Moss Motors, Ltd

Enfoperfect-

There is a very technical and correct description of the ackerman angle that would probably make your head explode if I were able to describe it using only words and no pictures so I will give you the short answer.....

The Ackerman Angle causes the difference in the amount that the inside and outside wheel turn when you turn the steering wheel. If you look closely when you turn the wheel hard left for example you will notice that the left wheel turns in more sharply than the right wheel. This is very convenient since the left wheel has to trace a sharper turn  than the right wheel during a left turn since it is closer to the inside of the turn and therefore turning a shorter radius. When you make a right turn the opposite happens, the right tire turns in more sharply than the left wheel with the same benefits.

If you have the diagram that shows how it is caused and you put some thought into what is going on that makes it occur you can modify your suspension to either exaggerate or lessen the effect depending on your goals. 

The reason Mike runs "Toe Out' on his car is so that when he turns the wheel the inside wheel turns in an exaggerated amount, doing more work, resulting in the car turning into the turn more sharply and abruptly.  Good for Autocross, maybe a little sketchy on the street. With the toe out while driving in a straight line the tires are both slightly scrubbing or skidding down the street. As the grip changes due to bumps or anything that can change the relative traction between the two front tires the car darts or wanders back and forth slightly. Under braking the same thing occurs, but since the tires are more heavily loaded the symptom is exaggerated and the car darts to and fro.

A car can also dart to and fro under braking due to "Bump Steer"  which is caused by a change in the" toe" on the car due to the suspension moving up or down.

LCJUTILA 

Thanks for the description LC. I guess then that the Ackerman angle is (or is at least related to) the angle between the steering arm at the knuckle (can't remember the roper name) and the stub axle. If that's right, I don't see how you could change it other than some cutting and welding since the whole thing is effectively one piece. And yes, I do understand how that works and why. Just never heard the name before or at least don't remember.

Bayless

 

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Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)

Oops, looked it up last night and discovered that the steering arm bolts on for the Spridget. Guess it wouldn't be hard at all to change the angle then.

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Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)

Enfoperfect-

Sure, throw in some washers and away you go!  HA HA HA! Very funny... (not making fun of you Enfo- I'm making fun of the fact that there are very few simple suspension geometry modifications.) 

Sure- You could change the ackerman angle so the toe changed more slowly or more quickly by modifying the steering arm, but if you did you would also be modifying the bump steer and potentially the steering ratio. This could be good or bad or both.

My 69 Mustang has a kit that changes the Ackerman Angle, the Bump steer, and makes the steering quicker all with a single piece that you bolt on to the bottom of each steering arm. SO SIMPLE! Until you think about all the time the guy spent designing it and cursing all the unintended consequences each tiny change made.  Hey, the thing works great and it's a great improvement over the stock set-up.

 If you wanted to do the same thing on an MGB you'd probably have to correct the bump steer generated  by either shimming the steering rack or the tie rod ends and testing the suspension after each correction through it's expected range of motion to see if your changes either improved or exaggerated the situation.  Very time consuming but if you got it right you'd have the "Unfair Advantage". The Holy Grail of racing.

LCJUTILA