Hydraulic clutch and 2,900 lb pressure plate causing firewall flex. Need advice!

[biomedtechguy]

I know some have had problems with aftermarket brakes causing firewall flex, and they use a reinforcement plate to resolve the problem.
I went from the factory mechanical clutch mechanism to an American Powertrain hydraulic throwout bearing and clutch mechanism, and I have a heavy 2,900 pound clamping force diaphragm style pressure plate.
The problem is that the firewall is flexing and that is preventing the clutch from disengaging. The shop owner is going to weld up 2 turnbuckles to an under dash factory brace and weld that into a brace on the firewall to prevent the flex.
He suggests this as a temporary solution, and when I'm ready to swap in my 541 stroker motor in about a year if all goes well, he will look at some kind of firewall reinforcement plate.
Have any of you or anyone you know had to brace up the firewall for clutch purposes? What did you use, or how did you fix it?
Thanks!

 

[odcics2]

Weld angle iron to the firewall....

 

[roadrunner69440]

Following

 

[Tony Tee]

I knew someone that had a HD clutch push the crankshaft into the timing chain cover and wore a hole into it making it leak oil, because the crankshaft thrust bearing wore out. Just saying!

 

[biomedtechguy]

I knew someone that had a HD clutch push the crankshaft into the timing chain cover and wore a hole into it making it leak oil, because the crankshaft thrust bearing wore out. Just saying!

I took a few seconds to think about the mechanical forces that a pressure plate exerts on a flywheel, that pressure plate "frame" or "basket" is bolted to the flywheel, and the movable part is what clamps the disc between the pressure plate and flywheel. I believe the physics of how a pressure plate works makes it impossible for it to have any effect on the situation you described. The only possible time there is any force exerted forward on the crankshaft is when the clutch is disengaged and the throwout bearing pushes forward against the diaphragm springs.
I appreciate all replies, and I'm open to being corrected.
Also I am definitely going to change my clutch disc and pressure plate for the stroker motor. My strong inclination is to run a dual disc RTS setup which I understand greatly reduces pedal effort.

 

[Tony Tee]

Yes, only while being depressed. But that's a lot of force! Over a lot of cycles..... My friend replaced the timing cover and hammered it to keep it from rubbing and then got rid of the car. Because it had way too much crankshaft endplay. and he didn't want to rebuild the engine.

 

[Hemirunner]

These cars weren’t designed for hydraulic throw out bearings. The mechanical linkage doesn’t exert any force on the firewall unlike a hydraulic setup. It also has much better clutch “feel” than a hydraulic setup. Converting to a hydraulic is a step backwards in my opinion. You’ll have to come up with some bracing to reinforce the area.

 

[5.7 hemi]

Did you use the “plates” that sandwich the firewall?

No, mechanical linkage sucks, to many moving parts to wear out and the feel of hydraulic is wayyyyy better. Do buy into that bs, it’s like saying carbs are better than efi!

 

[Hemirunner]

Did you use the “plates” that sandwich the firewall?

No, mechanical linkage sucks, to many moving parts to wear out and the feel of hydraulic is wayyyyy better. Do buy into that bs, it’s like saying carbs are better than efi!

I’ve raced them both. I’ll take the mechanical linkage any day. As to the carb debate, there’s certain benefits to each. My current build is Holley EFI.

 

[biomedtechguy]

The "debate" between manual linkage and hydraulic throwout bearing means nothing to my decision. My launch control requires a hydraulic throwout bearing, and that is what I'm going to keep.
The kit came with the mounting bracket that they call "firewall reinforcement" bracket, but it doesn't reinforce enough.
I'll get it resolved.
I was on the last hole to drill in the shroud for the fan in the GTO, and I was FINALLY going to be able to button that up and see if it ran w/in normal temperatures. Last hole of a project that we paid someone else to do and more.
Did I mention it was the last hole??

 

[Hemirunner]

Oh no! That stinks.

 

[biomedtechguy]

Oh no! That stinks.

I had texted my friend earlier this afternoon that I had finally turned the corner on the "installing the new fan and shroud assembly" project that has been fighting me relentlessly. I thought I had all of the hardware (L brackets, nuts, bolts) I needed, but then I decided to avoid draining the coolant in order to remove the radiator, I would change the bottom brackets to a different type that wouldn't require the removal of the radiator. That led to difficulties in accessing mounting points. I had that all figured out, brackets cut, driver's side lower bracket installed, one of 2 holes in the shroud drilled. Drill the 2nd hole, mount the passenger side lower bracket, 2 top brackets were already setup, wire the new fan into the existing wiring, program the controller and test drive.
NOW I have the coolant drained, and the radiator out anyway. I'm going to call a local radiator shop tomorrow. I went to High School with the owner. If the simple (for them) repair is quick and reasonable, I'll have them do it and mount the fan and shroud assembly's permanent L brackets top and bottom, and install the radiator with the fan and shroud attached. If the shop is outrageous in cost or time to get it done, I have some flux and solder and I may just fix it myself.

 

[Daves69]

Maybe some idea help on the firewall flex.........
https://www.forabodiesonly.com/mopar/threads/hydraulic-master-cylinder-firewall-flex-solved.474250/

 

[747mopar]

Got any pictures of your current setup? You guys have me thinking about having someone work my clutch so I can watch my firewall lol. I'm just curious if mines mounted differently because I've never noticed any flex but of coarse I may have a lighter pressure plate?

 

[BSB67]

3200 lb plate. No flex issues.