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grannyknot

Firewall flex or spongy brake pedal

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This mod is more aimed at racers and auto x cars, firewall flex is something a lot of unibody cars suffer from and Z's aren't immune.
 The brake pedal never feeling like it has a solid bottom could be caused by a number of things and firewall flex is one of them, I'm hoping this will help. It's an interesting experiment to try, have someone sit in your car and slam on the brakes, you can see the firewall move, the M/C move forward, a lot of leverage with that pedal.

 

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OK... You have just crossed over into the realm of waaaaaay too much time on your hands.

You spend all summer working outside, so in the winter you're bored out of your skull with cabin fever?LOL

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1 hour ago, Mark Maras said:

 Nice looking mod. How much flex in the f. w. were you able to detect?

Hard to measure, maybe 3/16 - 1/4" but the more you push the farther it goes.

8 minutes ago, Captain Obvious said:

OK... You have just crossed over into the realm of waaaaaay too much time on your hands.

You spend all summer working outside, so in the winter you're bored out of your skull with cabin fever?LOL

HA, I almost called this thread, "A solution in search of a problem". When the car is finished I don't want to be saying,   "You know, I should have done that when it was all apart." but at the rate I'm going I'll soon have bottle openers welded in to both rear fenders in case anyone needs to open a beer and they are on the wrong side of the car.

Not bored yet, this the funnest most challenging project I have done in years.`

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Looks like the G-knot workshop is a little frosty these days!  Have any elves shown up to help out?

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Only the elves from Summit racing and Eastwood so far, still waiting on MSA. I have 14" of snow outside my garage door and even with the propane infrared heater on full I still need a jacket and gloves.

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You need to get out of the workshop for a while.  Your friendly local Princess Auto outlet (heated) has a killer sale on right now for most of its steel stock -- tube, bar, channel, and sheet, all at about 40% off list.  Lots of other stuff at attractive pricing -- including the TIG welder and plasma cutter that I know your shop needs to be complete :D.

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10 hours ago, grannyknot said:

HA, I almost called this thread, "A solution in search of a problem". When the car is finished I don't want to be saying,   "You know, I should have done that when it was all apart." but at the rate I'm going I'll soon have bottle openers welded in to both rear fenders in case anyone needs to open a beer and they are on the wrong side of the car.

Well the project looks great, and I'm really looking forward to testing out those bottle openers.  :beer:

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I'm about to go in the opposite direction by bracing the firewall itself.

The idea of installing an adjustable "stop" at the end of the MC is an interesting way to solve this problem. 

We've taken out the booster, MC and pedal box and have a Wilwood set-up that has to be modified to complete the installation.

Will post pics after the Holidays....

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2 hours ago, gnosez said:

I'm about to go in the opposite direction by bracing the firewall itself.

The idea of installing an adjustable "stop" at the end of the MC is an interesting way to solve this problem. 

We've taken out the booster, MC and pedal box and have a Wilwood set-up that has to be modified to complete the installation.

Will post pics after the Holidays....

Interested to see how you go about it, I stared at the firewall for a few days and all the braces I came up with were heavy, and complicated. I think most of the forward movement takes place right at the bottom edge of the pedal box,  now that's an idea I didn't try, extending the bottom edge of the pedal box down to the stronger metal of the floor pan.

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lots of these mods are popping up for various other non-datsun or non-nissan chassis. it's a very effective mod, and I like your approach, chris.

I've seen versions that have waterjet cut brackets that loop down from the strut tower bolts and have an adjustable knob to preload the brake master or to adjust for manufacturing inconsistencies, just like yours. The most common one I've seen is for the S2000.

though the nicest one I've seen was beautifully TIG welded and integrated into a strut tower bar base plate for a car that was in Option jdm mag. Can't remember what car it was ... DR30 maybe.

 

I vote for yellow plating after a quick sandblasting :-D that'll do'er real noice for eye-candy points.

Edited by Careless

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1 hour ago, Careless said:

I vote for yellow plating after a quick sandblasting :-D that'll do'er real noice for eye-candy points.

There is an industrial powder coater up in Barrie with a conveyor chain production line, whatever colour and texture he's running the day I take all my stuff up to him, that's what colour it'll be. He usually runs black or grey and it's cheap.

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