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How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 05:46PM

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.




Edited 1 time(s). Last edit at 05/05/2019 06:03PM by MattNall.

Re: How is "Ackerman" adjustable????
Posted by: joelsplace ()
Date: May 05, 2019 06:12PM

If you can move the mounting point of the tie rod then it is adjustable. Matt is calling it adjustable because you can shim the mounting points which "adjusts" the Ackerman.
The way I understand it is what makes the inner wheel turn in more than the outer wheel since it is turning a larger circle.

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




Edited 1 time(s). Last edit at 05/05/2019 06:14PM by joelsplace.

Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 05, 2019 06:13PM

Interesting! I've always known of it as an "Effect" determined by the relationships between various parts of the system.

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

Re: How is "Ackerman" adjustable????
Posted by: Phil Dally ()
Date: May 05, 2019 06:30PM

Ackerman is complicated...this explains it.

[en.wikipedia.org]

edit: Forgot the link.



Edited 1 time(s). Last edit at 05/05/2019 06:31PM by Phil Dally.

Attachments:
Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 05, 2019 06:40PM

Quick Google search...

People also ask


How do you adjust an Ackerman angle?

Ackerman is created by your front end geometry. Tie rods that angle forward from the inner pivot point out to the spindle will have more Ackerman. You can usually adjust the Ackerman by moving the left front tie rod end in a slotted spindle arm.

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

Re: How is "Ackerman" adjustable????
Posted by: solo2r ()
Date: May 05, 2019 07:23PM

What kind of Liability insurance does One have to have to fabricate these arms?

Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 07:24PM

joelsplace Wrote:
-------------------------------------------------------
> If you can move the mounting point of the tie rod
> then it is adjustable. Matt is calling it
> adjustable because you can shim the mounting
> points which "adjusts" the Ackerman.
> The way I understand it is what makes the inner
> wheel turn in more than the outer wheel since it
> is turning a larger circle.




Joel,
The point of adjustment is not at the tie-rod itself - but where the tie-rod is located in conjunction with the center point of the rear end or rear wheels.

Moving a tie-rod up or down might help with bump steer but has nothing to do with the Ackerman theory.

MATT,

Remove my post again from his original thread.. and now from my post here.



Edited 2 time(s). Last edit at 05/05/2019 07:33PM by OttawaCorvairGuy.

Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 05, 2019 07:41PM

OttawaCorvairGuy Wrote:
-------------------------------------------------------

> The point of adjustment is not at the tie-rod
> itself - but where the tie-rod is located in
> conjunction with the center point of the rear end
> or rear wheels.
>
> Moving a tie-rod up or down might help with bump
> steer but has nothing to do with the Ackerman
> theory.
==============================================================

Tony... as usual you missed part of the explanation..

The tierod end position / relationship to the rear wheels... is moved Horizontally with the use of shim / bushing.

And belive me... the different layouts of the different front suspensions all react differently.

Beam / Solid / IND SUSP / front steer / rear steer , etc.

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

Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 07:48PM

MattNall Wrote:
-------------------------------------------------------
> OttawaCorvairGuy Wrote:
> --------------------------------------------------
> -----
>
> > The point of adjustment is not at the tie-rod
> > itself - but where the tie-rod is located in
> > conjunction with the center point of the rear
> end
> > or rear wheels.
> >
> > Moving a tie-rod up or down might help with
> bump
> > steer but has nothing to do with the Ackerman
> > theory.
> ==================================================
> ============
>
> Tony... as usual you missed part of the
> explanation..
>
> The tierod end position / relationship to the
> rear wheels... is moved Horizontally with the
> use of shim / bushing.
>
> And belive me... the different layouts of the
> different front suspensions all react
> differently.
>
> Beam / Solid / IND SUSP / front steer / rear
> steer , etc.


Matt,

I did not miss that.

If you are talking about the tiny shims that might be placed between the spindle and the steering arm.

That is NOT enough change in alignment to make that much of a difference.


If you are talking about shims under the tie-rod to raise it - HAs nothing to do with the ACKERMAN..

Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 05, 2019 07:52PM

Tony... Shims are 3/8" thick as supplied... you can use 1/4", 3/8", 1/2", etc. or NONE [ as I do ]

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

Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 08:06PM

MattNall Wrote:
-------------------------------------------------------
> Tony... Shims are 3/8" thick as supplied... you
> can use 1/4", 3/8", 1/2", etc. or NONE [ as I do
> ]

Matt,

Where are you putting these shims you are talking about that will change the Ackerman?

1. If you are talking about the large shim (seen below) being used under the tie-rod.
It will NOT change the Ackerman. It might help with any bump steer.
But a how high or low a tie-rod is mounted - has NOTHING to do with Ackerman.
Only the distance and angle from the center point of the rear end or center point of the rear wheels.


Re: How is "Ackerman" adjustable????
Posted by: 63turbo ()
Date: May 05, 2019 08:45PM

The other way to adjust the Ackerman is to adjust the toe in or toe out for the front. To increase how much the inside wheel can turn, and put the outside wheel on a longer arc, all one has to do is set the wheels slightly toed out... this does make the car feel quite "darty" at higher speeds and is not for everyone! I inadvertently learned this first hand when I bought my current Corvair 20 some odd years ago... I noticed that it didn't seem to have as tight of a turning circle compared to my other Corvair, but seemed fine otherwise driving it home on the freeway. After a week or 2, I was getting annoyed with its seemingly poor turning circle at low speeds, and decided to do check the toe in. It had a whopping 1" of toe in, and it was caused by someone in the long distant past thinking that the tie rod was a good place to attach a tow rope. Bent beyond belief!! It is weird to think that a car could be driven like that and me not notice anything hinky with its drivability with that much toe in other than it could not be turned in as tight of a circle as it should have been able to do, but its true! Im sure I would have ruined the front tires if I had left it alone but the tires didn't seem to have any unusual tire wear for the short time I drove it that way.

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

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



Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 08:49PM

The ONLY way to change the Ackerman is shown in the two pictures.

NOTICE: In the two pictures how the end where the Tie-rod is flipped - thus relocating the angle of where the tie-rod would be located compared to the center point of the rear wheels.

Another way is also by making the arm longer or putting the tie-rod end mount farther from the ball-joint.


Tie-rod is farther out from the backing plate in this picture.


Tie-rod is closer to the backing plate in this picture.

Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 09:53PM

Phil Dally Wrote:
-------------------------------------------------------
> Ackerman is complicated...this explains it.
>
> [en.wikipedia.org]
> eometry
>
> edit: Forgot the link.


Phil,

Ackerman Theory has to do with the location of the center mounting point of a tie-rod, and the relative angle to the ball-joint and then back to the center point of the rear end or between the rear wheels. A Large V if you will.

If one were to draw a line from the center point of the rear end through either the tie-rod then the ball-joint (on a rear steering setup), or the other way around; through the ball-joint then the tie-rod end (on a front steer setup) they all should be in a straight line of each other. Again the V shape.

Example:
On the UV with factory draglink steering the drag link is located farther back from the front of the coach and the outer tie-rods are located in their respected places for that kind of steering.

When one changes to R&P the draglink is removed and the R&P is placed farther forward of the factory draglink. This puts the tie-rods closer to the outer edge of the tire, or father out from the ball-joint, if you will and to keep the Ackerman Theory - the arms were made longer and also the tie-rod was placed closer to the backing plate. TWO changes in that one arm design. This helped to keep or be as close as possible to the Ackerman Theory as possible.

But then again Brent - Owner Of Fatman Fabrication says it better in the video I provided earlier.

Re: How is "Ackerman" adjustable????
Posted by: OttawaCorvairGuy ()
Date: May 05, 2019 10:03PM

Notice the line from center of rearend through center of ball-joint and center of Tie-rod.

Front Steer Ackerman


Rear Steer Ackerman

Re: How is "Ackerman" adjustable????
Posted by: dryenko ()
Date: May 06, 2019 05:19AM

The posts above show how sure some folks are about something they read on the internet.
Simply put, Ackermann, the tool used to make the inside wheel turn more inward, is affected by the angle inward of the steering arms.
For the reasons shown in the Wikipedia post.
By making the arm point more straight ahead, Ackermann effect is reduced.
If the steering arm pivot length is shortened, moving the tierod attachment point outward becomes part of what is needed to get correct to the Ackermann effect.
Matt's arms do exactly this.
This is helpful for racing cars in particular.
Some open wheel race cars run little to no Ackermann.
I won't get into tire slip angle at high lateral loads, which is another important consideration.

Bob C aka Dryenko
Dobson, NC 27017

Re: How is "Ackerman" adjustable????
Posted by: MattNall ()
Date: May 06, 2019 07:47AM

solo2r Wrote:
-------------------------------------------------------
> What kind of Liability insurance does One have to have to fabricate these arms?
============================================================

Tony can answer for Canada...

Here in the USA... an LLC is most common protection.

Otherwise an "Umbrella policy" that covers the MFG / Sellers "net worth" will protect.

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

Re: How is "Ackerman" adjustable????
Posted by: firevair66 ()
Date: May 06, 2019 09:34AM

I hear the term Bump Steer, is that when turning a sharp corner the wheels turn quickly at some point? And what is the cause and cure.

John Shoemaker,Riegelsville,PA.
1958 Impala Sport Cp. 348 ,pg/ac
61 Rampside full custom show truck
65 Monza 110/4 vert driver
65 Full Custom Monza 140 Cp
66 Monza 110/PG Vert
66 Corsa FITCH SPRINT Documented ( in Process,recondition)
66 CorV8 350 "firevair"Custom Show




Re: How is "Bumpsteer" adjusted????
Posted by: MattNall ()
Date: May 06, 2019 10:17AM

John, "Bump Steer" is when the TOE setting changes as the suspension travels up and down...and you will feel it in the steering wheel.

Bump steer is caused by the Tierod not being parallel in both planes to the Lower A-arm and the Tierod's pivots not being identical to the Lower arms pivots.

Modification is the cure...

For our cars with most Steering arms... Seth sells a T-Rod lowering kit

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

Re: How is "Ackerman" adjustable????
Posted by: firevair66 ()
Date: May 06, 2019 10:43AM

Thanks Matt, lsat year I replaced the ends and adjusters with new ones from clarks and the steering is a lot harder than should be, even after two alignments

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