Master Cylinder???

[mvh]

Thank you! Thats good to know! I'll go ahead and pick up a Power disc/drum master for a 74 Dart. Are the cheap Reman. Cardone ones any good???

There is nothing wrong with the Cardone MCs. They are a good value, if you can find the right application.

To "wracks71": What is it about the factory MCs that "sucks"? That they aren't painted bright red with a logo? The fact is, there is nothing about any correctly-sized master cylinder that can improve your braking performance, no matter what it costs (the braking is done at the caliper & disk, and most of all at the tire & road) -- the only benefit from an aftermarket MC is that an aluminum body will save weight.

Someone told you to get the 15/16" bore. This is good advice. The slightly smaller bore reduces the pedal effort. The 1-inch-and-over bore sizes without power assist will create a much stiffer pedal than most people are used to -- so stiff that some people will have a hard time locking up the brakes.

 

[mopowers]

There is nothing wrong with the Cardone MCs. They are a good value, if you can find the right application.

To "wracks71": What is it about the factory MCs that "sucks"? That they aren't painted bright red with a logo? The fact is, there is nothing about any correctly-sized master cylinder that can improve your braking performance, no matter what it costs (the braking is done at the caliper & disk, and most of all at the tire & road) -- the only benefit from an aftermarket MC is that an aluminum body will save weight.

Someone told you to get the 15/16" bore. This is good advice. The slightly smaller bore reduces the pedal effort. The 1-inch-and-over bore sizes without power assist will create a much stiffer pedal than most people are used to -- so stiff that some people will have a hard time locking up the brakes.

Thanks. Now I just have to figure out which one has the 15/16ths bore. Is that the factory 74 Dart manual disc/drum size???

***EDIT- just read back through the posts. Now I know which one I'm getting. Thanks guys!

 

[wracks71]

There is nothing wrong with the Cardone MCs. They are a good value, if you can find the right application.

To "wracks71": What is it about the factory MCs that "sucks"? That they aren't painted bright red with a logo? The fact is, there is nothing about any correctly-sized master cylinder that can improve your braking performance, no matter what it costs (the braking is done at the caliper & disk, and most of all at the tire & road) -- the only benefit from an aftermarket MC is that an aluminum body will save weight.

Someone told you to get the 15/16" bore. This is good advice. The slightly smaller bore reduces the pedal effort. The 1-inch-and-over bore sizes without power assist will create a much stiffer pedal than most people are used to -- so stiff that some people will have a hard time locking up the brakes.

for your information,mine is not a big high dollar "painted red with a logo" MC. it is a factory late model mopar unit. and you are correct,but obviosly you have not ever driven a car with good brakes or had to brake it down from 130 or so mph. maybe my SRT8 wagon should have had a 1968 MC on it and it would have worked better.

 

[mvh]

On the contrary, I have driven my car at Willow Springs on track day. My 273-powered car is not capable of 130mph on this track, but after repeated laps with hard braking from 110mph I experienced consistent, stable braking performance with zero fade. This is with factory K-H 4-piston calipers, upgraded with slotted, cross-drilled rotors and ceramic pads from Summit, hi-temp DOT4 brake fluid and, yes, the factory manual disk brake MC.

I would suggest that your experiences with your SRT8 are completely irrelevant to a discussion of A-body brakes, since they share no components in common. But I think I would go so far as to say that a master cylinder of the 1968 design, assuming that the capacity and bore were appropriate, would have no deleterious effects on the braking performance of your SRT8 -- the MC simply isn't a factor, unless it is actually "wrong", like using a drum MC on a disk system. The MC is just a foot-operated pump, moving X amount of fluid to the caliper -- if it moves the right amount of fluid with a reasonable stroke and pedal effort, it works -- there is no "high tech" magic about it, other than electronic ABS, which again is irrelevant to this discussion.

for your information,mine is not a big high dollar "painted red with a logo" MC. it is a factory late model mopar unit. and you are correct,but obviosly you have not ever driven a car with good brakes or had to brake it down from 130 or so mph. maybe my SRT8 wagon should have had a 1968 MC on it and it would have worked better.

 

[Robbie2734]

I'm going from manual drums to manual discs, so the recess should be the same, right?

After a little research, the bore diameter for a manual drum/drum car looks to be 1", whereas the bore diameter for a manual disc/drum car seems to be 1 1/32". Is that enough of a Difference to worry about??

So, it looks like my only hang up should be the residual valve in the master. Is it bad to run a front disc brake system with a master with a residual valve?

You won't be able to run!! The residual valve will put 10 lbs of pressure on the caliper, it will lock the front rotors. You can remove the residual valve and I'm told that works. I had NAPA swear that I could use a drum M/C on my 67. Thats how I know the what will happen. I went with a 15/16ths" bore on my M/C and it works well. I tried the 1 1/32" and it was a very hard petal!! The smaller bore will give you more travel but less pedal pressure is needed to stop.

 

[BillGrissom]

mvh is correct, there has been no technical improvement in Master Cylinders that I am aware of since the dual chamber ~1968, so one of those would work great on wracks71's high-tech SRT8 wagon. Robbie2734 is also correct that one should insure there is no "residual valve" in the MC. I don't think those have been used since the late 1960's and are no longer needed even for drum brakes if your wheel cylinders have the "improved" cup springs with spreader plates on the ends (or closed coils). Anyway, why retrofit a heavy, rusty iron MC instead of a newer aluminum MC? There are adapter plates for the 2 bolt holes, or just drill 2 holes thru the firewall/bracket.