rear disc conversion

[DionR]

Here is another brake pad/piston analogy. Tire patch ( contact area) width. What has more braking friction/traction a 5" wide tire or a 10" wide tire. Given same horsepower, same vehicle weight ?

Yep, been many a heated argument over that topic. I am one that feels that a wider tire gives better traction but their theory is that they should be the same. Makes no sense, I think there are missing variables in the theory like the fact that it is a soft(er) material on a rough surface. But the theory does seem to apply when it is two hard surfaces and making the brake pad bigger does not equal more friction.

All the brake torque calculators I have seen ignore the size of the pad beyond the width to calculate the averaged torque arm length.

What happens when a caliper bracket binds/sticks ? Uneven braking.

Completely agree. And a floating caliper has a good change of that. I even pointed that out myself.

But that's a different scenario than I am talking about. In a properly working setup, the inside and outside pads will probably be very close in how much force they apply. Not equal because the sliding caliper has some friction to overcome, but not enough to make it worth trying to figure into a calculation.

 

[MoparLeo]

I think theory and reality don't always line up. There is no doubt that Brembo brakes stop better and have less heat fade than factory Mopar brakes. Large rotor/ longer brake pads, multiple pistons. I would say there is probably a difference in brake fluid temperatures as well.

 

[DionR]

I think theory and reality don't always line up. There is no doubt that Brembo brakes stop better and have less heat fade than factory Mopar brakes. Large rotor/ longer brake pads, multiple pistons. I would say there is probably a difference in brake fluid temperatures as well.

Absolutely. Completely agree.

 

[DionR]

I think theory and reality don't always line up.

I got into a long winded discussion on a Challenger forum about this exact thing end of last year. Guy posted a YT video on why bigger tires will stop faster but bigger brakes wont. I agreed with some of the video but the reality was that a 2015 Scat Pack stopped shorter than an a 2015 R/T despite being on the exact same tire. There is something missing from the theory and application doesn't match at some point.

To be clear, I'm not saying a single piston floating caliper is better than a 4 piston fixed caliper. I much prefer the fixed caliper setup. I'm just saying there is more to it than just the number of pistons or if it is fixed or floating.

 

[Abodysrule]

OK, just to be clear, I'm not having any lockup issues since I upgraded to front disc/rear larger drums. And, again, from reading the feedback above, it is clear to me that I don't need rear discs. On the separate issue, I think a vacuum reservoir can would be helpful during frequent braking. I don't see any issues on occasional braking, but when in traffic on frequent braking, the idle is affected somewhat when I brake. Seems like a buffer tank would alleviate this issue. I'll wait until I do the engine swap, it may be different with the new engine. In that light, question, generally speaking, does a street cam or a performance cam create more vacuum at idle? This new engine will be more on the performance side.

 

[DionR]

In that light, question, generally speaking, does a street cam or a performance cam create more vacuum at idle?

Less. But how much will depend on how big the cam is.

 

[MoparLeo]

Remember that Changes in camshaft lift/duration/overlap move the powerband rpm.
Street cams were designed for street rpm driving giving maximum vacuum= max fuel efficiency.
The higher up in the rpm band your camshaft is designed for, the less efficient it will be at lower rpms.= poor /erratic vacuum. That it the rumpity rump you hear at low rpms that goes away as the rpms increase.
The reason that high rpm cammed engines need to be constantly revved up at idle is to clear the unburnt fuel from the plugs and combustion chamber, not just for the cool sounds.
Everything is a compromise.
The closer you try to build your car leaning towards performance, the less the car acts as designed for max drivability and economy. Domino effect. Change one thing, have to change 2 more to compensate for side effects. Like taking medications.
Street cars (old carbureted) make poor race cars and vice versa.

 

[Abodysrule]

OK, I thought so, so I'll likely need the vacuum canister to help the (smallish volume) brake booster. Great stuff.

 

[Dana67Dart]

OK, I thought so, so I'll likely need the vacuum canister to help the (smallish volume) brake booster. Great stuff

I still think you need to check the one-way valve on the booster.

All the power brake cars I have had have 1 to 2 boosts after the engine is turned off.

 

[MopaR&D]

OK, just to be clear, I'm not having any lockup issues since I upgraded to front disc/rear larger drums. And, again, from reading the feedback above, it is clear to me that I don't need rear discs. On the separate issue, I think a vacuum reservoir can would be helpful during frequent braking. I don't see any issues on occasional braking, but when in traffic on frequent braking, the idle is affected somewhat when I brake. Seems like a buffer tank would alleviate this issue. I'll wait until I do the engine swap, it may be different with the new engine. In that light, question, generally speaking, does a street cam or a performance cam create more vacuum at idle? This new engine will be more on the performance side.

Just convert to manual brakes and then you can run whatever cam you want. Power brakes on A-bodies aren't necessary and manual brakes are simpler, have much better pedal feel and are easier to modulate.