Tuesday, September 1, 2015

Sakura D4: Got lock?

I really like the design of the D4 overall, but as I have mentioned earlier, I feel like the front lower arms are just a little too big in diameter.  The insides of the wheels hit at full lock, and can stop the wheel rotating, inducing a spin.  I was able to gain a little more by adding 7mm hexes and 1mm spacers to get some decent angle, but the wheel still hit pretty easily.

Here is what it looks like with the wide hexes.  Not bad, but the wheel is hitting the y-arm at this point.

I like the design of the Eagle Racing y-arms that are used on the R31/TA05/TT02 FRD RWD kits.  I was able to source a pair of them locally to try out.

They are a very close match with the D4 y-arm.  You can see the difference in the diameter that will add some extra clearance for the wheel.  They are approximately 1mm wider in track overall (which can be adjusted with spacers) and are 4mm narrower at the inner pivot.  Just add some spacers at the inner pivot to make up the difference.  As a bonus, it opens up the range of adjustment for caster.  You will need to transfer over the shock mount ball, and the ball that is used on the knuckle.

Here they are mounted with the spacers in place.  I added 1mm to the front and 3mm to the rear in addition to the factory spacers.  I plan to strip the blue and pink off these once I get done testing.

The payoff is additional steering angle, and the wheel no longer contacts the y-arm at full lock.  The 7mm hexes are still in use.


  1. do you know where to source those y-arms from ?

    1. http://www.broadtech.hk/eagleshop/shop/ShopTop.aspx

  2. ok thanks! Just putting mine together this week, I took your advice with the M3 Tap its really helping..cheers

  3. Is still hitting the y arm and dumper