How much positive camber needed for radial tires?

[waterboychuck]

Will this thread help?
https://www.fordbarn.com/forum/showthread.php?t=27574

[rotorwrench]

The specification for toe in, caster, and camber may change a bit with radials but I think it's more of a "closer to one limit that the other situation". Radials like adjustments to be near zero while cruising. I say this because at a dead stop there is no road effect at all but going down the highway at 70, the road is pushing pretty hard on components. Toe in for example, is set for dead stop and therefore has to be set a bit toe in for it to be nearer zero degrees at 70 MPH.

Ford didn't start using roll control (stabilizer bars) till the early 40s. They were not near as stiff as the modern cars are set up to be plus the older cars are plenty heavy enough to get some substantial roll in a curve. Short and sweet of it is that entering a curve that is rated for 35 MPH, should not be attempted at 50 mph. These old cars aren't race cars after all.

This link is to a discussion about change of factory specs when adapting to radial tires on a car that was never designed for them. Post # 7 is the best I've read on the subject. http://forums.aaca.org/topic/169822-...s-for-radials/

Most front end shops know better to get carried away with modifications to factory specs. They are the ones who are liable for their work after all. What you want is a trial and error thing so don't shoot the messenger.

[Ol' Ron]

On the race car we use a heat gun to check tire alignment, and this usually requires a camber adjustment. Also toe in/out may be a problem.

[54vicky]

I totally agree with Coopman if you are open to some more advice you may want to check the toe 1/16 out will help a ton rear steer and front steer require different toe.also you mentioned you adjusted the box that is something that if you do not know how to do can be a big problem have some one that knows what they are doing check it out someone suggested using chalk to check air pressure and said if chalk remained in middle lower the pressure WRONG lowering will leave less in contact with road and cause a squirm feeling leading to tread roll in a turn.

[DocJohn]

Originally Posted by 54vicky

someone suggested using chalk to check air pressure and said if chalk remained in middle lower the pressure WRONG lowering will leave less in contact with road and cause a squirm feeling leading to tread roll in a turn.

I think that you misunderstand me. I didn't say 'middle of the tread'. I was referring to chalk marks on the shoulder from the edge of the tread onto the sidewall. It's a witness mark as to how far the tyre is rolling onto or off the tread as a function of tyre pressure and camber, and caster to some extent. There's no way chalk marks would stay on the middle of the tread unless something is seriously wrong.

[1931flathead]

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Who would drive a old car 50 mph in a 35 mph curve these old cars are not like the newer ones

[LazarusLong]

Originally Posted by V8COOPMAN

You've had several folks here-in trying to help you. Not an easy task from afar as a rule. Then, on top of that, you can't seem to remember the difference between caster and camber. Then, you want to throw-out a bunch of foul-mouthed lip service implying that WE are the idiots, all because you can't manage your meds. An attitude re-assessment would do you well on this forum. Plus, did ya ever think that trying to do 50 mph on a 35 mph curve (in a worn-out, old used car) may just be part of your problem in the first place? DD

While it is true I did have a couple of people try to help me,I also had several people insult me and try to do little "superiority dances" while doing it.


Is this high school?

[LazarusLong]

Originally Posted by waterboychuck

Will this thread help?
https://www.fordbarn.com/forum/showthread.php?t=27574

Thanks! I have it bookmarked for later reading.

[LazarusLong]

Originally Posted by 1931flathead

Who would drive a old car 50 mph in a 35 mph curve these old cars are not like the newer ones

Someone who forgets he is driving a old car,and is driving it like he is driving his modern pu?

[rotorwrench]

A person can figure where the caster and camber go as you load the car up with passengers & fuel so this is where the caster and camber are adjusted to get a decent figure for all around driving conditions. Middle of the road so to speak. You really have no idea where the camber goes on the outside wheel wheel in a turn but it definitely rolls that way and it has a big effect plus the steering gearbox is designed to give more turn angle on the inside than the outside and that can not be changed. It's built into the gearbox in the form of play. Wear will affect it but it can't be adjusted out. Also, if you adjust the toe in too close to zero, the car tends to wander around more so it has to have a bit of toe in left as a compromise.

[LazarusLong]

Originally Posted by 54vicky

I totally agree with Coopman if you are open to some more advice you may want to check the toe 1/16 out will help a ton rear steer and front steer require different toe.also you mentioned you adjusted the box that is something that if you do not know how to do can be a big problem have some one that knows what they are doing check it out someone suggested using chalk to check air pressure and said if chalk remained in middle lower the pressure WRONG lowering will leave less in contact with road and cause a squirm feeling leading to tread roll in a turn.

Thanks.

[LazarusLong]

Originally Posted by rotorwrench

A person can figure where the caster and camber go as you load the car up with passengers & fuel so this is where the caster and camber are adjusted to get a decent figure for all around driving conditions. Middle of the road so to speak. You really have no idea where the camber goes on the outside wheel wheel in a turn but it definitely rolls that way and it has a big effect plus the steering gearbox is designed to give more turn angle on the inside than the outside and that can not be changed. It's built into the gearbox in the form of play. Wear will affect it but it can't be adjusted out. Also, if you adjust the toe in too close to zero, the car tends to wander around more so it has to have a bit of toe in left as a compromise.

Thanks.

[1931flathead]

Originally Posted by LazarusLong

Someone who forgets he is driving a old car,and is driving it like he is driving his modern pu?

How can you forget you are driving a old car ?????????

[A bones]

Hey hi, Tom here in DE, I've re-read, also found the thread referenced by JSeery. I gotta take one more swing with the silly stick!

Sometimes, the obvious gets overlooked.

1. When you bought radials you (of course) paid for four. Right good.
( running radials on front only can spell bad squirrely-handling )
Been there done that, and got the Tee shirt.

2. Just to mention, those replacement wheels have been verified to have the same offset (or at least close to) as original. Yes/No?
.
AND and, To 31flathead, I'll admit I have pills that help me overlook the terrible shape my health has left me with, but I keep forgeting to take them

Hang in there..

[1948F-1Pickup]

Originally Posted by LazarusLong

Put new 2:15x75x15 radial tires on my 51 Victoria,and am wondering if anyone knows the exact amount of positive camber in degrees that is needed.


Car drives like a dream going in a straight line,but you do NOT want to hit a 35 MPH curve running 50. You know right away that you screwed up.


I am hoping getting the front aligned correctly for radials will help with this.

Just some general observations from someone who worked in the high performance suspension business many years ago.....
Assuming a double wishbone (SLA) front end, with rear steer spindles,
(and not knowing the camber curve generated by the upper & lower arms),
I would say you'd be looking at setting a zero static camber, if not a very slight negative number. This tends to help when your control arm geometry generates what is called positive camber gain. (If it's obnoxiously high positive gain, you would be more aggressive on negative camber settings.... at the expense of higher tire wear) This is not a race car, so you shouldn't be setting negative camber numbers that high anyway.
Rear steer spindles and you'll want to look at setting a very slight amount of toe in. Too much will cause tire wear and some other issues you don't want.
You'll want to run some positive caster..... way more than the "book" says.
Radial tires by construction have a specific "trail" that bias tires do not. Your
higher positive caster number speaks to this reality.

You never mentioned what your '51 does EXACTLY in this hypothetical "50 mph in a 35 mph turn"...... that would shed further light on your specific situation.

Even with correct alignment, you'll want to ensure any steering box play is addressed as well. You'd be surprised how that can effect things.

[FL&WVMIKE]

Originally Posted by LazarusLong

Radial tires need positive camber to handle correctly,but so far I can't find anybody that can give me a specific figure.

Radial tires do NOT need positive camber. You want to tire to be square to the road.
As the suspension compresses, the camber will change. Most cars go more positive to reduce traction, and make the front end slide before the rear in a sharp curve. This makes the car 'safer' to drive, as you simply let out of the gas, and the car regains control, as you're not chasing a rear end that is sliding out.

Race cars are designed for the camber to get more negative as the suspension compresses. Look up the 'Shelby' mod done to early mustangs. You lowered and upper control arm to help fix the camber issue.

Do NOT assume that radial tires 'need' more initial positive camber.

[LazarusLong]

Originally Posted by 1931flathead

How can you forget you are driving a old car ?????????

It's easy when you are driving a 1951 car in good mechanical condition on a 4 lane highway in good condition. It rides and drives as good as a new car. You only remember it's not new when you hit a sharp curve and experience the body roll.

[LazarusLong]

Originally Posted by 1948F-1Pickup

Just some general observations from someone who worked in the high performance suspension business many years ago.....
Assuming a double wishbone (SLA) front end, with rear steer spindles,
(and not knowing the camber curve generated by the upper & lower arms),
I would say you'd be looking at setting a zero static camber, if not a very slight negative number. This tends to help when your control arm geometry generates what is called positive camber gain. (If it's obnoxiously high positive gain, you would be more aggressive on negative camber settings.... at the expense of higher tire wear) This is not a race car, so you shouldn't be setting negative camber numbers that high anyway.
Rear steer spindles and you'll want to look at setting a very slight amount of toe in. Too much will cause tire wear and some other issues you don't want.
You'll want to run some positive caster..... way more than the "book" says.
Radial tires by construction have a specific "trail" that bias tires do not. Your
higher positive caster number speaks to this reality.

You never mentioned what your '51 does EXACTLY in this hypothetical "50 mph in a 35 mph turn"...... that would shed further light on your specific situation.

Even with correct alignment, you'll want to ensure any steering box play is addressed as well. You'd be surprised how that can effect things.

You'll want to run some positive caster..... way more than the "book" says.

Thanks. I am not an alignment tech,and wrote camber when I SHOULD have written caster. What I need to know is how MUCH positive caster to run.

You never mentioned what your '51 does EXACTLY in this hypothetical "50 mph in a 35 mph turn"...... that would shed further light on your specific situation.

The steering doesn't seem as positive,and I can hear the front tires screaming for help a little. The "panic" is probably accentuated by the body roll,something you don't have with truly modern suspensions.


And "No,I have no interest in playing "Boy Road Racer" with it,and really have no interest in going fast with it,period. It will keep up with the traffic a normal highway speed with no problem,and that is plenty fast for me,and most of my driving is done on 4 lane highways. I only occasionally get on roads with 15-35 mph curves when I am going to visit friends.


This whole thing is not a major problem. To me it just indicates the front alignment needs to be "tweeked" some to function as well as it should function with the radial tires,and I am anal enough to want everything to work as well as it can work.

[1948F-1Pickup]

Originally Posted by LazarusLong

Thanks. I am not an alignment tech,and wrote camber when I SHOULD have written caster. What I need to know is how MUCH positive caster to run.

Not trying to be a jerk here, but what is the caster spec?
My '48 F-1 truck with king pins wants 1 to 3.5 degrees. I run it with a
4 degree wedge. I may run more after I get done with king pin/bushing
replacement, etc.
Unless you run asinine numbers, the only determent to high positive caster numbers is steering effort at low speed.
I'd be really tempted to try 3 degrees worth on your '51. Or more.

Originally Posted by LazarusLong

The steering doesn't seem as positive,and I can hear the front tires screaming for help a little. The "panic" is probably accentuated by the body roll,something you don't have with truly modern suspensions.

Body roll isn't necessarily a bad thing. Negative camber gain in suspension movement is the "gold standard." You won't get that with a stock suspension but minimizing excessive positive camber gain is good. Another poster mentioned that factoid when they referred to the Shelby (Arning) mod done by lowering the upper control arm on vintage Mustangs to slow the onset of "bad" positive camber gain during cornering.

[1931flathead]

He has a new one going on now