What the ?? (Master Cylinder)?
 

Folks, I noticed poor braking in the front wheels of my ‘67 GTO with 4 wheel manual drum brakes. The other day, I noticed the pedal pressure slowly going away too.

Thinking I have a bad seal in the master cylinder’s front circuit, I thought I’d get a new one. Well, that seems to be a challenge in that all the service units have a blunt end to accept the push rod and the one on the car has a captured ball at the MC and clevis at the pedal. The part number on my MC looks to be GM 5452310 Y. Broadcast code is CT. Is this the original MC? If it is, I’ll take it off and send it to be rebuilt. If it’s not original, can someone recommend where I can get a new or rebuilt unit? I ordered one from Ames, however, their MCs don’t have the captured ball end for the rod.

Any help /advice appreciated.

Thanks!
Don

White post brake restoration in VA rebuilds them great turn around time. Not over priced had a couple done there.

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[QUOTE=rare4k;6424211]White post brake restoration in VA rebuilds them great turn around time. Not over priced had a couple done there.

Thanks, rare4k. I used White Post for the MC on my '63 Biscayne 409/425 car and was quite satisfied with their work.

If I can get confirmation here that GM5452310 is the correct part number for this car (my AIM's print is poor and I can't read the part number), I'll send it to White Post on Monday.

Thanks!

It is the original.
The number is not the part, but the casting number which was common across all BOP & Chevy, A body drum brakes from 67 to 71/72.
The CT code identifies it as a Pontiac (and possibly Olds IIRC) application.

The Pontiac part number is 5458522 grp. 4.650

Yes, that would be the original one or at least the correct one for the car.
White Post can sleeve and rebuild it for you.
Here's a couple photos of my original.

Thanks for the advice!

I've removed the MC and it's packed up and ready to go to White Post on Monday. On my Corvette, the cast body of the MC is black as per original finish and the cap is gold colored dichromate. Should this one be finished the same to best replicate a factory look?

I can't remember what mine was originally but it can go either way. From what I've seen and read, most were unpainted but there are several examples of MCs painted black.
Wish there was a definitive answer.

Yes, it should be similar to your Corvette. My original had remnants of black paint left. I requested satin black when having mine done. I elected not to have the lid done as it cleaned up fairly well. Here's a couple of finished photos.

It's been a while but if I remember correctly you remove the snap ring from the master cylinder, remove the push rod and retainer and install it in the new master cylinder.

Thanks all. My MC is due back from White Post tomorrow. If they don't re-spray it as part of their restoration, I'll paint it with satin black. The cap is in terrific condition, so it won't need anything.

I'm so glad that it's the original part. Can't wait to get it installed and the car back out on the road.

Regards,
Don