did you have to drop the control arm spring support that is connected to the steering rack ? or once you take the 4 bolts off it just slides off with no tension

the black washer that is meant to go inside the subframe is hugee, not sure if its worth risking the structure of the subframe by cutting a hole that big to fit a washer in.

would the bolt itself be okay to hold the inside subframe without a washer? if so id drill a small hole just to put it through. this 4was system is giving me a massive headache with the diff brace as its the last thing i need to help tighten the diff/rear end.

link of brace/ photo of black washer for reference :
https://au.gktech.com/products/z34-370z-diff-brace

 

That one is a little different from the brace I have. To answer your question, I drilled a hole into the subframe from the side where the brace is, because the factory hole won't line up for the brace. I then went in thru the rear hole which is at an offset from the hole I drilled. I could have made 2 holes to get this lined up nicely, but was able to get it on there with just drilling the 1 hole. The locking washers helped so that no socket was needed to keep the inside end from spinning.
Also as you can see on my pics, I drilled a new hole into my brace. I don't recall if I used the large washer or just went with something smaller. I recall trying to get that washer in thru other sections of the frame, but don't recall if we were able to or just skipped using that washer.

 

odd, since the factory hole seems to fit flush with the brace mounting hole. i just cant seem to insert the washer and bolt through the subframe to get it mounted.

I assume drilling a hole in the rear subframe would help me slot the bolt in, but since the washer is hugeee, im thinking of either skipping it or adding a smaller one? would having just a bolt through the subframe hold? or safer to keep a washer with it inside it.

ill post the results if im able to get it to work and maybe then ill be the first in the forum to add a diff brace with the least ammount of modification in a 4was system

 

Possibly you can go with just a bolt, but I would try adding a washer along with a locking one