MG Sports Cars

My stock '76 B needs new lower control arms up front. I was about to order a set when I noticed VB sells a set of negative wishbones that they say improve handling. What are the advantages and disadvantages of this change?

Unless you do a lot of autocross or racing I wouldn't bother with the longer lower arms. They would increase your cornering forces but at the cost of some accelerated tire wear. I'd say stick with the standard arms and get polyurethane bushings for those and the sway bar and you'll be quite satisfied.

Moss also sells them. I called my tech contact there, but he couldn't answer the simple question: "How much negative camber do they provide." (I believe stock camber on a chrome bumper MGB is +1 degree, which is more than most cars of its era. I DON'T know if that changed with rubber bumpers...)

IMHO, it's pretty weird that Moss and V.B. sell this clearly safety-related product without better knowing or defining what it does.

Ideally (and indisputably), when you're traveling on a straight road, zero camber is what you want. As most people realize, changing camber away from zero will cause tire wear. Maybe it's less obvious that changing from zero reduces traction, adds drag (which slows you down and reduces mpg), and increases stopping distance - at least when traveling on straight, level roads. Negative camber also causes cars to tend to want to self-steer or "wander" on bumpy roads. Why? When left and right side tires have equal traction, the "camber thrust" on one side cancels the other side - but when one tire looses traction...

MGB's weren't really build for straight roads... The reason to want some setting besides zero is to compensate for "camber change" that naturally occurs as the suspension moves while turning. (It's a geometry thing.) Adjusting static camber is a compromise - the "ideal" suspension would have no "camber change" in turns.

Although it's certainly feasible analyze suspension geometry and make an educated guess, most savvy racers test drive their cars and then take temperature readings across the width of their tires. Then, based on tire temps (and lots of testing), they can come up with a "best compromise" camber setting for their car on a specific track. Even this is affected by roll stiffness, torsional rigidity, ride height, tire air pressure, etc., etc. (You might have noticed in the Les Gonda article that Les modified his lower control arms to make them adjustable.)

Summary? I'd go with Bill's advice.



Incidentally, you'll find more discussion of suspension parameters here:
An Overview of Suspension Design Parameters, by Larry Shimp

Thanks for the great answers, guys! I took your advice.