924Board.org

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Hi
I noticed on the dyno that when the tuner depressed the clutch the firewall flexed, a lot! The entire brake booster assembly moved.
It flexes when you brake too but not as much and I feel that the pressure is less on the clutch pedal. Both clutch and brake pedals has a mushy feel to them.
Its hard to get under there and have a look, its got to be the pedal cluster pushing on the fire wall, right?
I've seen that there are reinforcement plates to bolt on to the fire wall, but I thought that was an issue only for the 931 and 944 with hydraulic clutch.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

[morghen]

firewall is identical...clutch is clutch so it will press on the firewall...i guess the NA firewall wont crack as soon as the 931 as the 931 obviously takes a bit more force for the clutch. Plate is a very good idea both for longevity and for clutch feel. Made one myself for my old 924 and would like one for the current one as the clutch feels a bit spongy and inconsistent.
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Supercharger and EFI kits
https://www.the924.com

[safe]

OK. I think I need to remove the brake booster etc and have good look at the fire wall to see if its cracked already or, quite probably har rust issues (haven't seen any rust in this area).
Making a reinforcement plate should not be that difficult! I hope I don't have to weld, its sort of bad to weld in my new garage/workshop due to its location.

Unfortunately I'm away from the car for a couple of weeks now. But it will give me some time to sort out my clutch slippage to. Maybe go with a 931 torque tube and gearbox.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

[morghen]

I made a plate to sandwich the firewall and be installed on the inside of the cabin, removing the need to take off the brake booster. Obviously this is offering less rigidity than a bigger plate, and there is one design available that braces the firewall from the outside, meaning from inside the engine compartment.
I found my little plate to be sufficient and solve my problem.

The firewall on my 924 turbo cracked near the bolt hole that secures the clutch master cylinder and obviously the clutch cyl moved and clutch was only engaging right at the end, so i made a small plate connecting the two bolts and i think another one and some surface support...and that held for many years, reducing the flex in the firewall and stopping that crack from aggravating any further.

So if you're lazy like me, know that there is an option to just have a plate on the inside of the cabin and solve the problem.
Or, if you like taking everything apart, doing a proper over-engineered thing and re-coating everything in the process, there is a design available that mounts inside the engine bay and covers a much bigger area...most likely making the firewall even stiffer in that area..if you think you need it.
_________________
Supercharger and EFI kits
https://www.the924.com

[BTRacing]

This :

https://www.only944.com/partscatalog/only/firewallbrace/
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www.btrpalmbeach.com
1979 931 GTR Le Mans replica to be
2008 Audi S4 Avant daily driver
2008 Aston Martin Vantage
1974 Moto Guzzi Cafe Racer
1979 Glastron CVX 20

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[morghen]

I may have the profile from mine saved somewhere, i’ll try to find it.
_________________
Supercharger and EFI kits
https://www.the924.com

[Tun'd Up]

Definitely should get it reinforced if you can. The firewall on my 924 turbo has rusted just below the clutch master cylinder and has separated from the firewall. It may have started out by just separating but over the years its rusted as well. It's looking like I have to weld a new section of sheet metal in to permanently fix it.
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Porsche 924 Turbo - Current Project

[morghen]