Sickness91Z28

iTrader: (1)

I was looking at my car...and noticed a small "stress" crack starting to appear on my upper sail panel going onto my roof. It's just a slight crack. My car is a hardtop 5.7 L98....and has about every bolt on mod. Is it time for subframe connectors or what? Would SFC cause it from stressing out more? Any help would be great. thanks

NJITIROC

iTrader: (2)

well, your car was ready for SFCs back in '91. they are always worth it. can you get a pic of the crack? im curious about it.

Sickness91Z28

iTrader: (1)

yep, I can take a picture of it tomorrow

onebinky

iTrader: (1)

At least 3/4 of the thirdgen's I've seen have had the issue. It's probably the most obvious sign that GM didn't reinforce the subframe as much as they should have

SFC's will definately make the car more rigid, and should prevent them from getting worse. Worked on my dad's old 92 at least...

Goumba T

And take care of that ASAP.

After I had my SFCs installed I didn't give it another thought, and now its starting to rust.

nolanr0413

a crack sucks, that could be a problem . like a serious one.

Sickness91Z28

iTrader: (1)

which set should I go with? I love the looks of the Kenny Browns..I can get them for $250.....the problem would be to have a descent welder weld them up....I go to college now for welding...and I have a welder....but nothing to do this kind of work....
I know that alot of the third generation Camaro's and Bird's have this problem....but I didn't realize this problem exsisted with the hardtop cars......

NJITIROC

iTrader: (2)

me either , i was surprised to read it. thats why i want to see a pic. my car is an original 350 with ttops car that just got sfcs installed within the past year, so it was 14 years without them, and no signs of any torsion or cracks in that area. interesting.

JamesC

iTrader: (5)

The cracks (I assume they're on both sides) are fairly common from the Unibody's twisting. My 85 hardtop has them.

JamesC

cougar20th

the cracks could be the filler that the factory used at the seams of panels.

onebinky

iTrader: (1)

It rusts up though, I think the filler they use is lead IIRC. When my dad fixed his, I think it was solid metal anyways

88firebird

That cracking seems to be a problem on many of the cars I've seen too... I'm not sure its always a problem with torque, cause my car has the same problem, and its a hard top with 2.8 V6!

88firebird

That cracking seems to be a problem on many of the cars I've seen too... I'm not sure its always a problem with torque, cause my car has the same problem, and its a hard top with 2.8 V6!

Sickness91Z28

iTrader: (1)

It probably is the lead that was used. I used to have an 84 Z28 that had the same problem. I had to cut out all of the old material, weld new metal in...and finish it. It got rid of the crack. On my 91....it's just the passenger side...but before I buy a set of Kenny Browns....I need to know if they will cure the problem.

Toolbox

are these any good



dose any one have som pic of them in ther car

Goumba T

Hard tops are especially prone to cracking. You'll even see First Gens and A-Bodies develop cracks also.

I had mine installed at a body shop. The guy who did the work said that SFCs alone will not cure the problem, even with SFCs cracks can still form given the design of the car.


From the top:


And underneath:

Sickness91Z28

iTrader: (1)

here is a picture....it's not really to noticable....but it still drives me crazy just knowing there is a crack

Fire"Dutch"Bird

iTrader: (1)

My car has the same crack for many years now, I'm not worried at all!!

88firebird

That's exactly what the crack on my V6 car looks like... how difficult is it to fix that crack? Once I finish putting in the new engine, I'll be repainting my car soon and want to fix that crack too.

Sickness91Z28

iTrader: (1)

well...for a show car..I'm kind of worried about it...but as long as it doesn't get any worse I guess I can live with it. If you know anything about paint/body repair...it's really not to difficult to fix....just have to grind out the cracked area, weld a new piece of metal in....and do the body work..not to bad really...but I'm not about to do it on my 91....i just got done with the body work last year..and it's pretty good shape...especially for a black car

SLAYER6669

iTrader: (1)

Mine had it also and has it again.. I got my car painted in september and it came back like a month later.. I guess they just didn't do a good enough job repairing it.. It was very small though.. I've got a STB, SFC and an entire new suspension too.

84_berly_84

no cracks on mine but I have floorpan ripples

kretos

damn gm for not installing sfcs at the facoty

benoit454

nice post guess i know for sure im not the only hardtop w/ a v6 that has this prob.
friend of mine theratdude has em to on his v6
i just sanded min down a bit and slapped on some fiberglass sanded down and primered over goin to paint son and i dunno if i had theese when i got the car or not and i havent put one mile on it unless goin in and out of the garage about 10 or 15 times put a mile on which i doubt lol.
im hopin mine wont come back and if they get worse ill have get some connectors prolly bolt ins since i dunno how weld yet and dont got or have access to a welder.
i think befoe doing more metal id weld the crack up then grind down but i dunno.
makes me wonder if mines inside as well need to check it i got my interior apart anyways.

Kandied91z

iTrader: (7)

i can't believe you don't have the subframes on that car....definately need to get a set of those and if you ever put any major power down i wouldn't suggest running sticky tires without a cage.

i have just about every possible thing on my car and the paint began to show signs a little which is why i put the 6 pt. in.

benoit454

kandied i wouldnt think u was reffering to mine and my v6 lol
like ill be puttin power down lol.
altho power isnt my concern id hate have nice street car for almost daily driving and shows esp shows and see a crack so im goin to see how long my works goin to hold up hoepfully wont show again.

Kandied91z

iTrader: (7)

nope..only L98 or faster cars.

Sickness91Z28

iTrader: (1)

I think I'll go ahead and get a set of the Kenny Brown's....I think I'm going to sell one of my Bass guitars (I don't play it much, plus, I have 3) that way to get the Kenny Browns. The biggest problem will be trying to find someone to install these properly....

Kandied91z

iTrader: (7)

problem with kb is they are large.....great but will detract from larger exhaust mods. i've been very happy with my mac pieces. anything is better then nothing though.

FireRed91Z28

def go with the KB's, i have those and theyre great. many board members also think they are one of the best. my 87 IROC was getting stress cracks in the paint, they were pretty fine but still noticeable if up close, or maybe the silver paint made them look smaller, but anyway i dont have that car anymore and bought my 91 Z with almost all of the suspension aftermarket. not one crack but clear coat is coming off on my pass side sail panel...hope thats not cause of chassis flex

Sickness91Z28

iTrader: (1)

I don't really think your clear would peel because of body flex...clear is actually pretty flexible...probably just the paint giving out. I've heard that KB are pretty bulky too...and my exhaust is completely modded...I'd like to see a set mounted...I'll try a search

FireRed91Z28

oh ya...the KB's are a little bit bigger than others but when it comes to strength i want the best for my chassis. also if your car had dual cats your gonna get a lot of "cat banging" on the cross mount. it annoyed the hell out of me then i just cut off my cats and welded up some straight pipes for the time being until i get my hooker longtubes to a mufflex 4" system.

87CIZ

iTrader: (8)

wow i was getting worried until i ran across this thread i just noticed mine two weeks ago. its small about 1/4 inch on the drivers side. what if i took the drip rails off and laid a mig bead and ground it down would that help?

benoit454

i was thinkin the same thing even posted it in my thread here.
i wouldnt se why not it last for a bit i fiberglassed mine so yur weld would last longer then my glass im sure.

85SportCoupeto89RS

My 85 sport coupe has a small crack in the paint, only on the drivers side. I know its from the bad dirt roads here in AR potholes are murder on the Fbodys. I need to put a set of subframe connectors on eventually and repaint the car.

Welding would help some but the metal cracking will still occour if you didnt drill thru the end of the crack. IIRC if you weld over a hareline crack and dont drill out the end it will still continue to spread because the crack was never fully removed. The drill bit only has to be slightly bigger than the crack's width.

Sickness91Z28

iTrader: (1)

as of now....it's only the passenger side for me...hopefully...if I get a set installed....it won't crack on the drivers side...

rcwest32

I am glad to hear this isn't an isolated problem. I've been looking at an '89 GTA for a great price, and the only thing that turned me off was that roof crack (about 3/4 inch long so far). I can MIG weld, so I will to the drill the hole at the end thing, MIG it, then SFC's right after that. THANKS!

irocbirdbuilder

Every thirdgen i have seen around town has the same issue i had very very small ones starting and i took care of it before i got it painted, need to get some sfc's on mine also. Been planning for it just havent done it