Drag/street tire and suspension questions
 

Hello! So trying to research these topics is literally useless. I've seen so many answers that it appears there is either no right answer or no actual experience with this stuff. Which can't be true! So I will first start by listing off the mods/specs of my car right now, below.

2014 Subaru BRZ w/ 2jz swap:

- CD009 trans
- 3.73 rear end LSD torsen
- 275/40r17 NT555R rear tires
- Tein flex z (6k f&r spring rates) coilovers lowered about 1"
- Stock rear sway bar
- Upgraded/stiffer diff mount bushings
- Boost by speed/rpm
- Motec traction control


Here's the problem: The car makes over 600ft lbs of torque and has terrible traction. 5th gear, rolling into boost at 60mph the car spins as soon as it gets into boost. Coilovers are cheap but they are set to full soft.

Here's my question(s):

1) With a 275/40/r17, what tire(s) would be better than my current ones?

2) What do I do with my suspension for better launches and adding grip to the rear end in a straight line? What is my goal regarding spring rates, what makes a coilover "better" than another anyway?


Thanks!!

If I had a BRZ (or any car really) with 600 ft/lbs of torque, I would really consider coilovers that are 2 way damping adjustable. Separate control of compression and rebound (aka extension) will give you more control over what the shocks are actually doing. Plenty of travel would also be really helpful.

Is your priority straight line grip or do you still want the car to handle well?

What type of tires are you using?

- Andrew

I'd hit up Pure Automotive and see if they have any recommendations. They should have a lot of experience since they have developed an FRS drag car.

275/40r17 NT555R

I don't really need it to handle great in turns. It's mainly a straight line car and cruiser. So long as it's controlled at 75mph on the highway, i'll be content.

What about spring rate? What if I get 2 way adjustable coils, and my spring rate is wrong? I am not really great at taking educated guesses with this stuff. There's a local guy selling some 2 way coils but they are 11kg front and rear which seems too stiff for my purpose.

Thoughts?

Yeah I would be on the softer side as long as you have enough travel. I would say that's too stiff.

The 6k spring rates you have now are about right (or softer), as long as the valving is right and you have the travel you need.

- Andrew

Thoughts on the tires? The general consensus so far has been to change them, but to what is the question!