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Does camber change when you install radial tires

Started by Bob Hoffmann CLC#96, July 10, 2007, 10:58:57 PM

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Bob Hoffmann CLC#96

What I'm really asking is: when you install radial tires on for instance a 1957 GM car, do you use the factory camber spec. which is of course for bias tires? I remember reading some discussion on the subject somewhere. What about caster? Thanks, Bob
1968 Eldorado slick top ,white/red interior
2015 Holden Ute HSV Maloo red/black interior.
             
Too much fun is more than you can have.

The Tassie Devil(le)

G'day Bob,

The front suspension requires realignment for all specifications, but just at this moment I cannot recall the Camber and Castor changes, but Toe-in is 1/16".

A reputable Wheel Alignment place could give you the correct figures, and also some of the more edumacated personnel on this message board.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Wayne Womble 12210

Bob,

You have helped me so many times, maybe I can return the favor here.  We do this a lot on early Corvettes that came with bias tires. In general radials require less camber and toe. I dont know the specs on the Cadi. but with a Corvette we set the camber at or near zero to very slightly positive, and reduce the toe to about 1/16 inch.  I like to set the caster as high as possible, at least the highest spec. even a little more.

Don Boshara #594

I found this article somewhere, don't remember where but it might help:

Caster
Positive caster improves straight line tracking because the caster line (the line drawn through the steering pivot when viewed from the side) intersects the ground ahead of the contact patch of the tire. Just like a shopping cart caster, the wheel is forced behind the pivot allowing the vehicle to track in a straight line.
If this is the case, then why did most cars have negative caster specs prior to 1975 ? There are a couple of reasons for this. In those days, people were looking for cars that steered as light as a feather, and cars back then were not equipped with radial tires. Non-radial tires had a tendency to distort at highway speed so that the contact patch moved back past the centerline of the tire (Picture a cartoon car speeding along, the tires are generally drawn as egg-shaped). The contact patch generally moves behind the caster line causing, in effect, a positive caster. This is why, when you put radial tires on this type of car, the car wanders from side to side and no longer tracks straight. To correct this condition, re-adjust the caster to positive and the car should steer like a new car.
1940 Sixty Special
1966 Mustang Cpe

The Tassie Devil(le)

Quote from: Don Boshara #594 on July 11, 2007, 05:50:07 PM
I found this article somewhere, don't remember where but it might help:

Just like a shopping cart caster, the wheel is forced behind the pivot allowing the vehicle to track in a straight line.

G'day Don,

Couldn't resist this but when have you ever found a shopping cart that tracks straight?

Down here, every shopping cart has a mind of its' own, and then at least one wheel flaps all over the place.

Bruce. >:D

PS.   Thanks for the rest of the information though.   Now to keep it in my brain.
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Wayne Womble 12210

I thought that was just an Aussie  thing.  Everytiing going around to the right. Your storms, your toilet bowls, your roundabouts, but your shopping carts go around to the left. Yep they got a mind of their own, ours go around to the right.

Roger Zimmermann

Interesting...I have 2 cars with radial tires: my '56 Sedan de Ville and my '57 Brougham. The alignment of the front axle is the same as with diagonal tires and I have no problem. Both cars are driven that way since at least 15 years.
My '56 Biarritz is equipped with bias ply tires; when they are shot, I will install radial ones without changing something at the front axle.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

The Tassie Devil(le)

Quote from: Roger Zimmermann #21015 on July 12, 2007, 02:49:01 AM
Interesting...I have 2 cars with radial tires: my '56 Sedan de Ville and my '57 Brougham. The alignment of the front axle is the same as with diagonal tires and I have no problem. Both cars are driven that way since at least 15 years.
My '56 Biarritz is equipped with bias ply tires; when they are shot, I will install radial ones without changing something at the front axle.

G'day Roger,

When you get the cars aligned to "Correct-for Radial-Tyres" specifications, they will handle even betterer still.

I have been using Radial Tyres on all my cars since 1966, and made sure that the wheel alignment was done to at least 1/16" Toe-in, and my Wheel Alignment Specialist always knew what to do.   

I was always coming to him with odd vehicles like Hot Rods and the like, with totally modified suspensions, and he always knew what was needed, and got it right.   Pity he was a lot older than me, and retired, so I had to find another specialist.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

The Tassie Devil(le)

Also, don't forget to pump the Radials up an extra 4psi at least, over the recommended pressure for the Cross-ply's

I run 34psi in the tyres on my '60 CDV.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Roger Zimmermann

Quote from: The Tassie Devil(le) on July 12, 2007, 03:26:43 AM
Also, don't forget to pump the Radials up an extra 4psi at least, over the recommended pressure for the Cross-ply's

I run 34psi in the tyres on my '60 CDV.

Bruce. >:D
Thank you for your comments, Bruce. It's possible that the toe-in of my cars are correctly adjusted for radial tires, I did not do it myself. And, of course, the pressure is higher with radials! I have 2.2 to 2.3 bar which is about 32 to 33 psi.
Have a good day!

Roger
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101