I've been looking for a new master cylinder for my 1967 Delta 88 Custom, but have run into a bit of a snag.

MasterCylinder.png

What I've found out is that it's a Delco Moraine Booster. However it looks like it has a master cylinder meant for manual brakes.

The part number for what it looks like I have:

18001122, turns up Dorman M71277 (for manual brakes)

The part number that the parts book says I should have:

5458521, turns up Dorman M66705 (for power brakes)

My brakes have never felt right (bought the car last year), I always assumed it was because the master cylinder was on it's way out (it definitely is now, the pedal went to the floor a couple times last summer). But could it be that it's been the wrong MC all along?

I guess my question is should I buy what I've had (about $30) or what the parts book says I should have (about $80)?


Thanks, Erik

 

Its possible the car was originally a manual brake car and a DPO (dumb previous owner) added the power booster wihtour changing the master cyl, or maybe replced the original cyl at some point in the car's life. I think also, the brake pedal can be mounted in two locations (pins where it hangs from under the dash) depending on whether its a manual brake or auto car, and that could affect the pedal feel if its in the wrong spot. Certainly the pedal going to the floor is not a good thing, but it is possible you have a leaky wheel cylinder? How is the fluid level in the reservoir?

 

check with John Andreotti at Ott's Friction supply. He can get you the right parts. Judging from the finish on the vacuum booster, you may want to replace it too. After all, it is your life not just a car part.

 

I was thinking the "DPO" might have put the wrong MC on it, however I came across this:

Fenco NM1489

It looks like what I have on there and says it's for power brakes. This is starting to get a little confusing.

 

The Dorman M66705 is simply a generic aftermarket replacement. The bore and stroke will be correct but the outer housing and cover are different. While not correct for a concourse restoration, the different cover won't affect performance. The only real difference between the manual and power master cylinders is the diameter of the bore.

By the way, the hard lines from the M/C to the distribution block on your car show it to be a factory power brake car. The rust on those lines show them to be original.

 

Thanks for the info everyone. So basically anything that matches the part number 5458521 will work? I don't really mind what the casing looks like if it works how it's supposed to.