Cross Caster vs Cross Camber....

[pitts64]

I was wondering what differences I would see switching to cross camber from cross castor.. My 64 Pontiac drifts to the right unless I add some extra positive castor to the right side. What I don't like is the steering is a little harder making a left turn and during light braking, the car has a slight favor to the passenger side..

I was going to try adding some negative camber to the passenger side with some positive caster to the drivers side to even out caster... The 64 Pontiac manual recommends cross camber for road crown..

My car is just a street car...

Any thoughts?

Thank you,
Jeff

[rustomatic]

The 49 year-old car will not be perfect. Shim stacks, in other words, along with caster settings, will more than likely never be the same on each side. I tried a perfectly square alignment on my (50 year-old) Falcon, but for normal usage, the right front still likes a bit more caster than the left. The number of shims and inequality between sides in my upper control arms has finally inspired me to get some adjustable Total Control UCAs; there are also many other benefits to these arms, but cost is not one of them.

In 2.5 years, I've probably changed the alignment on my Falcon 15 times (in my own garage, which is at least free). I'll be doing it again soon...

[pitts64]

I spent the last two days changing shims and toe settings. It handles like a formula car around bends toed out but straight away is a ping-pong match..

I had adjustable uppers made by Marc at SC&C, the car handled exactly the same as it did with the stock uppers with solid joints, only trouble was, when I lifted the car, the uppers hit the frame so I sold them, I took a beating ($$$) on that deal..

[MonzaRacer]

SLA cars you compensate for road crown with CASTER, as camber causes tire wear. Anywhere from 0.50 to 1.00 degree MORE positive(top of spindle farther back) on right front. With camber you will get some issues in tire wear AND tire temps and handling in road and autocross courses More positive caster means lighter, easier steering from car,,,want more "feel" or "heavier" steering use less caster.
Also remember CASTER IS NON TIRE WEAR FACTOR of alignment.
Also dont forget checking and adjusting bump steer so as to alleviate twitchy feeling driving straight down road with least amount of tow it/out possible and no tire wear.
EVERY car requires adjusting for mods and design of parts.

[Bryce]

More positive caster means lighter, easier steering from car,,,want more "feel" or "heavier" steering use less caster.
Also remember CASTER IS NON TIRE WEAR FACTOR of alignment.

I always thought it was the opposite.... More caster harder to turn the wheel.

[MonzaRacer]

I always thought it was the opposite.... More caster harder to turn the wheel.

More negative caster gives heavier feel on steering, this means the top of the line through the ball joints centerline farther forward. Tilt it farther back, more positive caster and lighter steering.
This is UP TO A POINT.

[Norm Peterson]

I would not be afraid to run a little cross camber, though I would not suggest trying to fully compensate for road crown in that manner. Maybe a little cross camber plus a little less cross caster than you already do have would work out. Emphasis on the "a little's".

Positive caster angle

The pivot points of the steering are angled such that a line drawn through them intersects the road surface slightly ahead of the contact patch of the tire on the pavement. The purpose of this is to provide a degree of self-centering for the steering - the wheel casters around so as to trail behind the axis of steering. This makes a car easier to drive and improves its directional stability (reducing its tendency to wander). Excessive caster angle will make the steering heavier and less responsive, although, in racing, large caster angles are used to improve camber gain in cornering. Caster angles over 7 degrees with radial tires are common. Power steering is usually necessary to overcome the jacking effect from the high caster angle.

http://en.wikipedia.org/wiki/Caster_angle


Norm

[Bryce]

Norm,

That agrees with what I previously thought.

[MonzaRacer]

Yeah well wiki has issues. Caster is used for road feel, crown drift and wheel return. Camber is for contact patch. Regardless of what some people think use camber to adjust for camber wear, contact patch, camber gain maximum (ie compression) cross camber will jack with most properly set up cars autocross or road course handling.
EXCESSIVE caster angle should have been how it was listed in wiki. Yeah if you go overboard on anything your going to get reduced benefits and have to FIX the issue ie power steering.
IF you require more than 1 degree split on caster for road crown your either on roads not properly resurfaced or some part of the steering design is NOT right. Generally .5 deg more caster on right front or LESS should handle most any North American paved road.
Also with wider/stickier tires you shouldnt require as much caster but this isnt a hard and fast rule.
For the protouring crowd unless your redesigning a suspension to actually USE and EXCESSIVE amount of Caster its has mucho diminishing returns. I have found most cars that run in our group max needed unless track only car might be 6 degrees.
I have gotten some older A bodies right off the frame rack, had them drove for about a month and gotten them to give me a 6 deg right/5.5 degree left positive caster setting, hold it and you could drive the cars, with manual slow boxes, with your pinky and literally they would almost follow the road, even around mild curves (assuming the road builder actually didnt get crown and curve angles botched up.
I have been doing alignments for 25 yrs, used everything from strings, digital levels and tape to Hunter Hawkeye/DSP series alignment equipment, even got to try out the Beissbarth (personally its a POS but the idea makes me wonder how long till it happens,,,ie touchless alignment/no heads on wheels) But even manufacturers use a basic head that either touches to hangs on wheel as far as I have seen,, but then every NEW car off truck should be driven and rechecked by dealer before prep begins. I would even recommend dealers offer a 90 check up for free as cars do settle some.
Only cars I have seen requiring over the 5 to 6 degree max caster would be a streamliner/speed record type car. Most guys on here LIKE turns and curves.
Use a 0.5 degree split and test drive if it goes straight, leave it. Most of these cars on here have enough time/wear on frames etc that 4 to 6 deg will handle 99% of all your needs.
Again CROSS CAMBER will affect your tire patch/handling more than caster.
Good luck

[Norm Peterson]

Yeah well wiki has issues.

I realize that. It was simply the first available.

OP was stuck with a factory recommendation to use camber instead, which I would have questioned as well. That said, I wouldn't be afraid to run the right side camber a tenth of a degree or so more negative than the left side (but I wouldn't ever set cross the opposite way). I haven't done nearly as many alignments as you have, but I have been DIY'ing all of my own for a little over 30 years at this point. Haven't screwed one up yet.

That wiki text actually did use the term "excessive", just that it probably isn't possible to nail it down any closer generally. That said, steering should still be heavier at +3° caster than at +2°.

But even manufacturers use a basic head that either touches to hangs on wheel as far as I have seen,, but then every NEW car off truck should be driven and rechecked by dealer before prep begins.

That's what they'd do ideally, not what happens in practice.

I've been kind of glad that neither Ford nor my Ford dealer was particularly conscientious about it with the Mustang in my sig - its cambers have been a whole quarter degree more negative than the max-negative end of the acceptable range ever since it rolled off the production line. About -1.75° vs -1.5° max negative, and I'm getting dead-even wear across 7 tires out of 8 (the odd one was only 0.02" more worn on one shoulder rib than the other the last time I measured tread depths).

Only cars I have seen requiring over the 5 to 6 degree max caster would be a streamliner/speed record type car. Most guys on here LIKE turns and curves.

Static +caster rolls into negative camber on the outside wheel as the wheels are steered, which is exactly what's wanted for hard cornering. In this situation, additional straight line stability is not the point at all. If anything, taking advantage of this effect allows you to set LESS static camber, which then benefits hard braking and tire wear in that situation. FWIW, the preferred static caster setting for the current Mustangs is +7.1° (with 0.75° factory-acceptable tolerance either side of that). Even for the V6 versions.

As a side note, this effect is what the alignment procedures using caster sweep take advantage of in order to determine caster. I doubt very many places have on hand the means to measure caster directly even though that is possible.



Norm