[73LeMans]

Like most of us with stock brake boosters, my 73 LeMans has a booster that angles upward about 18 degrees. The factory booster employs the factory, one piece bracket to attach it to the firewall. The bracket has an asymmetrical 4 bolt pattern on the firewall side and a symmetrical (square) 4 bolt pattern on the booster side. On the firewall side, the bolt centers are approx 1.5" apart on the passenger side and 2.75" apart on the driver. (picture) There are 4 studs/bolts that come out of the firewall to secure the brackets to the wall, but there are actually five holes drilled in the factory firewall - 2 on the passenger, and 3 on the driver. (You can see this when you remove the factory bracket, 2nd picture) The factory bracket utilized the top and bottom bolt on the drivers side, and of course, both bolts on the passenger side.

Here is the problem. I've got some reduced angle (9 degree) brackets for the Right Stuff 9" dual diaphragm booster and Wilwood master cylinder I'm using. It doesn't really matter who made the brackets - Summit, Jegs, Right Stuff, Detroit Speed etc all appear to sell the same unit for the A body, some listing it through 81, but most stopping at 72 - left and right sides, both utilizing symmetrical bolt patterns for the firewall and booster sides. When bolting the drivers side bracket to the firewall, I must move it down to utilize the previously unused 2nd and familiar 3rd hole/stud in the firewall so the booster rod can properly align with the firewall and the pedal. (2nd picture) Since there are no additional bolts or holes on the passenger side of the firewall with which to move that bracket down, and no room to drill one (steering column is there) it will not align with the studs on the booster. Comes up about 2 inches short of lining up with the studs. To correct, I see a few options -

1.) Lengthen the mounting pad of the passenger side bracket on the booster side and drill holes to align properly. (Funny, no one seems to sell an asymmetrical bracket that would align the passenger side of the booster correctly, even though some list this part as good for the A body through 81)

2.) I could move the booster up higher on the drivers side studs. (using spots 1 and 2) This would allow the brackets to function without modification, but would require a larger hole in the firewall in order to pass through, but then I'm not sure about pedal alignment. Not liking this idea.

Anyone run into this? I'm thinking my only way out is to modify the bracket but looking to see if there are any packaged solutions already out there.

[cdrookie]

I had a 9" booster on mine, but took it off and went with a manual master cylinder. I will take a look and see how it mounted.

[Tom Vaught]

This bracket, from Motorstate Parts in Michigan puts the booster location at a more friendly 7 degree angle vs the 17 degree angle.

Some fab will still be required.

https://www.motorstate.com/ You have to type in the part number 4650B

The part is made by tuffstuff It may work for you though

Tuff Stuff does not sell direct apparently

https://www.tuffstuffperformance.com...tegory:1267409

No pictures though.

Tom V.

[cdrookie]

My bracket is the same as yours. I now recall it mounted at a pretty good angle, but it never posed an issue. I'd just modify the existing one.

It's always something with these cars isn't it? The easiest mod I did was going with manual brakes. I'm surprised your car makes enough vacuum for power brakes.

[73LeMans]

Thank you gentlemen. I'll breakout the welder and see how good I can make this bracket look.

Originally Posted by cdrookie

My bracket is the same as yours. I now recall it mounted at a pretty good angle, but it never posed an issue. I'd just modify the existing one.

It's always something with these cars isn't it? The easiest mod I did was going with manual brakes. I'm surprised your car makes enough vacuum for power brakes.

This is just another instance where its evident the 73-77s are a completely different car. And as far as vacuum goes, a big vacuum can goes a long way for me. With this new setup, who knows if that will even be enough.

I've been thinking about manual brakes this whole time the car was down, (4 years) but was always skeptical of their ability to stop the car after some "questionable activities". Bought this booster/master many moons ago, so no going back now.

On a related side note, I have since picked up a nice 70k original 72 GS and its got manual 4 wheel drums. It stops real nice believe it or not. Granted its only got a couple hundred hp, but its a confident stop. Haven't done any real panic stops, but Im sure it will handle 1 ...maybe 2

I'll likely convert the LeMans over to manual if doesn't feel right when its all together. Its easier, cleaner and would have been cheaper if I made the decision from the get go.

Thanks again guys.