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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 06, 2019 10:54AM

Did you replace the idler bushing? those are usually too tight..

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Re: How is "Ackerman" adjustable????
Posted by: 65 Corsa Vert ()
Date: May 06, 2019 11:13AM

I have the same issue, where the steering is too tight after the rebuild. Is there a better Idler arm to use that is not so stiff or something that can be done to prevent it to from being so stiff to turn?

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 06, 2019 11:21AM

Take the bolt out and ream the bushing ID.... no slop... just move easily.

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Re: How is "Ackerman" adjustable????
Posted by: firevair66 ()
Date: May 06, 2019 11:22AM

No Matt just the ends and adjusters. I guess if tie rod is not aligned with the studs it might be binding. The alignment shop should have seen that.

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 06, 2019 11:29AM

Get it on a rack.... you'll find it..

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Re: How is "Ackerman" adjustable????
Posted by: Jonathan Knapp ()
Date: May 09, 2019 06:35PM

Sometimes the angle on the end of the radius rod (some call it the drag link) does not match the angle of the pitman arm. If their angles do not match each other the bolt in the bushing will always bind, especially if it is nylon and not rubber. The only solution is to heat the end of the radius rod and bend it or twist it to get the right angle.

This was a significant factor with the radius rod that I modified to cut down on bump steer.

Jonathan Knapp
Now in Martins Ferry, OH
'66 Corsa Autocrosser

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 10, 2019 08:12AM

Where's OttowaT? Has he Bailed again on a Topic he started? sad....

Hope he learned something!!! GGGG

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Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 10, 2019 01:30PM

MattNall Wrote:
-------------------------------------------------------
> Where's OttowaT? Has he Bailed again on a Topic he started? sad....
>
> Hope he learned something!!! GGGG


LOL @ Matt.

Let's get "your facts" straight.

1. I did not start this topic - You moved my reply to others in another thread to here.
2. You also deleted a lot of my post about this subject and removed one thread that I did start. Never giving the members a chance to read them.
3. Everything after my last post here, has nothing to do with the Ackerman Theory. It's about other stuff.

You just want someone to argue or fight with.

FYI - I went off and did research on my own. And I was right - even if you want to have blinders on about this.
Too many people toss terms around and a lot of the time they don't apply.
Example: People calling a street machine a street rod and the other way around.

Oddly enough - You would have been better off stating the fact that the steering is quicker and left it at that.
To say the Ackerman is adjustable is false and should never be a part of that sales pitch for those arms.

The Corvair is Forward steering and will NEVER be close to the Ackerman theory.
One would have to put the mounting point of the outer tie-rod about half way inside the front tire to meet the Ackerman theory guidelines.
Moving or "adjusting your so called Ackerman" with those spacer moves the arms in the wrong direction to match the Ackerman theory.
YES - one might be able to get quicker steering on the Corvair with different arms. But to state the Ackerman is adjustable is false.
WHY - Because the Ackerman theory has a fixed set of rules and guidelines - it either meets the rules set out by the person who came up with the theory in the first place Or it does not.
There is no in between.

As Brent of Fatman Fabrication stated in the video that I provided in this thread; there are some vehicles you can only get them close and make them better.
They will never meet the guidelines set forth in the Ackerman theory.

The Forward steering of the Corvair will NEVER fall in line with the rules and guidelines set forth in the Ackerman theory.
So it would be best to not even mention it at all.
Simply say these new arms provide quicker steering that you will notice and are made in the USA - if they are - is more honest and to the point.

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 10, 2019 02:04PM

TONY.... THIS IS A QUESTION.... NOT A REPLY!!!!



OttawaCorvairGuy Wrote IN THE FIRST POST OF THIS TOPIC:
-------------------------------------------------------
> Matt,
>
> I don't understand how the "Ackerman" is adjustable.
> The Ackerman theory is a principle and not adjustable!
>
> The Ackerman theory takes into account the front points of where the tie-rods are and how they align up with the center point of the rear end; if one were to draw a straight line forward out from the center point of the rear end, to each mounting point of the tie-rods.
>
> NOTE: One can be slightly off, with their setup, from the Ackerman theory and still be okay. But adjustable I think not!
>
> I read a very good article about this a few weeks back.
> Even Chevrolet has built cars that did not meet the Ackerman theory. Even newer ones too.
> In that article they talked about the pros and cons and what one could get away with.
>
> Here is a set of the steering arms I had made for UV owners.


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Re: How is "Ackerman" adjustable????
Posted by: Wills69 ()
Date: May 10, 2019 05:51PM

Making more popcorn

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 10, 2019 05:52PM

HMMM no reply....

Let alone answer the two questions asked of him.....

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Re: How is "Ackerman" adjustable????
Posted by: American Mel ()
Date: May 10, 2019 09:54PM

Okay, I think we can all agree that the angle created when a lines are drawn through ALL of the said suspension parts in this discussion, is commonly called "The Ackerman Angle." (even though some may disagree with this terminology.)
And, I think we can ALL agree that the "forward steering" of the Corvair falls way outside of PERFECT "Ackerman Theory".
You state that, "The Ackerman theory takes into account the front points of where the tie-rods are and how they align up with the center point of the rear end; if one were to draw a straight line forward out from the center point of the rear end, to each mounting point of the tie-rods."
But that does not even cover the most important part of it at all.
In PERFECT Ackerman Theory, those lines you just drew must also bisect the center pivot point of the front spindles!
What I see going on here is an argument about SEMANTICS, not facts.
One of you is screaming about "Ackerman Theory" while the other is talking about "Ackerman Angle".
Tony, you are correct when you say, "One would have to put the mounting point of the outer tie-rod about half way inside the front tire to meet the Ackerman theory guidelines."
But you are WRONG when you say, "Moving or "adjusting your so called Ackerman" with those spacer moves the arms in the wrong direction to match the Ackerman theory."
When you MOVE or Adjust Matt's spacers from the outside to the inside, it is locating the the mounting point of the outer tie-rod into a position that is CLOSER to your ideal of perfect Ackerman Theory!
Is it ideal, and perfect?
NO!
We already agree that this is IMPOSSIBLE on a stock, or quick-arm Corvair front-end.
BUT IT IS CLOSER TO THE IDEAL.
Therefore, since it is not where it was, and CAN be moved, ergo it IS ADJUSTABLE ! ! !
Have we changed your precious "Ackerman Theory"? NO!
BUT we have changed/adjusted, what is commonly, if possibly erroneously, referred to as the Ackerman Angle.


OH!
Since you brought it up, just WHAT IS the difference between a Street Machine, and a Street Rod ? ? ? eye rolling smiley
Oh, and please cite references.
We don't want opinions around here, just unalterable facts!

.
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WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater
'67 A/C Moredoor Monza - 140 4-spd. driver

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Re: How is "Ackerman" adjustable????
Posted by: American Mel ()
Date: May 11, 2019 11:13PM

.


.
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater
'67 A/C Moredoor Monza - 140 4-spd. driver

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 12, 2019 05:37AM

Yup!! Correct diagram for a "front steer " !!

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Re: How is "Ackerman" adjustable????
Posted by: tkalp ()
Date: May 12, 2019 07:41PM

I am no expert by any means, but have dabbled in "Ackerman" for over 50 years starting when I built my Corvair powered T-bucket when I was 17 to decades later when setting up the front end of the Corvair powered open wheeled formula racer. If you look at the diagrams Tony provided early in the discussion, then check out the steering layout of a stock Corvair you would discover that the lines thru the kingpin center line and tie rod ends cross somewhere in front of the car and not thru the center of the differential. Does that mean the Corvair has "reverse" Ackerman and corners like a pig? Of course not. Tony's chart shows a solid tie rod connecting the steering arm ends. A system used by Henry Ford and many others during the decades of the 30's and 40's

If you look under the front end of your Corvair there is no solid tie rod but a three piece system consisting of a center link and two outer tie rods. The center link is supported/controlled where it is attached to the pivots at the Pittman arm and Idler arm which move in an arc as the center link travels from right to left. The result is reasonable Ackerman in a stock Corvair. The linkage was engineered to work reasonably well which it does.

Adding "quicker" shorter steering arms upsets the relationship of the pivot points and the Ackerman degrades. Moving the steering box and Idler arm further back in the Corvair would improve the Ackerman.

Dropping in a rack and pinion steering unit is a whole different situation than the Corvair center link system. This is because with a center link system as the car is turned from left to right the center link moves closer and further from the front crossmember. A rack and pinion is mounted solid so the geometry is different.

By moving the center link outer pivot points forward and back in the car makes drastic changes in the Ackerman action for the car, same for the rack and pinion. Years ago a member of this forum sent me a program that calculates the Ackerman for different locations of the tie rod pivot points using a rack and pinion system.

Once you depart from the Henry Ford solid axle, solid tie rod system Ackerman can become very complex. If you have a lot of extra time either plot out or create a to scale Corvair steering system for better understanding.

T. Kalp
Wichita, KS

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 12, 2019 08:36PM

That's why it took me 5 prototypes before getting it ...no tire scrub.... less effort...reduce bumpsteer.... with a quicker Turn.....and the car had to "feel" comfortable.

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Re: How is "Ackerman" adjustable????
Posted by: Jonathan Knapp ()
Date: May 13, 2019 08:55PM

So far I've refrained from participating too much in this conversation but now feel compelled to offer some insights. The best suggestion in this conversation, in order to understand the Corvair's steering, is to graph the steering mechanism. I did that to full scale on graphing paper. For the performance minded owner, it is not a pretty picture. As T. Kalp said, the center link does move backward in an arc as the steering moves away from straight ahead. But given the interplay of the arc of the center link and the arc of the steering arm, you will see that the stock Corvair steering does, in fact, have "reverse" Ackerman.

That is to say, the outside wheel actually turns sharper than the inside wheel: the opposite of what is optimal Ackerman for performance. There is a reason that GM did this, however. Creating two intersecting circular pathways for the two front tires makes them scrub against each other, assuring that the car will understeer. This is not just a trait of Corvairs. GM did this on most front-steer vehicles with this type of steering mechanism.

Many Corvair road racers use a big front sway bar which effectively lifts the inside front wheel off the ground, so bad Ackerman doesn't much matter in their case. Furthermore, road racing doesn't demand the more extreme turning angles that are present in street use and autocross.

Autocross is where the bad Ackerman shows up the most: extreme cornering forces and extreme turning angles. If you set the car up to keep both tires on the pavement (smaller sway bar) for maximum grip and it has stock steering or (even worse) aftermarket quick steering arms, you are in for a big problem. The inside tire (turning less than the outside tire) pushes out against the outside tire in cornering, sending it beyond its adhesion limits well before the g-forces would have done so if the Ackerman were correct. This is why Corvairs with stock steering geometry understeer like crazy right up until they snap into oversteer from the inertia of the weight in the rear.

In my book, after high performance wheels and tires, (close to) proper Ackerman is the single biggest improvement you can make to a Corvair's cornering potential. It is that important. A Corvair with (close to) proper Ackerman will be very neutral right up to the point where you can feel the rear end step out a little from the inertia. At that point, steer with the gas pedal. Press harder on the gas and the car will drift out controlably. Lighten up on the gas (don't lift) and the front of the car will tuck in and turn a little sharper.

BTW, you can get absolutely correct Ackerman with a front-steer Corvair. You just can't do it with anything less than 17" wheels.

My 2 cents worth.

Jonathan Knapp
Now in Martins Ferry, OH
'66 Corsa Autocrosser

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Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 13, 2019 09:36PM

I finally got a chance in an easily measured area to test results of a "U-turn" / turning circle..

8 foot less than a stock long arm Corvair! This is with wheels / tires that are in the same plane as the brake's backing plate.

A-mel with his Vette 15" [ deep dish ] and 4-1/2 lock to lock, compared to my 3-1/4 SAME overall RATIO....should do better..

And following what Jonathan talks about... The Mark left by the OUTSIDE wheel was considerably LESS than before.

In conclusion... as stated by OTTO vair....if Rear steer Ackerman is just a THEORY.... then FRONT Steering Ackerman is a FACT!! and can be adjusted...as I just described..

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Re: How is "Ackerman" adjustable????
Posted by: joelsplace ()
Date: May 14, 2019 03:40PM

Jonathan, I'm thinking the steering arm needs to angle out instead of in like the stock ones? Hence the 17" wheel to clear the tie rod?

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

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Re: How is "Ackerman" adjustable????
Posted by: Jonathan Knapp ()
Date: May 14, 2019 03:58PM

Joel-

That's exactly right!

Jonathan Knapp
Now in Martins Ferry, OH
'66 Corsa Autocrosser

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