jkicak

my car is an 87 Formula 350. no accients that i know of...

i know this is due to the frame of the car but i really want to know if subframe connectors WILL fix this for sure? i plan on doing the SFCs asap but my hope is when i go to have the car painted next year that the body guy can fix the cracks (i konw that can be fixed) and that they will not come back. i plan on doing a full suspension upgrade also. please let me know if and how you have solved this issue.

thanks in advance for your time!

Codename 47

iTrader: (4)

I know a guy in town here that had an IROC that had the paint crack in that area. He said it was due to body flex during autocrossing. I believe his car was a ttop car.

Stephen

iTrader: (12)

Yeah, that is a common problem for our cars due to flex. Either high hp launches at the dragstrip, or high g's in autocross.

SFCs aren't a permament fix, nor a guarantee that that will NEVER return, but they go a LONG, LONG way to keep it from happening again.

It is possible, althugh VERY unlikely they will return, after SFCs.

My suggestion though is, get the body alignment checked at a body shop before instaling the SFCs, to ensure there is no body twisting that will be locked in by a SFC install.

I don't recall seeing a SFC equipped car being twisted like that, but by the time you reach that hp level, most people have some sort of cage installed, I bet.

JamesC

iTrader: (5)

I think the problem is common because of the inherent design (flex) and age of our cars. I don't think I've ever seen a coupe that doesn't have the cracks (of course, I haven't seen them all). SFC's will, I think, put an end to the problem. Did in my 85, at least.

JamesC

Anniversary-Z-man

iTrader: (2)

That's a known problem spot on all 3rd gens. I had the same thing happen on my '92....the car was never dragged or autoX'd....just street driving. Also the only mods done to it at that point were intake and exhaust work....nothing really major, just bolt-ons. That spot see alot of force (torque) and in turn starts to crack right at the corner. About 8 years ago I had a body shop here repair both cracks. They welded in flat plate steel at those corners, formed the metal, and re-painted. After that was complete I drove very carefully for a day or so until my appt. to get my SFC's welded on. The real test will be when I get the tune down on the new engine and get that thing to the track for some runs....I don't think I'll ever have to worry about cracking again though....the SFC's do an awesome job.

92RS(real slow)

I had this happen on my old RS, and I fixed it twice, and it kept coming back which im guessing I didn't do a good enough job

bigmaciroc

Its happening on my 92 RS(from launches) so i am going to do quite a bit of work on my IROC to keep the chasis from flexing, try a 10 or a 12 point roll cage. thats what im doing. other than that, from me being a painter, theres nothing really to prevent it, but you can slow the process. my

jkicak

do you have SFCs on yours?? i HOPE it didn't come back with SFCs!

i want to try and stay away from the cage, i'll use that as a last resort if i have to.... if i need to end up putting a cage in then i'll just chop the top and make it a targa.


thanks for the posts all... i'm starting to feel better!

jkicak

did SLP make SFCs for thirdgens? i guess somebody local has a set for sale but i can't find where SLP made them.. all i see from SLP are 93-02 SFCs

Camaroguy18

i had the crack as well, but the sfc's helped it, got the crack repaired and painted and it hasnt come back

spohn makes really great sfcs

jkicak

i can't find the SFCs for thirdgens on spohn's site..

EDIT: doh, i found em.. nevermind..

thanks for the input

Black85sport

my firebird cracked at the top and rear portion of the drivers side window

xpndbl3

iTrader: (5)

mine cracked before the subframes and the 6 point cage, and i'm pretty sure the crack will return after this paintjob. These cars just twist at that corner and when you're running high HP and hard launches it's to be expected.

Stephen

iTrader: (12)

Black85sport:
The driver's side window roof crabk is the only place I've ever heard of it happening.

xpndbl3:
As far as a crack returning after a SFC and cage install, it ain'tb gonna come back, unless the installs are made from PVC pipe!

xpndbl3

iTrader: (5)

it'll come back I'm sure of it. my buddy with a 10 point cage has a crack slowly returning with his combo.

Camaroguy18

Im sure some of it has to do with how deep the crack was and how it was repaired....but Im gonna bite my tounge on a guarentee because Im not a body man (though mine hasnt returned).


Other than the back corner of the windows, there are also some f-bods that get cracks underneath the side mirrors

Roc Me 2

iTrader: (2)

I have a hardtop and mine was doing the same thing. I had it fixed when I painted the car. I am going to put the SFC on and 8 point cage in. I liked the idea about having the body checked for twist's.

CrazyHawaiian

I have a similar problem but I'm guessing mine is way worse than what you guys have seen. Recently picked up a hardtop 91 RS for $500 because there was so much rust damage on the roof. Intentions were to part the car out, but have some fun with it while it still held together. After really checking it out, seems it had originally cracked in that same area by the top corner of the window on the pass side. Then someone tried to repair it and did a bad job, and then rust started and it was neglected. At this point I believe its gone beyond any possible repair, the roof has actually seperated all the way from the corner of the window to the hatch crease where the hatch hinges are, entire thing is rusted beyond belief. I'll get you guys some pics, you'll trip out. Goes to show people should never neglect rust and always goto a real bodyshop to get bodywork done. For now I continue to beat the **** out of this car until it either explodes, or I crash it, of the roof full on caves in. We'll see how long it lasts ...

92RS(real slow)

I goota see pics of this it goes all the way to the hatch that must suck

Jim 86 IROC

I had South Side Machine SFC welded into my '86 IROC-Z (T-tops) and it really stopped flex on launch at the strip.

These SFCs are a rectangular cross-section, weld to the front & rear sub-frames and tack-weld along each rocker pannel. The result is much like having a full frame under the car. BTW, each sub-frame weighs about 15lbs.

CrazyHawaiian

As requested here is a picture of a completely seperated roof due to rust. Prepare to cringe!

Z28guy83

wow if that car wasnt a canidate for being made a vert the climate where you are must suck

mlaskow86

iTrader: (4)

is that roof built for speed or looks?!!!, on my 89 t-top im developing a crack on the passenger side where the t-top covers when on but its in the corner of the roof. im not planning on driving it till the restore is done- around 2 years on my budgit. im gonna do some SFC, and fix the crack soon. hopefully that solves the problem

mlaskow86

iTrader: (4)

Jim 86 Iroc, do you have a link to those SCFs, looked on google couldnt come up with anything

90_T/AGTA

wow that roof is bad what are plans for it your going to fix it?

CrazyHawaiian

Nah, the only way to fix that is to cut a good hardtop off another car and weld it on this one. I think it would have been fixable if the rust was only in the center, but its everywhere (even more than you can see in the picture). For now I continue to beat the **** out of the car until it either explodes, or I crash it, of the roof full on caves in. Then I part it out.

STEEL

Now, I understand with high power/high traction/hard cornering this will happen, but i plan on buying a T-top, putting a freshly re-built 350 in, and racing that. I plan on keeping cheap tires on it though (cuzz im poor) so Im guessing I don't have anything to worry about, right?

Also, how much do these connectors cost?

Way down the line (if the car still moves) I would like to put a roll cage in, but can you do it in a way that the rear seat is still usable? Can you put on in that doesn't go over the doors (so the car still looks right with the tops off)

With cheap tires I assume i will loose traction before cracking the roof weather it be spinning on launch, or I will just start sliding around if I try to take a high speed corner...

black_highway

I bought my car with 61,000 miles on it and no cracks. I had subframe connectors installed immidietly, and this month the cracks appeared anyway