C5 Alignment Geometry
Thread Starter
Instructor
Joined: Apr 2002
Posts: 247
Likes: 2
From: Naples Florida
C5 Alignment Geometry
Always thought my C5 FRC felt a little loose on the track. If I pitched it into a corner, it got a little light in the rear and had to counter steer a bit. I also felt like I had to really modulate the power in corners to keep the back end under the car. Well................I checked my rear toe and found it was 1/16th out. No freakin' wonder! I changed it to 4/16th toe-in and driving around town it feels like the rear end stays a little more planted. I'll see at the next track event.
What are you guy's doing and what difference has rear toe adjustments made?
What are you guy's doing and what difference has rear toe adjustments made?
Le Mans Master
Joined: Dec 2000
Posts: 9,918
Likes: 1,879
From: Hot Springs AR
Re: C5 Alignment Geometry (ifeeltheneedforspeed)
Boy, that describes exactly what my '00 FRC felt like last weekend. I just got the car a few weeks ago, and I was using the Active Handling in Competition mode, and just assumed my problems were all driver. Think I'm going to check my alignment (at least the toe) before my next event week after next.
Have a good one,
Mike
Have a good one,
Mike
Instructor
Joined: Mar 2002
Posts: 106
Likes: 0
From: Columbus GA
Re: C5 Alignment Geometry (ifeeltheneedforspeed)
Toe out on the rear will certainly make the car feel loose.
Is that total toe in on the rear, or per side? Typically I would expect 1/16 toe in per side.
Also ride height and brand of tire can cause these same problems with poor handling. The run flat tires are awful. What is your ride height front and rear measured from the ground to the fender lip, and what are the brand and size tires that you are using?
Is that total toe in on the rear, or per side? Typically I would expect 1/16 toe in per side.
Also ride height and brand of tire can cause these same problems with poor handling. The run flat tires are awful. What is your ride height front and rear measured from the ground to the fender lip, and what are the brand and size tires that you are using?
Burning Brakes
Joined: Jun 2000
Posts: 1,122
Likes: 0
From: Annapolis, MD USA
Re: C5 Alignment Geometry (ghoffman)
Gary - When I have had my car aligned, I have always specified inches in setting toe-out (front) and toe-in (rear) but the printouts I get show toe in degrees (e.g., total toe = -0.21* front, +0.28* rear. Thrust angle is (+)0.01, which doesn't seem right.
How can I translate toe degrees to inches?
Regards, Robert
How can I translate toe degrees to inches?
Regards, Robert
Le Mans Master
Joined: Feb 2000
Posts: 5,708
Likes: 1
From: Bedford NH
Cruise-In II Veteran
Re: C5 Alignment Geometry (rbeckham)
To convert, take the sine of the angle and multiply it times the tire diameter. For example:
for a 27 inch diameter tire, and 0.28 degrees
(sine0.28)(27)= (0.00489)(27)=0.132 or a little more than 1/8 inch (.125)
This is for the total side to side toe. Conversly, to get the degrees from a inch figure, take the arcsine of the toe/tire diameter
OK for further reference,
Toe (in inches) Toe (in degrees)
for 27 inch overall diameter
1/16....................0.133
1/8......................0.265
1/4......................0.531
for 28 inch overall diameter
1/16....................0.128
1/8......................0.256
1/4......................0.512
[Modified by ghoffman, 9:23 AM 7/6/2002]
for a 27 inch diameter tire, and 0.28 degrees
(sine0.28)(27)= (0.00489)(27)=0.132 or a little more than 1/8 inch (.125)
This is for the total side to side toe. Conversly, to get the degrees from a inch figure, take the arcsine of the toe/tire diameter
OK for further reference,
Toe (in inches) Toe (in degrees)
for 27 inch overall diameter
1/16....................0.133
1/8......................0.265
1/4......................0.531
for 28 inch overall diameter
1/16....................0.128
1/8......................0.256
1/4......................0.512
[Modified by ghoffman, 9:23 AM 7/6/2002]
Burning Brakes
Joined: Jun 2000
Posts: 1,122
Likes: 0
From: Annapolis, MD USA
Re: C5 Alignment Geometry (ghoffman)
Gary - thanks! For my 25.3" tires, this works out almost exactly to 1/8". I am so glad the alignment folks are smarter than I am.
You REALLY da man!
You REALLY da man!
