
• M3x12mm Grub screws (2)

To mount the link arms you just need the following

• Tamiya 53969 5x8mm Hard hex Connectors

Installation.

Remove the rear arms and swap them out with your new front arms. 

Now remove the two rear screws on the gear cover. Replace them with the Hex connectors. 

Now you need to make the link arms. Simply screw one of the 12mm M3 grub screws into the Ball connector. Slide 3.5mm of the spacers onto the arm. Now attach the other ball connector. Tighten it up until it is tight against the 3.5mm spacer. You can obviously do this with a small turnbuckle. However this method is stronger, and much easier to ensure you have the same measurements left and right. 

Mount the Hex Connectors on the inner upright hole. Again add a shim here to tune the amount of extra toe-in that will be added once the car leans into the corner. 

Now you have TT02 Toe control Rear suspension on your TT02 :) 

The main thing that stands out to me is that there is obviously some rear negative caster as you are installing the front arms on the rear of the car. In reality it shouldn't make much of a difference as caster only really has an effect on the steering. Although speaking to a friend who has experience in race car mechanics, they mention that it can cause later force compliance understeer. Although they backed that up with it wouldn't really be that noticeable on a RC car.

Additive Toe on the corner. 

With these parts installed (3.5mm link arm shim, 1mm upright shim. You will get the following results.

Rear toe is 2.5mm on the straight.

When compressed into the corner, the rear toe will increase to 3.0mm

Tuning chart

Here is the chart that allows you to tune the rear toe-in. 

As you can see, I installed the Rear Toe Control Suspension on a stock TT-02. I like to do this so I can judge the baseline (Running the car in stock form), then add the new part and run it again to see the direct impact of the new part / option. 

At the track.

After setting a base time with the TT02, I then took to the track with the Toe Control rear suspension mounted on the chassis.  


On the sound of the tone I hit the throttle and drove fast into the sweeper at the end of the start straight. I eased of the throttle as I was used to driving the stock TT02, and I had to keep the rear in check at all times, this time I didn't brake as hard and carried a little more speed, the TT02 kept planted and I started to push harder and harder. 

The test track was small and twisty, so I was really testing the corner stability to the maximum. There was a very noticeable difference in how the car felt, especially on the hairpin section.

The first run was very much an exploration for the grip levels of the car. For the second run I was much more confident of the limits and I threw the TT02 much harder into the corners from the start. The car felt good, there were no ill effects from the mod, only positives. At the end of the heat I was 16.45 seconds faster than with the stock TT02. A decent improvement. 

For the final I drove even harder, and on a couple of occasions I did push a bit too hard. It must be remembered that this is a stock Tamiya TT02 with 1deg of camber all around, camber is a big component of ensuring a car is stable carrying speed at the apex.  Impressively, even with the stock upper arms I managed to win my final against a range of comp chassis and improve the best time by by a slight margin to post a time 19.23 seconds faster than the Stock TT02 time. 

Overall

This mod seems to have worked well. It was a fun experiment and I will run it more on my Stock TT02, and look to fit it on my fully hopped up TT02. 

It must be stated that the huge jump in times is because the TT02 without rear toe-in is a much harder car to drive. If you made this modification to a car that already had toe-in rear blocks you may not really notice any significant improvement in lap-time. 

With that in mind though, you will have more adjustability with this mod, as you can swap shims to change the amount of toe in and how the car acts in the corners without any extra cost. 

For me, it's just a cool little mod that I enjoyed experimenting with.