rr spring height

[35DIRT]

How does raising the spring higher effect the handling on the rr, thanks

[MasterSbilt_Racer]

If you raise the point on the chassis, where the weight is applied to the rr spring, then the weight of the car doesn't transfer onto the rr as easily for the same lateral acceleration in the corner.

In short, the rr picks up less weight when the car rounds the corner. If you run a taller spring that pushes on a screw jack mounted spring perch, this applies. If you have a coilover or slider mechanism and install a new spring, this doesn't apply. In that case, your chassis mount has not moved.

[ZERO25]

I know a couple that have tried it and claims the car was tighter with the shorter spring. Maybe one day someone will be able to provide some data!

[MasterSbilt_Racer]

I know a couple that have tried it and claims the car was tighter with the shorter spring. Maybe one day someone will be able to provide some data!

Carrera did a huge test with Rayburn cars back in the 90s. It's the year that Kevin Weaver ran second in the World. Every Rayburn, that was at the test, ran awesome in the feature. They made gains on pullbars and a few other areas. One of the things they confirmed during the test was that spring height didn't matter on a coilover. The pivot points of kinematic system such as that matters. Where a compressible link, that is fixed to linear motion, "gives" does not.

[Lizardracing]

Spring Table is the engineering term for what your taking about here.
The car feels the spring table at the connection point of the spring and chassis.

If its a coil over. the car sees the connection at the coil over heim to chassis point.
If the car has a jack bolt, The car sees the connection at the jack bolt to spring connection.

Generally speaking a lower connection point gives the chassis some mechanical leverage on the top of the spring.
It's kinda of placing a spring on table height at say 36" tall table. Stick your arm straight with your hand on the top of the spring and lean on the spring. There's not much leverage there and its hard to compress the spring.
If you move the spring vertically to a lower location, say a 10" table, Stick your hand on top the spring again, and lean over you'll be able to apply more of you're body weight downward to compress the spring.

Center of gravity is below the spring.
Raising the spring would reduce the load on top of the spring attempting to compress the spring.
(Loosens entry off throttle and tightens exit on throttle)
Center of Gravity above the spring.
Lowering the spring would increase the load on top of the spring attempting to compress the spring.
(tightens entry off throttle while loosening exit on throttle)

All other things being equal, which never happens.

[ZERO25]

Seems to me with the rising cg in the rear and the more radical movement of the fuel from left to right, there might be more to the story. Most of us will agree, what usually works on paper doesnt always transfer to the track.

[MasterSbilt_Racer]

Seems to me with the rising cg in the rear and the more radical movement of the fuel from left to right, there might be more to the story. Most of us will agree, what usually works on paper doesnt always transfer to the track.

In complicated systems, sometimes we miss things. A chassis connected to a beam axle is pretty simple geometry, physics, free body diagram.

[stock car driver]

Lowering my rr spring upper mount helped every dirt car I raced with side bite.

Wiffle balls in my fuel cell helped it also and running as small of a fuel cell as possible so there was less weight behind the rear axle.. keep all weight between the 4 springs and in one mass if possible. my weight was as close to my body as possible in all my good dirt cars.

[ZERO25]

Interesting......Couple of questions 1) Did you fill the tank with wiffle balls and then add the fuel?, 2) Did they ever get soft from being in the fuel?

[stock car driver]

Interesting......Couple of questions 1) Did you fill the tank with wiffle balls and then add the fuel?, 2) Did they ever get soft from being in the fuel?

They dont get soft, I bought one cut it in pieces and soaked it in pump gas with ethanol and also alky and also the race gas I was running which was sunoco gt260.