[adouglas]

Tip when adjusting preload:

You'll find that the adjusting collar is difficult to move. It helps a lot if you can unweight the rear end completely so the tire is hanging (hang from rafters via straps, floor jack under the engine, etc.) but that doesn't sound like it's an option for you. PS it's easier to reduce preload than increase it because you're relaxing the spring, not compressing it.

So this is one of those instances when you may want something that can help you apply more force. *

In your OEM toolkit you'll find the adjuster wrench, which looks kind of like a question mark. You'll also find a tube with one end flattened. The flattened end fits over the wrench to make a handle. However, you may find that the combo doesn't give quite enough leverage.

If this happens, find a longer of pipe large enough to slip the adjuster wrench into, thereby giving you more leverage than the stock handle thingie. Or, find a metal rod that you can slip into the end of the OEM handle (big screwdriver, piece of rebar, anything will do). Same idea... you want to create a bigger lever.

* NEVER EVER EVER try to increase your leverage when tightening fasteners. German torque (gutenteit) is NOT the answer. Correct torque is the answer when it comes to nuts and bolts. But this isn't a nut or bolt. It's a collar and you can't screw it up.