Alignment (Part 2)

Lots of websites describe camber, how to measure it and how to change it but very few seem to actually discuss why one car’s recommendation might be for 0° but another car calls for -2°. It’s all to do with the tire behaviour as it moves around on the car. The sole purpose of camber adjustment is to optimize the tire’s contact patch as the car drives along. Unfortunately, that contact patch varies when the car is turning so it’s a dynamic feature. 

The effect of camber on contact patch while cornering

More negative camber resists the outside tire’s inclination (haha pun intended) to roll and reduce its contact patch, therefore increasing contact patch and grip while cornering. But too much negative camber can make the car tramline over irregular surfaces and reduces straight-line traction. It also wears the inside shoulder of the tire. 

Inner shoulder tire wear from negative camber

So how much camber is the correct amount? Technically, the camber specification needs to defined in a collaboration between the car manufacturer and the tire manufacturer. From a layman’s perspective, I think it is hard to draw any conclusions on what the correct alignment should be for a modern tire because we have an inherent catch-22. Tire manufacturers cannot specify optimal camber because it depends on the car the tire is fitted too. Manufacturers only specify optimal camber for the tires the car originally came with.

Most cars sold will have camber set close to 0 to optimize tire life and braking stability. Performance cars are generally set up to have negative camber to provide more contact patch in corners and accept more tire wear. The contact patch is also affected by weight, tire pressure (and therefore temperature) and ride height (and therefore speed). That’s a lot of variables to optimize with one single, static setting. 

I have come to the conclusion that the 30-year old recommendation of Ferrari with a specific 30-year old tire of the correct rim size is a starting point but if I end up having a little more negative camber that is OK and may give better grip at the front and less understeer which is the biggest issue I have with the 308’s handling. Some owners that have tracked their 308s have recommended around -1.5° for best grip. Therefore, I am going simply aim for between -0.5° and -1.5° and as close to equal side-to-side. 

Since I am not setting up a race car, I will conveniently ignore most of those and just focus on cornering but will ensure my tire pressures are correct and I have 80 kilos in the drivers seat to represent me.

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Disclaimer: 308restoration.com describes the restoration work I perform on my car and only my car. I am not a professional mechanic. The website content is presented for entertainment purposes only and should not be seen as any kind of advice, information, instruction or guidance for working on any other car. The opinions stated here are my own and no-one else’s.

2 Responses

  1. ATSAaron says:

    Have you look s up the alignment specs for the pre-abs 328 and compared them to the specs of your 308?

    • David says:

      They were not in the Ferrari bulletin I have (from 1981). I found an old fchat post saying -0.33 +/- 0.17 so close to the 308 but even more conservative. I will shoot for around -0.66 to -1.0 I think. I suspect I may be limited by the amount of thread on the suspension fork.

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