Drum brake master cylinder studs

Were there different dia studs used in different years? I got a new master cylinder for my 69 charger and the mounting holes are too big and the studs just spin freely. I am thinking maybe some one swapped a different year master on years ago complete with the matching studs.

That just happened to me too. Bought a new aftermarket and the splines of the studs just barely hold them in the master.

I took the master back off and took a longer tapered punch to the back side and a couple of little whacks raised enough metal to hold the studs in place. Once I got it back on the car though I had to hold those studs while tightening the nuts.

how big are the holes ? you are going manual brakes, correct ? does the master cylinder have the recess in the piston ? any of these i have touched in my lifetime has been 5/16" studs, but i never really popped out studs to compare the knurl. maybe your replacement is kind of generic ? don't forget, you dumped off a master here quite a while back. we can compare it to what you got now. [and i got MORE floor . ]

I'm changing the master now,when I get down to the garage I will try to get you a measurement.

Dug up my old one of my 66 coronet tonite. I will measure tomorrow..Im whipped right now.

Ok

original off my 66 coronet manual drum car measures 0.340.

Both new parts store ones measure 0.360-0.370.What gives? I guess I am gonna have to look around for studs with larger knurl dia.

Put a little quick set JB Weld on the knurls,It should hold until you get the nuts started. I have used super glue, the thicker kind,but the JB would work better.

I found the stud holes to be 5/16,the holes in the adapter for my master upgrade are 5/16.BUT,,the adapter I bought has larger holes in them so everything will be nut & bolted.

How about putting sleeves on the studs, or sleeves in the holes?

i even thought about using a piece of shim stock wrapped around the original stud. i looked through my stud collection, but i didn't have anything. i suggested a nut & bolt, but he didn't want to go that route. the only manual stuff i have has the studs tacked to the pedal assembly, so no help there.