Suspension

Suspension is one area where a dramatic increase in performance can be gained simply by upgrading components. The syncro has the potential to have pretty good suspension, but the stock components are not up to the job. Better shocks, springs and suspension-related bushings can significantly enhance the feel and performance of the vehicle. Ground clearance can also be modestly increased through stiffer or taller springs. But increasing ride height beyond stock specs will result in increased stresses on and even premature failure of the CV joints, and may increase risk of a rollover accident..

Overview
The goal when upgrading the suspension should be to maximize the performance of the existing design. That means keeping static ride height within the range that the system was designed for in order to avoid topping out problems and to permit the wheels to drop into holes. Maximum static ride height for the Syncro is roughly 19.4 inches, measuring from axle center to the lower lip of the (metal) fender).

The damping on the stock Boge shocks and on the Old Man Emu shocks (which are valved a little stiffer than the Boge "C") also impose limitations. Both shocks are valved for 14" wheels (except the Boge "N" shocks are valved for 16" syncros) and neither is re-valvable or adjustable. This puts an effective limit on tire/wheel weights and spring stiffness options that will in fact result in optimized performance.

Specifically, a custom spring that is more than modestly stiffer than stock or a wheel/tire combination that is more than modestly heavier than the stock 14" setup will impose forces beyond the performance parameters of the damping of the available shocks.

Consequently, if you want to upgrade to bigger wheels and tires, the more they weigh than the stockers, the more they will impact negatively on suspension performance due to inadequate damping/valving of the shocks. The van will top out easier and the front end will pop wheelies easier over whoop-de-doo type bumps, especially at speed. It may affect cornering, too. In addition, if a custom spring is too stiff for the stock shock rebound valving, it will also cause the vehicle to feel too bouncy and too busy over bumps. The further away from stock you get in wheel/tire weight and spring stiffness, the worse the symptoms will be.

For this reason, unless you are going to have custom shocks made, or are going to purchase Boge "N" shocks for the 16" syncro, or do not mind some degradation of suspension performance, it is best to stay reasonably close to both stock spring stiffness and stock wheel/tire weight when making upgrades. Choice of tires is also critical to suspension performance since the tires work with and act as a de facto component of the suspension.