Wilwood or aftermarket Master cylinder that works with kelsey Hayes Calipers?

Does anyone here run a Wilwood or another good master cylinder with Kelsey Hayes calipers? My 70 Swinger has the KH setup, but the stock style master cylinders seem to always leak and ruin the paint on my firewall. I looked into it, and the K H MC bore is 1 inch, the Wilwood I believe is 7/8 inch. Will this conversion work? Any other suggestions, my nice firewall paint is ruined and needs touched up. Not looking forward to it.

IDK, maybe your brake push rod is not straight causing an uneven push on the piston resulting in leakage. Maybe you just got a hold of a few bad ones? My first Duster had the K H with the stock MC. never leaked. I had it 24 years. the one I have now has a stock MC for K H but I have the Wilwood set up. It does not leak. I suspect something is out of allinement.

An MC leaking down the firewall must be common since I don't think I've seen an A-body without rust below the MC (glycol removes paint). Often, it is spillage from the reservoir cap, or a sloppy mechanic long ago. When a manual MC piston leaks, you get fluid and rust in the cabin. A 7/8"D bore would work for manual brakes. The pedal might be "too easy" w/ a booster, but I recall the factory used the same MC bore for manual and power in those years. I recall someone recently posted about a problem with the Wilwood MC. Cheaper to use a factory 2-bolt w/ adapter plate (many posts, Dr. Diff sells kit), though Wilwood adds bling.

I stopped by SSBC today to look for a kit for my buddies 71 Valiant. They have aftermarket masters and they make the kelsey hayes stuff in house. They didn’t have anything for me, as I’m going BBJ. The sales man did mention something about the disc master being a slightly bigger dia than the stock drum one. Iirc 1 1/32 v. 7/8. He said I would have to get the bigger master for the kh disc set-up. Mopar Universal Master Cylinder -Power and non Power - 1-1/32" Bore , 4 bolt mounting flange

TheGrateRonzini said:

I stopped by SSBC today to look for a kit for my buddies 71 Valiant. They have aftermarket masters and they make the kelsey hayes stuff in house. They didn’t have anything for me, as I’m going BBJ. The sales man did mention something about the disc master being a slightly bigger dia than the stock drum one. Iirc 1 1/32 v. 7/8. He said I would have to get the bigger master for the kh disc set-up. Mopar Universal Master Cylinder -Power and non Power - 1-1/32" Bore , 4 bolt mounting flange

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Thanks, I checked it out, do you know if there is a 4 to 2 bolt mounting adapter? Mine is two bolt.

I don’t know off hand. I spoke to Tony in sales. He was very helpful.
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