Front End Caster, Camber

[lalessi1]

Caster is the angle of the axis (when viewed from the side of the car) that the wheel rotates around as it is steered. (Think of the forks on a chopper.) Zero caster means that this angle is 90 degrees to the ground. Positive caster means the angle is tilted to the rear, negative caster, the angle tilts to the front. Postive caster contributes to negative camber of the outside wheel as it is turned. It can be measured by the change in camber from straight ahead to full lock.

Positive caster causes the tires as they turn to actually raise the car. This makes the car difficult to steer. On the other hand the weight of the car wants to straighten out the wheels so positive caster increases the car's directional stability.

On '57 cars the caster angle is adjusted by changing shims on the upper control arm pivot shafts from one end to the other thus moving the upper ball joint forwards or backwards. A difference of 1/16" in the shim "stack" front to rear is a change of 1/2 degree in caster. No more than an 1/8" difference in the shim stacks is "allowed".

On '58 and '59 cars the upper control arm can be moved forward or rearward by "screwing or unscrewing" the pivot shaft inside the bushings. See the pic...

I tried to measure the difference between the '74 ish Gran Torino spindle angle and the stock '57 spindle and was unsuccessful. I do believe that the Gran Torino spindle has more positive camber by the "eyeball" test but that could have been a biased judgement.

I just rebuilt my front suspension and have yet to get it on the ground. I shimmed the lower conrol arm forward to help get as much negative camber and positive caster, and I used '59 upper control arms and moved them as far rearward as I could 

[lalessi1]

Rich, sorry we hijacked your build thread but you know how it goes..

I do get the math thing (not for everyone) .... Milling the shaft does not seem like a good thing to me. According to the shop manual, a 1/16" shim  equals a 1/4 of a degree! To get 1 degree of camber you would have to mill off 1/4 of an inch.... can't be safe. 

I believe that in the early 60's, Ford went to an eccentric bolt arrangement on the lower control arm for the rear mounting point that allows for better camber adjustment that perhaps could be adapted. That along with the later upper control arm bushing design gives us opportunities to better adjust alignment.

A while back I posted about "measuring the turning radius", this gives a "simple" explanation of measuring "turnangle1" and turnangle2". Just a thought...

http://57fordsforever.com/smf/index.php?topic=5428.msg41870#msg41870

[gasman826]

The latest and greatest in alignment is to adjust camber first.  Fat tires should be as flat to the road as possible...leaning a little to the negative (radial tires seem grip a little better with slight negative (-1/8° at the most) and no more than 1/8° difference side to side.  One side could should have 1/8 - 1/4° toward the positive (for road crown...most roads have a crown to run the water off to the shoulder).  This is to the driver's taste.  Fat tires and stiff suspension will require less side to side difference.  The more modern thought is to run both side cambers the same and use a caster difference to 'hold the road'. 

Caster is adjusted second.  Positive caster helps hold the road at higher speeds.  Positive caster means the upper ball joint is rearward of the lower ball joint.  Positive caster makes for more steering effort because turning requires lifting the vehicle.  Power steering eliminates this issue.  Manual steering requires a balance between stability and steering effort.  With power steering, set as much positive caster as possible while keeping the same amount on both sides within 1/2°.  Using the 1/2° side to side difference to 'hold the road' and keep fat tires flat to the road.  After making adjustments, camber must be rechecked and tweaked if necessary.  And then, recheck caster. 

Finally, toe in.

Plus this and minus that is all about the vehicle and the technician's experience.  Wide tires, narrow tires, bias vs radial, heavy vs lighter vehicles, stiff vs soft suspension, and driver preference all make for differences.  Most of these comments refer to common street driving (tire wear and stability)...speciality (performance, racing) driving has a complete different set of adjustments.  Don't even get started on anti-dive!

http://www.hotrod.com/how-to/chassis-suspension/0503sr-how-to-front-end-allignment/

[hiball3985]

If the camber only changes 1/4 with a 1/16 shim that doesn't sound like much. I seem to think it changed more then that when we were playing with it at the shop, I don't know if the Granada spindles would act differently to a small change as compared the OEM? I wouldn't think of taking off 1/4", I was just going to take maybe .050.

Adjusting for crown here in Calif is a waste of time  Most roads just follow the basic contour of the ground which changes constantly. We actually have freeways that are crowned the wrong way and flood in the middle rather then draining off the shoulder. Before I retired I spent 25 years building roads. State, county and city motto is build it as cheap as possible because it will cost twice what we planed anyways
So I try to have settings equal both sides. I like -2 camber but can only get -1 on one side and 0 on the other, caster at +2 and with the radials I find 1/8 toe in better the 1/16, the radial side wall flexes more then a bias. It's stable up to 90 mph, haven't had it faster then that..

[SkylinerRon]

FYI,
There are new aftermarket upper control arms for tri-5 chev with
the balljoint holes offset to the rear for 5* tilt !

Ron.

[Frankenstein57]

I used the torino spindles, and wasn't able to shim the caster the way I wanted it. I believe we milled 1/8 to 3/16 off the face of the cross shafts, we get some pretty rough roads up here when the frost goes out in the spring, no problems.  Mark