Cracks in Firewall...

[Pat]

Has anyone ever seen this? Any idea why it may have happened? The firewall has a number of cracks right around where the firewall turns back towards the exhaust tunnel. I also noticed that the car has bolts running through the ears on the frame rails on either side up through the floor. I bought this car just recently and it drove fine. I know the right side of the car has been painted before, so it's possible that it's accident damage of some sort, however, I'm now more curious about the bolts through the frame/floor.

Any input, suggestions, comments?

[mpgmike]

With only pictures to go on, here's my guess. The car was originally NA, as there is no heat shield against the firewall. Somebody either converted it, or removed the heat shield along the way. When it was impacted, the sheet metal cracked from the thermally stressed weakening.

Mike

[Tony Hanna]

I'm with mike about the cracks being heat related. It's the bolts through the frame rail that get me. That's pretty odd. I mean granted mine has a weld right there, but that's because I replaced a sizable chunk of rusted floor and wanted to tie the patch back into the frame for strength.
Is there any indication that the floor has ever been repaired? I can't really tell from the pics. If not, then maybe the frame rail has been replaced and they bolted it through to the floor instead of spot welding. That's the only thing I can think of.

[turbovanman²]

I see it all the time, my van has done it and other TD's I've worked on. I believe its the flexing of the Unibody. Mines bracked and use a strut bar and it still did it. All I did was drill at the end of each crack so it can't spread and welded it. Hasn't cracked again. Fixed the other cars the same way and didn't come back.

[Pat]

I haven't found any accident damage on the floor yet, although I'm now looking the car over very closely. It's a '92 Iroc R/T, so there was a heat shield at some point (I have it...came with the car), but I don't know when it was taken off.

Simon...did you get those hoses yet? PM me.

[JDAWG]

bolts deff dont look stock to me, but i have seen worse come out of Chryslers productions lines. Was it built on a friday?

[BadAssPerformance]

Wow, never saw anything like that before... and I have seen some tweaked TM's!

[rare_ram]

The car was probably rode hard and the bolts added to repair seperation of the floor from the unibody.

[racer-xerols]

I agree with the consensus - it doesn't look like accident damage. The floor is straight, the frame rails are straight...they look like they were just.....bolted together for some reason. Does the car creak or rattle more than usual? Might have been an attempt at a unibody noise "fix" at some point. At any rate, they look like they've been in there a while, and the metal all looks pretty OEM / stock as far as overspray and undercoating. What's the spacing? Was the car ever raced? Could be they're leftover from an old amplifier installation...or a racing seatbelt harness anchor...

The cracks...odd. Do they lead to or from anywhere? Like, one end at the K frame mount? I think it may just be bad metal. The cracks are just cracks, not burst apart or anything that would indicate accident. Usually if there's an impact, the halves of the cracks wouldn't line up, they'd be far apart on one plane or another. This just looks like metal fatigue. Throw some Franken-stitch welds on there, install the heat shield, and go racing, LOL.

[Turbodave]

I've seen cracked firewalls like that a lot on cars, primarily on Daytonas, but it seems to be a possibility for all body styles. Not sure why, I've noticed them on TBI cars as well as turbo cars, and on accident free cars as well.

Those bolts through the frame rail are unusual.

[88_pacifica]

bolts deff dont look stock to me, but i have seen worse come out of Chryslers productions lines. Was it built on a friday?

Nope... the Monday after New Years..

[JDAWG]

possibly there were super small rust holes where the bolts are. Prev owner drilled it out bigger and put in bolts and undercoated/painted over. That is a common place for rust seems like.

[Hemlock]

The bolts through the frame are supposed to be there. My IROC has never been touched and it has the exact same bolts in the same places.

[Tony Hanna]

That's really strange. I just replaced that section of floor in my Sundance and it was all spotwelded. No bolts.

[Pat]

Thanks for all of the info everyone. I'm not going to worry too much about it. I can weld up the cracks when the engine is out and clean it up some.

Pat

[glhs399]

This happened on a 88 CSX-T. It was a old road race car that I was told was running 500 lbs. spring up front! It just had a bolt in roll cage and none of the suspension points were reinforced or tied into the cage. So I could see how it happened!

Doug Folsom
Hillsboro Oregon
dirtydrifters.com

85 GLH Rally Car
86 GLHS #399
88 CSX-T (no budget rallycross car )

[BlueBaron]

That picture above is a dead ringer for my car. I'm running Mopar road race springs/shocks and had a rotted K-frame. The 1-1/4" sway bar was really the only thing that held the front end together.

[amcpacer]

My Daytona has the same kind of cracking on the firewall. I have taken excellent care of the car and it has no rust. Never been in an accident. No heat issues either. I think it must be a faulty batch of sheet metal. I am not looking forward to fixing it. I thought about sanding down the metal near the cracks and using JB weld to stick a new piece of sheetmetal over the cracked areas.

[BadAssPerformance]

Probably best to TIG weld a steel strap across the crack to the back of the firewall and fill as needed on the enginebay side so that it is invisible.

What years are the cars that everyone is seeing these cracks on?

[whywoody]

My '89 minivan has 2 long mirror image cracks also running down under the firewall,looks like fatigue rather than anything.I am pretending they are not there lol,as they look like they have been there for years and aren't getting worse.The van's shell is getting very rusty,so I'm not putting much effort into saving it.