Front end alignment
My friends '61 was pulling to the right slightly so knowing the history of this car we decided to investigate the front suspension. Found some issues and corrected them and now feel confident that all it needs is another correctly done alignment. My question is can the alignment be done by us or does it absolutely have to go to an alignment shop. Can the caster and camber be set properly somehow by us? I do believe toe in can be done fairly easily with a good tape measure but what about the caster camber issue? Thanks.
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Re: Front end alignment
David,
If you had a caster-camber gage you could do it yourself, but I would highly recommend having it done professionally. I have done them both ways and can attest to the fact that the best alignment will be done with a modern day computerized alignment rack. This is not that expensive, and most shops will provide you with before and after computer printouts showing the specs.
Lynn -
Re: Front end alignment
Just had my 62 aligned after a front end rebuild. My mechanic took it to a shop that had an old timer that did some of the old stuff. He explained setting the upper-outer bushing to the guy, etc. they got it as close as they could to the original specs. Their machine program had specs for a 62. It drives pretty good now but I told them I would drive it for awhile and bring it back to recheck.
John FComment
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Re: Front end alignment
There was a thread here about 2 weeks ago with specs for solid axles.
Just remember to take the service manual to any alignment shop for them to use.Comment
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Re: Front end alignment
My friend took his '61 back to the alignment shop Friday and got the same results as before. The shop could not get enough caster on the right side. Or was it camber? Well, it wouldn't adjust to specs. Any ideas here? We were careful with the upper outer to be sure it was centered correctly and seems to adjust things. Just not enough. Can it be offset to the front or back in order to gain some? Thanks.Comment
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Re: Front end alignment
I've done the alignment on all my cars for the last 25 years with a Sears inclinometer and tape measure and can get closer to the specs I want than some clown with a $150K alignment machine, but since I have never done a C1, I don't know the details of how they are adjusted.
In any event, the "cross readings" should be as close to zero as possible, which can sometime limits your options on achieving your targets.
If you want to get into more detail, post the OE alignment specs and what the machine measured. They all create printouts, and the customer should ALWAYS DEMAND the sheets that include the initial (before any adjustments) and final measured settings.
Otherwise, any discussion of alignment on a specfic vehicle is just a waste of electrons.
DukeComment
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Re: Front end alignment
You can align any car with a hardware store inclinometer and tape measure and get the camber and caster within a quarter degree of your target and equal on both sides.
The other thing you need is a "surface plate", and if you have a home garage built in the last 40 years that has no signs of buckling or severe cracks it will probably do. Measure the "tilt" in the width direction with the inclinometer, and if it's no more than about a quarter degree, it's a satisfactory "surface plate". Most garages have a slight "tilt" in the length direction to promote water drainage, but if it's less than about 1/2 degree, it's not a big deal.
Camber measurements can be made directly with the inclinometer.
Caster is the difference in camber readings with the wheel at full lock in each direction, but getting the sign right can be tricky.
On the left side postive caster is indicated when the camber reading at full right lock is in the negative direction relative to the camber reading at full left lock.
If the readings are -1/2 at full left lock and +1/2 at full right lock, then the caster is:
1/2 -(-1/2) = +1 deg.
Likewise on the RH side if the reading is +1/2 with the wheel at full right lock and -1/2 with the wheel at full left lock the camber is +1 degree.
I always record my readings and make a chart with symbols that show the wheels at full left and right lock with a space for the respective camber readings with the wheels in each full lock position.
Postive caster always produces camber gain in the negative direction on the outside wheel, which is good.
I set all my cars to maximum negative camber within the adjustment range, equal on both sides- up to -1 degree, and at this camber setting set both sides caster to the maximum (positive) achieveable within the adjustment range, equal on both sides.
Cars with power steering can run a lot more positive caster than manual steering cars. For example, I set my 1988 MBZ 190E 2.6 to the maximum achieveable negative camber, which was -3/4 deg., and the maximum positive caster I could get at this camber setting, equal on both sides was +10.5 degrees, which is at the top end of the spec range, but you can't run that much caster on a manual steering car.
My manual steering Cosworth Vega front camber is set at -1.0 deg. but the best caster reading I could get was zero deg.
In search of higher caster, I swapped the upper control arms - left side to right and right to left and was able to achieve +6.0 deg. caster at -1.0 deg camber. The car turned in like a go-kart, but the steering had enough kickback to damned near break your arms, so I spent the next day swapping the upper control arms back to their original sides and resetting the alignment to -1.0 deg, camber and 0 deg. caster.
Getting it right is a somewhat back-breaking, all-day job with many resets and measurements, but once it's done properly and the suspension components are in good condition, it should hold for many tens or thousands of miles and years.
BTW, for anyone with a ST-12 - how about posting the aligment setting data for C1s.
DukeComment
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Re: Front end alignment
C1 data as shown in Section 14 of ST12 is as follows:
Caster: 2deg, plus/minus .5deg
Camber: .5deg, plus/minus .5deg
King Pin Inclination ( towards center of vehicle ) 3.5-4.5deg
Toe in per wheel: 1/16"-1/8"
Toe Out on Turns:
a/Inner Wheel:20deg, plus/minus 2deg
b/Outer wheel:24deg, plus/minus 2deg
for Duke.. where are you placing the inclinometer to measure things? I have a digital unit that resolves to 10ths of a degree that has a magnetic strip .. seems like it would be just the ticket.. do you do this on the wheel? or remove the wheel and stick to the hub??
Best Regards to All, Dave.Comment
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Re: Front end alignment
Unless I am reading this all wrong, I believe the term Surface Plate to refer to a flat Level surface upon which to base your measurements.. without this, there is no reference point.
That being the case.. my take is that the dolly idea would not work.
Please feel free to shoot this argument down , I am making assumptions based on my own interpretation of the term "Surface Plate"
Best, Dave.Comment
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Re: Front end alignment
Dave,
I'll let the experts comment on this, but from what I've read on this and other posts, the surface plate is use to allow the front wheels to move easily from left to right. In another post, someone suggest using to pieces of cardboard with grease in between. This would be easier to set up since using the wheel dollies would require you to jack each corner up to get the dollies in position.Steve L
73 coupe since new
Capital Corvette Club
Ottawa, CanadaComment
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Re: Front end alignment
Toe out on Turns
+ - 2
Outer Wheel 24 + - 2Comment
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Re: Front end alignment
If guys are talking about Go-Jacks or something similar, I'm not sure they would work unless they raise each corner the same amount within a pretty tight range, but someone should give it a try.
One of the reasons DIY alignment in your garage takes so much time is that every time you make an adjustment, you have to roll the car back and forth while turning the steering wheel back and forth to get the suspension to settle out.
On alignment machines the tires sit on plates that are free to move, which negates the need to resettle the suspension.
One can place the inclinometer against the tire, but depending on the tire any raised lettering may affect the reading, so you have to be careful. You can also use the wheel rim flange. It takes a bit of practice and comes down to the specific tire/wheel, and the key is to make multiple measurements that are consistent, which should provide confidence that your measurements are accurate.
Given the posted C1 specs I would recommend shooting for zero deg. camber, which is the mid point of the OE spec or go as negative as you can up to -1 deg. if you drive aggressively and want maximum cornering grip.
As I said more caster is good for steering "feel", turn-in response, and staight line tracking, but it increases steering effort, so if you have good upper body strength go for +2.5 deg. caster, but if you're over 65 set it at 1.5 deg.
Radial tires have more self-aligning torque than bias ply, so running the caster at the low end of the range, should be okay with radials.
King pin axis inclination is the same as what is called steering axis inclination on a ball joint suspension, which is the inward tilt from vertical of a line through the ball joint centers when viewed from the front.
Is the steering axis inclination actually adjustable on a C1?
Steering/kingpin axis inclination creates another inportant parameter called scrub radius, which is the the lateral distance between the point where the steering/kingpin axis intersects the ground plane and the center of the tire contact page. In the C1 to early C4 era this number was positive - the point of intersection was inboard of the tire contact patch center.
If you can visualize, the larger the steering axis inclination the more the contact patch will move down as you add steering input. This essentially lifts the front of the car creating a self centering effect even with zero or slightly negative caster. But steering axis inclination also produces positive camber gain on the outside wheel in a corner, which works against the negative camber gain of positive caster.
Also, if you rotate the tire about something other than the center of the contact patch, it will increase the amount of torque required, which increases steering effort, so the further the scrub radius is from zero, the higher the steering effort.
I don't know why American cars had positive scrub radius for so long. Maybe Maurice Olley could have told us. Europeans pioneered negative scrub radius - probably as far back as the fifties. Actually it was near zero, and zero scrub radius reduces steering effort and pull if side to side braking is uneven and it's a virtual necessity on FWD cars to minimize torque steer.
I think it was the 1988 suspension redesign when the C4 went to a zero scrub radius design, and virtually all modern cars are zero or near zero scrub radius designs.
Since you have to package the ball joints inside the wheel to achieve zero scrub radius, large diameter wheels with lots of positive offset are required, and on a MacPherson strut design you usually end up with a fairly high steering axis inclination, so Mac Pherson strut designs require lots of postive caster to get a decent negative camber gain curve when the wheels are turned.
DukeComment
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Re: Front end alignment
Talking with a Corvette shop today the owner suggested that we need to use more "shims" where the front cross member attaches to the frame. Most cars of C1 vintage have one under each side but more can be added to correct for front end alignment issues. What do we know about this?Comment
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