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Discussion Starter #1
I need to know what the scrub radius is on a c5 corvette. Thanks. I know it changes with the amount of backspace behind the wheel.
 

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All C4's and C5's have a Zero Scrub Radius Suspension.

A fine point: It MAY change by increasing wheel backspacing.

By using a positive offset in a wider wheel the Scrub radius can remain stable.

For example: placing wider 10.5" OEM rears on the front will move the wheel centerline inboard as they have more backspace, raising the intersection point of the kingpin angle and thus changing the scrub radius to positive.

However by using 10.5" CCW wheels with the allowable SCCA 0.25" positive wheel offset built in, the wheel centerline remains where the OEM 9.5" 's is and the Zero scrub radius is retained.

NOTE: Scrub Radius is defined as the point of intersection of the king pin angle (a line drawn through the upper and lower ball joints and the mid line plane (steering plane) of the wheel (tire). If they meet at the ground surface the scrub radius is Zero. If the steering plane is moved inboard, the point of intersection is raised and the insection is above ground and is said to be positive (by some amount). Likewise if the wheel centerline is moved outboard (positive wheel offset) the intersection is below ground and the scrub radius is indicated as negative. This point of intersection scribes an arc (radius) during suspension deflection.
 

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Discussion Starter #4
i am building a tube frame car with a manual steering rack. I have been told it would be best for me to use about 1 inch of scrub radius to improve the feel at the steering wheel.
 

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DJWorm said:
All C4's and C5's have a Zero Scrub Radius Suspension.

A fine point: It MAY change by increasing wheel backspacing.

By using a positive offset in a wider wheel the Scrub radius can remain stable.

For example: placing wider 10.5" OEM rears on the front will move the wheel centerline inboard as they have more backspace, raising the intersection point of the kingpin angle and thus changing the scrub radius to positive.

However by using 10.5" CCW wheels with the allowable SCCA 0.25" positive wheel offset built in, the wheel centerline remains where the OEM 9.5" 's is and the Zero scrub radius is retained.

NOTE: Scrub Radius is defined as the point of intersection of the king pin angle (a line drawn through the upper and lower ball joints and the mid line plane (steering plane) of the wheel (tire). If they meet at the ground surface the scrub radius is Zero. If the steering plane is moved inboard, the point of intersection is raised and the insection is above ground and is said to be positive (by some amount). Likewise if the wheel centerline is moved outboard (positive wheel offset) the intersection is below ground and the scrub radius is indicated as negative. This point of intersection scribes an arc (radius) during suspension deflection.
What did he just say? That just went right over me but I am sure through proper translation, it means something. Yes, Worm...You seem to know ALOT! :usa:
 

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I recommend using a Sweet Manufacturing rack. Not necessarily a manual unit. The Sweet can be ordered in many different ratios.
 

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DJWorm is the "Ken Jennings" of the Vette World. :z: We're fortunate to have him on the site and thanks for sharing all your time providing insight and information. :ity: :thumb:

Bob
 

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Discussion Starter #11
worm it is funny you reccomend them. I have their catalog sitting in front of me. I believe they are a Michigan company. They make all kinds of different products, with a good reputation
 

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DJ Worm i race a outlaw super late model on asphalt oval tracks. I have a 5 and a half inch scrub radius on each side/ inside the center line of the tire. Car in the center of the turn has tendency to shove the nose up the track. The more the car is steered the worst it is. What do you think? I was thinking reducing the scrub to a .5 inside the tire center line. Thanks
 

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DJ Worm i race a outlaw super late model on asphalt oval tracks. I have a 5 and a half inch scrub radius on each side/ inside the center line of the tire. Car in the center of the turn has tendency to shove the nose up the track. The more the car is steered the worst it is. What do you think? I was thinking reducing the scrub to a .5 inside the tire center line. Thanks
Sorry bro, DJ hasn't been on the site for 4 years.

Mike
 

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MikesZ06, I have been away for awhile raising grandkids. came back to ask DJ a question, and two years later I find out he's left town? Is there an archive of his posts by chance?
 
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