Re: [DML] Upgraded Front Suspension

["Martin Gutkowski" <martin@xxxxxxxxxxxxxx>]

I'm not an expert on this stuff but Mike Loasby is, and I'm repeating what he said. Having said that, I do know that toe in is innately stable.

Martin


Sent from my BlackBerry®

-----Original Message-----
From: "Tom Niemczewski" <dmctom@xxxxxxxxx>
Sender: dmcnews@xxxxxxxxxxxxxxx
Date: Sat, 29 Oct 2011 14:31:12 
To: <dmcnews@xxxxxxxxxxxxxxx>
Reply-To: dmcnews@xxxxxxxxxxxxxxx
Subject: Re: [DML] Upgraded Front Suspension

Martin,

Please don't take me wrong here, I'm not picking on you... you are just 
wrong.

Changing caster from negative to positive helps on uneven surface? NO, you 
are wrong.
Unless pretty much all of the world engineers designing car suspensions are 
wrong.
Think about the setup as a whole. Let's say that a you hit a pothole in the 
road. The LCA moves back and causes the caster to become positive. At the 
same time the distance from the frame centerline and the lower ball joint 
becomes shorter causing the wheel to be pulled in at the bottom (positive 
camber). The steering arm is now at an angle causing shortening and that 
causes the wheel to toe in. How can that help on uneven road?? The weight is 
transferred to the outside edge of the tire and pointed in (toe in).
How come rally cars have very stiff suspension components that do not allow 
any change in caster or camber?

Negative caster causes self centering of the steering wheel because the 
weight of the car pushing down causes the wheel to want to track straight. 
Changing caster to 0 or even further causes loss of traction and 
unpredictable "wander" in the front end as well as neutralizes the self 
centering of the steering. That's the reason why new cars are being design 
with A arms that do not allow any change in caster. That includes rally cars 
or even off-road cars.

Take care,

Greetings from Poland!
Tom Niemczewski
Vin 6149 plus 2418, 3633, 5030, 16473, 17086
Google earth: 52°25'17.66"N, 21° 1'58.40"E

--------------------------------------------------
From: "Martin Gutkowski"

> No you are wrong, the changing from negative to positive castor serves to 
> track the car straight over an uneven surface. This is what Mike Loasby 
> said. And I've now said it twice.
> -----Original Message-----
> From: "content22207"
>
> The LCA wiggling back and forth obviously serves no useful purpose. It is 
> an unfortunate consequence of making the sway bar try serve as a backwards 
> thrust arm -- a task for which it is totally unsuited.
>
> --- "Tom Niemczewski" wrote:
>>
>> From: "Martin Gutkowski"
>>
>> > Ed's setup attempts to restrain the fore/aft movement of the arm
>> > altogether when there is a reason for it in the first place.
>> > Martin
>>
>> Martin,
>> What is the intended fore/aft movement in the LCA? What's the reason for 
>> it
>> and what good does that movement do?
>>
>> I can't see any advantage in having LCAs so sloppy. To me this setup is
>> nothing short of a disaster. Under braking when the arms move back they
>> compress the springs unevenly, put unnecessary strain on the shocks and 
>> the
>> most important thing it destroys the entire geometry of the suspension
>> system - caster becomes positive, camber becomes positive, toe goes way 
>> in.
>> If the goal here is to loose grip and destroy the tires then this setup 
>> is
>> perfect.
>>
>> Am I missing something? Please put me on the right track.
>>
>> Thank you
>>
>> Greetings from Poland!
>> Tom Niemczewski
>> Vin 6149 plus 2418, 3633, 5030, 16473, 17086
>> Google earth: 52°25'17.66"N, 21° 1'58.40"E
>>
 



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