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

Another example of a tack welded in place gusset.

Next, Zac did the final welding on the easier-tacked-up parts.  Next, it was time to tackle the more difficult parts, the differential mount reinforcement, and the lower control arm pick-up point relocation bracket.

The diff mount on the cross member is a weak area.  Only one thin layer of sheet metal one small doubler patch keep the diff from getting ripped out of the car.  Our own Project STurdteen had this happen.

Although it’s not a problem to weld on with a Mig welder or a bigger filler rod, Zac wanted a very tight fit between the reinforcement piece and the cross member.   He spent a lot of time hand-fitting it to keep the gaps to be filled by the welds tight.


  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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