1971 Mustang Mach 1 W/Power Disc brakes rear wheel cylinders

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1971 Mustang Mach 1 M code 351 4 speed
On the saga of the wrong parts. I keep buying parts and I keep getting the incorrect parts. Just happened with some U-joints, just updated a thread on that, and now also with rear wheel cylinders. Basic info so you can at least start navigating the rear wheel cylinder saga:
1- 6 cylinder and 302 cars got 7/8" wheel cylinders, 351 and 429 cars got 29/32" wheel cylinders. You cannot get this wrong as your cars rear brakes will not work correctly with the incorrect size wheel cylinders. Basically the 10x1 3/4" brakes (6 cyl and 302) use the 7/8" wheel cylinders, and the 10x2" brakes (351 and 429) use the 29/32" size. This is pretty simple. Here comes the mess in #2.
2- Napa, Cj Pony, and a host of other sellers list a 29/32" wheel cylinder, but they claim that there is a left side and a right side cylinder. So, I ordered one right side and one left side cylinder. Well.... My car uses 2 left (drivers) side cylinders...
So, for a 1971 car with 351 or larger engine, 10x2" rear drums, you need two left (drivers side) 29/32" wheel cylinders.
 
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1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
On the saga of the wrong parts. I keep buying parts and I keep getting the incorrect parts. Just happened with some U-joints, just updated a thread on that, and now also with rear wheel cylinders. Basic info so you can at least start navigating the rear wheel cylinder saga:
1- 6 cylinder and 302 cars got 7/8" wheel cylinders, 351 and 429 cars got 29/32" wheel cylinders. You cannot get this wrong as your cars rear brakes will not work correctly with the incorrect size wheel cylinders. Basically the 10x1 3/4" brakes (6 cyl and 302) use the 7/8" wheel cylinders, and the 10x2" brakes (351 and 429) use the 29/32" size. This is pretty simple. Here comes the mess in #2.
2- Napa, Cj Pony, and a host of other sellers list a 29/32" wheel cylinder, but they claim that there is a left side and a right side cylinder. So, I ordered one right side and one left side cylinder. Well.... My car uses 2 left (drivers) side cylinders...
So, for a 1971 car with 351 or larger engine, 10x2" rear drums, you need two left (drivers side) 29/32" wheel cylinders.
I have to disagree with 2 left sides, at least for my 72 351 ragtop. When I bought her she did have two driver side cylinders and the passenger side brake line was jacked up and pinched off a bit because the connector was pointed the wrong way (towards the front of the car) because it was mounted backwards. The left rear would lock up because it received full pressure. Attached is what it looked like after I redid the brakes. Also, these were delivered to the shop from the Autozone chick.
 

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1971 Mustang Mach 1 M code 351 4 speed
I can only vouch for a 1971 car, there may have been a running change in 1972. The interesting thing is that I bought a rear stainless steel brake line kit from CJ Pony, which they claim fits 1971-1973, and it fit like glove with the old wheel cylinders which are the original Ford ones with the 1/4" bleeders, and they are both drivers side. My passenger inlet is definitely looking towards the front of the car. NPD does list the wheel cylinders correctly in their catalog, they say that 1971-1972 Mustangs with 351 and 429 use the LH wheel cylinder on both LH and RH, but not 1973 meaning that there must have been a change late in 1972.

Here is the brake line kit that I got:
 
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1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
From engine blocks, to heads, to brake components, and on and on, shows some of our "girlz" can be some really strange "ladiez".
Please, no offense meant to the women on here! 🤷🏻‍♂️
 

Hemikiller

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All the 71-73 351 or better cars used two LH wheel cylinders. The part number and bore size changed in '73, but the fluid line configuration is the same.

Things get dicey 50+ years in when parts have been mix-matched and retrofitted, upgraded or just "made do". I've fitted 1 3/4" rear brake assemblies from an 8" onto a 9" when doing a rear end swap, just for expediency.



71_73_wheel_cylinders.jpg
 
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My all time favorite vehicle is our 1969 Shelby GT500
On the saga of the wrong parts. I keep buying parts and I keep getting the incorrect parts. Just happened with some U-joints, just updated a thread on that, and now also with rear wheel cylinders. Basic info so you can at least start navigating the rear wheel cylinder saga:
1- 6 cylinder and 302 cars got 7/8" wheel cylinders, 351 and 429 cars got 29/32" wheel cylinders. You cannot get this wrong as your cars rear brakes will not work correctly with the incorrect size wheel cylinders. Basically the 10x1 3/4" brakes (6 cyl and 302) use the 7/8" wheel cylinders, and the 10x2" brakes (351 and 429) use the 29/32" size. This is pretty simple. Here comes the mess in #2.
2- Napa, Cj Pony, and a host of other sellers list a 29/32" wheel cylinder, but they claim that there is a left side and a right side cylinder. So, I ordered one right side and one left side cylinder. Well.... My car uses 2 left (drivers) side cylinders...
So, for a 1971 car with 351 or larger engine, 10x2" rear drums, you need two left (drivers side) 29/32" wheel cylinders.
How frustrating n ordeal to have to go through. I hope you document that, and place the info in the glove box or center console (if you have one) for future owners. I need to document the upgrades on out 73 Mustangs (Mach 1 and Convertible) so our heirs will be able to figure what I did and why. Nothing radical, but without a little documentation it may be a bit baffling.
 

giantpune

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How frustrating n ordeal to have to go through. I hope you document that, and place the info in the glove box or center console (if you have one) for future owners. I need to document the upgrades on out 73 Mustangs (Mach 1 and Convertible) so our heirs will be able to figure what I did and why. Nothing radical, but without a little documentation it may be a bit baffling.
Best place for it would be writing it on the wheel cylinder itself with a paint pen. That way the next guy sees it before they even start to uninstall the old part.
 
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