Brake Master cylinder & booster improvement (using the K car parts)

slant6billy

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Before:
IMG_4182.JPG

After:
IMG_4226.JPG
 

old yellow 78

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Great idea! ;) Didn't know about this swap. OY is going to need a new master cylinder before too long, so i might try this K car swap out. Is the master and booster the same for all K's, or did you use a particular one?
 

Aspen500

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I've been considering this swap. My car has manual brakes and, while they stop the car fine, you have to push so hard on the pedal to do it and,,,,,,,,,,,my knees aren't what they once were when I was a younger man.:(

Not sure, do you think it would clear an RB?
DSCF0002.JPG
 

slant6billy

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The part numbers for the booster and Master:
62181629_1574139699386059_4780718476450856960_n.jpg
62478087_451680132275029_2177510223927836672_n.jpg


Rock Auto- very inexpensive especially with the 20% discount
 

slant6billy

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I've been considering this swap. My car has manual brakes and, while they stop the car fine, you have to push so hard on the pedal to do it and,,,,,,,,,,,my knees aren't what they once were when I was a younger man.:(

Not sure, do you think it would clear an RB?
View attachment 36808
IMG_4229.JPG

old booster was about 11 inches wide and measure from the fender inner edge
IMG_4232.JPG

20 1/2 inches

The new one
IMG_4230.JPG
about 9 inches an measures
IMG_4231.JPG
about 18 3/4 from the lip of the fender to give you an idea
 

Aspen500

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Maybe I'll make a model from cardboard to get a rough idea about clearance. My car never had power brakes so I've no idea if a stock f-body booster would have fit or not with the big block (I'm guessing not). On one hand power brakes would be nice, on the other hand, there's already so much crap packed under the hood there's not much room left.:eek: Thanks for the measurements!
 

BudW

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For brake booster pictures, go to Brake booster post # 8.

In my garage is an A1-Cardone dual/tandem booster p/n 54-73172, still in the box, which I can drag out and take measurements – if wanted. I also have a ’84 Gran Fury booster “loose/removed” as well, for measurements.

One thing to keep in mind is the power brake booster is mounted about 1½” (going by memory, which may or might not be correct) higher on firewall above the location of manual brake master cylinder, because of the multiplier linkage (or whatever you might want to call it).
There are three pairs of holes on firewall. The bottom pair of holes (4) are for manual brake master cylinder. The top pair of bolt holes (4) are for the power brake booster.

The tandem “K” booster has a smaller diameter than the single “K” booster is – but (I believe) both will fit with either the B or RB big block version.

The small block driver’s side rear-most valve cover bolt is almost impossible to access (need a wrist that bends in an impossible manner) with the stock booster in place. Trying to install some aftermarket (finned aluminum) valve covers is also impossible (the booster and valve cover wants to occupy the same real estate).

This doesn’t apply to big block cars with either “K” booster (I don’t think – not tried, yet):

I will try to dig out some parts tonight and take better pictures (if I can remember) if wanted.

This is a picture of a early ('76 to '78?, not sure of the year break) FM body from another forum member (Jim in AZ) - which uses cast iron master cylinder.
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100_1271 m.jpg

The top row of holes is hard to see because they are in a shadow, but they are there. I believe your gloss black firewall stiffener plate uses the top and bottom row of holes. The older (cast iron) master cylinders that uses 4 bolts (instead of 2 bolts for aluminum) uses the bottom two rows of holes. See next post for comparison.


These are some big block photos I’ve saved – but not sure whose car they are from:
‘77 Aspen with a 400. From the picture it is using a stock booster with 4-bolt cast iron master cylinder.
77 Aspen 400 IMG_0145.JPG

Pic 2 of the same.
77 Aspen 400 IMG_0149.JPG


’78 Road Runner with either a 413 or 440 (both RB, with a stock booster).
78 RR w440.jpg


’79 RT with 440 (with a stock booster).
79 Aspen RT 440 1.jpg


I’ve kept other pictures, but it is not clear as to which booster each car is wearing, so I didn’t include them.

It is assumed the engine came in from underneath, when using the stock booster.
If using headers, I would remove/install an engine (either small or big block) from underneath, anyway – for headers suck when installing an engine from above.
BudW

Edit - I missed a detail.
 
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BudW

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Some pictures and measurements I took.
The Circumference of my '84 Gran Fury booster is 36½” (92.7 cm) which is about 11.6” (29.5 cm) diameter.
The Circumference of my tandem “K” booster is about 28¼” (71.7 cm) which is about 9” (22.9 cm) diameter.
That would be about 2.6” smaller total or about 1.3” (3.3 cm) father away from engine.

20190918_225141r.jpg



This is my F-body manual petal assembly with '84 GF petal. Both are for Aluminum MC (Master Cylinder). I didn't think about it until now, but apparently the cast iron MC firewall (and petal bracket) is slightly different from aluminum MC firewall, hum...
20190918_223458m.jpg

This is upside down, so to compare with bolt-hole picture from Jim in AZ's picture (above), here it is flipped.
20190918_223458f.jpg



20190918_223728r.jpg


20190918_223742r.jpg


A took a picture of my '84 booster with '84 brake petal – but when I went to download it from phone, it wasn't there.

@Aspen500, if you are considering adding power brakes, this piece you will need (red circle), for it doesn't come with a reman (or new) booster.
20190918_225129m.jpg

If you want this one (which is a bit rusty), you can have it for cost of shipping - but you might want to talk to Jim in AZ to see if he has a less rusty one. I know how rust is a 4-letter word in your parts.
Note: the center-line of the bracket to right of picture is where your master cylinder currently resides at (without power brakes). The rod going into the booster is that much higher on firewall. I should have measured it - but I forgot.
BudW
 

Aka601

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The two photos in post 9, I think, is from my Volare 77 original slant car. Now 400 bb and hp exhoust manifolds. The original booster fit but tight as you kan see. Not possible to remove valve cover. I also got a tandem booster but think it was for a Daytona turbo, not sure. The hole at the end of the rod that comes from the booster is not the same size as on the original linkage. Can post part nr and photo if anyone interested.
 

BudW

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The two photos in post 9, I think, is from my Volare 77 original slant car.
You are correct. I went back and renamed the photos correctly, now.


Pretty much all the K, E, G, H, C, S bodies (front wheel drive) made in the ‘80’s are the same, as far as brake booster/master cylinder is concerned. The L-body (Omni/Horizon) and P-body (Shadow) are a bit different but these brake items might (should?) still be the same (maybe).

I know the booster studs are metric, so when you remove your old booster, don’t reuse the old nuts (or you will cause problems).

The hole at the end of the rod that comes from the booster is not the same size as on the original linkage.
I will do some measurements tonight and will report back.
BudW
 

XfbodyX

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Just to breifly interject this, hasnt anyone thought vs all this grief just to use a big bore master and two simple WW adjustable in line valves to end up with manual brakes that in the end are better then what your trying to achieve here. No matter what your doing here your still at the mercy of a non adjustable, not setup for all combos oem per portioning valve.
 

Aka601

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2429DB30-386A-4445-904A-FA59DD74321E.jpeg
I have the 50- 3122. Booster and master cylindern in the same box but whitout reservoar. And ofcours the one I have out of a b- van, do not fit..
Did a little measurements. The hole in de booster rod is 4 mm larger then fork and its bolt. The fork is 4.5 mm wider then the rod. An easy fix.
 

Duke5A

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While fixing the blown head gasket after Woodward I vowed to either go manual brakes or hydroboost next year. Still pricing out the ladder. Never driven a car with manual brakes either, so there is that. The booster being in the way made the job at least one order magnitude more difficult though.
 

BudW

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I did more measurements last night.
Side by side comparison
20190919_235602r.jpg


20190919_234938r.jpg

The linkage comes off via a small cotter pin (green arrow). The washer (blue arrow) is a wave washer (to prevent rattling). It is much easier to remove this linkage after booster has been removed from car.

20190919_235022r.jpg

20190919_235104r.jpg

The hole (and pin) diameter is 0.370” (a tad smaller than 3/8”) on original booster – but is hard to tell in this picture.

20190919_235255r.jpg

The hole on “K” booster is exactly 0.500” (1/2”) – but a very poor picture (sorry).

20190919_235507r.jpg

The thickness of rod on “K” booster is exactly 0.250” (1/4”).

20190919_235517r.jpg

The thickness of rod on original booster is 0.312” (5/16”), so new rod is 1/16” thinner.

20190919_235656r.jpg

The width of multiplier linkage (where It attaches to booster rod) is 0.370” (not quite 3/8”). The wave washer takes up that 1/16” difference but will still need a solid 1/16” spacer in there to keep clunks and squeaks to a minimum.

20190919_235736c.jpg

Old linkage with "k" booster rod.

20190919_235750r.jpg

Old booster with original linkage.

Continued:
 

BudW

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As far as the rod hole difference, I would go to a hardware store and get a plastic (or metal) sleeve 3/8”to ½”. The sleeve will need to be trimmed for length – but if plastic, that isn’t too hard to do. I may go get one this weekend and show how its done.


Length of original booster rod. It should be going by center of the hole. I couldn’t hold the booster, the tool and phone at same time to get a better picture.
20190920_000032m.jpg


20190919_235936m.jpg

Length of “K” booster rod. It appears the “K” booster rod is a bit longer. That would make the brake petal stick away from floor a bit more than original one did, and a person would need to adjust the stop light switch a tad. I have seen booster production differences of this much, before.
BudW
 

slant6billy

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Good info Bud. I should had reached out first. Still, the only difficulty was the original pin that goes through the pushrod eye was fussy. The other was the top two holes in firewall were too small for the metric thread studs on the K car booster. Finally, the threads on the K car booster that go through the firewall ended too soon (I guess the K car has a thicker firewall). Easy fix was a few flat washers on the inside under the dash. We did make a plastic sleeve bushing to compensate for the bigger eye on the K car pushrod. The pedal height seems fine and the brake light switch seems ok too. I got to get front calipers to put the car through the paces and give it a full power shakedown
 

volare 77

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BUDW, thanks for posting the location of the wave washer. I found it on the floor board when I was removing my brake pedal assy. I didn`t know where it came from.
 

brotherGood

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How do you adjust the brake light switch? After doing this a couple years ago, I've had instances where my brake lights are staying on. I've been just lifting the pedal up with my foot whenever I get off the brakes, but there are times that I forget
 
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