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The "Guldstrand Mod" works to correct three things.
Moving the upper A-arm holes back improves caster.
Moving them down improves camber
Because it moves the front mount hole down slightly more than the rear hole, it also improves anti-dive during braking. (At least one version of the G-Mod instructions I've seen show the front hole down about 1/16" more than the rear)

Shelby did the same thing to the GT350 Mustangs in the 1960's to make them handle also....of course, Ford guyd call it the "Shelby mod")


Kind of amazez me that this simple mod has fallen from the hotrodders lexicon....maybe it has just been buried by the "tall spindle merchants" so they can sell you more parts
 

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What Ericnova has stated is true but repositioning the upper cross shaft down and back doesn’t resolve the length of the upper control arms. So you end up having to do one of the following to compensate for this. Add more shims, reposition the upper mount inboard, or switch to shorter upper control arms.

The Guldstrand modification is a simple operation that makes a bounty of improvements. Today there are plenty of other ways to get the benefits by bolting on parts that do the that and then some.. The problem is that there a lot of parts available that look like up grades but are not making any improvements other the an aesthetic effect. Taking measurements tells the story that the aftermarket parts suppliers don’t.

If you want to have custom control arms made to your specs you can contact a company like UB Machine and they will make them for you. They probably already have a jig fixture for what you want..
 

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1970 2-Door Barn Find
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Discussion Starter #23
I'm looking at the results of both of your alignment attempts... and I am only seeing a positive caster of 1.8°(left) and positive 2.2°(right). I do not see the 3.25° of positive caster that you previously mentioned.
Yeah. I kinda screwed up on that. In my (weak) defense, you can see that was done back in July and I have had a couple things going on since then...
You can do a quick check of your front end toe-in with a long tape measure... and if your tire has a straight tread profile similar to the image shown below.
I am familiar with the technique. I have done it several times on previous cars (but not this one). Unfortunately, my current tread pattern doesn't have a straight line but I should be able to do the same trick using a couple of yardsticks on the outside of the tires.

Mike
 

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Discussion Starter #24
Your spindles would be the short spindles unless your replacement 2” dropped spindles were tall 2” dropped spindles which do exist.. You can easily measure what you have. The outside distance from the top to bottom ball joint surfaces I believe the short ones are 7” and the tall spindles 8.75”.
When you say "ball joint surfaces", does that mean the surfaces on the upper and lower arms where the ball joints bolt on?

My Control Arms

Mike
 

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Discussion Starter #25
What Ericnova has stated is true but repositioning the upper cross shaft down and back doesn’t resolve the length of the upper control arms. So you end up having to do one of the following to compensate for this. Add more shims, reposition the upper mount inboard, or switch to shorter upper control arms.
I think you have that backwards. I believe I need longer arms so it requires more shims to return the upper ball joint to its original position. More shims means mean more range of adjustment. Check out my earlier control arm pictures. I have zero shims now so I am at the limit of my adjustment.

I was considering something like this: Adjustable Control Arms
but now I am leaning towards something like the "Guldstrand modification". It is simple, no-cost and reversible. But I need to check the size of my spindles first.

Mike
 

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In effect, the Guldstrand mod also makes the upper control arm appear longer. When you move the inner pivot point down, that flattens out the angle uf the upper arm at ride height, which tips the top of the spindle out slightly and requuires you to shim the shaft inboard to get that camber back in spec....giving you back some adjustment range.

When you say "ball joint surfaces", does that mean the surfaces on the upper and lower arms where the ball joints bolt on?
No, he is referring to the top and bottom flat section of the iron spindle itself, at the point the ball joint stud fits into.
 

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Discussion Starter #27
If you want to have custom control arms made to your specs you can contact a company like UB Machine and they will make them for you. They probably already have a jig fixture for what you want..
"UB Machine"? University of Buffalo?
 

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Discussion Starter #29
Your spindles would be the short spindles unless your replacement 2” dropped spindles were tall 2” dropped spindles which do exist.. You can easily measure what you have. The outside distance from the top to bottom ball joint surfaces I believe the short ones are 7” and the tall spindles 8.75”.
I crawled under the car and measured the spindle height. Guess what... Its right at 7". It looks like the CPP 2" drop spindle is based on the factory short spindle.

Also, I threw a level on top on the upper control arm, weight-on-wheels, and it has a downward angle (away from the chassis) of 7.2 degrees. That kinda surprised me because I thought it was level. That "Guldstrand mod" is looking better all the time.
 

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Discussion Starter #30
Your spindles would be the short spindles unless your replacement 2” dropped spindles were tall 2” dropped spindles which do exist.. You can easily measure what you have. The outside distance from the top to bottom ball joint surfaces I believe the short ones are 7” and the tall spindles 8.75”.
I crawled under the car and measured the spindle height. Guess what... Its right at 7". It looks like the CPP 2" drop spindle is based on the factory short spindle.

Also, I threw a level on top on the upper control arm, weight-on-wheels, and it has a downward angle (away from the chassis) of 7.2 degrees. That kinda surprised me because I thought it was level. That "Guldstrand mod" is looking better all the time.
 

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You kinda have to not look at the actual shape of the arms because they are very distorted and usually look angled down more so then the actual operating relation. You need to visualize an imaginary line going through the upper cross shaft and the ball joint.

This Chevelle Chassis has no weight on it no body or drive train. It has flat aftermarket arms and stock spindles with 1/2” longer ball joints. With the normal full weight on it the arms would be pointing slightly upwards. The arms have a slight offset to give more caster and are adjustable with the rod ends. It’s a pretty tunable setup.
C1D1E11F-BEDA-48A1-9A61-BB0ED2CE93A1.jpeg
2B6CA3E7-0E70-4CAF-98BD-3D7ADC9CEE52.jpeg
 

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Discussion Starter #32
This Chevelle Chassis has no weight on it no body or drive train. It has flat aftermarket arms and stock spindles with 1/2” longer ball joints. With the normal full weight on it the arms would be pointing slightly upwards. The arms have a slight offset to give more caster and are adjustable with the rod ends. It’s a pretty tunable setup.
I really like the construction of those upper arms. How do those heim rod ends work for daily driving?

I used them on another car a long time ago and, after a while, they started squeaking. I had to squirt them with WD-40 periodically. (That seems to be the only lubricate that would penetrate into the ball.)
 

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The rod ends will transmit feedback from the road since they are all metal construction. They will also require lubrication..
 
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