Does anybody know where I can get a 3/4" bore master cylinder with stock sized outlets for the lines. That might fix my brake problems.

Chrysler K cars use GM size flare fittings and are available in 3/4, 13/16 and 7/8 bore sizes depending on appliaction.

Thanks for the info, I'll check into it.

What brake problem are you trying to fix? If you are looking for a bigger bore for the master cylinder, use one off of an '86 Caprice, it has a 15/16" bore. I'm not sure if the fittings are the same as yours.

Well, I think the b bodies had 1 1/8" bore and stock was 1". I'm looking for 3/4" to make the pedal a little harder and give more pressure to the calipers.

I went to Pepboys and thry pulled out a MC from a Dodge Aires. Looked right, but the fitting for the lines were to small. Any idea on what make/model MC will be the right sizes with a 3/4" bore? If anybody knows tell me. I'll be searching 8-)

Was it just that the mounting flange lined up or is there actually a MC with the correct fitting sizes? If there isn't, I can just get some adapters, right?

If you find a mc that will bolt up correctly, you can always use reducers/adapters to fit the lines to the mc. Take a trip to your hardware store. Carry the mc and a correctly sized piece of the metal lines (flared) with you to jury rig the adapter. Once one is built/assembled, you can duplicate the others from the parts bins.

Supercharged, I think by going with a smaller bore you are going to run into trouble!! If you are just replacing the master cylinder alone, the calipers and wheel cylinders are still going to need the same amount of fluid to push the pistons out as it did with the stock one. With a smaller bore you'll have less capacity so you will have to push the pedal further to fill all the pistons and you may end up running out of stroke before enough volume is supplied TO the pistons. The pedal will hit the floor and you will slowly come to a stop. I posted a reply a few days ago to you about a Caprice MC and after some more investigating I decided to go with an '84 Impala MC from Advanced Auto (p/n 10-1870) and put it on yesterday. Wow, what a difference in pedal feel it made 8O !! It is a lot firmer than the old ever was!!! Just remember that a bigger bore is going to take less of a stroke to push the same volume of fluid that a smaller one will. I hope that made some sense.
I know what you are probably thinking...... smaller bore will make more pressure but the brake system moves volume, THEN pressure will build up as the pistons fill and the pads and shoes meet the metal.
As a side note, the pedal is firmer but it didn't make the car stop any quicker. It just takes less travel to get it to slow down. I'm going to do some experimenting with a different booster and wheel cylinders later on so keep in touch and I'll let you know what I find. I'm trying to find a good setup without going to the B-body brake upgrade. It just looks like to big a pain in the a$$. (Notice $ signs, yeah, I'd like to keep more in my pocket).

As a side note...

Oh, another thing... the hood clearance is VERY close to the top of the lid. I believe the hood insulation is actually resting on top of the lid itself when the hood is shut. The hood closes without forcing it down but it is a tight fit, I'm sure.

Seems I was right when I was think of a bigger bore MC last month or so :lol:

I'll try the b-body cylinder first. I have 4 wheel discs and a fiberglass hood with no insulation. I'm going to check this out. Were the holes for the lines the correct threads?

If your trying to figure out the different sizes of MC's, Carquest brake catalog has them listed in the Master Cylinder New section. I've got a 1990-2002 that I'm looking at now. Also MPbrakes has in their tech section some info on selecting MC bore diameters and pedal positions. The following site has some info on MC comparisions www.geocities.com/torkerscamaro/torker.html Mark Williams site has info as well. An idea is to search the different brake sites plus others printing copies that you can look at and compare later to determine where you'r going. I've done just that, some of what I see sugest a 15/16 others sugest a 1 1/8 MC. Keep us posted on your results.


Bill

Yes, Supercharged, the bolt pattern for the MC and line sizes matched up perfectly. I didn't realize that you had 4-wheel discs. You might have to experiment with proportioning valves so this is above my knowledge. :baa:

War Pony, what was the bore size of the MC that you used? Oh, btw the your right on about the effects of volume & pressure.


Bill

Bill, the M.C. I used is a dual bore that has both 1 1/8" and a 1 19/32" pistons in it. Yeah, that's almost 1 5/8" for the one piston but I don't know which one is the front one. My guess is the big one is the front one.

Well, the M.C. I installed back in March is now in the trash. I don't know what it was about that particular model but it just didn't work. Yeah, the pedal was firmer but it just didn't make the car stop very fast at all. I bled the brakes like I'm supposed to and couldn't even slide the tires. The real clincher was when I tried to power brake one day and the front tires wouldn't hold. I actually believe the front brakes weren't working at all, if any. I bought a 15/16" bore master cylinder this morning and haven't bled the lines out completely and I can now skid the tires. One of these days I'm going to put the Cadillac disc setup on the rear but for now the $38 M.C. will do just fine.

The trashed MC was probably too much volume and not enough pressure. Is 15/16" stock?

John, I think the stock size is 7/8".

War pony> Some of my thoughts on this thread. I have an 87. I replaced the whole front system when I did the B-body swap. My donar car was an 89 caprice station wagon. The wagons,taxi's and police are the only B-body's with the 12 inch rotors and thicker snout where the hub rides. If your gonna pull them might as well get the most for your money. You also need to purchase a -NEW- a master cylinder for that donor car, it has a 1 1/8 bore. They are also what is called a fast take up M/C. Basically, it moves alot of fluid fast to reduce pedal travel then step down to provide the higher pressure. Do not use one thats been sitting in the wrecking yard! Its almost guaranteed the seals will be shot. I think mine cost about $59. I too have disc's on the rear. They are wilwood 12". The discs require more volume. More volume equals more pressure. The B-body front calipers are larger than the G-body. Because of that you need the power booster from the donor car. It provides more boost- otherwise your pedal effort will be too high. You will need to remove and bypass the junction block because it has an internal check valve that holds 10 lbs of pressure in the rear line to keep the brake shoes from retracting completely when useing drum brakes. But you will need to add an adjustable proportioning valve to balance the front/rear brakes.I tried useing the cadillac rear brakes but it was way too much work fabricating brackets for the calipers. I got the entire b-body parts from the junk-yard for $135. It all made a huge difference. Calipers-pads and rotors are all available at any local parts store. Hope this helps you in some way. Good Luck

Heatsoaked, I didn't realize the fast takeup feature on the b-body masters. I wonder now if the reason for my hard pedal and lack of stopping power was that, because I am using stock brake components, is I was "short-stroking" the M/C and not getting the pressure I needed. Thanks for the info.