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Re: Corvair EMPI Camber Compensator
Posted by: joelsplace ()
Date: October 02, 2019 10:04AM

flat_six Wrote:
-------------------------------------------------------
> Basically, in fast corners, the lower limit of adhesion up front causes you to go off the road nose first, before the back end has the chance to break loose.


That is understeer. How is it also oversteer?

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Corvair EMPI Camber Compensator
Posted by: 63turbo ()
Date: October 02, 2019 10:23AM

Joel it is a matter of what happens, when it happens, and how fast it happens, and which end of the car is responsible.... this is why gaining under steer isn't exactly the same as reducing over steer.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Corvair EMPI Camber Compensator
Posted by: joelsplace ()
Date: October 02, 2019 12:43PM

That is not correct.
[en.m.wikipedia.org]
This page references SAE document J670 that describes the terms if you don't trust the wiki article.
Neutral is in the middle between oversteer and understeer. Everything on one side is understeer and everything on the other side is oversteer.
Granted it is possible to have a car that understeers in low speed sharp turns and oversteers in higher speed turns but it can't do both in the same situation.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Corvair EMPI Camber Compensator
Posted by: 63turbo ()
Date: October 02, 2019 02:17PM

> Granted it is possible to have a car that understeers in low speed sharp turns and oversteers in higher speed turns but it can't do both in the same situation.

Yes it can do both and that's the point! the classic, and relevant example is to reduce the front tire pressures a lot. The reduction in tire pressure "causes" an initial understeer. Because of the excessive body lean, this leads to jacking on the rear and then oversteer. One simple change caused 2 separate things to happen, and they weren't at the same time.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Corvair EMPI Camber Compensator
Posted by: joelsplace ()
Date: October 02, 2019 08:54PM

I've never had an EM Corvair understeer. The 10 psi pressure difference reduces oversteer but doesn't make them understeer.
Just for sake of the discussion let's take your example as what actually happens.
You described a situation where a car understeers until the situation changes (excess body roll) and then it oversteers. It still isn't doing both at the same time or in the same situation.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Corvair EMPI Camber Compensator
Date: October 03, 2019 12:01PM

v8vair Wrote:
-------------------------------------------------------
> Take the leaf off, Put a few degrees of negative camber in the rear with 63 springs, If you think your gonna go wild in the turns, get side ways, take a few dirt excursions add some limiter straps. Just enjoy your early and drive it. Mike


This is literally what I did. Car drives outstanding.

1961 Corvair 700 Sedan - 3sp - Gasoline Heat - Lowered a bit - Rust in Progress
I live my life 19.5 seconds at a time.


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Re: Corvair EMPI Camber Compensator
Posted by: ensys ()
Date: October 03, 2019 10:35PM

Hoo-o-o Doagies... This discussion is a painfully apt demonstration of the metaphor of the Blind Men and the Elephant.

There's an awful lot of mis/dis information floating around here. More than any one person could hope to clarify to everyone's satisfaction (tho the comments from Mr.Skirmants probably come closest to a relevant Truth in the context of this particular discussion about "camber compensators").

It would take a person more persuasive (and heroic) than I to sort things out, so I reckon I'll just grab a beer and enjoy the show.

Bring on the dancing ponies!

Keep 'em flying...

S.J.Szabo

From America's
Automobile Heartland

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Re: Corvair EMPI Camber Compensator
Posted by: MattNall ()
Date: October 03, 2019 10:58PM

SJ..... We have a lot of new people here....

Why don't you state your qualifications once again....

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Corvair EMPI Camber Compensator
Posted by: ensys ()
Date: October 05, 2019 11:12PM

Mr.Nall:

Well, I can walk backwards and chew gum at the same time, and, I do know s**t from Shinola....

Does it take more to proselytize simple approaches to complex problems?

An impromptu synopsis I'll admit, but I didn't realize we are expected to post resumes to qualify our opinions. This should make for some interesting reading going forward.

Keep 'em flying...

S.J.Szabo

From America's
Automobile Heartland



Edited 1 time(s). Last edit at 10/05/2019 11:17PM by ensys.

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Re: Corvair EMPI Camber Compensator
Posted by: joelsplace ()
Date: October 06, 2019 06:35AM

So enlighten us instead of just saying everyone is wrong.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Corvair EMPI Camber Compensator
Posted by: Pacerace ()
Date: October 06, 2019 06:39AM

joelsplace Wrote:
-------------------------------------------------------
> So enlighten us instead of just saying everyone is wrong.


That's not how the internet works though eye rolling smiley

________________________________________________________

Chandler
Powder Springs, GA.



1965 Corvair Monza 110/4sp Coupe

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Re: Corvair EMPI Camber Compensator
Posted by: The Californian ()
Date: October 06, 2019 08:06AM

This drawing shows the good part about a swing axle.

Vertical diagonal line indicates centerline of differential.

Notice wheel stays in contact with ground plane.

Left out the other axle and wheel because that is where the split axle starts to

'fail'.

Another wrinkle is the 'torque control arm'(swing arm, a arm) angled at about 45

degrees.That adds a wild card or imperfect element.

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Re: Corvair EMPI Camber Compensator
Posted by: ensys ()
Date: October 06, 2019 02:13PM

Mr.joelsplace:

I didn't say "everyone is wrong"; but it's a cinch that not everyone is right.
Sadly, telling one from the other rarely educates, and more often than not, just picks a fight and wounds egos. I am proud to note that my innate masochism doesn't indulge such fruitless (and thankless) exercises any more.


Mr.Pacerace:

Spot on, Olde Sticke. For that one, you don't need a resume.


Mr.Californian:

Nice drawing. It also shows the "good part" of a solid axle, so double points.
By the by; I'm guessing that "semi-trailing arm" is the phrase you're looking for.



Pass the popcorn......

Keep 'em flying...

S.J.Szabo

From America's
Automobile Heartland

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Re: Corvair EMPI Camber Compensator
Posted by: The Californian ()
Date: October 06, 2019 04:28PM

Ensys

'guessing that "semi-trailing arm" '

Torque control arm was what it was called in drawing of Corvair rear suspension.

I will accept your version.Although that is a generic description or definition.

Here is picture from wikipedia.

[en.wikipedia.org]

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Re: Corvair EMPI Camber Compensator
Posted by: joelsplace ()
Date: October 06, 2019 04:51PM

Chandler,
If only one came close to the truth everyone has to be wrong so you obviously have no clue and are being the typical internet definition of a troll.
I guess the SAE parper I linked to is wrong.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...




Edited 1 time(s). Last edit at 10/06/2019 04:55PM by joelsplace.

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Re: Corvair EMPI Camber Compensator
Posted by: The Californian ()
Date: October 06, 2019 05:12PM

Ensys

Here is drawing with 'Torque Control Arm'.

Drawing seems to be '65 and up suspension.

Think that engine hanging off the back leads to suspension quirks.

Look at the space between axles and back where engine meets bellhousing.

That is a whole bunch!

Notice in the semi trailing arm drawing that it looks like a live axle.

A conventional tube axle.

Corvair used an idea for a different axle than they were using.

THE CALIFORNIANS

BIG HORSEPOWER HIGH SPEED ONLY THE STRONG SURVIVE!

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Re: Corvair EMPI Camber Compensator
Posted by: JerryM ()
Date: October 07, 2019 06:39AM

Whether or not this is significant or useful, I'll offer what I know about early and late Corvair rear suspension design and IRS evolution. An understanding of instant centers, couple/ moment centers and other fundamentals would be beneficial but are beyond the scope of this.
Rear suspensions fall into three categories: beam axles, twist beam axles and independents and are generally defined by degrees of freedom in 3D space or, occasionally, in degrees constraint.
A simple swing axle would be among the rudimentary independents. Theoretically a swing axle has one degree of freedom and translates wheel load through the axle to a center pivot (instant center) which is also the roll center. It is challenging to design a pure swing axle and is seldom done.
Semi-trailing arm suspensions are an evolution of the swing axle and typically described as not having suspension links parallel to the wheel plane, have at least 2 degrees of freedom and offer flexibility to choose the instant center and roll center. Low center designs like the early Corvair were known as "Diagonal Pivot Swing Axle" or "Semi-swing axle" as the swing arm path rotates around an instant center at some angle viewed in all 3 planes.
In plan view, the axis of the EM Corvair swing arm trunnion projects through the u-joint at an angle of approximately 37 degrees, therefore "semi-trailing". That axis intersects the wheel plane at 30 inches forward of the axle center. Side note; given the axle at 23 inches (approx.) from the u-joint to the wheel plane, toe angle change is approximately squared per degree change in the Z axis to the bounds of wheel travel. Corvair "Low Pivot" swing arm: For an EM, in front view; project a line from the outer swing arm trunnion to the opposite tire's contact patch center for both. The swing arm here is roughly 57 inches. Where the lines intersect is the roll center. LM, in front view project a line coaxially through the axle and a line through the camber link pivots for both. From where those lines intersect project a line to the center of the opposite wheels contact patch. Where those lines intersect is the roll center.

The LM Corvair rear suspension (and pre-'84 Corvette) is a further evolution of the EM's semi-trailing concept. In front view, the swing arm is lengthened by two links – the fixed-length half shaft and the lower “camber link”. In side view the swing center is, however, still controlled by a single trailing arm. The arrangement still has the toe vs. wheel travel characteristics of the early semi-trailing arm (toe-in with bump and droop). The major improvement is the significant lengthening of the front view swing arm which slows down the camber change. Projecting a line from the trailing arm pivot through the u-joint at the transaxle – this is the swing arm axis – is still roughly 37 degrees. Axle/Wheel plane length is still the same, toe, however, is constrained with an additional isolated link. The half shaft and camber link form a short/long arm type arrangement with significant virtual swing arm length. As much as 200 inches or more is possible determined by the inner camber link length and pivot location.

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Re: Corvair EMPI Camber Compensator
Posted by: The Californian ()
Date: October 07, 2019 07:19AM

Thank you Jerry

Came up with the toe in situation on our own.

Call it jounce and rebound.

That puts toe in at the rear wheels.

Here is a little drawing showing what happens.

There is also a situation where the wheels toe out under braking.

That has to do with load pulling and pushing on bushings of control arm.

That is sort of a 'real world' wrinkle not an ideal theory situation.

The control arm deflects.

THE CALIFORNIANS

BIG HORSEPOWER HIGH SPEED ONLY THE STRONG SURVIVE!



Edited 2 time(s). Last edit at 10/07/2019 07:25AM by The Californian.

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Re: Corvair EMPI Camber Compensator
Posted by: kmart356 ()
Date: October 07, 2019 07:55AM









Ken
'62 Spyder Coupe
Florida


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Re: Corvair EMPI Camber Compensator
Posted by: JerryM ()
Date: October 07, 2019 08:00AM

The Californian Wrote:
-------------------------------------------------------
> Thank you Jerry
>
> Came up with the toe in situation on our own.
>
> Call it jounce and rebound.
>
> That puts toe in at the rear wheels.
>
> Here is a little drawing showing what happens.
>
> There is also a situation where the wheels toe out under braking.
>
> That has to do with load pulling and pushing on bushings of control arm.
>
> That is sort of a 'real world' wrinkle not an ideal theory situation.
>
> The control arm deflects.

Somewhere I made notes on approximation for toe angle change deg/inch, I'll try to find them and post.

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