Caliper and Master Cylinder Info

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mguner

How many is too many?
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First off let me give you the link to this super handy PDF master cylinder identification catalog from Cardone that has pictures, bore diameter and fitting specs. It is a little over 21MB so it takes a second or ten to download.

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The master cylinder I use on my cars in place of the 10-1571 is the 10-1945 (less reservoir) 13-1945 (with reservoir) for the 89-94 Shadow and others which has a smaller bore of .827 giving you a better hydraulic advantage when the power booster is removed. This does require swapping out fittings or using adapters. I also am finding that instead of forking over for the high dollar adjustable rod that a much cheaper aluminum spacer will fit on the Mopar adapter with the long studs and set the proper length to draw fluid. The other thing I would mention that you may not know is that in 76 the single piston caliper piston size was increased from 2 19/32 to 2 3/4. By swapping to the larger piston calipers you can further increase your hydraulic power and advantage. The A, F and M body cars still use the D84 pads and so called 11" rotors but you will notice part numbers for calipers, kits and pistons are different from 76 up.
 
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When I went to the larger bore caliper, i had to use a 1 1/32 bore MC to get a pedal. The 15/16 bore MC didn't move enough volume.
 
When I went to the larger bore caliper, i had to use a 1 1/32 bore MC to get a pedal. The 15/16 bore MC didn't move enough volume.
That is unusual. The factory 10-1571 is a 15/16 bore. My pedal moves a little further down but well off the floor and stops where I want it now.
 
When I went to the larger bore caliper, i had to use a 1 1/32 bore MC to get a pedal. The 15/16 bore MC didn't move enough volume.

I use 15/16" on all of my cars. Works great, moves plenty of volume when properly set up. You've got a mismatch somewhere.
 
First off let me give you the link to this super handy PDF master cylinder identification catalog from Cardone that has pictures, bore diameter and fitting specs. It is a little over 21MB so it takes a second or ten to download.

View attachment 1715160934
The master cylinder I use on my cars in place of the 10-1571 is the 10-1945 (less reservoir) 13-1945 (with reservoir) for the 89-94 Shadow and others which has a smaller bore of .827 giving you a better hydraulic advantage when the power booster is removed. This does require swapping out fittings or using adapters. I also am finding that instead of forking over for the high dollar adjustable rod that a much cheaper aluminum spacer will fit on the Mopar adapter with the long studs and set the proper length to draw fluid. The other thing I would mention that you may not know is that in 76 the single piston caliper piston size was increased from 2 19/32 to 2 3/4. By swapping to the larger piston calipers you can further increase your hydraulic power and advantage. The A, F and M body cars still use the D84 pads and so called 11" rotors but you will notice part numbers for calipers, kits and pistons are different from 76 up.

.827" seems pretty small, I don't think I'd want to go below 7/8". 15/16" works great, I really like the pedal feel with that combination. With .827" I'd be a little concerned about the amount of pedal travel, but I haven't tried it.

Also, the 2.75" piston calipers didn't just start in '76. They started on the A-body platform in '76, but all of the B/E body calipers had 2.75" pistons starting in '70.
 
.827" seems pretty small, I don't think I'd want to go below 7/8". 15/16" works great, I really like the pedal feel with that combination. With .827" I'd be a little concerned about the amount of pedal travel, but I haven't tried it.

Also, the 2.75" piston calipers didn't just start in '76. They started on the A-body platform in '76, but all of the B/E body calipers had 2.75" pistons starting in '70.
Yes but those calipers are of a different design. That is why I specifically mentioned the A, F and M bodies. They use the same pads which mean the calipers interchange on the spindles for an easy swap. If you pull up the 10-1571 in the PDF it shows 15/16 as the bore and it is the factory MC for my 75 Duster.
 
When I went to the larger bore caliper, i had to use a 1 1/32 bore MC to get a pedal. The 15/16 bore MC didn't move enough volume.
If you require that much volume it would seem the rear brakes are too far off the drum. Disc brakes ride the rotor so that is not where your volume is required. If the rod is not the correct length of the MC is not spaced properly you may not be allowing the MC to draw fluid. That is where the spacer comes in on mine. It wouldn't pick up fluid to bleed until I let it back off the adapter plate about 1/4 inch.
 
Yes but those calipers are of a different design. That is why I specifically mentioned the A, F and M bodies. They use the same pads which mean the calipers interchange on the spindles for an easy swap. If you pull up the 10-1571 in the PDF it shows 15/16 as the bore and it is the factory MC for my 75 Duster.

Yes, the E-body stuff was the pin type caliper. But actually, so were some of the later cars. I've harvested pin style calipers off of 76+ cars, they came on some of the B body stuff for sure. At any rate not all the 76+ calipers are the slider type either.

Anyway, I get the point, you can swap in 2.75" calipers onto an A-body with the 2.6" slider calipers just by bolting them on if you use '76+ slider calipers. I just wanted to clear up that the 2.75" calipers didn't just start in '76.

If you require that much volume it would seem the rear brakes are too far off the drum. Disc brakes ride the rotor so that is not where your volume is required. If the rod is not the correct length of the MC is not spaced properly you may not be allowing the MC to draw fluid. That is where the spacer comes in on mine. It wouldn't pick up fluid to bleed until I let it back off the adapter plate about 1/4 inch.

I'm pretty sure the car he's talking about is a C-body anyway. Not that it should matter, but he's brought it up before saying that the 15/16" bore is too small, which isn't true. I've used the 15/16" on A, E, and B body cars with no issues whatsoever. Maybe the C-body pedal ratio is totally different, but I would bet he has something else going on.
 
I drove around for a while with a 1-1/32" MC but while (boosted) braking was 'adequate', I couldn't panic stop the car at all if I wanted too.
Now with the 15/16" braking is much better and feels more as it should be.
I'm using '73 C-body pin-calipers by the way.
 
I use 15/16" on all of my cars. Works great, moves plenty of volume when properly set up. You've got a mismatch somewhere.
I don't have a mis match. I went from the 11 inch rotors, to 12inch. Everything worked fine. I wanted more stopping power, so, i put on the 2 3/4 calipers. Changed nothing else. Couldn't get a pedal, no matter how much bleeding. I went from the 15/16 bore MC, to the 1 1/32 MC. Instant pedal. No changes were made to the push rod, rear brakes, or anything else. I agree a 15/16 MC works best most of the time. But if someone has an issue similar to mine, I want them to know this is something that might help.
 
Another hiccup I found. The calipers I set back to rebuild were from a 75 Dart. Both calipers had stuck pistons. One was phenolic and the other steel. Apparently they were late production because they were the 2.75 piston models. I already had the parts to build the 2.59 piston models so now I have to order more parts..... The up side is I will try the larger piston calipers on one of the cars with the cloud car master and see what power advantage I get... Just a thought furyus2, do you have the residual pressure valves installed on your front brakes? I have not needed them yet but it may be something your setup would like. I'm guessing you are using OEM style master and not the cloud car two bolt type with adapter?
 
I'm happy with the way my car stops. I fine tuned it a little more by using smaller bore rear wheel cylinders, per Richard Erinbergers article. Probably could have done the same with an adjustable prop valve. I don't have residual valves on my car. I understand they are for when the MC is lower than the wheel cylinders, as in a street rod with the MC under the car.
 
Residual pressure valves are only needed for: A) Drum brakes. B) Whenever the master cylinder sits lower than the brake calipers.
 
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