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What you need to remember is that when the alignment specs for the Squarebirds were written for the Shop Manuals, they were for Bias Ply tires, not the radials of today... I understand there is a difference... Unless I am wrong...
Good info on radials vs. bias is hard to come by, but based on a general article I read years ago on the adoption of radials in the US, the change is toe should be zero to a max of 1/8" in.
I can see bit of toe in, since we have all that slop on the many pieces of the steering linkage, but why would you not run a hair of neg camber (or zero at least) and as much caster as you can crank in?
........., since we have all that slop on the many pieces of the steering linkage, but why would you not run a hair of neg camber (or zero at least) and as much caster as you can crank in?
Adjusting the front suspension specifications to rectify "slop" would amount to the proverbial "two wrongs don't make a right"!
As far as the camber values, general it is revealed that in these types of suspension systems, the positive camber number coupled with a more conservative caster value will provide aid in reduced low speed turning effort. This is particularly of concern in heavier vehicles and/or those equipped with wider tires (and woman drivers); this at the sacrifice the of higher speed handling characteristics available if a negative number were utilized.
Note that the suspension alignment values as printed are those deemed by Ford engineering at the time, to be the best compromise for the average intended operator, in the typical environment. Therefore, one may deviate from the "printed word" for ones' own applications as best suited; values often established thru observations in the tire wear exhibited.
Adjusting the front suspension specifications to rectify "slop" would amount to the proverbial "two wrongs don't make a right"!
As far as the camber values, general it is revealed that in these types of suspension systems, the positive camber number coupled with a more conservative caster value will provide aid in reduced low speed turning effort. This is particularly of concern in heavier vehicles and/or those equipped with wider tires (and woman drivers); this at the sacrifice the of higher speed handling characteristics available if a negative number were utilized.
Note that the suspension alignment values as printed are those deemed by Ford engineering at the time, to be the best compromise for the average intended operator, in the typical environment. Therefore, one may deviate from the "printed word" for ones' own applications as best suited; values often established thru observations in the tire wear exhibited.
Scott.
It's not slop from bad parts, it's multiple part tolerance buildup (no rack and pinion), softer rubber bushings in suspension than you have in today's vehicles, taller sidewalls that squirm more, etc....
You have low speed steering effort problems? I don't (exactly the opposite, steering could use some firming for effort), except the ratio is ridiculous by today's standards. If I could get 5 degrees caster, I'd take it in a heartbeat. 2 degrees would be for a manual steering setup.
And your going to have to give me a much better reason for positive camber than the one you did. Maybe tracking was a bit better with non radial tires back in the day. The only vehicle I know of that uses positive camber is a unimog (and only because I have those axles in my 79 bronco), and thats only for better traction on "sidehilling" from the tire that is uphill (inherently less traction).
Unless someone could give me a real good reason not to, I'd align to
1/16" toe in
-1/2 degree camber
max attainable caster.
I would have to recommend, one to follow the O.E.M.'s alignment specifications, as the real engineers set forth these specifications with the considerations of the engineering at hand, and not just some sound-good values with comparisons to other non relevant engineering and of a different period.
And, since we brought up other engineering observations; I purchased a new 1979 Ford F350 4X4, and realized that the front suspension exhibited significant positive camber, far in excess of that exhibited in my 1978 F250 4X4. As this is a straight axle front unit, the camber value is set in assembly and adjustments are not intended (although minor sums can be achieved with shims, yes). Upon inquiring, the engineering rep. for Ford stated that this was done intentionally, because the F350 4X4 received as standard equipment, the Dana 60 front axle from the previous year(s) "Snow Plow Option" from the F250 4X4, and that the positive camber sum as set by Ford, was to aid in the steering effort with the additional weight of the installed snow plow, and with the additional loading on the front suspension when in use.
As far as heavier vehicles such as trucks, particularly of old, I happen to own several military vehicles (2-1/2, 5, 10, & 22 ton 6X6's & others) ALL of which exhibit a positive camber value, for the reasons stated previously.
Again, do I feel that the numbers supplied originally as being correct for any and all instances, NO! But remember, when one chooses to deviate from the O.E.M.'s specifications, that makes you the new engineer!
So, in my previous post I mentioned one might observe the tire wear characteristics and thru such determine if the specifications match the environment. Are you, the typical driver as Ford intended, do you operate the vehicle on the roads envisioned in mid 20th century, and yes, are you riding on radials? And also, keep in mind that some of the driving characteristics as experienced by the driver are those as intended within the period, and as expected by the purchaser, then, not now.
With the alignment set at the O.E.M.'s specifications (if one can find anyone who can accomplish such properly), are there any issues, that one feels can be addressed thru alignment value deviations? Or perhaps, one feels that some of the newer understanding of suspension values can be infused into their older engineered example and improve upon that which was originally delivered? There's plenty of information available on this subject, beyond the capacity of this forum, and I would recommend one become familiar with the subject if one intends on something other than the known. Do keep in mind, if one wishes to be aggressive, there are going to limitations to what can be accomplished without major endeavours. But, with some experimentation, one may reap the reward of a system tuned to their personal tastes.
Controlling a bias-ply tire with all its squirm and only 32-PSI is truly a challenge. One way to help control this squirm is to actually produce squirm equally on both sides by using excessive toe-in. This is exactly what engineers did, at the expense of more tire wear. Back in the day, if we got 15,000 miles out of a tire, that was HUGE.
Truck tires are a different animal altogether. Those tires have more plies and are pumped up, sometimes to 100-PSI. That eliminates squirm, makes the tire stiff but it also creates less drag, less friction and more miles out of the tire. Tire 'ride' and 'noise' isn't considered.
Our books are clearly engineered and written for using bias-ply tires because that's all there was at the time. Conveniently, your 'personal luxury car' needs a soft ride that bias ply tires produce.
The most expensive 1960 tires were horrible by today's standard. When Sears introduced radial tires from Michelin, Dayton, Ohio wasn't having any part of it. U.S. tire makers fought the radial market for many years, even after Motor Trend and others proved positive improvements with radials. Sears was getting 25-35,000 miles from their 'Guardsman' radial tires while we were stuck in the 'fiberglas' era.
There are plenty of examples of modern Ford cars (not trucks) that have ball-screw steering and radial tires. Which ones? Grand Marquis, Crown Victoria, etc. Use those spec's for your Squarebird alignment as the suspension geometry and vehicle weight are similar. - Dave
There are plenty of examples of modern Ford cars (not trucks) that have ball-screw steering and radial tires. Which ones? Grand Marquis, Crown Victoria, etc. Use those spec's for your Squarebird alignment as the suspension geometry and vehicle weight are similar. - Dave
Excellent idea Dave, as those right around the 90's early 00's had very similar weight, solid rear axle, full set of steering links (with even an idler arm like SQ's), and upper and lower A-arm suspension. Can't get much closer than that. Interesting
they allow positive toe with the tolerance.
And as I suspected, very close to what I would do (suspect you can not get that much caster, but still max it out) and recommend.
1991-02 Crown Victoria, LTD Sedan and Wagon, Grand Marquis, Colony Park Wagon
CASTER (degrees)
5.5 +/- 0.75
Henry, because Ford has invested in great Automotive Engineers (mechanical and electrical), I always ask myself: 'What do the car manufacturers use?'
So many materials and practices have changed since Squarebirds were engineered and produced. We have two things that work to our advantage; improvements in cost & function and the time to prove these new techniques are in fact improvements (many were not).
Some things were carried over for many years then slowly replaced like, recirculating ball screw steering boxes, incandescent bulbs and the transition from SAE to metric standards.
Radial tires, electric wipers, electric coolant, fans, relays, etc., are used exclusively now.
Grounded (metal) lamp housings, floor headlight dimmer switches, vent windows (wings), sealed beams are gone.
Radial tires became popular when Ford still produced full-size models with ball screw steering. Any yes, this directly pertains to our classics. (So does retrofitting to Rack and Pinion.) - Dave
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