Disc brake conversion master cylinder question.

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DusterJoe410.4

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I’m converting my 71 Duster to 73-^ BBP disc brakes and 11” BBP drum rear brakes. The car will have manual brakes, and I’m trying to determine what master cylinder I need. I have a leftover new unused DBMC10 from Right Stuff, it lists as a 1.063 bore size. It was bought for a power brake 73 340 Duster we built. I was under the impression that power vs manual masters were different but recently found some saying they used the same master on a manual brake car. Am I correct or will it work for my application? Thanks for any help you can give.

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Since that is a new aftermarket part... first is to check that its piston was machined for the manual brake pedal rods rubber retainer. We can't take anything for granted.
Do your 11 inch drum brakes have larger bore wheel cylinders than standard 10 inch brakes? That master cylinder bore might be about right. I have used the info/specs shown at rockauto to sort the differences.
 
That master cylinder will give you a high, hard pedal with those brakes. It will work and some people do like that pedal feel, but I’m not one of them. I run 15/16” master cylinders on my manual disk/drum cars, and I also run the larger 11” rear drums. The 15/16” master cylinder gives a slightly softer pedal with a little more travel. It makes it easier to feel the friction point on the brakes and makes things a little easier on your leg too.
 
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Thanks for the info guys! Now I know what I need to look for. I have this master posted in the for trade section if anyone has a 15/16” one in the same condition they would like to trade.
 
Go 15/16
Bet we can drag this post out to 45 responses. And still not have a answer.
 
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