Master cylinder questions

[74@scamp]

Im finally coming close to the point of purchasing some brake parts. I have a 1974 scamp with disc brakes in front and an 8 1/4 rear end with 11 inch drums. I have sent an email to Dr. Diff on what master cylinder they recommend but haven't heard back. Anybody else running this set up and what master cylinder did you use?

Thanks

 

[Professor Fate]

Power or manual brakes?
Factory used 15/16 for power, 1 1/32 for manual. The 15/16 also is a popular mod for manual brakes, more brake feel.

 

[74@scamp]

Well at first I wanted power but manual is a lot cleaner. So I could run manual brakes with a 15/16 and be good?

 

[Professor Fate]

Well at first I wanted power but manual is a lot cleaner. So I could run manual brakes with a 15/16 and be good?

Yes, it's a pretty common change.
It'll require a bit more effort, but has better "feel".

 

[74@scamp]

Yes, it's a pretty common change.
It'll require a bit more effort, but has better "feel".

Got ya. I think i need the adapter from Dr. Diff. Do you know what else needs to be done?

 

[Bob67Barracuda]

I have similar setup on a '67 Barracuda. Disc front. Drum rear. I just got done replacing a failed '90s era power booster and master cylinder. Parts from Dr. Diff. I found him responsive. Maybe he's on vacation or something. In addition to booster, MC and linkage, I ordered a Mopar-style proportioning valve, but then wound up not using it because I would've needed to redo some brake lines, and I was lazy and eager to get back on the road. So I reused my existing valve unit (which according to Dr. Diff is GM style). My valve is under the booster and the Mopar one would need to be mounted to the fender. Brake performance much, much better now. I contemplated converting to manual brakes, but wasn't certain of my ability to make it happen and I'm used to power brakes. My understanding is that going with power vs manual will affect the bore of the MC you choose. Photos of my invoice and completed project...

 

[Professor Fate]

Got ya. I think i need the adapter from Dr. Diff. Do you know what else needs to be done?

You only need the adapter if you're changing over to the late model aluminum master. The factory '73 and up master (any bore) will bolt right on, no adapter needed.

 

[go-fish]

Quick question: Is a single circuit master (early-A) and later dual circuit master (~1973) pushrods the same?

 

[Inertia]

Quick question: Is a single circuit master (early-A) and later dual circuit master (~1973) pushrods the same?

Pretty sure they are .

 

[74@scamp]

I have similar setup on a '67 Barracuda. Disc front. Drum rear. I just got done replacing a failed '90s era power booster and master cylinder. Parts from Dr. Diff. I found him responsive. Maybe he's on vacation or something. In addition to booster, MC and linkage, I ordered a Mopar-style proportioning valve, but then wound up not using it because I would've needed to redo some brake lines, and I was lazy and eager to get back on the road. So I reused my existing valve unit (which according to Dr. Diff is GM style). My valve is under the booster and the Mopar one would need to be mounted to the fender. Brake performance much, much better now. I contemplated converting to manual brakes, but wasn't certain of my ability to make it happen and I'm used to power brakes. My understanding is that going with power vs manual will affect the bore of the MC you choose. Photos of my invoice and completed project...

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That's awesome. He got back to me. How do you like it with the booster? I cant decided if I want manual or power haha

 

[Bob67Barracuda]

I like power brakes. I have no idea what manual would feel like on my Cuda. I have manual steering, and that can be a pain in the driveway and in parking lots. So why torture myself with manual brakes?

 

[74@scamp]

I like power brakes. I have no idea what manual would feel like on my Cuda. I have manual steering, and that can be a pain in the driveway and in parking lots. So why torture myself with manual brakes?

Oh got ya. Haha yeah I get that