posted on October 21, 2013 17:01
Project FR-S: Getting More Grip with Whiteline, Cusco, Rays Wheels and Achilles 123S Tires!
In our last suspension installment of Project FR-S we were rushing to get the car in rolling condition for the SEMA show. We had installed the stuff you could see, like lowering the car with KW Variant IIIs and installing the excellent StopTech big brake system.
Now we are back to working on the car, focusing on the things you can't see. We knew we were going to be upgrading the wheels and tires for much bigger ones and we knew bigger tires were going to load the suspension a lot more due to greater grip. More grip equals more body roll.
More grip also means more deflection in the bushings holding the subframe to the chassis. We also wanted to add a bit more adjustability into the car's suspension. Finally, more grip means more stress and flex being induced in the chassis.
To keep things tame, we went to Whiteline for a set of anti sway bars and subframe and transmission bushings and to Cusco for some of their extensive chassis bracing. For wheels and tires we contacted Rays Engineering and Achilles Tires. Will this stuff help? Check it out!
Want more Project FR-S? MotoIQ Project Scion FR-S
For this go around we opted for Whiteline's 20mm non adjustable front bar as this was the only bar available for the FR-S/BR-Z at the time. The Whiteline bar is is 2mm larger than the stock 18mm bar. Since stiffness rises to the 4th power of the diameter more or less, the Whiteline bar is around 50% stiffer than stock. Currently Whiteline has 3 different front bars for the FR-S/BR-Z: 20mm non adjustable, 20mm adjustable and 22mm adjustable. We will be evaluating them later. The Whiteline bar comes with firmer bushings for better response and uses the stock end links. The bar also has lock rings to prevent it from moving from side to side.
The rear bar is 16mm in diameter up from the tiny stock 14mm part and is about 70 percent stiffer than stock. It is three way adjustable. We really believe in adjustable bars for tuning a car that will see track use. You usually can't manage a spring change with a grassroots budget when testing but it is easy to adjust a bar. Like the front bar, Whiteline has three rear bars for the FR-S/BR-Z family. A 16mm non adjustable, a 16mm adjustable and a 18mm adjustable. We will be evaluating some different bar options from Whiteline in the near future.
More loading from fat tires and supercharged power means lots of deflection in the stock rubber crossmember bushings. This deflection can lead to wheel hop and a loose feeling in the rear. The stock rubber bushings have big voids in them designed to give a smooth tide under the loads generated by the tiny stock tires. These bushings will allow for over 1/2" of movement under load. The Whiteline bushings fill the voids in the stock rubber to give more firmness without sacrificing much ride comfort or quietness. Whiteline has recently come out with replacement bushings for even greater stiffness and we will be evaluating those as well very soon.
The stock rubber transmission mount has a huge void in it. We are amazed just how much flex and movement it will allow. This will probably result in shifting difficulties and stress on the drivetrain. There is so much movement it will probably contribute to wheel hop as well. The Whiteline transmission mount bushing fills the void while retaining the factory rubber piece for smoothness.