CUSTOM LINK SUSPENSION SCIENCE

Q I’m working on building a custom three-link front suspension for my very custom ’48 Willys CJ-2A. The tub is stretched and it’s on a custom frame. I mainly use it for trail riding and rock crawling, but I do drive it to and from the trails so road manners are important. The tires are 39s but I may go bigger. My axles are Dana 60s and I will be using 12-inch-travel shocks. Are there any hard and fast rules to follow when considering link suspension geometry? I’ve done a ton of reading on the subject, but it’s honestly all a little overwhelming.

- VERNE SIMONS

A There is a ton of good information on the Internet about link suspensions, but it is hard to wade through. Experience counts, and books have been written on this subject. Still, some of the info out there isn’t that great and some is good but hard to understand. Much of the online geometry talk is aimed at road cars that have independent suspensions with very little travel (compared to off-road rigs) and need to only handle in the turns. That just doesn’t translate into a solid axle suspension that works well off-road and has decent on-road manners. Also, much of the information online, as it relates to off-road performance, is aimed at a specific off-road activity (mud racing, rock crawling, rock bouncing, go-fast desert racing, rally racing, and so on) and/or that person’s experience and their opinion, which you should balance against how much you trust them as a source. You don’t want to build a suspension that would work well for a road racing car or a mud race track if you are going rock crawling. People (ourselves included) also tend to overthink suspension geometry. It’s a good idea to focus on it and understand what you are doing, but not to get lost in the details. Also know that compromises will have to be made, especially when adding link suspension to a pre-existing frame with a pre-existing steering system, engine location, exhaust, and more. That’s why full tube chassis buggies work so well. You can more easily control the placement of all the parts to optimize function.