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Underdash brake pedal support
#1
quick question for you guys. I know the pedals from manual brakes are different from power brakes but are the underdash brackets the same?? I am doing the swap soon and wondered if I need to swap the whole bracket or just the pedal?? I have both. Thanks

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
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#2
(07-15-2018, 08:00 AM)turtle5353 Wrote: quick question for you guys. I know the pedals from manual brakes are different from power brakes but are the underdash brackets the same?? I am doing the swap soon and wondered if I need to swap the whole bracket or just the pedal?? I have both. Thanks

 Just the pedal. If you have a PB pedal, it is the same mount. Just use new bushings. On the pedal arm, the push rod pin is 2" lower on the power brake than it is on the manual.
Even if your swopping from auto to manual trans or visa versa, the bracket is the same. In the case of going to manual, adding the clutch pedal, buy a kit and install either ball or roller bearings. Mustang Steve has the kit I used and Scott Drake make another. I'm putting this in as an aid to others who might be following this post.
Good luck,
Geoff.

Take a look at David's reply in NOT A T5's post "Brake pedal push rod" in this section. There is a good pic of the mounting bracket where you can see the bolt that holds the brake pedal and the big hole to the front of it where the clutch pedal would mount if so installed.
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#3
Well that’s good news. Saves me a lot of work. My car is auto and staying auto. I have a brake booster, master cylinder, brake pedal, and underdash bracket from a 72 vert. I already did the disc swap years ago. Just finally getting around to going to power instead of manual.  
Thanks for the info. 
Any have any pics of the firewall where the hole needs cut? Hard to search the forum on my phone!

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
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#4
(07-15-2018, 08:31 AM)turtle5353 Wrote: Well that’s good news. Saves me a lot of work. My car is auto and staying auto. I have a brake booster, master cylinder, brake pedal, and underdash bracket from a 72 vert. I already did the disc swap years ago. Just finally getting around to going to power instead of manual.  
Thanks for the info. 
Any have any pics of the firewall where the hole needs cut? Hard to search the forum on my phone!

 The "hole" is already in the firewall, it's the cover plate that needs to be cut to match. Don't discard this plate as it has 4 small bosses welded on that are spacers to position it all correctly. I think I have a pic that may help, but I wish I'd got in the habit of taking pics as I went when  doing all the upgrades I've done.
Huge tip, but likely you already know this, is remove the seat (and steering column if necessary) to get at it easier. Not too hard to do and besides, you may need a new rubber seal at the bottom anyway after all these years. Believe me, adding the booster will be easier with it out.
Also, you'll need to drill out the bottom holes in the bracket, spacer and firewall for the 3/8"(?) studs on the booster.


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#5
Great!! Thank you. Now I just need to check and see what kind of vacuum my motor is making. Hopefully it is enough. Anyone know on average how much vacuum you need to run a booster??

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
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#6
I was at 13" and i felt that it was borderline. Maybe 12" but thats about it.
Edit PS: If i were you I would try and if you need more boost you can try changing timing or adding a a vacuum booster pump.


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        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#7
(07-15-2018, 09:25 AM)tony-muscle Wrote: I was at 13" and i felt that it was borderline. Maybe 12" but thats about it.
Edit PS: If i were you I would try and if you need more boost you can try changing timing or adding a a vacuum booster pump.


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Thanks Tony. I will check it and see where I’m at. Don’t wanna touch the timing. Car has been running perfect.

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
  Reply
#8
+1 on Ton-muscle post, 12 is close to the edge. Less than that and it likely to become a "one shot" power brake system. A secondary vacuum reservoir helps a bit. I've run a vacuum pump, it works but, makes a noise that doesn't complement the engine sounds. Boosters with a small leak are kind of hard to diagnose. I had one that passed all the common tests but when replaced the vacuum pump was no longer needed. Good luck with the upgrade. Chuck
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#9
I was just reading about new rotary vanes vacuum pumps that are allegedly quieter.
This is the one I was reading about. Expensive though.
https://leedbrakes.com/c-1183495-master-...pumps.html


Sent from my SAMSUNG-SM-G930A using Tapatalk

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#10
Ok I checked vacuum tonight. At low idle in gear I’m around 10. In park high idle 12. And give it some throttle and it goes up to around 15-18. Would this be sufficient to run a brake booster??

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
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