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Cracked firewall at Clutch Master

25K views 119 replies 36 participants last post by  Glynn 
#1 · (Edited)
So recently I have been getting a cracking sound from my clutch when I let it out all the way. Well it turns out around my clutch master cylinder there is a crack about 2inches long. Any ideas what caused this? I have a monster stage 2 clutch in the car. Has anyone every expercienced this before? What did you do?


Here are the pics everyone has wanted:




 
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#2 ·
So recently I have been getting a cracking sound from my clutch when I let it out all the way. Well it turns out around my clutch master cylinder there is a crack about 2inches long. Any ideas what caused this? I have a monster stage 2 clutch in the car. Has anyone every expercienced this before? What did you do?
I have personally never witnessed this, easy enough to fix just a mother to get to.
 
#3 ·
you thinking take everything off and put a bracket on there so it is stronger???
 
#6 ·
I've seen it on some older cars before, just never on a newer GTO.
 
#7 ·
does anyone think this could be my clutch or is there some other issue
 
#9 ·
This has nothing at all to do with any clutch. It's simply a week area. Most vehicles have doubler plates in this area much thicker than that of the GTO. I knew I would hear of or see this issue eventually, just didn't expect it so soon.
well what the hell do i do now???
 
#14 ·
Definitely interested in seeing some pictures... my buddies GTO has a weird creaking sound everytime he pushes the clutch in. He has the Tick master... and the problem developed after about a year of good use. I wonder if this might be the issue and its slowly been getting worse over time...
 
#16 ·
I have some pics but they are terrible. I am going to get better ones. The car is currently at the shop right now. There was a hole drilled in the firewall to temporarily fix the crack from going any further. that will be all welded up along with a plate for more support.
 
#22 ·
My clutch pedal makes an annoying click sound which I feared was a firewall crack. I was running a Monster stage 4 with Tick master and the pedal was ridiculously heavy.

Fortunately it's not the firewall. I've switched to an LS7 clutch and stock master and have a nice light pedal again, but it still clicks and creaks and pops.

Apparently there is a TSB for the pedal clicking. Wish I had more details on it though.
 
#24 ·
hey guys,, sorry for no pics yet. I should have pics monday some time. I am waiting for the shop to take everything off the firewall so I can get some good pics.
 
#25 ·
Just so you guys know, he's pulling the motor to get in there better. Be patient guys. :)
 
#27 ·
hahaa thanks Jon...

Yes the motor is getting pulled to do the work.. I know it is not required to do the work but the shop wants to do it that way so I am letting them.
 
#29 ·
PICS ADDED EVERYONE!!! SORRY IT TOOK SO LONG
 
#30 ·
The car is fixed and running. I just picked it up. Everything is well. there is no plate on the firewall with a bracket welded on the inside of the cab supporting everything. I will post pics of the bracket before it went into the car. hopefull this holds up!
 
#32 ·
just guesses in all honesty... the only thing we can think of is sense firewalls are so thin the heavier clutch finally cracked it. I have had the clutch in for a little over 30k miles so idk to be honest. I am open to ideas of what caused this. I do encourage people with heavier clutches to look back in there. It is a PITA to see but if you catch it earlier then I do it would be a lot less work.
 
#33 ·
Glad you got this fixed.

The reason this happened is as I said before in my original post. There should have been a doubler plate to help spread out the load over the surface area of the firewall in this area. It is not the fault of any clutch at all. It is simply a design flaw from an engineering prospective. I did not expect this to happen so soon, but I do believe most of us will have this issue over time if a reinforcing doubler plate is not added. Unfortunatly... :bomb:
 
#35 ·
It's my opinion that we may see more in the future. Only time will tell. I did say that I believe his was premature, and I didn't expect to see it this soon. A single wall non-reinforced master is going to cause this after X amount of cycles. I believe after doing a bit of research on it a while back, that a few things were overlooked from the right hand to left hand drive change on this platform. I believe this is why you are not finding this issue across the pond.

I am using the stock master at this time, but I believe he was thinking that a stiffer clutch was the cause of the issue. It will accelerate the problem, but it is not the underlying issue.
 
#36 ·
I am using the stock master as well. Time will tell if this was just my car or not but it is fixed better then new i can reassure you of that!
 
#37 ·
This can be prevented by a simple plate attached on the inside using the existing hardware. All that needs to be done is to make a metel plate shaped similar to the old thermostat gaskets, big hole in the middle and the two bolt holes.

Unhook the clutch pedal pushrod, remove the clutch MC retaining nuts, slip the plate on and reassemble. Seems simple enough.
 
#38 ·
you could do this if you already don't have a big crack... the way mines is set up mines doesnt put any pressure on the fire wall itself. I have driven the car once so we will see how it does over time.
 
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