Keith
Lifetime Supporter
Wheel alignment and set-up, Part 1:
This weekend I installed the wheels and tires and put it on the floor for the first time. My first impression was "wow that is low".
To make a level platform to do the alignment I purchased two ten foot long 2 x12's and marked them with 95 inch center lines to approximate the wheel base. I marked two 20 degree reference lines from the inside portion on each 2 x12 at the front wheel location so that I could use my snap-on alignment gauges to measure caster on the front. After shimming the 2 x12's to get them level side to side and front to rear I set the car down on the them and again I said "wow is that low". I did an initial once over on each wheel with a carpenters level to roughly get camber and caster set and I "eye balled" the toe to get that close.
I placed four 60 lb bags of "play sand" ( one front, one rear and one on each fuel tank) simulate the weight of the body and interior. The Gt 40 chassis does not lend itself to a triangular measurement to make the rear axles perpendicular to the center line of the chassis. After some close measurements I found that the front edge of the chassis cowl (the part the dash sits on) is well within 1/32nd of and inch to being perpendicular with the chassis (thank you Fran!) so I used that to set the front to rear position of each rear axle using the trailing arms for the adjustment (once this is set you would only use one trailing arm to make the caster adjustment to keep the location the same side to side).
Here are a few observations to help other RCR owners in the future:
1. The coilovers have twelve threads per inch so twelve turns of the adjustment collar will bring the chassis up or down approxilately an inch.
2.Turning the upper ball joint one complete revolution will change camber approximately 1/4 degree. To get a finer adjustment you have to use the rod ends on the inside of the upper control arm, approximately 1/8th degree per turn or 1/16 degree per half turn.
3. Caster changes approximately 1/2 degree for every two washers moved on the upper control arm.
4. Set/check your ride height several times during the process as small changes in ride height can make changes in camber ( both front and rear)
5. When making adjustments to the front upper control arm you do not have to remove the wheel/tire. Just lift the front with a floor jack to get the weight off (coil over spring is loose), remove the castle nut ftom the upper ball joint and the arm can be removed/adjusted. The tire /suspension will just stay on the floor.
The suspension is very adjustable. I experimented with the max range of caster on the front and was able to change it from +8 to -3 caster with just the washers. You can easily get 3 degrees of camber change with just the upper ball joint alone. The rear has even more adjustment. (Thank you Fran)
As my car is intended more for street use I set it as follows:
LF RF
Ride height 4.5 inches 4.5 inches
Camber -0.5 -.05
Caster +3.5 +3.5
Toe in 1/16 in 1/16
LR RR
Ride height 4.75 inches 4.75 inches
Camber -0.75 -0.75
Caster +5 +5
Toe in 1/32 in 1/32
Keith
This weekend I installed the wheels and tires and put it on the floor for the first time. My first impression was "wow that is low".
To make a level platform to do the alignment I purchased two ten foot long 2 x12's and marked them with 95 inch center lines to approximate the wheel base. I marked two 20 degree reference lines from the inside portion on each 2 x12 at the front wheel location so that I could use my snap-on alignment gauges to measure caster on the front. After shimming the 2 x12's to get them level side to side and front to rear I set the car down on the them and again I said "wow is that low". I did an initial once over on each wheel with a carpenters level to roughly get camber and caster set and I "eye balled" the toe to get that close.
I placed four 60 lb bags of "play sand" ( one front, one rear and one on each fuel tank) simulate the weight of the body and interior. The Gt 40 chassis does not lend itself to a triangular measurement to make the rear axles perpendicular to the center line of the chassis. After some close measurements I found that the front edge of the chassis cowl (the part the dash sits on) is well within 1/32nd of and inch to being perpendicular with the chassis (thank you Fran!) so I used that to set the front to rear position of each rear axle using the trailing arms for the adjustment (once this is set you would only use one trailing arm to make the caster adjustment to keep the location the same side to side).
Here are a few observations to help other RCR owners in the future:
1. The coilovers have twelve threads per inch so twelve turns of the adjustment collar will bring the chassis up or down approxilately an inch.
2.Turning the upper ball joint one complete revolution will change camber approximately 1/4 degree. To get a finer adjustment you have to use the rod ends on the inside of the upper control arm, approximately 1/8th degree per turn or 1/16 degree per half turn.
3. Caster changes approximately 1/2 degree for every two washers moved on the upper control arm.
4. Set/check your ride height several times during the process as small changes in ride height can make changes in camber ( both front and rear)
5. When making adjustments to the front upper control arm you do not have to remove the wheel/tire. Just lift the front with a floor jack to get the weight off (coil over spring is loose), remove the castle nut ftom the upper ball joint and the arm can be removed/adjusted. The tire /suspension will just stay on the floor.
The suspension is very adjustable. I experimented with the max range of caster on the front and was able to change it from +8 to -3 caster with just the washers. You can easily get 3 degrees of camber change with just the upper ball joint alone. The rear has even more adjustment. (Thank you Fran)
As my car is intended more for street use I set it as follows:
LF RF
Ride height 4.5 inches 4.5 inches
Camber -0.5 -.05
Caster +3.5 +3.5
Toe in 1/16 in 1/16
LR RR
Ride height 4.75 inches 4.75 inches
Camber -0.75 -0.75
Caster +5 +5
Toe in 1/32 in 1/32
Keith