Guldstrand Mod on 2nd Gen Camaro

[dipren443]

Ok, I hope this isn't a stupid question, but after using the search function and reading through multiple threads, I wasn't able to find exactly what I was looking for. What is the applicability of the Guldstrand Mod on the 2nd Gen Camaros? Is it as beneficial as it is for the 1st Gen Camaros? And is a template available for the 2nd Gen?

Thanks in advance.
Nick

[chicane67]

In a short and simple answer........ no.

The geometry used on the 70 and later chassis was designed with the changes they made and learned from in and on the 67-69 platform. So, there isnt any real need for a relocation.... unless you feel experimental and know what you are getting into with a geometry re-location.

[dipren443]

Chicane,
thanks for the response. That is honestly what I figured. The term G-mod just seems to get thrown around rather loosely and I was wondering what the applicability was on my car.
Thanks,
Nick



In a short and simple answer........ no.

The geometry used on the 70 and later chassis was designed with the changes they made and learned from in and on the 67-69 platform. So, there isnt any real need for a relocation.... unless you feel experimental and know what you are getting into with a geometry re-location.

[Marcus SC&C]

Actually there is a G type mod for 2nd gens. I have an old High Performance Guide put out by Chevrolet in 1970. It outlines engine mods and suspension mods for road racing. In it there`s a diagram showing the relocation of the UCA mounting points to improve the camber curves. The problem is that it requires either mods for clearance either to the frame,UCA or both. We have a package that achieves similar geometry with tall UBJs and adj. upper arms instead (2nd gen. Street Comp Stg.1). Same perks, no cutting and welding. :) Marcus

[David Pozzi]

A second gen has more camber gain than a stock first gen, but less than a first gen with Guldstrand mod.
Upper A arms that allow high positive caster help a lot.
Someone here posted a link to "The Trans-Am and Corvette Chassis" which was published in the early 70's. It showed the upper A arm mount was lowered and some clearance mods done, but that was strictly for road racing with the Goodyear Blue Streak bias-ply tires.
I can't find the link now though.

[Lowend]

In my experience its not really needed. Camber gain on a 2nd gen is pretty good, about equal to that of a C4 Vette.
Where 2nd gens do benefit from geometry change is the Castor, namley you really can't get enough without effecting the rest of the alignment.
Global West has a Tubular A-arm with a rotated upper balljoint mount that is supposed to address this. I have heard good reports but have no firsthand experience.

[jeffandre]

I believe the GW offset cross shafts move the UBJ rearward, supposedly increasing castor while maintaining a good camber curve. I will be using them since I need new shafts for my GW bushings anyway (my Vette Brakes shafts are too big in diameter for the GW bushings).

[chicane67]

The cross shafts do nothing with castor..... they are offset from shaft center, so that you can use less shims and have more thread left for high offset adjustments.

[jeffandre]

The cross shafts do nothing with castor..... they are offset from shaft center, so that you can use less shims and have more thread left for high offset adjustments.

Makes sense, I asked the tech guy for specifics but he was unable to provide them, other than his statement that they increased caster and maintained a good camber curbe with the increased caster. Maybe I should turn down my Vette Brakes shafts to make the GW bushings fit them, at least I would be able to position the shaft forward in the UCA, essentially moving the arm rearward. What do you think Tom, is it worth it for autocrossing?

[1977nova]

I found the article for the g-mod for second gen f-bodies. It looks like the front hole is lowered 3/4" and the rear is lowered 1 1/4" to increase antidive. I am still considering doing this on my nova but I dont know if this would be too much for the street or if it would be worth all the work as it seems like the starting point is pretty good to begin with. I was wondering if what the best castor setting would be? I dont really want to go with aftermarket a arms because I would like to keep it look stock.

[1977nova]

http://www.74-77camaro.com/Articles/TransAm-chassis/TA-chassis.htm


sorry here is the link. click the links for "building the trans am chassis"

[chicane67]

Makes sense, I asked the tech guy for specifics but he was unable to provide them, other than his statement that they increased caster and maintained a good camber curbe with the increased caster. Maybe I should turn down my Vette Brakes shafts to make the GW bushings fit them, at least I would be able to position the shaft forward in the UCA, essentially moving the arm rearward. What do you think Tom, is it worth it for autocrossing?

I guess he meant that..... it will allow you more room for caster adjustment with higher static camber settings.

As for autoX, you dont really need alot of caster. Unless you looking to increase the camber gain from the higher initial caster settings. I have always used less static caster for a hard use autoX setting and more caster (like around +6*) for street and faster road course work. How much caster are you looking for ??

I have that prep book, that is in the above link. Let me decipher it and give you some input on it. Most everything in that book was for a specific 'track only' chassis.

.........

What they did in this build was remove the entire UCA mount, cut 0.75" off of it and re-weld it onto the sub-frame. Even this was illegal by the "rules" as it does effectively change the stock mounting location for the UCA. Then they lower the rear hole to for an anti-dive change which also necessitates the upper shock location to be moved up as well.

And a thing to note..... this is old school. Lots has happened since then in the suspension world but more importantly, the tire world. But..... for something I wasnt going to cut up and wanted to use OE parts on this would be a great way to go. And in essence, it is the "Guldstrand mod" for the second gen.

But.....

You gotta use the required spring rates for this to do its work. Too many people forget that when certain things are done to a chassis, that they need to follow thru on the rest to get the wanted results. So, I guess if you were up to running 700/200+ rates, I would give this consideration. I run rates bigger than that and I am more than happy........

[primate]

so what would happen if you did this mod and also had the global west a arms?

[dipren443]

so what would happen if you did this mod and also had the global west a arms?

Taken from GW's website...

Increased Caster = With 5-1/2 degrees of positive caster built into the control arm, straight line stability and corner entry is dramatically improved.
Camber curve is improved for high speed maneuvering.

That being said, the suspension geometry modifications should be taken care of with just the GW A-arms. They may not be as extreme as the mods discussed above by chicane67, but probably more than sufficient.

[primate]

ok, but i already did the g mod for 2nd gens, and was looking at the global arms too. would that be a bad idea?

[chicane67]

Noooo.... not a bad idea, as the control arms really dont do much to the camber curve, yet they do wonders for the castor. Static or dynamic.

I think a total gain in bump of around -3.25* camber with somewhere around 5.5 to 6+ castor would be the ticket with the use of a 500 to 700 rate spring.

[dipren443]

Noooo.... not a bad idea, as the control arms really dont do much to the camber curve, yet they do wonders for the castor. Static or dynamic.

I think a total gain in bump of around -3.25* camber with somewhere around 5.5 to 6+ castor would be the ticket with the use of a 500 to 700 rate spring.

So are you saying that this would be accomplished using the GW arms and performing the Guldstrand mod?

[Marcus SC&C]

If you`re doing a G mod type modification you don`t need GW arms at all. Just move the holes (or perch if you`re moving the whole thing) rearward. You`ll have to mock it up and measure the caster to get it right but that ought to be the easiest part of the day. :)
UCAs DO NOT and CANNOT alter camber curves,period. Any effect resulting by changing UCAs is due to the altered static alignment specs NOT the arms themselves. Mainly when you add more + caster the rearward spindle inclination increases - camber a bit when turning. If you want to change the actual camber curves and RC heights you need to change the vertical orientation of the suspension pickup points. That`s what the G mod and our tall stud modular ball joints do. We sell adj. UCAs to allow proper UBJ angles and to allow a wide range of alignment specs not because they`re a magic bullet. That said the 2nd Gens work pretty well as is with the right springs,shocks etc. I`ve had 8 of them myself. :) Marcus