Firewall brace

[chris white]

My black car has no issues. This brace is a preventative measure. My red car absolutely lost the welds at that point.

Did your red car have any crash history?

[Tom]

Did you make that brace or is that one of the kits (only944?)... Pretty epic rabbit hole you went down with the grinder. Very nice. Might want to turn up the gas if that's MIG...? I generally keep turning it up the gas until the soot gets as minimal as it's going to get.... You might be picking up junk that's inaccessible behind the sheet metal though....

MIG welds and yes, you can't get all the crap out of the seam welds. Burns off a little crud in front of the weld but the welds are solid. For real structural welds I wouldn’t live with that but for seam welding it will work

I have a rust repair to do on the old Mercedes and would love to TIG in the patch, but I suspect I'll never get it clean enough for good TIG welds. I'll probably use the old Craftsman MIG welder for that reason. As you say, you can get a strong weld with the MIG even if you can't get it surgical-room clean....

Where did you get the firewall brace. Next time I have the chance, I want to do that....

[Thom]

Shortly after installing the previous 3L engine with a rather stiff KEP Stage 2 pressure plate 13 years ago at 170k miles the firewall was already slightly cracked and was clearly bending when pushing the clutch so I added a small home-made plate which prevented the crack to spread, but last Summer at 240k miles I had a long drive planned and the pedal had already started to feel somewhat spongier for quite a while - the plate itself had started to crack after 70k miles of use, so I bit the bullet and installed one of these braces. It is a bit of a pain to install, and I should not complain too much as the fuel evap set up is long gone on my car, but never has the clutch pedal felt as consistent since I have had the car. This is clearly one of the best drop-in part I ever installed that helped with general driving dynamics, and I have no more concerns with my left foot possiby going through the floor whenever changing gears.

There are 2 versions of this brace. The initial version was a little beefier than the second one but would not clear the brake booster and the second version is the only one available now I believe. This is a must IMO, short of tearing the engine bay apart to make a proper plate as pictured above. The firewall really isn't that thick anyway.

[AudiSport]

Thank you Thom. As a preventative measure the brace adds a second load point besides the firewall. I shouldn’t have any cracking issues to worry about. As for just doing the plate. I wouldn’t do it alone as you have said. It’s not enough.

Check the attached pictures and you can see the seam at the FW to fender is broken and the cracks started there and spread.

And Chris, the car still has all the original VIN stickers on all the front panels. So no major damage sustained.

[Thom]

Well, like yours mine had started to crack along the white line on your photo, and also there that the small home-made plate I had installed started to crack as well. I have not fixed the crack(s) and left the plate installed but even then the brace seems to fix the issue in bringing the extra support needed, and in my case without any real need to reweld the cracks.

[chris white]

Interesting. I never liked the original KEP pressure plate, they just doubled up the diaphragm spring, way too much spring pressure.
The plate kit that I used is very thick and you are supposed to bolt it in place (don’t really like that). I plug welded all the bolt holes. In theory it transfers all the load into the brake pedal assembly which is pretty substantial. Does the brace you are using get welded in or does it just rest on the wheel well? If my fire wall was cracked I wouldn’t be going with a ‘bolt on’ repair, especially if you are keeping the KEP pressure plate

[chris white]

Thank you Thom. As a preventative measure the brace adds a second load point besides the firewall. I shouldn’t have any cracking issues to worry about. As for just doing the plate. I wouldn’t do it alone as you have said. It’s not enough.

Check the attached pictures and you can see the seam at the FW to fender is broken and the cracks started there and spread.

And Chris, the car still has all the original VIN stickers on all the front panels. So no major damage sustained.

Looks like metal fatigue from lots of flexing at the firewall to wheel well. Can’t really say if the cracks came before the spot welds or the other way around.
I’m with the amount of disassembly you have done you might want to go with both fixes!

[AudiSport]

On the red car yes. Welded crack +plate and a brace. My black car for the purposes of just the brace is just so I hopefully don’t have to fix a broken firewall again. Boost brothers garage sells the brace. It loads agains the strut tower as an extra point.

[Thom]

Interesting. I never liked the original KEP pressure plate, they just doubled up the diaphragm spring, way too much spring pressure.
The plate kit that I used is very thick and you are supposed to bolt it in place (don’t really like that). I plug welded all the bolt holes. In theory it transfers all the load into the brake pedal assembly which is pretty substantial. Does the brace you are using get welded in or does it just rest on the wheel well? If my fire wall was cracked I wouldn’t be going with a ‘bolt on’ repair, especially if you are keeping the KEP pressure plate

Well, the Kep St2 was quite stiff when it was new but it seems to have softened with use and feels good to me now, if perhaps still a little stiffer than really needed.
I agree with you on the theory, but the crack in my firewall was never large enough to justify a reweld, and as said the brace does its job of preventing the firewall to move at all and regardless of its thickness or rather lack thereof as it rests against the strut tower with no welding needed.

[chris white]

Well, the Kep St2 was quite stiff when it was new but it seems to have softened with use and feels good to me now, if perhaps still a little stiffer than really needed.
I agree with you on the theory, but the crack in my firewall was never large enough to justify a reweld, and as said the brace does its job of preventing the firewall to move at all and regardless of its thickness or rather lack thereof as it rests against the strut tower with no welding needed.

Was that posted at 6am Christmas Day?! Merry Christmas or what ever you feel like celebrating!!