Rear End Narrowing Effect on Handling

[ImaBadMan]

I am considering narrowing the rear end on my 71 cutlass to fit some deeper dish wheels and installing weld-in coilovers. If I move the shock perch in closer to the center, I see this requiring stronger springs the further inboard they go. Any experience on this and how it effects handling? I was thinking around a total of 4" shortening.

[raustinss]

4 inches??? Whats the reason for that much ? 68-72 A bodies have huge wheel wells to begin with

[ImaBadMan]

4" total for 2" on each side. Lots of room yes, but more dish is what I'm after. I'm just curious how moving in the perch effects handling.

[Rod]

I'm just curious how moving in the perch effects handling.

even though the tires are the ones touching the ground, it is the shocks that determine the cars stability they link the tires and axles to the chassis, the wider the shock stance the more stable the car, stand up and put you feet together ankles touching... if some one pushes you do you fall over easier? the stand feet shoulder width and same test, then stand with your feet a foot wider then your shoulders.. way more stable

now you need to think about the shock angles and how the angle helps control roll also

[Tsaints1115]

even though the tires are the ones touching the ground, it is the shocks that determine the cars stability they link the tires and axles to the chassis, the wider the shock stance the more stable the car, stand up and put you feet together ankles touching... if some one pushes you do you fall over easier? the stand feet shoulder width and same test, then stand with your feet a foot wider then your shoulders.. way more stable

now you need to think about the shock angles and how the angle helps control roll also

But doesn't a wider stance increase the leverage the wheel at it's mounting point has over the spring/shock?

[SSLance]

Technically yes but I think in this case the OP will end up with tires at same width with the changes in wheel offset.

[Mr Nick]

My understanding is the farther inboard the shock & spring are, the less effective they are when one wheel is loaded... either via leaning during cornering or hitting a bump with one tire.

Hitting a bump with both tires should not be affected by location of the shock and spring.

[ImaBadMan]

Everyone is right. The wider the stance of the coilovers, the less spring force would be required to maintain stability. As the mount locations are brought closer in, the lever arm that the coilover has to work with is getting shorter. Increasing the stiffness of the spring and dialing in the shock would compensate, but this is in a perfect world. Once you add in all the "squishiness" of the bushings and flex of all the parts in the real world then the situation starts to get less clear.

Anyone with experience on rear end narrowing have some input? I'd be interested to hear how this has worked out.

Nick, that is a nice ride.

[Lonnies Performance]

You could always run a sway bar (or larger sway bar than you currently have) to compensate for the added body roll.

[Rod]

even with the rear narrowed you can still design and install a wide stance on the shock mount, just my two cents

Everyone is right.

glad i was right... whew

You could always run a sway bar (or larger sway bar than you currently have) to compensate for the added body roll.

running the bar that way is a stop gap for a poor design.... I'm not saying you cant... hell there are a lot of really bad ideas out there that work...