Sunday, September 6, 2015

Sakura D4: Steering and Suspension Mods

As of right now, 3 Racing has not released any upgrade parts for the D4. But that doesn't mean some simple improvements can't be done in the mean time. I noticed that the center link in the steering has some flex as the angles get closer to full lock. It would have been nice if 3 Racing made a straight link for the RWD kits, but I am sure that keeping parts to a minimum is what helps keep cost down. Another problem with the center link is that it is a fixed length, so Ackermann cannot be adjusted. I made a center link out of two Sakura shock ends and incorporated an adjustable turnbuckle.

You have to make a little room for it first...

Space is really tight where the steering bellcranks, linkages, and suspension blocks are located. The front bulkheads need to be removed and the little nubs on the back side need to be cut down. I used a Dremel tool to accomplish this.

Here you can see the area to be removed:

Once that is done and everything is put back together, you can see that there is just enough clearance for the linkage to move through without contacting the bulkhead.

The flex is completely gone, the steering is more responsive, and the Ackermann can be adjusted now.

I also reduced the spacer size where the servo linkage mounts to the bellcrank. You may have noticed that there is a lot of flex here, and only the aluminum bellcranks are going to cure that. Reducing the spacer length will not cure the flex, but it will help the steering be more responsive to inputs by the servo.

The front upper suspension arms are an interesting design, but I don't think they work so well in this application. 3 Racing made the arm very durable, but it is not so easy to adjust. Once I added the new KPI holes on the stock uprights and adjusted the rod ends to the camber I wanted, they were no longer shrouded by the outer portion of the arm. All that extra material became useless at this point, and the factory turnbuckles became a little bit short. So I cut the arms back to the inner turnbuckle threads and replaced the factory turnbuckles with 25mm ones.

With plenty of thread going into the base of the arm, they still are very sturdy, and now adjusting them is easy.


  1. I will be using your mods very closely when I build mine in a few months. I almost pulled the trigger but I have the TT02 FRD RWD I need to get runnin first.

  2. Tried a friends D4 last time at our D1 event, that thing needs rear weight and was funny to drive but different, when you compare it to the TT02 FRD and the MST FXX-D Vip and the RMX Vip RWD...

  3. Hey man,

    these are great suggestions. I want to do the center turnbuckle mod but had a few questions. How long is the turnbuckle and what do you use to reconnect it? Thanks!

    1. The turnbuckle is 38mm. I just used 3mm screws to attach it to the steering wipers. I think they may have been 8mm long.