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Discussion Starter · #1 · (Edited)
I am in the process of installing an SSBC A120-20 front disc brake conversion on my auto '65 coupe. From the factory, it was a manual drum car; about 10 years back, I added a booster, and now I'm doing the whole SSBC conversion (with new booster).

However, I noticed that where the original rod/pin (that connects to the master cylinder/booster plunger/rod) is much lower than where it needs to be to connect to the power booster. The first two photos show where the rod comes through the firewall and past an open hole in the upper part of the pedal; the third photo is from the previous power booster (with original drums) and shows that it had a drop eyelet to connect to where the pin/rod is.

I can't seem to find much by way of 64-66 pedal assemblies being sold online so I can't find a good photo to compare to - some say all auto 65-66 brake pedals were the same, others say there were variations depending on factory brake configurations (auto vs power, disc vs drum). It looks like either removing and re-welding the pin to the higher hole is a fix for this (or just welding in a new one, assuming they can be sourced anywhere), but I'd like to understand the "why" of how I got here first. Is it possible my pedal has been altered in the past for some reason? Or does the weld around the pin look factory to you experts?

Any suggestions from anyone who has gone through a manual drum to power disc conversion or dealt with SSBC kits would be appreciated, thank you!
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It looks like the pedal have been modified to "power" pedal ratio, by lowering the pin when it got the former booster conversion. All factory power brake setup have a different pedal ratio than manuel brakes. On the early Mustangs and other Fords it was done by adding a bellcrank outside the cowl behind the booster. Later cars got a different length pedal.to get the same ratio change. The aftermarket conversion kits often have some kind of "shortcut" engineering, that gives the pedal a weird feel or long travel.
 

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Discussion Starter · #6 ·

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Discussion Starter · #7 · (Edited)
It looks like the pedal have been modified to "power" pedal ratio, by lowering the pin when it got the former booster conversion. All factory power brake setup have a different pedal ratio than manuel brakes. On the early Mustangs and other Fords it was done by adding a bellcrank outside the cowl behind the booster. Later cars got a different length pedal.to get the same ratio change. The aftermarket conversion kits often have some kind of "shortcut" engineering, that gives the pedal a weird feel or long travel.
Thank you for this insight - considering this is a factory manual drum car and I'm converting to front power disc, would the appropriate pedal ratio be achieved using a drop eyelet at the end of the rod and using the existing, modified pedal pin location, or am I better off grinding it out and putting a pin back where it belongs in the upper factory location?

I can also confirm that, being that I installed the previous booster, I did not modify the pedal and it already had the pin welded in the lower spot - perhaps someone in the past thought that by lowering the pin even with no booster would increase braking power?
 

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I'd prefer that you not play brake system design engineer. I'm guessing there are a few others on here who probably share this sentiment.
Your questions indicate to me that you should not be attempting mods to a brake system.

ex-Global West GM
1991-1995
 
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Discussion Starter · #9 · (Edited)
I'd prefer that you not play brake system design engineer. I'm guessing there are a few others on here who probably share this sentiment.
Your questions indicate to me that you should not be attempting mods to a brake system.

ex-Global West GM
1991-1995
I do appreciate the condescension but as an engineer and long time tinkerer of cars, I understand how a brake system works and am just looking for some community guidance on how these cars' brake pedals came from the factory considering it appeared altered to me. I am using a complete kit from a reputable manufacturer to modify the system which I don't think is an unreasonable thing to do in the name of increased safety and performance relative to a system bases on 50+ year old design principles.

From a mathematical standpoint, the lower pin would result in a lower pedal ratio indicating lower leverage (and by extension, more pedal effort) required to apply braking pressure. If in fact this is how factory power brake cars came from the factory, this makes total sense - I just need some indication on how factory power brake cars are setup relative to what is in my car as it sits. It still wouldn't explain the snot weld and why someone did this to a full manual drum car in the first place but there are also many unexplained things in this universe.

Thankfully, there other people in this thread who have been able to provide useful feedback :)
 

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I do appreciate the condescension but as an engineer and long time tinkerer of cars, I understand how a brake system works and am just looking for some community guidance on how these cars' brake pedals came from the factory considering it appeared altered to me. I am using a complete kit from a reputable manufacturer to modify the system which I don't think is an unreasonable thing to do in the name of increased safety and performance relative to a system bases on 50+ year old design principles.

From a mathematical standpoint, the lower pin would result in a lower pedal ratio indicating lower leverage (and by extension, less pedal effort) required to apply braking pressure. If in fact this is how factory power brake cars came from the factory, this makes total sense - I just need some indication on how factory power brake cars are setup relative to what is in my car as it sits. It still wouldn't explain the snot weld and why someone did this to a full manual drum car in the first place but there are also many unexplained things in this universe.

Thankfully, there other people in this thread who have been able to provide useful feedback :)
I stand by my comments. My feedback is useful and here's some more- I wouldn't waste my time trying to run power brakes on a vintage Mustang.
That's coming from someone with way, way more experience designing, building and modifying suspension and brake systems than you.
If you were truly an engineer, you would already know what to do and wouldn't be posting.

Have a nice day.

ex-Global West GM
1991-1995
 
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Discussion Starter · #12 ·
There was never a factory power disc 65-66. Any out there are "engineered" solutions.
Good to know - would explain why I can't find one out there. I did find some pictures of a factory power brake 67+ pedal which does appear to have a lower pedal pin position - looks like someone in this car's past saw fit to try and replicate that.
 

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NPD sells this unit

Which in effect relocates the pin to a lower position, however it states that it's for manual drum to manual disc conversions to change the pedal ratio. Is it possible that someone in the past did a manual disc conversion and relocated the pin to its current position to take advantage of the pedal ratio?

If it were me, I'd move the pin to its original position since you're using power brakes.
 

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NPD sells this unit

Which in effect relocates the pin to a lower position, however it states that it's for manual drum to manual disc conversions to change the pedal ratio. Is it possible that someone in the past did a manual disc conversion and relocated the pin to its current position to take advantage of the pedal ratio?

If it were me, I'd move the pin to its original position since you're using power brakes.
 

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Check with "Mustang Steve".......Google mustang Steve and you'll find him easy......why Mustang Steve?.....he sells Brake conversion kits and one of his kits include a "weld in" pin like you have and the PO might have used his parts............FWIW..........

sandybob
 

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Since your conversion "kit" is designed to work with the original pedal then you should use the pin location that was original.
 

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My 65 had 4 wheel power drums, single jar master cylinder, C code 289/C4.

The bell crank assembly, booster and master cylinder took all space from firewall to shock tower. The four port distribution block is tucked in that same corner as well.

As I used to tell my Mechanical Engineer father in law…it’s always a mechanical problem.😁
Electricity will flow as long as the mechanical connection is intact.

Hope this helps.
 

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not taking sides, but there are long, long, threads about the SSBC power disk brake kit. I have yet to see one where the result was great. scary passable maybe, mostly frustration. great? nope. and yes, I have tried it. Ditched the booster and went to manual disk with a different master. Much better. If you are looking for the "feel" of modern disk brakes from this kit, I don't think you will get it. The effort required to stop a light car like a first gen mustang just doesn't require power assist.

Second, you have to be really careful as you read through the responses. Folks want to be helpful, but you have to sort out those talking about experience with a different year car or different kit. their experience might provide an insight, but these are definitely not cookie cutter and each is unique. You really need an apples to apples comparison if you are going to stick with the SBCC.

I wish I could offer more, but believe you will be happier ditching the booster with this kit.

If someone has a clear fix with a great outcome for a SSBC power disk kit, document in great what you did to make it work and be a hero with all the adulation and gratitude. Alternative looks to be to recommending as a group, that this kit just is not the way to go.
 
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