Project Silvia’s Girlfirend Part 2: Making it Handle


Pressing these bushings in place was like trying to wash a cat. Even softened by the heat, these bushings proved very reluctant to go where they belonged. One side would always drop in first, letting the bushing turn sideways and jam on the way in. 


To hold the bushing straight up and down in the press, I made this contraption with a 15mm Harbor Ffreight socket (gotta love the color coding!), an old spring perch, and a bolt.


With the bushing on the socket, it could no longer turn sideways on the press.

Then, to make sure the press had the widest, most stable footprint possible when pressing on the spring perch, I used this giant socket I had for removing Mazda rotary flywheels.

Mystery LSD:

The final major handling ingredient is the diff. Project Silvia uses a Quaife helical diff, and given the budget, I would have done a helical diff again. I’m a big proponent of relatively mild LSD setups. A tight diff can make the car reluctant to turn in, and can make the car feel funny as you roll on the throttle in a corner as the wheels suddenly try to go the same speed and either push the car into understeer, or break traction and suddenly oversteer.

On a pure track car, a tight clutch diff can work really well. As long as the car is set up properly and driven aggressively, a tight LSD will send most power to the outside wheel on corner exit, helping the car rotate under power. It’s really hard to get a tight LSD setup to work well on both the track and the street, though. For a car that is neutral and consistent in all driving conditions, I prefer the smoother engagement and lower torque bias ratio of a helical diff.

Still, when this mysterious factory-looking 2-way clutch diff landed in our laps for nearly free, we weren’t about to turn it down.


The diff was so cheap largely because nobody seemed to be able to make it fit their car. The axle bolt pattern was a 5-bolt (on the left) common on JDM Nissans of a certain age, while the U.S. cars demand a 6-bolt pattern. 

1 comment

  1. Trying to do this same GC coilover setup on my S13 with rear z32 knuckles for that OEM+ type ride all these years later. I have already had to step up from the original 7” 250lbs rear springs to 8” 250lbs which are still at the top of the threaded collar on the yellow KONI with not enough clearance between fender & tire. Currently about 1.8” of clearance between the rear fender & tire which still doesn’t seem close to the early pics of this project car. Do you recall if you had to use longer springs on the rear like I am (about to move up to the 9” 280lbs spring next in order to hopefully have a better range on the threaded collar)?

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