Front or rear steer? Ackerman?

[jercars]

I always see suspension systems with the rack on the front and even the cars that start out with a rear mount get converted to front. Other than oil pan clearance is there a handling advantage for this. With my basic understanding of Ackerman I would think it is easier to get a good ackerman effect with the tie rods on the rear rather than the front. Can anybody help me understand what i'm missing?

[jercars]

I guess this is either a difficult question or just a stupid one. Hopefully one of those engineers can make sense of it for me.

[Cobra 498]

Rear steer is the way to go if you can package it, I moved my rack back 1" and my tie rod ends are almost touching the brake disks and I still can't get enough ackerman on my front steer setup.
I would go rear steer in a New York minute if I could package it, but the frame structure is in the way.

[Motorcitydak]

The answer really depends on what you are using for bushing material at the control arm ends. Actually front steer is more preferred. With rubber or even poly bushings you will get some flex and movement with load.

Say you are making a hard turn and compress the bushings inward slightly. With rear steer this will cause your tire to actually steer more which can cause even more understeer. If you have front steer in the same situation this will cause the tire to steer less and allow the inside tire to do some more of the steering work.

Ackermann is great if you can package it but it can be difficult to get perfect. If you have the room, go for it

[ace_xp2]

The other thing about front steer is it generallyputs the steering assembly under tension (or at least that heavier loaded outer link), which lets you go a little lighter duty on parts without getting deflection.

[Cobra 498]

The answer really depends on what you are using for bushing material at the control arm ends. Actually front steer is more preferred. With rubber or even poly bushings you will get some flex and movement with load.

Say you are making a hard turn and compress the bushings inward slightly. With rear steer this will cause your tire to actually steer more which can cause even more understeer. If you have front steer in the same situation this will cause the tire to steer less and allow the inside tire to do some more of the steering work.

Ackermann is great if you can package it but it can be difficult to get perfect. If you have the room, go for it

If you are using anything but good quality rod ends (NMB) and hard bushings you are not getting precision steering and if you don't have proper ackerman your car will be a pig in tight corners IE GoodGuys Autox. Street use is a different matter where compromise might be the best solution on a car that is not intended for competition use. Original 427 Cobras had reverse ackerman
because the steering arms were bent inward (by heating with a torch at Shelby American) to clear the front wheel rims. These cars under steered like a dump truck and the general consensus at was that it was due to the heavy iron block 427 when it was actually due to the lack of ackerman steering.

[jercars]

Looks like I'm on the right track then. I have no intentions on actually racing this car once it's done but I figured if i'm spending all this time and money building the it that I might as well build it right. My intended use for the car is a nice driver but when I decide to break laws I want to have fun doing in.

[j-c-c]

From what i have read FWIW, Ackerman is mainly a street and./or low speed attribute, and the intended use determines its worthiness.
Seems like a 427 Cobra understeer problem could be easily corrected with the right pedal.lol

[Cobra 498]

From what i have read FWIW, Ackerman is mainly a street and./or low speed attribute, and the intended use determines its worthiness.
Seems like a 427 Cobra understeer problem could be easily corrected with the right pedal.lol

Actually, Carroll Smith, author of a number of books on race car engineering and preparation wrote that parallel steer was all that was necessary on a race car because of tire slip angle differences between loaded and unloaded wheels. Years later in one of his last books he recanted and said that it was "the" answer for street courses. It is more important than ever with the extremely short sidewalls on modern tires and can make a big difference in how a car turns in and generally responds to driver input. You will see people toe their cars out at autox's because
they have little or no ackerman, if you can, put it in. Problem with the right pedal, massive understeer or snap oversteer unless you get it just right.