Guldstrand Mod ?? [Archive] - Team Camaro Tech

: Guldstrand Mod ??


oddrod
Dec 13th, 04, 01:53 AM
Hi
Im about to do the the Guldstrand Mod,and I see that the relocation template dont match my A arm mount holes to frame measurments.

From the frame and up to the front hole,I measures 3,26",the template shows 3,5".

From the frame and up to the rear hole It`s 2,095",the template shows 2,25".

This is the LH side,the RH is closer to template.

My question is: should I use the Frame As Reference for height ,or the stock holes in the A arm mount.?? Will the A arm sit too low if I use the holes??

I have welded a jig and the mount will be trimmed in the bottom and moved 1/2"rear.

Thanks for any help..

OK

CReM@$TeR
Dec 13th, 04, 06:17 AM
oddrod,
Where did you get the template. I bought mine originally from Guldstrand, and yes the template was off. I actually redrafted the template in AutoCad and printed it out so that the center bolt measurements are exactly 6.5". My template has the hole measured from the center of the stock mounting holes to the center of the new hole so that they are .875" lower in the front, .775" lower from the rear, and set back .25" toward the rear of the car. So I would suggest going off of the stock holes because I have also found that not all tolerances used when manufacturing the frame were stricltly adhered to (ask me how I know :mad: ).

JimM
Dec 13th, 04, 07:49 AM
The 6.5" is the key. You need to open the image file in a program that will let you resize it, such a photdeluxe or photoshop. Resize it and print it over and over until the center to center on the holes is 6.5" on the print.

I cut out the original hole locations on the templlate, and just slid it over the existing bolts.

Be very careful as far as which side is which!! Once the first side is marked, the template needs to move to the other side IN THE SAME Orientation, don't let it flip over. The side that was against the a-arm bracket on the drivers side will be open to air on the pass side.

There is a post from last week, detailing another members trials with this, with pictures of a couple that are done

CReM@$TeR
Dec 13th, 04, 08:49 AM
Here is the post, yeah Jim it was me!

Guldstrand Mod - What the ..........? (http://www.camaros.net/forum/ultimatebb.php/topic/7/7396.html)

JimM
Dec 13th, 04, 11:39 AM
Thought so, did you get through it?

CReM@$TeR
Dec 13th, 04, 12:04 PM
I still haven't whacked off the ears yet. But the holes are all drilled and I mocked everything up so I could mark where I need to cut and grind. Just got to get over the fact that cutting will mess up the powdercoat, and then jump in and get it done. I'll probably finish this week, so I can get all of the subframe back together and bolted down. The rest of my Z06 brake parts should be here by Wednesday, so that will be good motivation.

oddrod
Dec 13th, 04, 01:04 PM
Hi
Thanks for all the replies..

The template did i download from David Pozzi page, it is printed out and it is perfect.
The holes Is 6,5" apart.The measurment are typed on the template.
It is my frame and mounts that is the problem.

Using the template and lower the front hole 1" and the rear 0,8" I am afraid that the A arm shaft will be to close to the frame.
The rear hole will be 1,3" over the frame and the front hole will be ca 2,2" over.

I'm just worried that when i have cut down the mount and rewelded it,the A Arm interferes with the frame or something.

Ok

[ 12-15-2004, 01:56 AM: Message edited by: oddrod ]

HwyStarJoe
Dec 13th, 04, 02:32 PM
Oddrod,

Before you cut or drill anything, measure where the new locations for the holes will be in relation to where they are now, mark them with a Magic Marker on the towers, then place the a-arm (with the cross-shaft in place) against the two marks and check for interference.
That way, it'll help you decide right where things need to be cut.

JimM
Dec 14th, 04, 05:46 AM
I'm just worried that when i have cut down de mount and rewelded it,the A Arm interferes with the frame or something.

Does that mean you're going to do this by cutting off the entire mounting bracket, trimming the bottom, and welding it back on the frame?

If it's a yes, then that is by far the best way, as well as the hardest, it will leave you with a completely stock looking frame, but it has to be done completely differently.

is this how you're doing it?

cody
Dec 14th, 04, 07:53 AM
you don't have to cut the ears if you use tubular control arms

oddrod
Dec 14th, 04, 01:18 PM
I Have made a jig and cut off the entie mounting bracket,and are about to trim the bottom of it.
I have good control with everything,its just that the mesurment printed on the template is not the same when it comes to frame to holes height.


Ok

69copo540
Dec 14th, 04, 02:54 PM
try david pozzi motor sports or look at the pro tour site in there tech section

JimM
Dec 14th, 04, 05:32 PM
Do some more searching here, odd, and studdy David's site real close. I remember people have done this by removing and trimming the brackets, then welding them back on... the details are fuzzy, I just drilled and cut.

What I'd do, is start with the tallest side, measure the difference in hole locations on the template, then measure and cut off that much from the bottom of the bracket, cut will be at an angle, cause the holes don't drop the same amount. Then measure how far back they go, and that's how far you shift the bracket back then you weld it back on.

For the shorter side, I'd measure from the holes on the side you just did, and use that #, then they should turn out even. You'll cut less off the short side.

davidpozzi
Dec 14th, 04, 07:17 PM
I measured the template, then measured down from the holes and scribed lines on the mount and cut that amount off the mount as low as possible.

There is a small difference between the measurements I have and what Tom, Chicane67 got from Guldstrand's blueprints when he worked there.

He feels the difference is significant. I haven't modeled the difference it would make, but feel a slight bit more camber change wouldn't hurt if I am the one who is "wrong".

There have been questions asked about whether the Guldstrand mod is ideal or if a lower position would be "even better". I tend to discourage going lower than Guldstrand deemed "best" but it has been a long long time since those holes were determined and tires have changed a lot since then.

Anyway, I'm not so sure there is a big difference to be seen between the two but be aware my measurements are more agressive.
David

oddrod
Dec 14th, 04, 11:05 PM
JimM,You meen using the frame as a refrence point for height?
I was about to use the old hole locations and follow the template and see where it gets me.
Its very difficult to try the A arm on,because of the jig.

Ok

JimM
Dec 15th, 04, 05:46 AM
I'd suggest starting with the one that seemed the tallest, as you said they were different, and they really shouldn't be.

Do that one so the holes end up where they would be if you'd just drilled new holes using the template. Do NOT use the frame as a reference. Use how far the holes will move from where they were.

Then pattern the second one off the first, so when they go back on, they end up the same.

Remeber what we're really trying to do here. As the a-arm moves, the ball joint describes an arc. This arc causes the camber to change as the suspension moves up and down. In the stock configuration, the pivot points of the upper a-arm are not horizontal, the outer pivot is lower than the inner. When the outside wheel suspension compresses in a turn, the ball joint moves outward, pivoting the tire off the road. We want to get it horizontal or a lil higher, so when the body rolls in a turn the tires cambers INWARD, keeping the full contact patch on the pavement.

I personally think ANY change of the upper a-arm angle will have a good effect, either by lowering the inner pivot, or raising the outer (with taller spindles) All the rearward shift does is build more caster in, so you con't need as many shims. (I got 3.5 degrees, with almost no shims at all)

The exact dimension's, either David's or g/s's, were developed by REAL racers back in the 60's. It musta worked, or the change wouldn't have been outlawed after the '68 season. I would trust David's numbers, in fact I did. H'es the real deal. I don't know how much of his stuff you've read, but I learn new things everytime I kill an hour on his site, and these are REAL things, from the eyes of a privateer professional trying to compete against big dollar factory sponsered teams, back in the days when it was possible for a smart guy to do it and bucks weren't everything.

MarkM
Dec 15th, 04, 05:48 AM
David, what's the difference between the specs you have posted on your site, as compared to Chicane67's?

davidpozzi
Dec 15th, 04, 10:36 AM
Here is the text below my version of the Guldstrand Template:

If you print this template out, it most certianly will NOT be exactly the correct size. Right click and select save, then you can try printing it out.

My measurements off my template are lower ft bolt 1.060" lower rear bolt .775" To measure, draw a line through the top hole centers, the cross hairs are accurate reference points, the circles are a bit off center so don't use them. Measure down from this line. The lower holes are also offset 1/4" to the rear to increase positive caster adjustment.
NOTE Chicane67 was an employee of Guldstrand Ent and says his hole lowering measurements are: F .875" R .775"

I used to have a link to a Pro-Touring.com web discussion on this topic, but I found out the dimensions I posted there were wrong. The dimensions posted here are from my template.

All I can say is, I used the top measurements and they worked well on my 67 Camaro.

This is the template, "the Guldstrand Mod" that is used to improve the front suspension geometry. The Camaro front suspension has too low a front roll center, and almost no negaitve camber gain in bump. If you do this modification to your Camaro, make sure you trim the bottom of the first thick alignment shim you place on the rear bolt. The A frame mount face changes angle and the lower part of the shim will hit and prevent the upper shaft from properly seating on the mount.

In addition, if you use stock upper A arms, the upper part of the mount must be trimmed off to about the height of the holes to allow enough clearance. The mount braces will also need to be trimmed or the A arm will hit in the middle.

If you call Guldstrand ent, they will send you a template

[ 12-15-2004, 09:59 PM: Message edited by: davidpozzi ]

oddrod
Dec 15th, 04, 12:44 PM
Tanks for all the replies,it really helps me alot.
I made a template in steel and there did i move the holes back additional 1/2INCH compared to the printed template, is this too much??
I think i remember have read here that when you cut off the entire bracket you should move it back more.because what JimM said about caster.

Ok

JimM
Dec 15th, 04, 02:42 PM
move it back the same amount as the holes are shifted on the template...1/4" total, like David said. can't get too crazy with it.

davidpozzi
Dec 15th, 04, 06:54 PM
If you will use stock upper arms move the mount back a half inch and you will have about 3 deg positive caster with no shims, a good starting point.

It might be a bit too far if you use the Global West upper arms but not with Speed Tech or DSE arms.

The Guldstrand mod does not move the holes to the rear more because there isn't room for the bolt heads.
David