blunto

My '94 Z has t-tops; good for cruising , not good for autox .

I know roll cages can help to limit flex in this area, and I've seen some y-bod guys install harness bars that could help to compensate for targa tops, but I was just interested to see if there were any other structural mods that could help me out.

Thanks in advance!

LT1Squirrel

SFC's will make a drastic improvement....the brand will be based on how much you want to pay and how hardcore you wanna be

blunto

SFCs are definitely on my list!

I can already feel the difference going into and coming out of corners just w/ a STB; I can't wait to see what the SFCs will do!

The t-top flex isn't a major concern at this point, but over time, esp time spent at Solo II practice/competition, I could see it becoming an issue, and frame flex isn't on my list of things I'd like to adress after the fact .

Thanks for the input!

Jay-Roll

Another vote for SFC's. By far the #1 thing you can do to prevent body flex.

dnovotny

I have a hardtop 3rd gen which I can compare to my T-top 4th gen T/A. First thing you need to do is add a 3-point SFC. Either LGs or SLPs. I removed the KBDD because they are inferior in strength compared to the other two (1" tubing vs. 2-3" tubing). Comparing my 3rd gen which has two sets of SFCs with my 4th gen, in bending the 4th gen is more rigid. Torsionally the 4th gen falls short. That includes several inches of the SFCs welded to the pinch weld along with some other reinforcement. The front end still feels slightly disconnected from the rear when making sharp turns or transitions.

I've been waiting over 2 months for my custom 6-pt. roll bar to be completed, I'm very curious how the car will feel after that.

blunto

SFCs will come next, so thanks for the reccommendation on manufacturer/measurements.

Let me know how the cage feels/performs once you get it!

Red96Lt1

The hard top cars and the t top cars are the same structurally except for a piece of sheet metal on top of it.

blunto

I always thought that hardtop coupes made the chassis a little stiffer due to the the solid beams on the sides of the roof, where as t-top cars have lock-in glass that is susceptible to shift...

Injuneer

It looks like this on the "hardtop" cars:

http://dw-zone.gotdns.com/t-tops/drv_roof_gone2.jpg

dnovotny

On thirdgens that's pretty much correct. However, Injuneer posted pics of a 4th gen with some of the SMC roof removed. C5s have a 2-3Hz difference between a hardtop/coupe version. That chassis is about 22Hz bending/torsionally for a coupe. I have an old magazine article that lists our cars as 22Hz (probably bending), I've seen some posts that torsionally we're around 18Hz. Not sure if these numbers are for a hardtop or t-top car. Convertibles are around 14Hz. Hz is a log scale, so a 2-3 Hz difference exceeds 10%.

blunto

Nice pic Injuneer; just what I was looking for.

And thanks for the numbers dnovotny; very interesting