5 replies to this topic

[Tmeranda]

Anyone have any idea why EB designed this car with so much positive wheel camber?

[Jones Foyer]

I would assume the geometry of the suspension is based on the traction of the wheel working better during compression of the suspension. The camber goes more neutral under load with that layout. It is a solid front axle, so you don't maintain camber angles like you do with independent/double wishbone setups.

[David M. Woodhouse]

I would assume the geometry of the suspension is based on the traction of the wheel working better during compression of the suspension. The camber goes more neutral under load with that layout. It is a solid front axle, so you don't maintain camber angles like you do with independent/double wishbone setups.

This doesn't seem right to me. I think that the camber angle is determined by the front axle and will not change regardless of suspension compression, assuming no distortion of the axle itself. The axle is an extremely stiff piece of engineering and, in any case, there is precious little suspension compression at the front of a GP Bugatti. Remember also that the tires were very narrow and ultimate grip was low by today's standards.

I don't know the answer to the question, but think that it may have something to do with the road surfaces upon which the cars were intended to run. In the early 1920s most roads were unpaved and many races were run on roads that were less than smooth (think Targa Florio). The cars remain a delight to drive, and the inside front wheel leaning into the turn seems to pull the car through with minimal steering effort - at least that's how it feels to me on the rare occassions I've been fortunate enough drive GrandPrix Bugattis.

Woody

[robert dick]

From
http://www.bugatti-t...etter-no-27.pdf
page 8

Technical Appraisal
of the Bugatti Chassis
Hugh Price

"The steering geometry is discernibly Bugatti, due to its pronounced positive camber, but does not stray from convention otherwise. The chassis engineer of today might predict the positive camber to lead to understeer. Modern cars, passenger or racing, are, however, designed to work on smooth tarmac, and to fit relatively wide tyres. Bugatti settled on his ‘layout’ at a surprisingly young age, when roads were unmettled and tyres were narrow, beaded-edged, and when a car’s balance was not so much a matter of tyre contact. It seems remarkable, therefore, that decades later the set up provides such a well-balanced car using tyres with markedly different characteristics. No doubt the expected understeer from the large positive camber acts as a foil for the oversteer that tends to dominate the behaviour of the front-engined, rear-wheel drive layout."

[cpbell]

Is it a rule that writers from the Bugatti Trust must be called Hugh?

[fbarrett]

Friends:

I'm no Bugatti expert, but early Mercedes cars also had a lot of positive camber. I was led to believe that this was mainly because the narrow roads of the time were more steeply crowned than today's roads, to facilitate drainage, and cars were often driven straddling the center crown of the road. At least one Mercedes model, the early 1920s Targa Florio, had a dual ring-and-pinion set-up, so the rear axles could have more camber.

Frank

Edited by fbarrett, 25 June 2009 - 16:40.