BS on changing tire alignment specs from stock.

[toolmanmike]

@Scott Engelhardt , what's your take? I bet you aligned your B body. What specs did you use?

BTW, Scott has been in the alignment business for years. Well, decades. I think it was back in 89 or 90 when I met you at Haydens.

 

[kiwigtx]

I imagine you set your timing at 7-8deg advanced and your carb a bit on the rich side as well.

That reminded me of this one.....

 

[toolmanmike]

That reminded me of this one.....

View attachment 1756086

 

[j-c-c-62]

I remember years back a discussion on combat fighter aircraft, and the one's that flew a bit skittish were the best in a dog fight, in that they did not resist course corrections.
Wonder if that might be a valid analogy here, in reference to ride/driving vs handling in this alignment discussion.

 

[TorRed]

I've read before (possibly here) that if one wanted to go to a 'radial friendly' somewhat performance front geometry, to use a 90's or 00's Mustang's specs. Can anyone confirm which year they were referring to?

Reading this thread with great interest, Thx

 

[toolmanmike]

I've read before (possibly here) that if one wanted to go to a 'radial friendly' somewhat performance front geometry, to use a 90's or 00's Mustang's specs. Can anyone confirm which year they were referring to?

Reading this thread with great interest, Thx

Mustang specs? Only if you have a Mustang II based front suspension.

 

[kiwigtx]

Mustang specs? Only if you have a Mustang II based front suspension.

Mustang specs you say .....

Rhubarb patch here we come.

 

[toolmanmike]

Mustang specs you say .....

View attachment 1756104

Rhubarb patch here we come.

One of those should be labelled "Rhubarb". Frickin cars are always up in the Rhubarb.

 

[copper67sat]

I remember years back a discussion on combat fighter aircraft, and the one's that flew a bit skittish were the best in a dog fight, in that they did not resist course corrections.
Wonder if that might be a valid analogy here, in reference to ride/driving vs handling in this alignment discussion.

Yes, same logic applies.

Most modern fighter aircraft are statically unstable (negative static stability) from a control perspective. Think of a ball sitting on top of an arch (statically unstable) vs. one sitting inside an inverted arch (statically stable, aka positive static stability). Perturb the positively stable ball and it will return to its initial position whereas the negatively stable ball will not. Negative static stability makes an aircraft maneuver quicker, but often requires computer controlled fly-by-wire systems to make the plane flyable. By comparison, a Cessna 172 is statically stable. Move the stick in steady level flight and release it and the plane should return to steady level flight.

Neutral stability is when you impart a path change and it stays on the new path versus returning (positive) or continuing to depart from the original path (negative).

Apply that to your car and you absolutely want positive stability. At most you may opt for less positive stability to make it turn quicker.

 

[Cranky]

mine was done with a laser so the specs should be what they say they are. mine handles very nice no numb feeling to speak of and I can take my hands off the wheel for 5 seconds at least. the tires were 1.3 negative camber before and were jarring over the bumps.

Jarring? Don't really know how much negative camber I had in mine but you could actually see it if you looked hard and can't see how negative camber could make a car be 'jarring'.....? Mine surprised me at the modifications at how well an old car could really be. I remember my first 'home alignment' I did and took it to a shop to see how is was. The tech said everything look pretty good except for the toe. Thought that was odd since setting toe isn't that difficult. Anyway, he 'corrected' it and charged me 25 bucks (years ago) and off I went. Man, that car felt like it wanted to fall over some bumps and dips. I checked the toe when I got home from my slow ride and found it to be more than 1/2" in!!! How do you do that on an alignment rack? Never took my older cars to an alignment shop again and this guy was recommended by several of my buds. Maybe he was looking for some beer money that day?

I posted previously a quote here from a recent "Racecar Engineering" magazine and it commented on the handling negatives of too much caster. We are not talking about harder steering nor the benefits straight line consistency. The article was taking about how caster effects corner weights and load transfer on the chassis when turning. I am definitely of the school too much caster has a downside, for handling. They even referred to unsuspended go karts to illustrate chassis jacking from caster. What amount of caster is too much, I suspect is very subjective.
I may not condone the OP's solution, but I can't broadly say his thinking is wrong

I agree with you on having too much caster but imo, the factory settings on Mopars can be improved on. Chassis jacking is definitively a thing and have seen it on some GM cars where people turned the steering wheel lock to lock while moving very slow. How much caster did those cars have in them!!? Anyways, thought it was strange the first time to see it.

 

[Cranky]

Yes, same logic applies.

Most modern fighter aircraft are statically unstable (negative static stability) from a control perspective. Think of a ball sitting on top of an arch (statically unstable) vs. one sitting inside an inverted arch (statically stable, aka positive static stability). Perturb the positively stable ball and it will return to its initial position whereas the negatively stable ball will not. Negative static stability makes an aircraft maneuver quicker, but often requires computer controlled fly-by-wire systems to make the plane flyable. By comparison, a Cessna 172 is statically stable. Move the stick in steady level flight and release it and the plane should return to steady level flight.

Neutral stability is when you impart a path change and it stays on the new path versus returning (positive) or continuing to depart from the original path (negative).

Apply that to your car and you absolutely want positive stability. At most you may opt for less positive stability to make it turn quicker.

I understand a bi-wing aircraft is even more statically stable......?

 

[j-c-c-62]

Jarring? Don't really know how much negative camber I had in mine but you could actually see it if you looked hard and can't see how negative camber could make a car be 'jarring'.....? Mine surprised me at the modifications at how well an old car could really be. I remember my first 'home alignment' I did and took it to a shop to see how is was. The tech said everything look pretty good except for the toe. Thought that was odd since setting toe isn't that difficult. Anyway, he 'corrected' it and charged me 25 bucks (years ago) and off I went. Man, that car felt like it wanted to fall over some bumps and dips. I checked the toe when I got home from my slow ride and found it to be more than 1/2" in!!! How do you do that on an alignment rack? Never took my older cars to an alignment shop again and this guy was recommended by several of my buds. Maybe he was looking for some beer money that day?

I agree with you on having too much caster but imo, the factory settings on Mopars can be improved on. Chassis jacking is definitively a thing and have seen it on some GM cars where people turned the steering wheel lock to lock while moving very slow. How much caster did those cars have in them!!? Anyways, thought it was strange the first time to see it.

Personally, bang for buck in improving handling on my cars, more improvement for me is found simply with negative camber, with increased uneven tire wear the biggest possible downside, the big smile big (relatively) negative camber puts on my face upon corner "turn-in", is all worth it.

 

[Speedbird]

I'm beginning to wish I had used my F body spindles instead of my A body ones.
Who knows?
This is a PITA. The original arms were too rusty and those things that are supposed to be threads were not really present.
This should be archived.
There is also that famous earlier article by you know who.

https://www.hotrod.com/how-to/mopp-0503-swapping-a-and-b-disc-brake-spindles/

 

[Rennkafer]

Exactly. As far as I know, about the only thing that caster will do for you is straight line stability (take your hands off the wheel and the car tracks straight down the road) Because of Chryslers "loosie goosey" power steering, some think that a lot of extra positive caster is needed to make up for the power steering. Not really. Correct the over zealous power steering pressure and a degree or so of caster is all that's really needed.

Caster also affects camber gain, so on suspension designs that don't have much built in (or worse, go positive), it can help in hard cornering. Like anything else, you can overdo it. The only real way to figure out what works best on any given combination of parts is testing different specs.

 

[j-c-c-62]

I should make a distinction here in my comments, "turn in" is the very initial bite response IMO noticeable before great steering input and/or significant suspension movement/chassis loading has occurred.

 

[AR67GTX]

I owned a 17 Shelby GT350 for a few years and while it was pretty much a track ready car it wasn’t a great car to drive around in on less than perfect city streets having a lot of tramlining and followed every rut and bump in the road. I discovered that factory alignment specs called for toe out, the engineers reason being that it sharpened initial turn in response in corners. It also promoted tramlining and scrubbing off the inside tread edge in short order. Checking with my gauge and sure enough it was toed out. I reset it for 1/16” toe in and while still a bit darty on rough roads it did calm down some of the tramlining and road wander. Sometimes engineers get a little carried away.

 

[copper67sat]

I understand a bi-wing aircraft is even more statically stable......?

They can be and often are, but not necessarily. Mostly the 2nd wing was needed to provide enough lift before lightweight, high strength materials were developed. It wasn't practical at the time to make a single wing large enough so a 2nd or even 3rd was added. They aren't used much today except for aerobatics due to their high roll rate and overall maneuverability.

 

[moparsaver]

I've read before (possibly here) that if one wanted to go to a 'radial friendly' somewhat performance front geometry, to use a 90's or 00's Mustang's specs. Can anyone confirm which year they were referring to?

Reading this thread with great interest, Thx

 

[j-c-c-62]

I owned a 17 Shelby GT350 for a few years and while it was pretty much a track ready car it wasn’t a great car to drive around in on less than perfect city streets having a lot of tramlining and followed every rut and bump in the road. I discovered that factory alignment specs called for toe out, the engineers reason being that it sharpened initial turn in response in corners. It also promoted tramlining and scrubbing off the inside tread edge in short order. Checking with my gauge and sure enough it was toed out. I reset it for 1/16” toe in and while still a bit darty on rough roads it did calm down some of the tramlining and road wander. Sometimes engineers get a little carried away.

I have heard of toe out on circle track cars to help turn in and assist stagger, but never on road race applications, but then if I knew everything, I would not be here.

 

[Scott Engelhardt]

Yes I have aligned my Satellite. Manual steering car. I have played with the caster and camber quite a bit. Stock suspension I started by adjusting the right side caster as high as possible, I think it was 3.75 caster and -1/4 camber. I adjusted the left side to match less 1/4 degree caster. The car drove great and straight. I liked everything about it except the parking lot maneuvering. After several hours and several test drives repeated. I found that right side 3 caster 0 camber. Left side 2.75 caster 0 camber. My car drives great, parking lot maneuvering is ok
Caster Has a great influence on cornering and straight line stability. Castor trail or mechanical trail helps with bringing the wheel back to center.
I believe that our cars can drive ok using that chart, but cars are individuals just like us.. Play with the numbers and road test to see what fit your car and driving style.
Also with our B bodies having torsion bars, make sure you set the ride height to where you want it before you have it aligned.
Remember there are other angles in play that need to be checked during a proper alignment
S.I.A. And included angle are diagnostic angles.