Whats a Radial Tuned Suspension?

[Guest brh]

I know the great debate on radial tires versus bias ply. I run radials on my 65 Buick Skylark. What I would like to know is what makes a suspension "radial tuned". I use to work on these cars and as near as I can tell all the basics are the same. I am sure someone here has the answer, more of a curious question on my part. Thanks.

[Guest John Chapman]

I remember Pontiac making a big deal about this, even to the point of them having a "Radial Tuned Suspension" plate on the glove box door.

To the best of my knowledge, the package consisted of recalibrated shocks, slightly stiffer springs, and firmer suspension bushings to compensate for the more compliant sidewall of a radial tire.

Cheers,

JMC

[55PackardGuy]

Yup, that "compliant sidewall" is what I think makes an older car feel "mushier" in corners with radials. Radial vs bias is a classic engineering tradeoff. As long as they're both <span style="font-style: italic">quality</span> examples of the breed, you pays your money and takes your choice. I would not agree that bias ply tires are inherently less safe. Police cars and racers used them for years after radials were available. But GOOD bias ply tires are scarce and expensive, while good radials are plentiful and relatively inexpensive. (The opposite was more the case in the early days of U.S. radials, in my experience--I lived through that time.) <img src="http://forums.aaca.org/images/graemlins/crazy.gif" alt="" />

[Guest John Chapman]

I think a bit of the 'mush' can also be attributed to the compliance of the suspension bushings and the suspension hardware itself. These were not designed for the higher side loads (angular acceleration) that radials can produce before traction is lost.

JMC

[Guest brh]

I do remember the "wide track Pontiac" promo. Bias ply or radial I would not want to take my 65 around any sharp corners, that front end loves to dip down in a turn with any speed. Thanks for the comments.

[Philippe Racicot]

Mid-seventies full size Pontiacs had that "Radial Tuned Suspension" plate just above their radio.