Brakes Rear Brake Conversion, how to tell small from large? 1970 Mach 1 4 Spd 3.75 rear

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wicked93gs

15 Year Member
Sep 30, 2006
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Nashville TN
rear-id-jpg.jpg


Its pretty easy. Is the flange flat at the top? If yes, you have a small ford, if the flange has a "peak" at the top you have a big ford, if it also has a "peak" at the bottom, then that big ford is late rather than early...and of course double checking by measuring bolt pattern gives you peace of mind.
 
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wicked93gs

15 Year Member
Sep 30, 2006
1,189
222
93
Nashville TN
I will also pass on a piece of advice: Rear discs on a Mustang will not decrease your stopping distance....nor will they decrease stopping distance on any other car. To take that a step further... no brake "upgrade" out there for either front oar brakes will decrease your stopping distance(with the possible except of an ABS conversion). If your car can already lock up the brakes(which is pretty much every car made in the last 50 years) adding more braking power does nothing. Your brakes already lock up just fine from the factory. The only way this changes is if your TIRE contact patch increases to the point that the braking power you have is no longer sufficient to lock up your brakes.

That being said, there are still reasons to swap to a different braking setup. Disc brakes stop better in the rain(not that you find many people driving classics in the rain these days)...and pads are easier/faster to change than shoes. Disc brakes are aesthetically more pleasing to some people and larger discs fill larger aftermarket wheels better...so there is the "looks cool" factor.

The only performance related reason to go to bigger brakes(and discs in particular because finding larger drums is well nigh impossible) is that they absorb and dissipate heat faster...which means that in racing applications(or towing applications, or applications in which you ride your brakes down a mountain road) and ONLY then can brake fade be reduced...and for brakes in heavy use, reduced fading does indeed translate into reduced stopping distance....just bear in mind that type of use is impossible to see on the street. So there are 5 questions to ask yourself before buying a brake "upgrade" kit:

1. Am I unable to lock up my brakes with my current wheel/tire(or future wheel/tire) combo?
2. Am I using the brakes to race/tow/ride my brakes down mountain roads?
3. Am I driving in the rain?
4. Am I willing to pay a lot of money for the "cool" factor?
5. Am I missing a braking system entirely?

If you can't answer yes to at least one of these questions...I would suggest you do not waste your money on a new brake kit and instead buy a brake rebuild kit to repair what you have. You need to realize that when people report better braking after putting on this brake kit or that brake kit the brakes they are replacing are used...as are the lines and other misc components of the braking system...usually being decades old. Of COURSE new parts stop better than used parts. You never see a comparison in new OEM vs. new aftermarket upgrade brake kits with everything else being the same(including wheels/tires). If you did, you would see no real difference.