Less BS about changing tire alignment specs from stock (a.k.a. let's rant about Mopar suspension some more)

[pnora]

Easier said than done, given that the suppliers of modern digital alignment racks continue to include factory settings which - as has been mentioned time and time again here - are not usable for radials. Not unless you want to wind up in a tree, anyway.

Happy Mopar owners having their cars serviced at Mopar dealers isn't exactly a good sample size, especially since - 50 years later - there's no sign of consensus regarding B-body geometry, only fervent schools of thought in direct opposition.

"Easy steering" is a vague (irony not intended) term and has multiple interpretations, as is "old car" steering.

As I mentioned in my original commentary, the 3-turn variable ratio Saganaw side-mount steering box in my '71 Mustang and the other 4-turn Saganaws I've experienced in 1970's-era Fords and Craprolets all meet the definition of "old car" and "easy steering." They're light and can be turned in with little effort. However - in my opinion - I wouldn't call them "sloppy," and in my experience, they are definitive in directionality. You turn the "easy steering" and - for normal street driving - it goes exactly where your brain estimated that amount of steering input would place the car.

I have nothing against this "old car" steering and I like it very much.

The Mopar box can just as easily be called "old car" and "easy steering," but not anywhere on the same level as the Saganaw box. I would absolutely classify the feeling as sloppy, excessively light (i.e., the shaft is not connected to anything light), and extremely vague. This isn't my assessment of a Mopar A or B-body with bias-ply alignment settings (yes, that experience is in my wheelhouse), this is my assessment after nailing down a correct, modern alignment with proper caster and camber.

That type of "old car" steering I can do without.

I'm inclined to believe much of the lore that has been passed down to these days around old car experiences comes with a caveat of single-brand loyalty, so these experiences - even within the same era - are sometimes not representative of the era. Heck, this even applies for late model vehicles. An LX or LD Charger rack doesn't feel the same as some Kia/Hyundai racks of the same era (though similar), and if the regular driver of either were to step into a BMW of the same era, they'd discover a much stiffer beast.

Incidentally - side note - similar side-mount Saganaws to the Fords were fitted to Dodge B-vans after 1994 and up to 2003 as well. While the springs in them are tuned to provide more resistance to turning, the general directionality and self-centering is on par with the 1970's Saganaws. They may not have the feel of a power rack-and-pinion, but somewhere, someone at Chryco - prior to DamilerChysler - decided that a Saganaw box designed back in the 1960's was fit for a vehicle of the 1990's...and the Mopar box wasn't.

-Kurt

My head hurts.

 

[cudak888]

My head hurts.

Better get that checked out along with the hot air button.

-Kurt

 

[toolmanmike]

See post #13. Scott has sold and set up alignment equipment for decades and was a front end/ alignment tech at a dealer before that. The post is what he recommends.

Camber / Castor

 

[pnora]

Better get that checked out along with the hot air button.

-Kurt

I had to replace the battery in it. Someone must of wore it out.

 

[cudak888]

I had to replace the battery in it. Someone must of wore it out.

Last time I had to replace it, I found out it was an English reproduction with non-OEM Lucas smoke fluid.

-Kurt

 

[dvw]

How is that? Don't many machines also reference directly off the rim flange?

Everyalignment machine I ever used had compensation for runout during the setup procedure. So any wheel or hub runout was corrected for. Tire runout didn't matter since nothing was touching them except the ground. As far as alignment adjustments? They can get you only so far. After that geometry may need a change. But by then you are talking Auto-Cross, Road Race or Oval. I seroiusly doubt anybody is taking corners on an unknown public road surface as fast as the car could actually corner. If anybody really wants to know. They should read up on weight transfer, roll center, ackerman, anti dive, and bump steer to start. Learn what these terms are and how they affect handling. The Mopar factory stuff is pretty good. Just depends on how carried away tou want to get. Anyone thinking adding tube arms, solid joint strut rods and setting the caster high hasn't done much to improve anything. For sure the old specs don't translate to modern tires. Power steering boxes can be upgraded. Offset bushings will usually allow alignment specs in a decent range. Want to look into some of the most tricked out suspension systems? Take a real close looke at a dirt Late Model.
Doug

 

[j-c-c-62]

"Every alignment machine I ever used had compensation for runout during the setup procedure. So any wheel or hub runout was corrected for. "
That would be very interesting to know how, unless maybe the wheels are lifted and spun?


"Tire runout didn't matter since nothing was touching them except the ground"
You lost me on that one.

Most of what else you mentioned seems to be irrelevant here when the often common accepted suspension mods are often based mostly on "what harm could it do?".
Beyond that it seems bragging rights, the next new thing and a car driving straight without hands with a smooth ride is the holy grail.

 

[j-c-c-62]

Not exactly. From reading other posts, I was led to believe it was the major determinant towards improving self-centering (short of tire width, of course).

Knowing what I’ve experienced since, caster has since become a much lesser, secondary deity.

-Kurt

And with that we agree, "caster is God" is my takeaway of the normal mindset and my point, and you discovered "God is Dead" and my apologies to those put off by my poignant analogy.

 

[cudak888]

And with that we agree, "caster is God" is my takeaway of the normal mindset and my point, and you discovered "God is Dead" and my apologies to those put off by my poignant analogy.

He's not dead, he's just pining for the fjords.

 

[Keith926]

I may as well jump in! No expert on old Mopars but I've dabbled, well versed in wheel alignments professionally. On any brand of car, especially older RWD models, squish play in tie rods can be a common oversight and contribute to loose/poor feel. Longitudinal torsion bar Mopars are often in need of lower control arm bushings. If the car doesn't pull and the cross caster is ok I am not too concerned with caster being in spec, especially if it's a stock car, it likely had that caster setting all along, and caster is a non wearing angle. If the camber is out just a little sometimes a torsion bar adjustment can give the couple degrees with ride height staying the same. Looking at all your measurements on a machine, a lack of caster can be compensated with some camber and adjusted easier. Even if the caster and camber are slightly out of spec and can't be brought in, with the right cross caster/camber ratio you should be able to make it drive OK and keep tires. Whether you run 1/8" or 9/16" toe in they have their pluses and minuses. Say a late 90s BMW 3 series, some owners claim stability at speed vs an older American sedan, tight parking lot maneuvers in that BMW can feel like it's a 4wd on dry pavement, crank 35-40 degrees of total toe in your classic and it will be more stable at speed too. The biggest trick I find is having tight tie rods and easy adjusting sleeves, no resistance from the threads, 4 wheel alignment, and compensate for the thrust angle with the front toe adjustment. The alignment readings shown here for that white car are something like +20 left rear toe, -20 right rear toe, +12 left front toe, +12 right front toe. Say the total toe spec for the front was 20 plus or minus 5, you would leave the RF at 12 but set the LF at 10 to compensate for the thrust angle

 

[j-c-c-62]

"non wearing angle" Meaning tire wear contributor?
"squish" meaning sloppy?
"no resistance from the threads" that does not affect end result just the ease of obtaining it?

 

[Keith926]

"non wearing angle" Meaning tire wear contributor?
"squish" meaning sloppy?
"no resistance from the threads" that does not affect end result just the ease of obtaining it?

caster does not play a major part in tire wear

squish play is found by compressing the tie rod up and down, say with a channel lock plier from the top to end of the stud, lots of times tie rods are only checked for side to side play

If there is resistance it is harder to achieve the end result, multiple attempts vs one, sometimes you go back and forth between the two sides bringing it in, when it moves like butter things happen. Even on a modern rack and pinion in salt country, when you replace an outer tie rod end, wire wheel the inner and make sure the jam nut moves freely. Me talking about how that .02 degrees compensates for a thrust angle isn't easy to achieve if you are wresting with it

 

[dvw]

caster does not play a major part in tire wear

squish play is found by compressing the tie rod up and down, say with a channel lock plier from the top to end of the stud, lots of times tie rods are only checked for side to side play

If there is resistance it is harder to achieve the end result, multiple attempts vs one, sometimes you go back and forth between the two sides bringing it in, when it moves like butter things happen. Even on a modern rack and pinion in salt country, when you replace an outer tie rod end, wire wheel the inner and make sure the jam nut moves freely. Me talking about how that .02 degrees compensates for a thrust angle isn't easy to achieve if you are wresting with it

I agree with your tie rod statements. Though I haven't found squish in many older Mopar tie rod ends. Idler arm play seem to be a big concern. In this same topic. Performed over 5000 aligments in my day. All in Michigan. I found many turnplates on the racks at various shops were bound up. Obtaining an accurate toe reading without having easy moving turn plates is pointless. At home the best you can do is at least roll the car back and forward a good distance. Then again there isn't to much you can do to compensate for runout. It's funny about tougts of people needing a ton of caster. My 64 Belvedere regularly hits over 147 mph. Drives straight as a string with 2 1/2 degrees of caster.
Doug

 

[cudak888]

I agree with your tie rod statements. Though I haven't found squish in many older Mopar tie rod ends. Idler arm play seem to be a big concern. In this same topic. Performed over 5000 aligments in my day. All in Michigan. I found many turnplates on the racks at various shops were bound up. Obtaining an accurate toe reading without having easy moving turn plates is pointless. At home the best you can do is at least roll the car back and forward a good distance. Then again there isn't to much you can do to compensate for runout. It's funny about tougts of people needing a ton of caster. My 64 Belvedere regularly hits over 147 mph. Drives straight as a string with 2 1/2 degrees of caster.
Doug

What's your current toe, Doug?

-Kurt

 

[dvw]

What's your current toe, Doug?

-Kurt

1/8" in
Doug