Cracks In Firewall

Douglas Walker

Registered User
Ok heres my problem Ive ran across some cracks while cleaning my engine compartment. One of them is going up from the heater hose hole and one is going down from the heater hose hole towards the curve for the transmission. theres also another on the drive side right at the curve for the transmission. My question is what is the best way to repair these cracks. As of now the motor is out. But I will be pulling the dash sometime in the future to replace heater core and box. Would it be better to fix it from the inside or to take the chance on the outside. I havent seen any posts on this kind of problem. Is this something that is common or is it just because the car is old and has 226,xxx miles on it.

Thanks
Doug


__________________
 
remove anything that is close and will burn including carpet from the inside, then weld the crack shut. withe the engine out it would be pretty simple. my son's is cracked on the driver side.
 
Repairing them in My opinion is only going to be a cosmetic fix...And knowing someone who has done so already it involved ripping the dash out..Id work on reinforceing the chasis
 
What would be some things I could do to reinforce the chassis. I will be tearing out the dash in the future and I thought Id patch them then. I dont want to take the chance to catch anything inside on fire.

Doug
 
what you need to do is stop-drill the cracks with a 3/16 or so drill bit just make sure nothing is behind where you drill obviously. i do that all the time at work on airplanes it works very well also after you drill it make sure you debur the holes or it will crack more and i would follow the advise from the previous poster and reinforce the chassis you dont really need to weld it just make sure it clean and put a little bit of permatex on the crack
 
I wouldnt worry to much about a fire//However Kenny Brown as well as a guy named JL from the TCCOA sell an assortment of reinforcement parts for our cars
 
If you have cracks in the firewall, you might want to take a gander under the rear seat and trunk carpet. You could find this hiding under there.
 

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Nooooooooo!

I didnt need to know that. :eek: Cracks in the firewall are enough for now. I just hope when I redo the rear seat I dont find any of that. Ill check it out. Thanks Everyone

Doug

Ps: If I run across cracks in the rear what would be the best to do. Besides weld them
 
Holy ****!!!!!! I've recently been adding welds to my unibody and front K member to stiffen things up abit but I havent run accross anything like that yet, WOW!!!
I'll say this the factory welds are some of the worse I've ever seen many of them on my K member werent even tied into both pieces of metal. The ones that looked good proved to be full of trash, gas pockets and slag. I'm really shocked at the poor level of quality control in this area. In all my years of welding I have never found a place that would let me turn out work like that and get to keep a job.:rolleyes:
Heres just one of the welds I'm talking about, notice the dark line on one side of the weld. Thats were its not even tied into that side so that weld was serving no purpose at all. Ahhh MIG welding at its finest!LOL!!!:p
 

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I like TIG welding myself. I was a thin wall alum. welder for over 6 years at my job. I have welded alum thinner than a piece of printing paper, and as thick as 3".

Thanks for the heads up on cracks. I going to start taking the SC apart in less than a month for a 2 year project, I keep my eyes open for them...
 
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Most people aren't aware that what Dave has shown here is happening to their cars.
 
Originally posted by Bill McNeil
Most people aren't aware that what Dave has shown here is happening to their cars.

I've been playing with vintage Mustangs for at least 20 years and with Fox Mustangs for about as long and I've never seen anything like what's shown here. Sure the Foxes show some cracking at specific points, like under the drivers seat and rear LCA torque boxes, but those locations have a direct cause. Well, so do these, but you know what I mean.

I'll bet Dave is only showing a small fraction of what is to be found if you start looking. I also expect that those poor welds Mike is describing is a lot of it. I have heard for years that doing complete welds on the seams of a vintage Mustang stiffens them up considerably. It would be interesting to know what would happen to an MN12. But how coud we quantify the difference?
 
There were a few more cracks on that car. The cracks are noticably more frequent on 5spd cars and also on cars that have a fold-down back seat.

I will personally not consider stiffening the stock suspension without first reinforcing the unibody. You're just asking for trouble. :)
 
I dont know that wheel hop is the cause but with cracks like that in the unibody wheel hop damn sure could be a symptom of severe cracking like that. Theres alot of flexing going on to cause cracks like that.
I'm like Parker Dean, I've worked on many old cars building street rods out of them and working on old muscle cars and I've never seen anything like that.
I've been rewelding my K member and rear subframe and to be honest I just dont see how they manged to never fold in two......its pitifull.:rolleyes:
Next I'm rewelding the entire unibody. I've already found many places for improvement in the framerail channels and shock towers.
 
I'm quite certain Mike knows what he is doing, but you have to remember that the car was designed as a whole package. Each part of it is critical to the balance and strength of the body. Reinforcing one area will result in the transfer of stress to the next weakest part of the car. Keep that in mind as you stiffen certain parts of it. Unless you really know what you are doing you can just make matters worse.
 
Dave-

What was done to fix the car you showed in those pics? I found the same thing yesterday in my 93, and I want to get it taken care of before it gets worse.
 
Sorry Tony, this was the solution for that car. It had about 120K on it at the time.
 

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