1964 Monza Sprint - A Bear of a Corvair

The Sprint by John Fitch
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UNSAFE
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1964 Monza Sprint - A Bear of a Corvair

Unread post by UNSAFE » Tue Feb 02, 2010 11:46 am

From Road & Track magazine July 1964
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Kevin Willson
1965 Monza 3.1
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Ecklund
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Re: 1964 Monza Sprint - A Bear of a Corvair

Unread post by Ecklund » Sat Mar 18, 2017 12:44 am

Interesting article.

I wonder if those seat track extensions were custom or if someone still makes them today...
1964 Corvair 900 (969) four door with powerglide - new project

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Allan Lacki
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Re: 1964 Monza Sprint - A Bear of a Corvair

Unread post by Allan Lacki » Sat Mar 18, 2017 6:50 am

It's interesting to read about the suspension modifications that Fitch & Company made to early-series Corvairs, namely the removal of the front anti-roll bar and stiffening of the rear suspension. This is directly the opposite of the common cure for jacking in rear-engine swing-axle cars.

In other words, with a swing axle suspension, you generally want to increase roll stiffness at the front end and decrease it at the rear end. Take a look at the rear suspension of any Formula V car and you'll see - Many of them have a Z-bar at the rear to promote roll, rather than a conventional roll bar to prevent it.

The last of the swing axle Beetles had Z-bars, too.

The better Formula V's have a rear suspension setup that has zero roll resistance! In the photo, you'll see that it has one horizontal coil-over spring. It serves as the spring for both axles so that the axles work against each other instead of against the chassis. So, there is no resistance to body roll whatsoever. I've seen Formula V cars like this at the Duryea hillclimb. Very clever!

Overall, the premise of this is to let the front suspension provide roll resistance while letting the rear suspension roll around the U-joints, thus eliminating jacking. Personally, I drive a late-series Corvair, so I don't have any direct experience with this, but I thought it's interesting none the less.

Al ::-):
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Ecklund
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Re: 1964 Monza Sprint - A Bear of a Corvair

Unread post by Ecklund » Sat Mar 18, 2017 7:59 am

Allan Lacki wrote:
Sat Mar 18, 2017 6:50 am
It's interesting to read about the suspension modifications that Fitch & Company made to early-series Corvairs, namely the removal of the front anti-roll bar and stiffening of the rear suspension. This is directly the opposite of the common cure for jacking in rear-engine swing-axle cars.

In other words, with a swing axle suspension, you generally want to increase roll stiffness at the front end and decrease it at the rear end. Take a look at the rear suspension of any Formula V car and you'll see - Many of them have a Z-bar at the rear to promote roll, rather than a conventional roll bar to prevent it.

The last of the swing axle Beetles had Z-bars, too.

The better Formula V's have a rear suspension setup that has zero roll resistance! In the photo, you'll see that it has one horizontal coil-over spring. It serves as the spring for both axles so that the axles work against each other instead of against the chassis. So, there is no resistance to body roll whatsoever. I've seen Formula V cars like this at the Duryea hillclimb. Very clever!

Overall, the premise of this is to let the front suspension provide roll resistance while letting the rear suspension roll around the U-joints, thus eliminating jacking. Personally, I drive a late-series Corvair, so I don't have any direct experience with this, but I thought it's interesting none the less.

Al ::-):
Thank you Mr. Lacki,

I was second guessing myself about that exact topic.

I'd always thought/read/observed that stiffer springs, an anti-roll bar or a bigger anti-roll bar and/or stiffer shocks all add to the 'roll couple' of whichever end to which they are ADDED. An increased in the front roll couple would INCREASE understeer and if REDUCED/REMOVED from the front would DECREASE understeer.

And of course the inverse would be true of the rear of the car. ADDING roll coupling through an anti-sway bar or a larger one, stiffer springs, stiffer shocks or any other device that would limit roll, like a transverse spring, would INCREASE oversteer and a reduction of roll couple would DECREASE oversteer.

Tire size, compound and air pressure also have a large effect.

The article on the Sprint seems to make the opposite conclusion.

The lateral spring on a '64 isn't really an anti-roll bar. It clearly has impact on roll resistance and adds to the total rear spring rate for the car, but its primary role seems to be to keep the rear wheels from dropping under the body at too much of an angle which might lead to undesirable suspension action.

It looks like it would be difficult to add a rear anti-sway bar to the '64.

I wonder if the '64 Corvair really does oversteer that much. Or is it that at the edge of tire adhesion the rear engine pendulum effect exaggerates the snap when the rear end finally does come loose and becomes much like the so called 'widow maker' Porsche of the day

Oversteer and car behavior at the edge are not the same thing. A car can understeer horribly but can snap at the edge of adhesion and be a handful.

I look forward to actually driving my humble '64 four door with automatic. I suspect its classic GM understeer.

While the Sprint Corvair article may have been incorrect in explaining the suspension forces involved, the effect it achieved by increasing rear roll stiffness/couple with stiffer springs at the same time reducing front roll stiffness/couple buy removing the front anti-sway bar may well have countered some of the unwarranted understeer GM added to the car.

With massive understeer designed into the Corvair GM certainly kept typical drivers further away from the unfamiliar effect of having a rear weight bias and harsh reaction when tire adhesion is lost in an extreme cornering situation. But the '64 Sprint car shows that the stock Corvair's had significant understeer and removing some would make a much more sporting car that had still addressed the original Corvair suspension design limitations.
1964 Corvair 900 (969) four door with powerglide - new project

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