Strengthening and Improving the Geometry of the S13 Subframe With GKTech and ZSM Custom

Since were are building the ultimate suspension system for our S13 with GKTech, we also got some of their parts to beef up the often ignored rear subframe. With stronger tubular chrome molly arms using spherical bearings instead of stamped sheet metal and rubber bushings, more force will be translated into the subframe.  The S13 subframe has rather weak suspension pickup points and GKTech makes a cool gusset kit so the subframe can be reinforced. As a note, some of these mods may not be legal for Formula Drift Pro competition but our car is never going to be used for anything other than fun drifting and being mostly built for road racing.  The gusset kit reinforces all of the suspension pick-up points, strengthening them and reducing their flex, and the rear differential attachment points which are prone to crack with hard use.

Another cool GKTech part is this lower control arm relocation kit. The S13 has a problem with excessive anti-squat in the rear suspension geometry.  This causes torque reaction bind in the rear suspension that effectively increases wheel rate when the throttle is applied.  This causes a sudden transition to oversteer and wheel hop if you have a decently powerful engine.  In drift it also causes you to lose forward bite.  Modding the suspension pickup points is one of the innovative things we did on Dai Yoshihara’s championship-winning S13 and this kit does most of what we did on his car by lowing the front pickup of the lower control arm.  We had to custom-make this piece but now GKTech does it all for you.  This bracket takes the anti-squat percentage from 45-35% and lowers it to 10-0%.  There is something to this as Nissan has done the same thing on later S-Chassis models like the S14 and more on the S15.

We also will be using GKTech’s solid rear subframe bushings.  The stock rubber parts have as much as 1″ of flex under load and contribute to both wheel hop and rear instability while cornering at high speed.


  1. Thats some awesome attention to detail. I can only see myself crashing the car on its maiden voyage with all these nice parts. Love the photo documentation as well.

    1. You guys always do it right. Kinda of rare. If I ever need or one of my friends needed some work done or just good advice I would reccommed your outfit 100% Mike. Thanks.

  2. i’ve installed quite a few of the s13 and s14 gktech weld in reinforcement kits (haven’t done the s13 roll center correction one yet) and i HIGHLY recommend this for ALL 240 owners. if you’re dropping the subframe to install solid bushings, its a great time to have the whole thing sandblasted and the gktech kit welded in.

    Personally, i mig weld them, but if someone wanted to pay for the additional time to tig weld (most of the time is spent getting super tight fitment for all parts prior to welding) i don’t see any downside to it in this application.

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