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Re: Factory quick steer question
Posted by: UGLYTRUK ()
Date: August 07, 2018 04:03PM

It makes one realize what it takes to engineer these various seemingly simple but actually complex parts. I guess GM did a really good job back in the day. I've rebuilt a few original steering boxes, the problem is when you open them up you never know what the Pitman shaft is going to look like. If it's in good shape you can just cut the bushing and shim it to tighten up the shaft, but if the shaft is a rusty mess, and you can't tell from the exterior of the box, then you have to start over.

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 08, 2018 07:53PM

Getting back to the original topic of this thread...

For me, the best, and most affordable, option for the best quick steering is to use a stock GM steering box with the regular ratio (not a quick box) with custom steering arms that are shortened and moved outward to improve Ackerman, and to use a smaller steering wheel (14 or 15 inches). I find this to be the best approach because the improvement in Ackerman has an amazing effect on the cornering power and steering precision of the car. The shorter arms give a sufficient increase in steering quickness (2.7 turns on my car). The somewhat smaller steering wheel still gives enough leverage so that the steering effort is manageble (With Hoosier A7s on 9" rims at the autocross course I admit it is pretty hard to turn at a dead stop).

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

Re: Factory quick steer question
Posted by: Seth Emerson ()
Date: August 09, 2018 09:41PM

Jonathan do you have a drawing or a lits of specs for the location of the tie-rod, when your mod is complete?

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 10, 2018 10:03PM

Hi Seth,

When I did this more than 10 years ago, I graphed all of the movements of the front suspension at full scale on drafting paper. But I don't have it in a digital form. But again, I could not get the outer tie-rod ends in the ideal place. That would be where the inner edge of the rim is. I moved them as far out as my drum brakes (at the time; now upgraded to disks) and the rim would allow.

From the pictures you can see how close the outer tie-rods are to the rotors. They were even closer to the brake backing plates and edge of the drums when I had drums. With disks, I could build steering arms that are slightly better, slightly farther out, but not much.


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

Attachments:

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 10, 2018 10:07PM

The real limitation in my case, however, is that I am running 15" wheels. You can't make steering arms that are short enough to fit inside 15" wheels. When and if I go to 17" wheels, I will remake the steering arms.

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

Re: Factory quick steer question
Posted by: toms73novass ()
Date: August 11, 2018 06:20AM

Jonathan just to clarify.

When you say you can make them shorter with 17" rims is the "shortness" the perpendicular distance from the pivot point of the lower ball joint to where the arm attaches to the tie rod?

In the picture below if you were to throtically straiten out the arm as I have drawn and it aligned with dot above (where the other end of the tie rod would attach to the center link. This would be the "shortest" optimal ackerman arm?



-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block
86' BMW 325es
98' Dodge 2500 12v Cummins Diesel with 1200 lb torque!
98' VW Jetta TDI, for daughter
01' Audi Allroad Stage 3 twin turbo

NFCC
Grand Island, NY

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 11, 2018 11:09AM

Hi Tom,

I don't quite understand your question. So let me clarify in my own terms. When I talk about the length (or shortness) of the steering arms I am talking about one thing: the distance from the pivot line of the spindle (line drawn through the upper and lower suspension ball joints) to the hole in the steering arm where the outer tie-rod attaches. This dimension of the steering arm addresses the "quickness" of the steering. The steering arm at the bottom of the picture will go lock to lock in far fewer turns than the one at the top of the picture. Hence the bottom one is the "quickest" and the top one is the "slowest". That dimension has nothing (intrinsically) to do with Ackerman.

If you think of steering quickness being a function of the front-to-back position of the steering arm hole where the outer tie-rod attaches, then Ackerman is affected by the left-to-right positions of the steering arm hole where the outer tie-rod attaches. Ackerman is the differential turning angle of the two front wheels. Think of each front wheel describing an arc when turning. The arc radius of the inside front wheel is much shorter than the arc radius of the outside front wheel. Another way to say this is that the inside front wheel has to turn sharper than the outside front wheel. The left-to-right position of the end of the steering arm will affect this.

On a front-steer car (where the steering mechanism is ahead of the front axle) like the Corvair (and many older American cars). The end of the steering arm needs to be positioned significantly outboard of (a line parallel to the car drawn through the) lower suspension ball joint.

On my car, in order to get the outer tie-rod position to be farther outboard, the steering arm would have to be even shorter to tuck everything inside the rim (closer to the brake rotor). This would cause clearance problems on the lower suspension arm and the cross-member at full lock and it would make the steering far too "quick" (because the arm would be so short: see above). 17" wheels would allow the steering arm to be the same length (for the same steering quickness), but positioned farther outboard tucked inside the rim (for better Ackerman).

Hope that helps.

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

Re: Factory quick steer question
Posted by: toms73novass ()
Date: August 11, 2018 11:31AM

Ok I think I understand, if you had larger wheels the point I circled would not contact the rim and you could move the end of the arm more in the direction I indicated below.




As for length of arm, how long are your arms approximately compared to the ones above?

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block
86' BMW 325es
98' Dodge 2500 12v Cummins Diesel with 1200 lb torque!
98' VW Jetta TDI, for daughter
01' Audi Allroad Stage 3 twin turbo

NFCC
Grand Island, NY

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 12, 2018 11:44AM

Tom,

Now we're on the same page. My steering arms are probably in the range of the "really short arms" at the bottom of the photo. They started out as "typical short arms" and got shorter in the process. Also, I had to do some trimming and rewelding of the cross member so that the tie rod sleeves did not hit on the front of the cross member coil spring pockets at full lock when hitting a bump.

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

Re: Factory quick steer question
Posted by: toms73novass ()
Date: August 12, 2018 12:14PM

Jonathan Knapp Wrote:
-------------------------------------------------------
Also, I had to do some trimming and
> rewelding of the cross member so that the tie rod
> sleeves did not hit on the front of the cross
> member coil spring pockets at full lock when
> hitting a bump.
Do you have a shot of that part of the crossmember? I assume the idler are is hiding that in your current picture.

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block
86' BMW 325es
98' Dodge 2500 12v Cummins Diesel with 1200 lb torque!
98' VW Jetta TDI, for daughter
01' Audi Allroad Stage 3 twin turbo

NFCC
Grand Island, NY

Re: Factory quick steer question
Posted by: Jonathan Knapp ()
Date: August 12, 2018 03:39PM

Hi Tom,

No, I don't have any pictures of that specific work. It wasn't that substantial, so I never thought to take pictures. Your are correct about it being behind the idler arm in the picture above.

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

Re: Factory quick steer question
Posted by: LateModelMike65 ()
Date: September 15, 2018 05:49AM

Using the photo of the collection of arms above.... where do Clark’s arms length range?

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