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Old 01-26-2003, 10:21 AM   #346
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Originally posted by fReShJiVe
What are the effect of increasing ackerman angle???
Increasing ackerman will produce toe-out during a turn.

... not very helpful, huh?

This article explains ackerman steering pretty well.

http://www.rctek.com/handling/ackerm...principle.html
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Old 01-26-2003, 10:35 AM   #347
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the post doesnt help that much...but the link is GREAT!!
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Old 01-26-2003, 10:40 AM   #348
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In my experience, a greater ackerman angle (i.e. inside wheel turns in more than outside wheel) gives a smoother steering response, but less overall steering.

A smaller ackerman angle (inner and outer wheel turning similar amounts) gives a more aggresive steering response, and more overall steering.
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Old 01-26-2003, 10:53 AM   #349
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sosidge - as dalem said more ackerman will make the inner tires turn in more to the corner inner radius....will it give more turn in respose with less mid to exit steering??

thanks
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Old 01-26-2003, 10:58 AM   #350
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Quote:
Originally posted by fReShJiVe
the post doesnt help that much...but the link is GREAT!!
Now that you've had a chance to read the article I'll give you my $.02.

I just build per the kit instructions, determine how close to 'true' the ackerman is, and then go run the car. I then adjust the ackerman to 'true' and test again.

I tend to find that 'true' ackerman works best for me. 'More' ackerman seems to cause a push and 'less' ackerman scrubs corner speed.

Other people swear that adding or removing ackerman helps their car.

So my next answer is... it depends.
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Old 01-26-2003, 11:34 AM   #351
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ok let's see if i already understand the ackerman effect.....with more ackerman i will get more turn in steering with less mid to exit steering as more weight will be on the outside tires during that point of time and also due to outside tire is turning lesser in the direction of the turn which is alo why is has less overall steering with maybe an understeer effect....

and for less acker man why does it scrub off speed???is it because that the inner tires doesnt turn enough to the radius of the turn and which also cause the inner tires to slide on its sidewall rather than pointing towards the direction of the turn

hmm all these ackerman stuffs is making me fell like we are taling about caster.....

less caster - more initial turn in less on exiting steering(same as more ackerman)

more caster - less initial turn more exiting steering(same as less ackerman)

anyone care to enlighten me more on this??
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Old 01-26-2003, 03:45 PM   #352
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Looking at the picture in the link I gave earlier you see the outer tire tracking a perfect line for the circle it is following. The inner tire is either...

1. running a tighter circle than what it is following (more ackerman)

2. running a looser circle than what it is following (less ackerman)

Imagine instead that both tires are working together to make the turn (more realistic, just harder to point out the difference). Now you get...

1. more ackerman = toe-out (more entry steering, less on exit)
outside tire running outside of its circle, inside tire running inside of its circle

2. less ackerman = toe-in (less entry steering, more on exit)
outside tire tunning inside of its circle, inside tire running outside of its circle

Using front toe adjustments to get the same result hurts top speed on the straightaways, generates tire heat, and tire wear.
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Old 01-27-2003, 04:44 AM   #353
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Quote:
Originally posted by schumacher
alvin, mini coopers do not have rear roll bars, the rear suspension is not wishbone its trailing arm.

sanj
Hi!
For the record, I am not familiar with the mini cooper; the driver of the car told me himself. ANyway here is a trailing link suspension. I believe the "stabilizer bar" counts as a roll bar yes? 2nd, I am not familiar with trailing bar suspension. Haven't read that much yet



Finally, i went through my books here's a small section on the roll centre for trailing arm suspensions.
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Old 01-27-2003, 04:56 AM   #354
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Seems like ackerman affects the directions the tires point in a corner, whereas castor affects the contact patch in a corner.
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Old 01-27-2003, 05:26 AM   #355
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Every change you make to the suspension geometry has a slight impact on other things.

Ackerman is essentially to do with wheel angles during steering, affecting how efficiently the car uses it's tyres, and toe angles - but it will also have an effect on the tyres camber (depending on the caster setting, the tyre gains more camber as it steers).

The caster setting affects camber during steering as well - but it also has an effect on the cars desire to self-centre the steering (larger caster angles "lift" the front of the car more during steering, and because of the car's weight, that increases the car's desire to force the wheels straight again, decreasing steering).

So it's all very complex - and several adjustments can give the same kind of effect - that's why balance in set-up is so important (a car running strange wheel angles and drastically different spring and damper rates will not work as well as a balanced car, even if it feels right on the track).
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Old 01-28-2003, 08:51 PM   #356
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hey guys just wanted to clarify a question i have, the way i understand it a more angled camber link will cause more camber change while cornering than a link that is more parallel to the arm would. am i correct?
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Old 01-29-2003, 12:12 AM   #357
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yes
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Old 01-29-2003, 06:38 AM   #358
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spaz,

if you ran the arms parallel you'd get weird camber when you corned, i supsect it would end up going positive. In my friends Racing car Dynamics book, it suggests angling the upper camber link downwards to get negative camber on that side while cornering.

sanj
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Old 01-29-2003, 02:43 PM   #359
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ok thanks, yes i do run my camber link angled.
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Old 02-03-2003, 01:12 PM   #360
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