Master Cylinder ?
Here’s the Chrysler 09104-3766185 master cylinder in my car that is not correct for the brake calipers that is has. This 83 Camaro has stock front single piston calipers and 4 piston rear calipers.
I know there is not enough pressure to the rear calipers as the discs are blued. They are plumbed to the front port. I have recently purchased a test pressure gauge to check this rear pressure with a replacement master cylinder.
Here’s my question. What master cylinder could I use for replacement that will fit the mounting where this one presently is and correct this problem? This car also uses the stock brake pedal and rod location.
I also question if switching the position of the brake lines on this master cylinder could make this work properly. The master cylinder rear position has a much larger opening and assume more volume for 4 piston rear calipers. The front calipers are only stock single pistons.
What say you?
|DRR Top Comp
Switch em, that's how I've always ran mine. It'll stop better, if the car has any preload though, the back of the car will go left on hard braking.
On a positive note, it won't flat spot the front tires, no smoke hard braking.
Check line pressure at both front and rear on the first hit of the pedal...Make sure you "bleed" that caliper as you move from the front or rear location.. Then think about master cylinder,
The Mark Williams site on Brakes can provide recommendations on bore sizing and pressure...Given the stock brake pedal mounting locations you might be able to relocate M/C pushrod pivot to help with pedal Ratio....That Chrysler master cylinder comes in several bore sizes....
this is the master cylinder on my Firebird with 4 wheel Mark Williams disc brakes, This 1.063" aka 1 1/16" bore MC was originally installed by MPR when the car was built. I also have the stock brake pedal, mount and ratio.
Good info Ed. Are front calipers 2 or 4 piston? Is Master Cylinder plumbed with rear outlet to front brakes?
I use Strange MC's. 1.062" is what you want. The port closest to the mounting flange should go to the rear brakes as that supplies the most volume.
calipers are 4 piston MW and after checking my photos, it is not. The front port is plumbed through the wheel well to the line lock.
That is what I have on my car. But, I only see a 1.032" and a 1.125" available on their site now.
Disclaimer: The opinions expressed here are the views of the writer and do not reflect the views or opinions of any entity other than myself.
72 Nova 370 ci (Stealth Black)
The port furthest (closest to radiator) from the mounting flange is to front line lock?
MW website says 1” bore using their 2 piston front and 4 piston rear. But, they don’t list which port is plumbed where.
The Chrysler MC that I have is 1.032” bore. The front calipers are stock metric 2.38 single piston which is more sq in area than a MW 2 piston front. The rears are 4 piston 9.6 sq in.
I’m going to switch line plumb positions and see what happens. I also need a pressure gauge with correct fitting that’ll fit the stock metric front calipers to check pressure.
Switched the brake lines going to the master cylinder. Rear brakes on the port closest to mounting flange now. Bled the brakes with new fluid. Pedal is as solid as prior.
I checked both rear calipers and have 840 # pressure on both. MW lists 1000 # as minimum.
Anyone else have maximum brake pressure in the 800# level ?This message has been edited. Last edited by: markemark,
Easy fix if you have room to move the push rod up on the pedal 1 3/4 inch. drill a new h ole and use a 3/8 rod end to mount a new push rod . put a stop on the pedal so the rod wont fall out of the master cylinder.
Mark Williams 4 piston calipers with Ferodo pads
1st hit 760psi
2nd hit 860psi
3rd hit, hold the brakes for a moment 1420psi
Stock pedal. MC Rod bolt is 2” from pedal arm mount bolt.
I’m thinking now that the master cylinder could be replaced.
I don't believe there's any air in the lines or calipers.
I use that MC with single piston frt. calipers and drum rear. On my Camaro I was able to move the pin higher for more pedal ratio. I removed the pedal quadrant and welded in a guide so there is no way the rod can get out of alignment with the MC and have a pedal stop. Those MC's are the same bore size for frt. and rear ports so no gain in pressure. Difference in most MC's is the size of the reservoir. Disc brakes self adjust by the piston moving out as the pad wears. As the piston moves out the fluid level drops to allow it so self adjust.
Good Link on the information of the Master Cylinder I have Eman.
My car stopped well even at 142 in the 1/4 mile that I haven’t raced in over 3 yrs. All my racing is now 1/8 and have no plans to return to 1/4. The problem I’m trying to correct is the overheating of the rear discs from low rear brake pressure.
In the pic the stock pedal mount bolt is 2” from the master cylinder rod bolt.
Just an update. Although switching the brake line positions on the master cylinder only increased the pressure to the rear calipers to 840# , it did improve my problem. After 2x out the rear discs are turning silver in color. Car stops well like this, so I’m leaving as is. Thanks All for the suggestions.
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