Wheel Alignment Specs for Radials

[TexRiv_63]

I am replacing all springs, shocks, and front end bushings / ball joints on my 63 Starfire. After that I will have to get the front end aligned - what are the correct specs to use with Radial Tires? I have the original specs in the shop manual but they were for bias ply tires, I assume radials would be different??

[Guest Jim_Edwards]

I am replacing all springs, shocks, and front end bushings / ball joints on my 63 Starfire. After that I will have to get the front end aligned - what are the correct specs to use with Radial Tires? I have the original specs in the shop manual but they were for bias ply tires, I assume radials would be different??

Don there are numerous threads on this question the below link is to one of the better ones.

http://forums.aaca.org/f162/alignment-208875.html

Jim

[TexRiv_63]

Thanks again Jim. Back in March you gave some alignment specs to Dave Yaros for a 62 Starfire:

(QUOTE)Dave you can try these as they are known to work well on some '60s cars. Beyond that it may become trial and error for individual handling preference.

1. Basic rule - No more than .25 degrees difference between driver's side and passenger's side.

2. +2.0 to +3.5 degrees caster.

3. -.5 to 0 degrees camber. No positive camber, please. There is no problem having a slight variation from driver's side to passenger's side to account for the crown in the road (only a big deal on older 2 lane highway driving.

4. 1/16" to 1/8" toe in (QUOTE)

I assume these would also apply to my 63, are these specs you have used on your Starfires? If so how do they handle and are there any issues with tire wear?

[Guest Jim_Edwards]

Thanks again Jim. Back in March you gave some alignment specs to Dave Yaros for a 62 Starfire:

(QUOTE)Dave you can try these as they are known to work well on some '60s cars. Beyond that it may become trial and error for individual handling preference.

1. Basic rule - No more than .25 degrees difference between driver's side and passenger's side.

2. +2.0 to +3.5 degrees caster.

3. -.5 to 0 degrees camber. No positive camber, please. There is no problem having a slight variation from driver's side to passenger's side to account for the crown in the road (only a big deal on older 2 lane highway driving.

4. 1/16" to 1/8" toe in (QUOTE)

I assume these would also apply to my 63, are these specs you have used on your Starfires? If so how do they handle and are there any issues with tire wear?

Don those deviations from Bias Ply tire setup would be generally applicable to any car upon which radials have been placed. As for handling no difference noted beyond the change of tire type. Tire wear is not an issue unless both the camber and toe in are off, in which case you will know because of the handling issues. If the caster is off you'll know it because the tires will be "tramping" and the sound will be unmistakable. Pretty much the same as a tire being unbalanced or incorrectly balanced.

I run Bias Ply tires on one '62 Starfire and Radials on the other. I've not had to worry about alignment issues because the tire shop I use has been in the same family for decades and they have people that have been around long enough to know the alignment is different once radials go on a car originally having Bias ply tires. I really don't worry about tire wear on either car simply because before they have been driven enough for that to become an issue the tires will have become too old to be safe at any speed. Realistically if alignment is out enough to cause abnormal tire wear you'll be fighting it at the steering wheel to keep it out of the ditch or from wandering into oncoming traffic.

Jim

[TexRiv_63]

Thanks Jim.

[Oldsfan]

Been wanting to comment on this. Maybe its not relevant anymore...

Recently had my '62 aligned with new radials. New specs are:

Camber - 0.2 left, 0.0 right - range -0.4 to 0.4

Caster - 1.4 left, .8 right - range 0.8 to 1.8

Toe - 0.07 left, 0.07 right - range 0.00 to 0.13 (given in degrees, not inches)

Cross Camber - 0.2 - range -0.5 to 0.5

Drives like it's on rails.

Unfortunately I don't have my shop manual in front of me to quote the factory specs for bias ply.

Paul

[NTX5467]

Back when radials were becoming popular in the later 1960s and early 1970s, there typically was not any difference in alignment specs from GM or other brands. An article in CAR LIFE magazine, back then, stated that radials were much more critical about "toe-in" being correct than bias ply or belted-bias ply tires were, but less critical of camber than bias ply variants (due to the more flexible sidewall).

This was well before the "all season", more segmented tread OEM radials came out in the early 1980s. When these radials came out, there WERE wear problems due to the more-segmented tread pattern rather than the more "ribbed" pattern of earlier radials. This is when GM changed their toe-in specs to, basically, "zero" AND started giving toe-in specs in "degrees" rather than "inches". The revised toe-in specs plus tire rotations every oil change were the only way good wear could be had from this tread design of OEM radials.

Remember, as a tire rolls, it puts forces into the steering linkage. The "static toe-in" spec is designed so that once these forces are at play, the "rolling toe-in" should be approximately "zero". Naturally, with less rolling resistance, a radial should put less of these forces into the linkage, so heading toward the low-end of the toe-in spec might be advisable. It should also be noted that some of the earlier fwd cars were set to "toe-out" rather than "toe-in", as under torque, the front wheels would "toe-in", so the static setting had to compensate for this.

The increase of caster to max values might not really matter for either tire type. What it does (on a GM architecture front suspension) is make the outer wheel go into more negative camber as it turns, with the inner wheel going the opposite way. What this does is better ensure that the tire sidewall remains more perpendicular to the road surface as the vehicle leans in the corner. In this situation, many GM front suspensions let the outer wheel lean with the car, which tends to let only the outer section of the tire tread do all of the work. Putting more caster into the mix, with the outer wheel going into negative camber, keep the sidewall more perpendicular to the road, further bracing the sidewall, and keeping more of the tire's tread "working". Adding more caster is something of a "bandaid fix" in camber patterns as these things were designed into Chrysler's front suspensions and they did this with normal +1 degree caster settings, back then.

In 1969, or 1970, Buick changed their "camber gain" situation by relocating some control arm pivot locations on their full size cars. They called it "Accu-Drive" as the car was more prone to keep going straight when it encountered a bump in the road. Seems like it helped cornering some, too?

On many power steering cars of the later 1950s and earlier 1960s, it was common for power steering cars to have more positive caster in their alignment specs, with manual steering cars having "zero" or "negative" camber. The greater caster settings require more effort to turn the steering wheel, hence the "armstrong" steering cars having less caster for easier effort at lower speeds and in parking situations. Power steering compensated for the additional effort needed with the higher caster settings. The higher caster setting also helps with the "self-centering" of the steering after completing a turn.

Another thing to consider is that very few roads are really FLAT. There has to be a little crown or slope to ensure that water drainage happens. Where the cross-caster situation was more needed was in the situation where the vehicle was usually driven on two-lane, more highly crowned roads. Much better to have the steering wheel in the "flat" position than seemingly turned opposite direction of the crown.

As was mentioned in many articles on wheel alignment in the later 1960s and such, to be really accurate, the alignment should be done with the car loaded as it's normally driven. This includes the weight of the driver in the front seat (or simulations thereof). Some even state to have at least 1/2 tank of gasoline, too. Camber and caster would be the main things affected, as the suspension compresses slightly from the "empty" situation.

Not all vehicles can be set to the same specs, as caster, for example. So, if factory specs are going to be deviated from, for any reason, my personal recommendations would be to "max caster" (which might be only 2 deg positive), camber at basically "zero", and toe-in as close to "zero" or "min-spec" as possible, consistent with good tire wear of the tire's particular tread design.

As mentioned, max caster can make tire balance more critical. Many of the European and USA vehicles which have a high (3 deg plus) positive caster usually had some sort of steering damper on the front "relay rod" or "drag link" for this reason. Over time, though, this has seemed to be a variable situation.

Many "younger" people seem to like the alleged accuracy of computerized alignment systems. Nothing wrong with that as that's what they have usually grown up knowing about. And it can be very accurate when properly calibrated. But a second or third-generation shop with a set of tried-and-true bubble tools can be just as accurate, if used properly. Not to mention QUICKER, as there's less set-up time involved!

I know of one of those shops, locally. When the local Porsche dealer was having issues with their alignments, they sent these trouble-some cars to Randy to figure out. He pinpointed where the problems were with his bubble machine that clips onto the outer edge of the wheel's rim. To check toe-in, there's the old "Bear Toe-In" checker that the vehicle drives over on the way into the alignment bay.

Back in the early 1970s, we were seeming to have some alignment issues on our then-newer 1969 Chevy pickup. After I got loose from college one day, I took it to an old-line, first gen alignment shop. The man who owned/ran it was renouned for fixing "problem childs" which others didn't seem to be able to fix. I watched as he used the bubble mounts on the front wheels, which clamp onto the spindle/wheel bearing area. Then, to check toe-in, he used a side-to-side tool which scribed a pattern on the middle tire tread rib, then after doing that to both tires, he measured the marks on the front and rear of the tire . . . getting toe-in. He worked slowly and deliberately, but when it was done it drove better than it ever had.

In reality, though, with all of the rubber bushings in vehicle suspensions, as soon as a wheel encounters a road irregularity, the control arms flex their rubber-mounted pivot points, absorbing the impact forces, and things change for that instant, then return to normal afterward. This is one reason that the condition of these rubber items is important in older vehicles!

The "max caster, min camber (0), min toe-in (approach 0")" are general rules that can be followed on almost every vehicle, even if the particular numbers for different vehicles might not be exactly the same. BUT, I should also mention that these orientations might work better with tires which have a "normal sidewall height" rather than some of the more recently popular "short sidewall" tire/wheel combinations! The wider the tread, shorter the sidewall, the more critical that camber will become if it's not at or near "zero", to result in good tire wear across the tire's full tread width.

Respectfully,

NTX5467

Edited May 29, 2011 by NTX5467 (see edit history)

[wmsue]

"Not all vehicles can be set to the same specs, as caster, for example. So, if factory specs are going to be deviated from, for any reason, my personal recommendations would be to "max caster" (which might be only 2 deg positive), camber at basically "zero", and toe-in as close to "zero" or "min-spec" as possible, consistent with good tire wear of the tire's particular tread design."

Having read a few of threads concerning alignment are the above suggestions by NTX5467 a good place to start?

I have a 65 Electra with all new suspension (springs, ball joints, shocks, tie rods, bushings, idler arm....) and radials. Since getting it painted I've only put 10 miles on it because it tends to wander all over the road above 35 mph. The closest shop is 10 miles away that is able to align the car. I haven't put the seats back in the car because I'm working on the conv top. I'd like to drive it a bit even though I've only got an old bucket seat bolted in place for now. The alignment shops records only go back to 1982 and I figure my old specs are out of date since I put radials on it.

Any thoughts?

Thanks

[NTX5467]

Howdy . . .

Check the similar thread in the Buick Riviera Forum.

Enjoy!

NTX5467