I figured let's start with a larger bore master cylinder and see if we can lower the pedal and reduce the travel, then see how the pedal effort is. I went to the extreme and got a 1-1/4" MC for a 60s pickup. Turns out it's about 1/2 longer and 1/2" taller, so won't fit the shock tower and brace. Hard to find dimensions on the various Ford style master cylinders. Now I'm thinking a 1-1/8" GM style (shorter to clear shock tower brace) may be the hot ticket. 3/16" more bore should help reduce pedal height and travel, but I suspect it'll be too much effort for him with the limited space for a booster. Any options short of hydroboost? Any dual diaphragm boosters that will fit? Trying to figure out what can work for him with limited leg mobility to give fancy new car braking effort and work in the limited space available on this car.
'63 disk brake, need lower pedal and less effort
Moderator: Wklink
'63 disk brake, need lower pedal and less effort
The old man picked up a '63 Tbird a while ago. PO did a disc brake and dual circuit conversion using some compact booster and a Ford 15/16" master cylinder. Shock tower brace is slightly notched. No idea on calipers or rotors, I'd guess S10 calipers and maybe Granada rotors since that's a common swap for many old Fords. Brake pedal was very high so I cut down the adjustable pushrod about 1/2", it was adjusted all the way in/low. We now have adjustment enough to make it low enough to hit the floor wanting for more braking effort or a few turns out and have good brakes without having to lift your foot high to use them. Brakes work well and I can lock them up from 70 MPH. Problem is Pops has some mobility issues and can't easily lift his foot high enough and I suspect not push hard enough. It's not safe for him to drive.
I figured let's start with a larger bore master cylinder and see if we can lower the pedal and reduce the travel, then see how the pedal effort is. I went to the extreme and got a 1-1/4" MC for a 60s pickup. Turns out it's about 1/2 longer and 1/2" taller, so won't fit the shock tower and brace. Hard to find dimensions on the various Ford style master cylinders. Now I'm thinking a 1-1/8" GM style (shorter to clear shock tower brace) may be the hot ticket. 3/16" more bore should help reduce pedal height and travel, but I suspect it'll be too much effort for him with the limited space for a booster. Any options short of hydroboost? Any dual diaphragm boosters that will fit? Trying to figure out what can work for him with limited leg mobility to give fancy new car braking effort and work in the limited space available on this car.
I figured let's start with a larger bore master cylinder and see if we can lower the pedal and reduce the travel, then see how the pedal effort is. I went to the extreme and got a 1-1/4" MC for a 60s pickup. Turns out it's about 1/2 longer and 1/2" taller, so won't fit the shock tower and brace. Hard to find dimensions on the various Ford style master cylinders. Now I'm thinking a 1-1/8" GM style (shorter to clear shock tower brace) may be the hot ticket. 3/16" more bore should help reduce pedal height and travel, but I suspect it'll be too much effort for him with the limited space for a booster. Any options short of hydroboost? Any dual diaphragm boosters that will fit? Trying to figure out what can work for him with limited leg mobility to give fancy new car braking effort and work in the limited space available on this car.
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sacredsteel
- Posts: 64
- Joined: Thu Apr 15, 2021 10:45 am
Re: '63 disk brake, need lower pedal and less effort
The one I use is for a 67 Mustang disc/drum. Works fine.
Re: '63 disk brake, need lower pedal and less effort
I swapped on a '67 Corvette disc/drum 1-1/8" bore master cylinder. There is some slop in the linkage I need to adjust out but even so, with the pedal to booster rod at the same adjustment as the 15/16" Ford master I can't get the pedal near the floor. I can probably get the pedal to a comfortable height for the old man to quickly go from gas to brake, but as expected pedal effort is significantly higher which I think will be a problem for him.
With the 15/16" Ford master I could easily lock the brakes, but with this GM master I took a test drive today and while it'll stop quick with a lot of effort I'm not sure I could lock the wheels. There was a lot of traffic in my short test drive so I didn't have any opportunity to really give it everything but it'll be too hard pedal effort for him to stop quickly.
I don't know what booster is on this, but I'm wondering if it's a dual diaphragm and if not maybe a dual diaphragm might help. Alternatively hydroboost is an option, involving more cost and work though. Problem with that is this car has an Eaton power steering pump and air conditioning. I'm not sure what bracketry would fit a Saginaw pump and York compressor, or at least a C2 pump and York compressor. Thoughts on a vacuum booster for more assist or brackets to go hydroboost? I'm assuming the Eaton pump is not serviceable for hydroboost, it seems to struggle with just the power steering box but maybe it just needs a rebuild.
With the 15/16" Ford master I could easily lock the brakes, but with this GM master I took a test drive today and while it'll stop quick with a lot of effort I'm not sure I could lock the wheels. There was a lot of traffic in my short test drive so I didn't have any opportunity to really give it everything but it'll be too hard pedal effort for him to stop quickly.
I don't know what booster is on this, but I'm wondering if it's a dual diaphragm and if not maybe a dual diaphragm might help. Alternatively hydroboost is an option, involving more cost and work though. Problem with that is this car has an Eaton power steering pump and air conditioning. I'm not sure what bracketry would fit a Saginaw pump and York compressor, or at least a C2 pump and York compressor. Thoughts on a vacuum booster for more assist or brackets to go hydroboost? I'm assuming the Eaton pump is not serviceable for hydroboost, it seems to struggle with just the power steering box but maybe it just needs a rebuild.
Re: '63 disk brake, need lower pedal and less effort
I realized the master was not sitting flush against the booster. GM master and booster is set up for an early Ford master. I had to grind down the mating surface edge of the master to get it to sit flush, tapered it into the recess of the booster and reset the booster to master pushrod clearance. Pedal effort is improved (reduced) as I suspect the booster gives more assist right off the hop than halfway down where it was engaging before.
I was able to adjust the pedal to booster pushrod in to get the brake pedal about 1.5" above the gas pedal. Comfortable for me but I'll have to see what the old man thinks about pedal heights.
In normal driving the pedal effort is not excessive for me, a relatively young and healthy person. To lock the brakes from 60-70 MPH it takes significant effort but is possible, and less but significant effort for a panic stop short of locking anything up. I'll just have to see how it feels for the old man if we need to pursue a better vacuum booster since we have a little room for a larger diameter booster, or if hydroboost is required.
I think pedal height will work for him with to 1-1/8" bore master. We'll see about the rest. The car is definitely nice to drive and switch gas to brake with the new floor pan installed and gas pedal at a normal position. It's hard to tell about front or rear locking first but I think I may be able to adjust the proportioning valve to get a little more out of the rear brakes. Every bit helps.
He also had the manual passenger seat on the driver side and the broken power 4 way driver seat on the passenger side. I fixed the power seat and moved it back to driver side. It seems more comfortable to drive, as if there's more range on moving the seat back on the power seat track but I might be imagining that.
I was able to adjust the pedal to booster pushrod in to get the brake pedal about 1.5" above the gas pedal. Comfortable for me but I'll have to see what the old man thinks about pedal heights.
In normal driving the pedal effort is not excessive for me, a relatively young and healthy person. To lock the brakes from 60-70 MPH it takes significant effort but is possible, and less but significant effort for a panic stop short of locking anything up. I'll just have to see how it feels for the old man if we need to pursue a better vacuum booster since we have a little room for a larger diameter booster, or if hydroboost is required.
I think pedal height will work for him with to 1-1/8" bore master. We'll see about the rest. The car is definitely nice to drive and switch gas to brake with the new floor pan installed and gas pedal at a normal position. It's hard to tell about front or rear locking first but I think I may be able to adjust the proportioning valve to get a little more out of the rear brakes. Every bit helps.
He also had the manual passenger seat on the driver side and the broken power 4 way driver seat on the passenger side. I fixed the power seat and moved it back to driver side. It seems more comfortable to drive, as if there's more range on moving the seat back on the power seat track but I might be imagining that.