[JV69z/28rs]

Lately between here and the P/T website there has been lots of talk about the tubular upper arms based on price and quality which seems to come down to the big 3 - DSE - Global West - SpeedTech.
Everybody more or less agrees they all produce similar results. Now a taller upper balljoint has been added to the mix. Enter SC&C with the Polepostion upper arm and the modular taller upper ball joint. My question is if the taller upper ball joint is a good way to improve the suspension geometry on a 1st gen then why aren't the tubular arm companys using them in their arms? Is it a case of a little is good but more is too much? I would really like to hear your opinions on the theory. Thanks in advance for your input. Jack

[JimM]

The first gen's have a "bad" camber curve. As the suspension compresses (in a turn) the outside tire leans out, which puts it on it's edge. It should lean in, to compensate for the body roll and keep the tire flat on the ground.

This can be fixed by either moving the inner a-arm pivots closer together (guldstrand mod) or the outer pivots further apart (taller spindles or balljoints.)

It is not possible to directly change this with a new a-arm. They are strong, and they look really cool, and they locate the upper ball joint further to the rear, which builds in more caster, and that can have somewhat of the same effect. (the turning of the wheels, rather than the compressing of the suspension, changes the camber due to the large amount of caster.)

Guldstrand mod alone is fastest/easiet way to make it right. Taller spindles or balljoints would be #2. #2 AND fancy a-arms works too and looks really cool.

[davidpozzi]

The A arms allow more caster to be used, this tilts in the tire when cornering which is good.
The taller ball joint just came out, It's made by Howe, the race chassis builder, but it's a special version since they usually make chrysler and GM pickup sized/tapered balljoints and not the early Camaro/nova parts.

The Guldstrand mod reduces anti-dive a little which the taller balljoind doesn't do.

If you don't want to drill your upper mounts, get tubular arms and taller balljoints.
If you can drill the mounts, just get the arms and do the Guldstrand mod.

The Guldstrand mod WITH the taller balljoints MAY be going too far, it needs to be tested out.

The (best) stages do go with are:
1. Tubular arms alone, use 5+ deg caster.
2. Tubular arms with Guldstrand mod (drill and cut).

If no power steering, just do the Guldstrand mod and try 3+deg positive caster, add or reduce caster for best feel/effort level.

[oldchevy]

David you stated that the Guld Mod reduces anti dive that the taller ball joint doesn't' why would the 2 used together be a bad idea? They would be too much what?

[JimM]

The Guldstrand mod changes the "angle" of the upper a-arm pivot, that is, one bolt is lowered more than the other.

The 2 together may simply be "two" much change.

[davidpozzi]

Jim is correct, the Guldstrand mod lowers the front bolt more than the rear bolt reducing anti-dive.

Lowering the inner pivot via the Guldstrand mod PLUS raising the outer balljoint with a taller balljoint would raise the roll center which may cause problems, also the front view swing arm may be shortened too much.

The result of going too far could be: too much roll center movement, too high a roll center, with resulting jacking of the front end under hard cornering, excessive front weight transfer which is not controllable by use of antiroll bars, springs, or shocks.

[oldchevy]

So if you had a choice of the two? Didn't the old Trans Am Camaro's actually use a taller spindle and the mod? I have talked to Mark at SC and he is quite convincing in that they will work together. I appreciate the advice and have read your site many times over so I do respect your opinion.

[davidpozzi]

There is no doubt that they would work together, just how severe it would be. [img]smile.gif[/img]

SIGNS YOU WENT TOO FAR:
The inner tire edges may wear out before the rest of the tire, the car may experience the front end bobbing up and down when cornering hard on a flat or slightly off camber surface due to the higher roll center and resulting jacking effects.

The pro-motorsports upper ball joint spacers raise the upper BJ 1 15/16", users have reported excessive tire inner edge wear. The Guldstrand mod plus half inch taller balljoints is around 7/16" shorter than that.

On a banked surface there are no worries.

The 69 Trans-Am Penske Camaros had a taller spindle homologated. They were not allowed to do the Guldstrand mod by the restrictive SCCA rules, so this was a "legal" way to improve the geometry.

With just the Guldstrand mod and sock UBJ you will have a higher roll center and a more agressive camber curve than any newer vette or second gen Camaro. Guldstrand tried lower holes but settled on the ones on the template. Other holes may work better with todays tires but that's not been tested or proven.

If I had a street only driven Camaro and didn't want to cut or drill the sub, I'd use tubular uppers with the taller UBJ from Marcus.

But the most ideal way to go is to do the Guldstrand mod plus Tubular arms and stock UBJ's.

The addition of the taller UBJ's may be going too far unless it's a track only car.

I'll be testing the Gmod plus taller UBJ but probably not until next year.

[oldchevy]

Was the Guldstrand mod an exact location or one chosen out of the lowest point that would actually fit drilled on upright? I would think the answer would be just what fit so then why not go lower to maybe a medium point with more extensive mods to rail? I already have the PP set up and am impressed more with the ball joints and tie rods than the arm itself. If there are any measurements you need for evaluation let me know I would be more than happy to provide.

[oldchevy]

Sorry I reread your reply ignore my above question.