Historical suspension issues
Thread Starter
|
Cargo Master
Joined: Apr 2003
Posts: 3,476
Likes: 224
From: Frequently frozen MN
Historical suspension issues
Hi,
I ran across this while checking on swing axle suspensions -- I was looking because I thought that VWs had the same issues as Corvairs. Apparently the early ones did. I can't say that I know why the roll center is so high on a swing axle suspension, but there are a lot of things about suspensions that are pretty vague to me.
"The problem with the swing axles though, and the reason that VW stopped using them (and why Chevy got crucified over the early Corvair), is that the roll center ends up being extremely high, like 3-4" higher than axle centerline high, which is dangerously close to the center of gravity height.. And the roll center moves around a lot with suspension motion. So you have a suspension that already is extremely resistant to motion in roll, in the rear, in a rear-heavy chassis (not great), and then if you go over a crest or lift off the throttle (already a bad idea in a rear engined car) the roll couple can actually change signs with the roll center being HIGHER than the center of gravity.
When the roll couple changes signs, the suspension wants to lean "IN" to the turn. But since the CG is above ground level, the car won't. The outside suspension just extends.
This is swing axle jacking"
So I guess that Nader should have gone after VWs too
.
hj
.
I ran across this while checking on swing axle suspensions -- I was looking because I thought that VWs had the same issues as Corvairs. Apparently the early ones did. I can't say that I know why the roll center is so high on a swing axle suspension, but there are a lot of things about suspensions that are pretty vague to me.
"The problem with the swing axles though, and the reason that VW stopped using them (and why Chevy got crucified over the early Corvair), is that the roll center ends up being extremely high, like 3-4" higher than axle centerline high, which is dangerously close to the center of gravity height.. And the roll center moves around a lot with suspension motion. So you have a suspension that already is extremely resistant to motion in roll, in the rear, in a rear-heavy chassis (not great), and then if you go over a crest or lift off the throttle (already a bad idea in a rear engined car) the roll couple can actually change signs with the roll center being HIGHER than the center of gravity.
When the roll couple changes signs, the suspension wants to lean "IN" to the turn. But since the CG is above ground level, the car won't. The outside suspension just extends.
This is swing axle jacking"
So I guess that Nader should have gone after VWs too
.hj
.
Super Moderator
Joined: Apr 2004
Posts: 34,530
Likes: 2,833
The VW was much lower power and was probably driven less aggressively in most cases. In the Corvair there was a transition from understeer to oversteer somewhere just under 30 mph. Add all this to the early swing axle issues you note and all of a sudden mom is going bass-akwards into the ditch.
I don't know the breakdown of Corvair accident stats regarding the nature of the crashes.
I don't know the breakdown of Corvair accident stats regarding the nature of the crashes.
Super Moderator
Joined: Apr 2004
Posts: 34,530
Likes: 2,833
This is the video:
https://www.hagerty.com/media/videos...vair-kill-you/
More commentary on the same:
https://www.roadandtrack.com/car-cul...dful-to-drive/
As to VW, those were down on power and probably not driven as aggressively as the Corvair might have been. The video mentions the VW and the Porsche 356 which also had the swing axle.
Also as to Nader and VW:
https://www.nytimes.com/1971/09/12/a...-by-nader.html
But VW wasn't GM. And they didn't do the stupid things GM tried to do to discredit Nader.
https://www.hagerty.com/media/videos...vair-kill-you/
More commentary on the same:
https://www.roadandtrack.com/car-cul...dful-to-drive/
As to VW, those were down on power and probably not driven as aggressively as the Corvair might have been. The video mentions the VW and the Porsche 356 which also had the swing axle.
Also as to Nader and VW:
https://www.nytimes.com/1971/09/12/a...-by-nader.html
But VW wasn't GM. And they didn't do the stupid things GM tried to do to discredit Nader.
Lead Driver
Joined: Nov 2020
Posts: 7,128
Likes: 1,945
From: Sportsman's Paradise
Wow, learn something new. I had heard about the Corvair death trap and Nader reports on it as a child, way back before there was any thought of being an auto tech, especially surprising being a suspension specialist that I am now and never heard of this swing axle design so I looked it up before posting and HOLYHELL!!! It's easy to see what a design mistake that system was, also noticed Mercedes used and abandoned it in the 50's.
Thanks for the 411.
Thanks for the 411.
Fleet Owner
Joined: Aug 2010
Posts: 21,255
Likes: 1,657
From: Reynoldsburg, Ohio
Another aspect of Corvair's vs VW was they did NOT have higher powered engines available from the factory---my Dad had one of the Spyder's that had somewhere near 150 HP. 
Most people have far more problems when a vehicle goes into an under steer attitude as its correction is not as intuitive or taught as is over steer. Its safe to say a Corvair WAS "dangergous" when the inexperienced driver pushed on past its suspension's capabilities. We also have to remember tire technology was far, far behind what's available which is another factor to consider.
The Wikipedia page is an interesting read if you're so inclined: GM Corvair
Most people have far more problems when a vehicle goes into an under steer attitude as its correction is not as intuitive or taught as is over steer. Its safe to say a Corvair WAS "dangergous" when the inexperienced driver pushed on past its suspension's capabilities. We also have to remember tire technology was far, far behind what's available which is another factor to consider.
The Wikipedia page is an interesting read if you're so inclined: GM Corvair
Thread
Thread Starter
Forum
Replies
Last Post
Update: Rear axle info questions. Anybody have some pics of dentsides with the Crown Vic suspension?
pidaster
1973 - 1979 F-100 & Larger F-Series Trucks
21
Dec 22, 2011 10:35 PM
Greywolf
General Automotive Discussion
24
Mar 22, 2006 06:49 PM
