Wednesday, August 28, 2019

Wltoys 12428b (part 19: Tamiya CVA suspension upgrades)

Well, with the vertical front dampers mod, the front was as hard and bouncy as the rear.  The net effect was a very twitchy car, prone wildly bouncing off minor bumps and over-steering.  Was fun to a point, but I wanted something more controllable.

After a bit of research i discovered much respect for a line of damper kits by Tamiya, the T50519 for the front and T50520 for the rear.  The latter has been discontinued :( but still available online if you hunt around a bit.

These are very versatile parts, and not expensive (around $AU30 each):
  1. They can be built in multiple lengths 
  2. They come with 2 pairs of springs and damper ends
  3. And three different pistons, for soft, medium hard.
  4. Three internal spacers (piston travel, ride height) and three external spacers (preload)
  5. ..and you can then of course use whatever shock oil you like, some is included.
Setup correctly they can match the stock dimensions of the 12428b (in compression and extension) with the exception that they're larger diameter.


Given the car is has previously run very hard suspension I'm hoping to achieve a softer ride to see how that feels.  I expect more ground contact (better acceleration & steering) at the cost of body roll (pitch/yaw).  The suspension slightly depresses at rest when under it's own weight and travel is remarkably easier and smoother than with the stock setup.

My front setup:

As I've mentioned, for the front was running my vertical shock mod and the T50519 setup as follows:
  1. The longest spring (for overall length).
  2. The shortest damper end.
  3. The softest piston (the one with three holes in it)
  4. The V7 (thickest) external spacer (for spring preload and to stop the top falling off).
  5. No internal spacers (for longest travel).
  6. The OEM shock ends from the 12428b (they do fit).
  7. Some 750 shock oil i had sitting around.
NOTE: Installation uses the original stainless shock ends

My rear setup: 

The rear shocks went together the same as the front, and were installed (upside down) in the same position as the OEM shocks, no changes required.  I did arrange the shock in the most vertical position.  Setup:
  1. The stiffer spring.
  2. The longest damper end.
  3. The softest piston (the one with three holes in it)
  4. ALL the external spacers i had, including those from the front shocks.
  5. Some closed cell foam rubber on the bottom of the battery tray.
  6. No internal spacers (for longest travel).
  7. The OEM shock ends from the 12428b.
  8. The 750 shock oil i had sitting around.
Even with all those spacers, when allowing for spring compression at rest, the ride height is lower than standard, so the foam rubber acts as a bump stop should it be needed.

It's a shame, but the rear shocks I sourced were possibly the last in Australia :(


This is a completely different vehicle and am very happy with this mod.  Some things I didn't expect and am really happy about:
  1. When dropped on the bench, the solid thud, like a lump of wet clay.
  2. That the unplanned reduction in ride height helped with expected body roll.
  3. That body roll now was SO much more predictable, you can steer it out.
  4. To be able to spend SO much more time at full throttle (hot batteries!).
All in all, this thing is quite awesome :)

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