I have a regular 68-72 GM booster that I took off to clean up the engine compartment and I had bought a mini 7" or 8" booster a long time ago. I have bigger issues. I never put it on an It looks like it would not be much help.


I'm switching to disc/ disc fairly soon and I want to use like a 9" or so dual diaphragm unit. But I hate to pay all most $400 for one from SSB or Master Power. Can I use a different GM one? I have the brackets from the mini booster to bolt to it and then to the fire wall. I could use those and the other hard ware.

How about a 83- up Camaro or a 90's unit? What did the Impala SS come with?

Lil help. :confused:

Whittaker,
Bill (TC username "BC") did this swap. I'm pretty sure he had to modify his clevis pin/brake pushrod & drill out the stock booster bracket welds (same for the dual diaphram) and use them on the new booster.

I do remember Bill saying though that your car needs to have a lot of vacuum at idle to operate these boosters correctly.

Joe

I put one of these 9" dual diaphragm boosters on
my '67. It is outstanding - and cheap too.

http://www.true-connections.com/cat/page76.htm

I just bought some stuff from them. I should have bought that too.

I have an 8" dual diaphragm Master Power Brakes booster on my car. It requires 18" of vacuum to operate properly. I don't have enough vacuum & it feels as if I have manual brakes. If I had to do it all over again, I would get a larger diameter booster.

Mike Sibbitt
66 396 SS

I'll second or third what Joe and Mike have already said... the dual diaphram units require AT LEAST 15" of vacuum and most do better at about 18"!! If you don't have enough vacuum, it will feel like a rock! Much harder than 'standard' manual brakes! Joe is also right in that I tried to use on my Chevelle and had a few things to overcome! First, if locating one, I found that GM changed to the smaller boosters in 79 I believe, or possibly 80. These were just smaller units that bolted on to the stock bolts. In 81, GM changed the arrangement so that the mounting bolts were now a part of the booster itself and you had to screw/unscrew the nuts from up under the dash... a real PITA! I've heard you either grind off these bolts or cut and weld on your old brackets, but I didn't try that, I just tried a unit from an 80 Camaro. My motor did not have enough vacuum, so it was really hard to push. I finally gave up and went manual and will never go back!!

Anyway, best of luck,
Bill C.

I've got around 14" of vacuum and my dual 9" does fine. I think it would be good with 12" or less.
It is awesome and I'd definitely consider trying it.

I don't why the dual 8" one from Master Power brakes needs 18", as it's really just a question of total diaphragm surface area. From the picture it looks like maybe the second diaphram is smaller than 8".

FWIW - master Power is showing a sale on the 9" Bendix booster with M/C & Firewall Bracket in the July 2003 issue of Car Craft - page 84. If you really want one, its only $125.00 Available for A-Bodys, F-bodys. Phone # 888-251-2353.

Here is what you need to do to modify the booster to fit in a A-body!

July '96 Car Craft Mag. by Marlan Davis

Picture you'll need to see (http://www.carcraft.com/tipstricks/p23611_image_large.jpg)

Late Booster On Classic Musclecar

Retrofitting late-model four-wheel disc brakes to classic GM musclecars is gaining popularity. To achieve peak performance with such systems and a modern, high-tech look, it’s best to install a late-model dual-diaphragm power booster. However, commonly available late-model units (such as the 1982-1988 G-body, code "FB," GM 18010120) typically have a different firewall mounting angle and brake-pedal attaching rod than the early unit. The G-body booster can be modified to the hybrid configuration shown in the photo, allowing it to fit the early A-body (intermediate) or F-body (Camaro/Firebird):

1. Locate a 1967-1972 A- or F-body booster, and grind off the rivet heads that hold the firewall mounting bracket to the booster. Pry the bracket off the booster with a screwdriver.

2. Measure and record the length of the pedal pushrod between the brake pedal clevis and the rear face of the booster.

3. Extend the length of the G-body booster’s pedal pushrod by cutting the clevis end off the booster and either grafting on the "A" pedal pushrod or using a piece of Grade 8-quality 3/8-16 threaded rod stock to make the overall length of the G pushrod the same as that from the original "A" booster.

4. Thread the portion of the G-body pushrod that extends out from the booster body with a 3/8-16 die.

5. Procure a 3/8-16 coupling nut (McMaster-Carr #90264A210 or equivalent, photo, A), and assemble the pushrod halves using red Loctite(R) on the threads. Attach the old clevis and retain with a jam nut (B).

6. Place the previously removed firewall-to-booster bracket on the "G" booster’s existing firewall-mounting studs, and fasten with self-locking metric M10x1.5 nuts (C). In some instances it may be necessary to elongate the "A" bracket’s mounting holes slightly inboard.

7. Attach the clevis rod to the brake pedal, then fasten the booster to the firewall using self-locking American 3/8-16 nuts.


Good luck!
Joe

72SSAbody,

Thanks a bunch for the detailed breakdown and pics. I couldn't have asked for any more details.

Originally posted by Whittaker:
72SSAbody,

Thanks a bunch for the detailed breakdown and pics. I couldn't have asked for any more details. No problem Whittaker. I've put that on my website as well for future reference too.

One thing I did see what that McMaster-Carr has changed the part number on their coupling nut. I did look in their catalog and it just looks like a part number change so you won't have any problem getting a coupling nut from them that will work (though you might want to search locally first as McMaster charges $$$ on shipping).

Good luck with your swap!

Joe

quick note to Rick I purchased the Master power booster for 125.00 yes it bolts right up but it comes with a FORD mc. the tech ppl at master power say well it bolted up didnt it we never said it would work. after about an hr or so I finally got them to take it back. my idea of "bolting up" and theirs was deffinately different.

good luck
Mark