Performance front suspension

swiss · 09-12-2007

OK, I am looking for information on setting up the GT/Kadett front suspension for fast street and performance handling. Some of the racers may have some tips, I read the info on setting up the coil-over Koni front shocks. Problem is that I understand that the front A-arms are lacking in strength. I think that I readone time that someone built a converted Mustang II front suspension system for it? I also understand that the M II is not a performance system either although it is probably stronger than the Opel A-arms.
Best suggestions? Bracing? Boxing the arms? bushings- delrin/poly?
There are lots of tips on setting up different springs and shackles forthe front end, but are these just limited by the basic suspension design?

Your thoughts are appreciated.
Swiss

opelwasp · 09-12-2007

First, coil overs won't fit in the GT/Kadett A-arms. The stock shocks barely do.
For coil overs you're going to have to make tubular A-arms and some serious structural support. Can't just bolt em in, they'll rip right through the sheet metal.

swiss · 09-12-2007

Well, somehow they do fit if they are small enough for tuning and not complete support for the suspension. This post was done for the Koni shock mods.

http://www.opelgt.com/forums/group-3...tble-coil.html

Swiss

jeff denton · 09-13-2007

With that thread you are on the right track, I think. That is exactly how I would do a street car, or a race car if the rules allowed it.
The stock setup lacks in bushing stiffness, start there first. And it's hard to tune the leaf spring. Shackles are a must as far as I'm concerned, to keep the spring from binding up the lower A arm bushings.
I'd use the lowering spring from OGTS, minimal length shackles, and just enough coilover spring rate to prevent bottoming out in a hard turn.
Study our posts about centering the spring and locking it there.
There is a thread or post about putting in a Z-bar, check that out.
Myself, I haven't wrecked a lower A-arm yet, but I've tried. Not so lucky with the uppers, they bend really easily!

swiss · 09-13-2007

So would boxing help the upper arm? Any real geometry changes that would work better than stock?

Swiss

opelwasp · 09-13-2007

I stand corrected. But, where the hell do we get the set up from. In that thread some one asked for part numbers and it died right there.

jeff denton · 09-13-2007

Stiffening it is simple but keep in mind, the next part down the line (thru-bolt, tower) gets bent next. Which is easiest to straighten? The a-arm.
My setup has all these parts beefed up for rigidity (no flex under severe stress) but it's just more to fix after a crash... hopefully you won't be crashing yours as much as I do. It's part of the fun, you know.
A tubular upper would be incredibly simple to fabricate.
Ask the road race guys about the geometry setup. My experience here is only all about turning real hard to the left at full throttle. Impossible to drive on the street!

StefanLee · 09-13-2007

Hi guys.

Don´t know if this will be of interest to anyone, but I came to think of these pictures when I saw this thread.

The pictures are of a reinforced shock tower for a LEDA coilover, no leafspring.

It also has a new stainless lower a-arm. These pics are from the building process, but it is now finished and running.

The car is a killer (400hp 16V turbo) and pictures are credited to lofa (the builder)

Stefan

http://www.pipe-arts.com/project/lof.../framvagn1.jpg

http://www.pipe-arts.com/project/lof.../framvagn2.jpg

http://www.pipe-arts.com/project/lof.../framvagn3.jpg

This last one is of a finished lower A-arm.

http://www.pipe-arts.com/project/lof...ing/a-arm4.jpg

edit:

How the heck do i directlink to images, img tags won´t work!

Stefan

jtb · 09-13-2007

Swiss, did you look at this thread?

http://www.opelgt.com/forums/perform...ed-advice.html

HTH,

jtb

swiss · 09-13-2007

Just got done going through LOTS of posts with plenty of pics. Ideas will help out a bunch. Interesting that some built new bottom a-arms which are said to be strong enough already, and left the stock top arm. This stuff is sometimes hard to dig out of the archives and a little experienced help works wonders!

Thanks guys,
Swiss

09-12-2007	#1 (permalink)
swiss Opeler Join Date: Jan 2003 Location: Alamogordo, NM Posts: 70 Classified Rating: 0% (0)	Unanswered: Performance front suspension OK, I am looking for information on setting up the GT/Kadett front suspension for fast street and performance handling. Some of the racers may have some tips, I read the info on setting up the coil-over Koni front shocks. Problem is that I understand that the front A-arms are lacking in strength. I think that I readone time that someone built a converted Mustang II front suspension system for it? I also understand that the M II is not a performance system either although it is probably stronger than the Opel A-arms. Best suggestions? Bracing? Boxing the arms? bushings- delrin/poly? There are lots of tips on setting up different springs and shackles forthe front end, but are these just limited by the basic suspension design? Your thoughts are appreciated. Swiss

09-13-2007	#4 (permalink)
jeff denton former opel racer Join Date: Nov 2002 Location: near some glaciers Posts: 2,774 Classified Rating: 0% (0)	With that thread you are on the right track, I think. That is exactly how I would do a street car, or a race car if the rules allowed it. The stock setup lacks in bushing stiffness, start there first. And it's hard to tune the leaf spring. Shackles are a must as far as I'm concerned, to keep the spring from binding up the lower A arm bushings. I'd use the lowering spring from OGTS, minimal length shackles, and just enough coilover spring rate to prevent bottoming out in a hard turn. Study our posts about centering the spring and locking it there. There is a thread or post about putting in a Z-bar, check that out. Myself, I haven't wrecked a lower A-arm yet, but I've tried. Not so lucky with the uppers, they bend really easily! Last edited by jeff denton; 09-13-2007 at 01:04 AM..

09-13-2007	#8 (permalink)
StefanLee Opeler Join Date: Nov 2006 Location: Sweden Posts: 199 Classified Rating: 0% (0)	Hi guys. Don´t know if this will be of interest to anyone, but I came to think of these pictures when I saw this thread. The pictures are of a reinforced shock tower for a LEDA coilover, no leafspring. It also has a new stainless lower a-arm. These pics are from the building process, but it is now finished and running. The car is a killer (400hp 16V turbo) and pictures are credited to lofa (the builder) Stefan http://www.pipe-arts.com/project/lof.../framvagn1.jpg http://www.pipe-arts.com/project/lof.../framvagn2.jpg http://www.pipe-arts.com/project/lof.../framvagn3.jpg This last one is of a finished lower A-arm. http://www.pipe-arts.com/project/lof...ing/a-arm4.jpg edit: How the heck do i directlink to images, img tags won´t work! Stefan Last edited by StefanLee; 09-13-2007 at 01:49 PM..

09-13-2007	#9 (permalink)
jtb Member Join Date: Oct 2004 Location: Vancouver Canada Posts: 334 Classified Rating: 100% (1)	Have you seen this? Swiss, did you look at this thread? http://www.opelgt.com/forums/perform...ed-advice.html HTH, jtb

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09-12-2007	#2 (permalink)
opelwasp Non Civilian Join Date: Mar 2003 Location: Between Chico and Sac, CA Posts: 1,371 Classified Rating: 0% (0)	First, coil overs won't fit in the GT/Kadett A-arms. The stock shocks barely do. For coil overs you're going to have to make tubular A-arms and some serious structural support. Can't just bolt em in, they'll rip right through the sheet metal.

09-12-2007	#3 (permalink)
swiss Opeler Join Date: Jan 2003 Location: Alamogordo, NM Posts: 70 Classified Rating: 0% (0)	Well, somehow they do fit if they are small enough for tuning and not complete support for the suspension. This post was done for the Koni shock mods. http://www.opelgt.com/forums/group-3...tble-coil.html Swiss

09-13-2007	#5 (permalink)
swiss Opeler Join Date: Jan 2003 Location: Alamogordo, NM Posts: 70 Classified Rating: 0% (0)	So would boxing help the upper arm? Any real geometry changes that would work better than stock? Swiss

09-13-2007	#6 (permalink)
opelwasp Non Civilian Join Date: Mar 2003 Location: Between Chico and Sac, CA Posts: 1,371 Classified Rating: 0% (0)	I stand corrected. But, where the hell do we get the set up from. In that thread some one asked for part numbers and it died right there.

09-13-2007	#7 (permalink)
jeff denton former opel racer Join Date: Nov 2002 Location: near some glaciers Posts: 2,774 Classified Rating: 0% (0)	Stiffening it is simple but keep in mind, the next part down the line (thru-bolt, tower) gets bent next. Which is easiest to straighten? The a-arm. My setup has all these parts beefed up for rigidity (no flex under severe stress) but it's just more to fix after a crash... hopefully you won't be crashing yours as much as I do. It's part of the fun, you know. A tubular upper would be incredibly simple to fabricate. Ask the road race guys about the geometry setup. My experience here is only all about turning real hard to the left at full throttle. Impossible to drive on the street!

09-13-2007	#10 (permalink)
swiss Opeler Join Date: Jan 2003 Location: Alamogordo, NM Posts: 70 Classified Rating: 0% (0)	Just got done going through LOTS of posts with plenty of pics. Ideas will help out a bunch. Interesting that some built new bottom a-arms which are said to be strong enough already, and left the stock top arm. This stuff is sometimes hard to dig out of the archives and a little experienced help works wonders! Thanks guys, Swiss

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