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What am I doing wrong with my ‘61 Deville master cylinder?

Started by 61canadiandeville, September 21, 2020, 11:12:21 AM

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61canadiandeville

Hello all,

I just purchased this vehicle knowing that the master cylinder needed replacement. I ordered a Delco from my work (GM dealership) thinking that it would bolt on and away we go. It came in, looked at it, seemed to be exact, I bench bled it, took the old one off and the piston from the cylinder stayed attached to the booster which at the time seemed weird as I’m used to working on newer vehicles where it’s all one unit.

So, after messing around on it an essentially damaging the piston that is still attached, I decided to remove the booster.

After the removal and dismantle of the booster, I find the c-clip that is holding the old cylinder piston. Remove that, go to see if the piston from the booster fits into the new master cylinder and it doesn’t, it’s too big.

Did I buy the wrong master? Am I missing something? Any help would be greatly appreciated

Michael Petti

If it not fit probably wrong one. Have you considered rebuilding the old one?  Your post indicates a good level of mechanical knowledge. If not want to. I suggest get a new one locally. NAPA is a good choice. Many new or rebuilds not great quality and could leak right out of the box. That happened to me.

CadillacFanBob

There are 2 different master cylinders, Bendix OR Delco Moraine, you do not have to remove push rod to replace master cylinder, if you already removed it, look at the area for adjustment threads to put back where it was originally. There is a kent moore tool, one for Bendix # J7723-01, OR Moraine # J8531 used to check this adjustment. Bill Sawrey in Tennessee sells used Kent Moore tools. I hope this helps.

Bob
Frankfort, Illinois