Would this same camber mod theory apply well to a trifive?

[Geoff]

http://www.popularhotrodding.com/tech/0607phr_car_handling_tech/

[Rick_L]

It would work, except that the Camaro bracket on the frame is much taller than the 55-57 frame bracket. I don't think you can re-drill the holes lower on the bracket and get the bolts and control arms to clear the frame. Same with drilling them further back, the control arms won't clear the brackets. So to do this you'd have to cut the top of the frame and fab a new bracket. Even then maybe there are difficulties.

An easy cheap way of getting more caster without using aftermarket control arms is to cut the welds on the front of the bracket, and move the front of the bracket outboard 3/8". You have to have the frame bare to do this. A lot of trouble on an assembled car, not so much on a bare frame.

If you wanted the camber gain that the "Gulstrand mod" gets you, one way to accomplish that on a 55-57 is to use C3 Corvette spindles. They are about 1" taller than the stock spindle. You have to fab some adapter bushings for the lower ball joint. The upper control arms will have to be shortened about 3/4". You also would use C3 Corvette brakes. I have done this mod on my car. Not tested yet. The biggest issue is ride height, as the C3 spindle is not "dropped", it's the same height as a stock spindle. And I want a low ride height for my car.

I can detail more info if you wish.

[chevynut]

How exactly does lowering the upper a-arm pivot points do anything to the lower a-arms? Seems like you would have to change the springs to change the lower a-arm angle relative to the ground. And how does it add caster? I don't see how just dropping the upper a-arm shaft changes anything at the spindle but pull the top of it inward, requiring more shims to get zero camber back.

"Using the template designed by Guldstrand (for First Generation Camaros and Firebirds) will let you lower the upper control arm pivot points by .75 inch. This raises the front suspension roll center from below ground level, to a point well above the road. This will reduce the angle of the lower control arms and make them more parallel to the ground, giving you a more favorable camber curve. The new holes will also move the top of the spindle rearward .25 inch from stock. This will create more positive caster, which will make the steering feel more "snappy.

I have wondered why someone doesn't just make upper balljoints with longer studs. Wouldn't that behave like a taller spindle?

[Geoff]

Great discussion. The corvette spindle and extended ball joint are cool ideas.
I really like the idea of improving the geometry using ingenuity instead of high dollar parts.

Now, how would you modify a stock a-arm for more caster?

[Bihili]

Now, how would you modify a stock a-arm for more caster?

Many years ago at Chevytalk forum, a now deceased member named Michael McVeigh came up with the idea of moving the upper ball joint inside the stock upper A-arm.
He re-drilled the holes for the ball joint. I don't remember the how much he moved the ball joint but he had the right idea. This was before aftermarket tubular A-arms became popular.

[NickP]

The issue there, without some other modifications to the perimeter of the control arm, specific to the landing zone for the ball joint - not a lot of room due to the housing design.

[Rick_L]

How exactly does lowering the upper a-arm pivot points do anything to the lower a-arms?

You are correct, the Gulstrand mod does nothing to the lower control arm, spring, ride height, etc.

The author misspoke, he should have said "upper control arms". Lowering the inner pivot on the upper control arm does do what was described.

The "Gulstrand mod" has been around for many years, I think first applied to early Mustangs. Early Camaros can use it too.


I have wondered why someone doesn't just make upper balljoints with longer studs.

I think they are available for early Camaros/Chevelles.

Seems like just this week I saw a photo of a stock 55-57 control arm modified to move the ball joint rearward, chevytalk perhaps.

Here's the photo.

http://i1261.photobucket.com/albums/ii597/John_Jbchevy/TriFive/chevexhaust011_zpsa333ce1a.jpg

[chevynut]

Now, how would you modify a stock a-arm for more caster?

Anything you can do to move the upper balljoint REARWARD will improve caster. That includes adding shims at the rear of the shaft. However, that most likely will screw up the camber. You could LENGTHEN the upper a-arm, then add those shims to bring camber back into spec. The upper a-arm isn't really under that much stress except when cornering. You could also use offset shafts or bushings to gain more caster. Those were available years ago to correct camber problems that were common on these cars.

The method Rick described where the front of the a-arm upright is moved outward will also improve caster, but it's a frame mod that some guys don't want to do.

[chevynut]

Take a look here:

http://www.fabquest.com/tci-tri-5-chevy-55-56-57-offset-upper-control-arm-shafts.html
https://www.performanceonline.com/1955-57-CHEVY-BELAIR-210-150-OFFSET-UPPER-CONTROL-ARM-CROSS-SHAFT-EACH-UCS5557S/

[Rick_L]

Note that 4º = 2º really equals 1.5º. You can only offfset the shaft so far and still have everything fit.

[Tabasco]

Many years ago at Chevytalk forum, a now deceased member named Michael McVeigh came up with the idea of moving the upper ball joint inside the stock upper A-arm.
He re-drilled the holes for the ball joint. I don't remember the how much he moved the ball joint but he had the right idea. This was before aftermarket tubular A-arms became popular.

I miss Michael McVeigh. He had practical and cheap ways of making modifications rather than using expensive aftermarket parts.

Here is what he posted on the modification on the upper a-arm mount:
If you want to set your castor like a more modern suspension setup this is an easy way to gain 5° which is about normal for your set up. You leave the backside weld on the inner side of the frame (closer to firewall)connected, break loose other welds and move front (closer to bumper)towards the outside of car as much as you can without climbing up the spring perch. You can feel it when it first starts to climb by pushing down on it as you tap it toward the spring perch.

I saved a photo but I saved it in document rather than photo format and I can't figure how to post it here. It just shows what he described.