## For the road racers: front rocker wheel rate

Did a little experiment with front rocker geometry that might be of interest.

Working on two conditions which emerge from using an off-road chassis for on-road purposes:

1) If you run a low ride-height with the TRX road springs, you need to have the spring collars backed way off... but doing this leaves a bunch of wheel travel effectively free and un-sprung.

2) The geometry of the rocker is off-road optimized; the front rockers have a very long input arm (pushrod side) and a proportionately short output (shock side), something on the order of nearly 2:1 wheel to shock ratio.

This lets the suspension stay nice and compact for off-roading but poses a problem for road use. On road, the wheel movement is far less so it only ever uses a tiny fraction of the shock's length. To account for this narrow range of motion, the shock and spring have to be quite stiff to hold the car up and control the wheel movement.

If you have a look at your average road-racing car pushrod suspension, you'll notice that the input radius of the rocker is much smaller than the shock-end output radius. Completely opposite geometry, let's say 1:2... So a little bit of wheel travel is amplified and spread along a long shock and spring.

Given some constraints - I wanted to still be able to swap a few parts and go from on-road to off-road so had to retain stock pushrods and suspension arms - my execution to increase the shock ratio was to drill a new pushrod hole as inboard on the rocker as possible.

Did some careful measuring of droop and desired ride-height, then drilled a new hole for the pushrod bolt to screw into.

The effective wheel ratio is now pretty much the same as the rear rocker at 1.4:1 ish. As good as we're going to get up front anyway.

This position took out a bunch of un-sprung droop as well as increased the wheel rate by a significant amount. Now the front rocker uses almost all of the shock action, so the damping and spring can both be more compliant. Ride-height is both very low and very well controlled.