1973 dart sport brake booster

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ratty dart 340

ratty dart 340

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Hey there.

I have a 73 dart sport factory power brake car and I’m having issues with my booster.

I do not have a video currently, however maybe someone can guide me in the right direction. I was idling the car after putting the transmission back in, and I lost brake pressure about 80%. The moment this happened, my rpm went from around 800 to 2k or higher.

Sounds like vacuum leak to me. I plugged the vacuum line from the booster, to the intake. I have some brakes, but currently no power assist. The idle stayed calm and steady about 700 to 800 rpm.

So my first question, is my booster shot?

And if so, do they sell rebuilt boosters by them self?

I’m aware they sell booster and master cylinder combos, however these are for cars that didn’t come with power brakes from the factory.

Thanks for the help.
 
Professor Fate said:
Currently out of stock at RockAuto, but this will give you some part numbers to look for.
1973 DODGE DART 5.2L 318cid V8 Power Brake Booster | RockAuto
Most auto parts stores (NAPA, O'Reilly, Autozone, etc.) should be able to look one up for you.
Click to expand...
I have a 360. Shouldn’t matter though. I went to said auto part stores and they said that part was discontinued basically. They told me to look at eBay. However I’d rather buy new instead of used. But maybe your part numbers will help. Thank you
 
Yes, you can get yours rebuilt and thus keep the original part... :)

As I am abroad, I couldn't do this as Harmon Classic Brake doesn't ship booster overseas.


François
 
Last edited:
French demon said:
As I am abroad, I couldn't do this as Harmon Classic Brake doesn't ship booster overseas.
Click to expand...
Francois, make a posting to see if someone in the states will receive it, and facilitate shipping for you........worth a shot if you are stuck.
 
Hi Troy

I'm not stuck. I have had to adapt a generic booster/MC kit (found on ebay) and it works.
Doesn't look original, but it works.

François
 
Most large cities here in the U.S. have a booster rebuilder.....or at least used to. I would expect Denver to have one.
 
You're right, but all these rebuilders are progressively disappearing.
40 years ago, it was easy to have a starter, an alternator or a booster rebuilt. Now, it's more practical (and quicker) to change it.
Old know-how becomes rare... good mechanics too.
 
Y
French demon said:
You're right, but all these rebuilders are progressively disappearing.
40 years ago, it was easy to have a starter, an alternator or a booster rebuilt. Now, it's more practical (and quicker) to change it.
Old know-how becomes rare... good mechanics too.
Click to expand...
Yes precisely. I have been thumbing around and a lot of people were suggesting a shop in denver, which closed just a few years back.
 
Hey there again. I have run some tests and have pulled the brake booster for the 5th time now. Something is for sure wrong inside the actual booster. I found a rebuild kit online that i think will work. This is around $300 though. I have read other forums and some people say you cant put a dual diaphragm booster on a single diaphragm car, and other sites say you can. At this point i want a booster that will be safe, and something I wont have to take off for awhile. Are there universal boosters that could work? Any info appreciated.
 
I purchased this kit on Ebay, and it works well.
Booster on Ebay
Also exists in 8" and 9" diameter for high-performance cars.
DSC_0849.JPG
The main problem with universal boosters is that they have only two mounting studs for the master cylinder (today's standard).
And old mopar master cylinders need four mounting studs.
So, it's easier to buy a complete kit including matching booster and MC.
 
Last edited:
French demon said:
I purchased this kit on Ebay, and it works well.
Booster on Ebay
Also exists in 8" and 9" diameter for high-performance cars.
View attachment 1716138116
The main problem with universal boosters is that they have only two mounting studs for the master cylinder (today's standard).
And old mopar master cylinders need four mounting studs.
So, it's easier to buy a complete kit including matching booster and MC.
Click to expand...
Okay I think this might be the one I need. I have a 360, should I sized up to the 8 inch booster?I have front discs and rear drums. I also would still like to be able to take off my valve cover without taking the booster off..
 
For your consideration:
Lotta motors I put in don't have enuff vacuum for a booster.
I have always tossed the booster and put on a small bore manual master cyl, Raybestos 36406 when avail.
It's straight bolt on, you'll need a pushrod from Mancini?, (make sure it doesn't bind at the pedal pivot bolt.)
The small bore gives more "mechanical advantage",
I have also been known to use an "alternative master cylinder, and I don't see why not an alternative booster" out of the auto wreckers, sometimes requiring fabrication", especially with your location.
Good luck

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RAYBESTOS Brake & Wheel Hub Parts and More for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.
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ratty dart 340 said:
Okay I think this might be the one I need. I have a 360, should I sized up to the 8 inch booster?I have front discs and rear drums. I also would still like to be able to take off my valve cover without taking the booster off..
Click to expand...

I also have discs/drums combo, but not a V8 and I don't know if a 8" booster will block your valve cover.
Surely not. Original Midland-Ross boosters are 7 1/2" and they leave enough clearance for the SB valve cover.
 
French demon said:
I also have discs/drums combo, but not a V8 and I don't know if a 8" booster will block your valve cover.
Surely not. Original Midland-Ross boosters are 7 1/2" and they leave enough clearance for the SB valve cover.
Click to expand...
On that eBay link you sent, it states it is for Chevy. Or at least an upgrade from “GM” boosters. Is that still okay? Is it sort of universal?
 
Yes, sort of universal.
Designed for Chevy because it looks like a Corvette booster.
But like all universal parts, these boosters have to be adapted to the car, e.g. the mounting studs are in a square and measure 3 3/8" center to center. On our A-bodies, the holes of the mounting bracket have a rectangular scheme. So, you'll have to enlarge them to match the mounting studs squared scheme. Quick job with a good round file.

And another trap : the brake line ports
On our original Mopar A-bodies master cylinder, the brake lines fitting nuts are 9/16"-18 in front and 1/2"-20 in rear
MC3.jpg
The "Chevy" master cylinder has the brake lines fitting ports are inverted : 1/2"-20 in front and 9/16"-18 in rear.
You'll have to modify your line ports or use Edelmann master cylinder adapters #258306 and #258307 (cheap and easy)

And don't forget to buy the extension rod eyelet to connect the brake pedal link (it's not provided with the booster)
Extension rod eyelet

Other than that, it's plug n' play. :)
 
French demon said:
I purchased this kit on Ebay, and it works well.
Booster on Ebay
Also exists in 8" and 9" diameter for high-performance cars.
View attachment 1716138116
The main problem with universal boosters is that they have only two mounting studs for the master cylinder (today's standard).
And old mopar master cylinders need four mounting studs.
So, it's easier to buy a complete kit including matching booster and MC.
Click to expand...
Grab one of these while you are at it! LOL............. :poke: :lol:
1694133607961.jpeg
 
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