Request for terminology definition

[tyoneal]

To All:

Could someone explain to me what, "Custom designed independent suspension to achieve a zero scrub radius with a low king pin angle", means?

This is a term I have not come across yet, and I am curious what exactly it means and what it does for the cars handling?

Here is some more context, and some questions within the statement that I added.
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ROAD STEEL CHASSIS DESIGNED FOR, "0", SCRUB FRONT SUSPENSION

BENEFITS:

*VERY SMOOTH COMFORTABLE FEEL OF THE FRONT TIRES

*DOES AWAY OF JARRING AND TWISTING FOR ON FRONT WHEELS (Does this mean that you can run really big front wheels and tires and it wont try and track the grooves in the street?)

*BETTER STABILITY ON STARAIGHT AWAYS

*LESS TIRE WEAR/CAN USE SOFTER COMPOUNDS

*TOUGHER DUE TO LESS LEVERAGE ON SUSPENSION COMPONENTS

*LONGER CONTROL ARMS EQUAL LESS ANGULAR CHANGE/LESS ROLL CENTER MOVEMENT

*COIL-OVER ASSEMBLY CLOSER TO L OF TIRE/GIVING BETTER SHOCK AND SPRING MOTIONS

*CONSISTENT ROLL CENTER LOCATION DUE TO LESS ANGULAR CHANGE

*LESS STEERING EFFORT

*LESS BENDING LOADS ON FRONT UPRIGHT ASSEMBLY

*TIRES ROTATE ABOUT THEIR OWN CENTER RATHER THAN BEING DRAGGED THROUGH AN ARC DEFINED BY SCRUB RADIUS

*STEERING IS MORE PRECISE

*LESS SCRUB ALLOWS SOFTER TIRE COMPOUNDS TO BE UTILIZED

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Is this basically what the DSE and Speedtech front sub-frames do, or is this a totally different animal?

The terminology sounds like it is different, but I just really don't know.

I look forward to hearing all your comments and clarifications.

Best Regards,

Ty O'Neal



Thanks again,

Ty

[rwhite692]

The angle (as viewed from the front of the car) between the steering axis and 90 deg vertical is the kingpin angle. The more severe this angle, the more scrub you get. The more scrub, the more the car responds to any given amount of steering input and the more it eats up the front tires..

Kingpin OFFSET is the horizontal distance (again as viewed from the front) between the point where the steering axis would intersect the ground and
the center of the tire's contact patch. Kingpin offset and scrub radius are the same thing... Scrub radius = positive when the center of the tire's contact patch is outside of the steering axis' ground intersection point on the ground.

You want to measure Kingpin offset/Scrub Radius at zero degrees camber. Of course, you can modify your effective kingpin offset, with your wheel offset configuration.

[tyoneal]

Originally Posted by rwhite692

The angle (as viewed from the front of the car) between the steering axis and 90 deg vertical is the kingpin angle. The more severe this angle, the more scrub you get. The more scrub, the more the car responds to any given amount of steering input and the more it eats up the front tires..

Kingpin OFFSET is the horizontal distance (again as viewed from the front) between the point where the steering axis would intersect the ground and
the center of the tire's contact patch. Kingpin offset and scrub radius are the same thing... Scrub radius = positive when the center of the tire's contact patch is outside of the steering axis' ground intersection point on the ground.

You want to measure Kingpin offset/Scrub Radius at zero degrees camber. Of course, you can modify your effective kingpin offset, with your wheel offset configuration.

=============================

Thanks very much for the insight. Is this type of precision unusual, or just not mentioned when most people set up the front end of their cars? (As a Given)

I guess I'm trying to put it in perspective with what many people on this board are trying to install into their cars. I just had not heard it used as a, "Special Feature", in some of the really nice subframes on the market.

It has been mentioned that tires on the front that are much bigger in width than a 275 can be difficult to drive on the street. Is this what is referred to in red?

*DOES AWAY OF JARRING AND TWISTING FOR ON FRONT WHEELS (Does this mean that you can run really big front wheels and tires and it wont try and track the grooves in the street?)

Thank you for your patience.

Regards,

Ty O'Neal

[deuce_454]

with zero scrub radius (which it will only be with the specific tire.. or one that is wider by the same amount both inwards and outwards) your steering wheel will be VERY hard to turn without power assist as the tire wont roll, only twist....

and a wider tire will usually be wider outwards.. hence increasing trackwidth.. and scrub radius.. so yes.. and no to that question

and it will only have zero scrub at a specific camber/wheelsize combination so to say its a built in feature is somwhat non-sense.. my malibu also has zero scrub radius with the right front wheel on it

[tyoneal]

Originally Posted by deuce_454

with zero scrub radius (which it will only be with the specific tire.. or one that is wider by the same amount both inwards and outwards) your steering wheel will be VERY hard to turn without power assist as the tire wont roll, only twist....

and a wider tire will usually be wider outwards.. hence increasing trackwidth.. and scrub radius.. so yes.. and no to that question

and it will only have zero scrub at a specific camber/wheelsize combination so to say its a built in feature is somwhat non-sense.. my malibu also has zero scrub radius with the right front wheel on it

=====================

(Ah yes, Marketing!)
Thanks for clearing that up.

Best Regards,

Ty O'Neal

[ccracin]

Originally Posted by tyoneal

=====================

(Ah yes, Marketing!)

Ty O'Neal

Ty,

You hit the nail on the head. All of the information these guys gave you is accurate. The real point is that you have asked the question to begin with. Most people would read that description a say WOW that must be good. I'll take it. The folks you mention DSE and most others on this site can prove what they publish. There are alot out there that cannot. They play buzzword bingo and try to put stuff past you. Just give one of the street rod shops a call and start to have an in depth technical discussion. It will end just after "we have it polished as well" !

Later,

[deuce_454]

LOL exactly.. that reminds me of the sales material that came with a Glock.. it read "construted from hydra-treated space age polymer" which means its made from cheap PA 6. (nylon) and when this it injection molded the watercontent is low and as a result its brittle... and to remidy this you boil the part...

so instead of saying "we made this sucker from the cheapest nylon we could find to keep cost down... and as a result we have to boil it in water to keep it from breaking" some marketing guy came up with the above "hydra-treated..." BullS#1t .... or buzzword collection!