Hi John, hope all is well with your JZ-Z.
I was just wondering if you noticed much difference in terms of shell stiffness after fitting the cage. I am considering fitting a half cage, primarily to further stiffen the chassis but as it would likely add nearly an extra 30kg to the car I want to make sure its worthwhile.
Well, safety is a big reason as well, but I'm running only a fraction under 500lbft, I want my shell to last so I reckon some reinforcements can't go a miss. Why do you say a cage would spoil the shell? Yes, it would have a cage, that might take away value, but as it will never be sold I don't see it as an issue. I would still plan to have the trim in the car even with a cage so it will still look nice inside.Hi Ian, the reason for fitting a cage and in your case a half-cage should be for safety reasons. If you are doing it for shell stiffness then I would think it less important. A welded-in cage that attaches to the pillars, roof and suspension top mounts (front and rear) would stiffen the shell but spoil it.
My thoughts. My chassis currently seems nice and stiff and handles the power perfectly, but I want to keep it this way as long as possible.The other thing to think about is the amount of torque your putting though the chassis, this is what'll cause twist in a 50 year old design, that was never meant to have anywhere near that much put though it. It can only help
Not a bad idea if I don't go for a half cage. At the minimum I could add a bar between the struts with perhaps an additional bar or two, perhaps like you sat to the factory cage mounting points (assuming you mean the ones higher up near the roof) I really don't want to add much weight and I am hoping connecting the chassis rails up to the rear subframe stiffens it up a lot.As this is going to purely be a road car I may just look at light weight small tubular bracing at key points around the car. I will probably pick up on the strut top along with seat belt points to triangulate these areas and link to the factory rollcage mount point. There is a well known car that has done similar. He has built a lightweight modded 240z and wanted the stiffness without the weight. I'll have a dig around for his build info.
Thanks. Funny enough I had only seen exterior photos of that car on Sunday as I was researching Watanabe wheel fitment and his runs Watanabe F8's.Here's a link to the car.
Not a bad idea if I don't go for a half cage. At the minimum I could add a bar between the struts with perhaps an additional bar or two, perhaps like you sat to the factory cage mounting points (assuming you mean the ones higher up near the roof) I really don't want to add much weight and I am hoping connecting the chassis rails up to the rear subframe stiffens it up a lot.
Thanks. Funny enough I had only seen exterior photos of that car on Sunday as I was researching Watanabe wheel fitment and his runs Watanabe F8's.
I actually have the same type of bracing up front as he has fitted, interesting looking at the rear though.
Here is how I did the rear section of mine. Plus a picture of the braces I will use in the red car in addition to the other bracing I'm considering.View attachment 27589 View attachment 27590
But when connected to join up with the rear subframe its bound to make the whole chassis a good amount stiffer. They are fairly solid rails so joining them to the fairly rigid subframe can only make the rear more solid.the rails you mean are just floor support rails, I think they'll help reduce floor flex at the seat mounting point, however I can't see it stopping any chassis flex, I did mine to the rear of the floor to to strengthen the seat area.