You can regain control by modulating the brake.. Just as you can keep control by countersteering...

It comes down to what are you better at in your car (taking into consideration the brakes and steering ratio).

I've been in situations where I couldn't countersteer fast enough due to the slow ratio, and happen to be pretty good at modulation, so I'll pick fronts lock first. If I had quicker steering, I might revise my opinion....

Go with what you're most comfortable with, and can deal with......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Ok I have the factory manual sitting here on my desk, but without even looking at it...... All cars are engineered so that the fronts will lock first in a panic stop. Note the words FRONT, FIRST and PANIC. The exception would be a newer car with ABS or even newer with electronic bias modulation. This is nothing new, and there are good reasons for it.

If you brake on a curve in the rain, there goes the rear end trying to pass you.

The loss of steering with the fronts locked first is moot. If you are on top the situation and know how to drive then you know to get off the pedal to steer and have the response already trained. This assumes that you have somewhere to steer to. Even if the fronts are not quite locked they will be with the added load of direction change. If the rears are locked and you are trying to steer in a panic stop you are going to spin, more or less traveling in the same direction. While you are spinning your stopping distance will be much greater than it would have been if you had just left things alone and skidded straight. If you are going to crash anyway, going straight in is much better that taking it on the side.

The other reason for the fronts locking first is that the weight on the rears can vary quite a bit more than it does on the front because of people in the backseat or the trunk loaded, so the rears are set up for the light load.

On every car of mine that I have done serious suspension work on I have increased the rear braking, not so that it locks first but just to get more stopping power overall. The way to make this work is with stiffer front springs, Good shocks to keep it in control and better front brakes and good rear shoes that are not prone to grab. At the limit for dry pavement the car will be a hazard in the rain. Usually I have worked this out with rear cylinder diameter. On our dart I have an adjustable proportioning valve, but I will likely change this as I am wary of the long term reliability.

I would stay away from playing with this without a complete understanding of why it is set up the way it is. Factory cars that lock the rears first are factory screw ups. Older and cheap shoe linings can grab when cold too and then not want to stop at all when hot. If you do make any changes start with a complete brake job first and see where things really are before making changes. For a daily driver it should be set up with just the driver, empty trunk and rear seat, half tank of gas and on wet pavement. This will be the safe setting, not the ultimate road race setting.

Road racers make changes to adapt to track conditions. On a a street car the conditions change all day long so the car needs to be set up to handle all of them safely.

That is demonstrably incorrect. Many of the Chrysler-built vehicles we know and love have pronounced tendencies to lock the rears well before the fronts. Notable offendors are A-bodies with disc brakes. This is not new information; "Consumer Reports" complained about it in their otherwise-favorable reviews of Darts and Valiants in the '70s. And that's just one example, and an old one. There are many vehicles that pass all applicable government brake system standards in whatever jurisdiction they're designed for, which in stock configuration lock the rears before the fronts.
Uhh...all of this is moot if you know how to drive. Most people don't know how to drive, and when things start to go awry they panic and stand harder and harder on the brake pedal or do other counterproductive things. If you really know how to drive, well enough not to panic when faced with an emergency situation, and the situation presents you with any time at all to react, you will have the skill and presence of mind to modulate the pedal to unlock the fronts or to countersteer and bring the locked rears back in line, or both. That being the case, there are way too many "ifs" stacked up to claim that fronts-locked is safer than rears-locked, or that rears-locked will cause a dangerous situation faster than fronts-locked. It's almost on the order of claiming it's safer not to wear your seatbelt because that way you can get thrown clear of the car in a crash.

When we eliminate as many variables and "ifs" as possible, we are left with this:

Fronts locked: Almost no stopping, and no steering.
Rears locked: Some stopping, some steering.
Yes, but I disagree with your statements about how cars are generally set up -- especially the cars most of us on here are working with.
Perhaps, but there are many such vehicles out there, whether or not they were "screwups". Disc-brake Darts and Valiants locking the rears first are the rule, not the exception, and the screwup is in the engineering phase, not the manufacturing phase. With any normal cargo/passenger load, they will tend to lock up the rears first. They were that way when brand new, and as long as the brake system is maintained with factory-spec or similar parts, they will remain that way.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan, A screw up is a screw up, whatever the phase of production. The thing about factory engineering is that factory engineers don't make all the decisions. Is it cost or cost that often gets the final word? Does it make any sense from an engineering standpoint that the same proportioning valve ends up in a whole automakers line, from small 6 cylinders all the way up to huge big block cars? Not to me! I am well aware that disc brake A bodys usually lock the rears first, it's not supposed to be that way.

People in a panic stop (again, note the word panic), not controlled stop, jam on the brakes as you note. The next thing they do is try to swerve. It is not a good situation. It is how to make a car spin if you want to.

I actually know how to drive a car fast and have done so with most all of the configurations of cars, front engine rear drive, mid engine rear drive, rear engine rear drive, front wheel drive and even 4 wheel drive. I've not driven an all wheel drive hard. In spite of this I cannot agree that having the rears lock first is ever good, no matter how on top of your game you are. There is that time just before they lock, and it counts too. I have seen it many times on performance cars on the street and track when smoke starts to come off the tires in hard braking but they are not locked up, skidding or out of control. They are just near the limit. If the rear bias is too high you have hell of a time keeping the rear in the rear. It's bad enough when you expect it. You want to be in control of the car, not reacting to try to stay in control. Myself I still make mistakes driving and street cars in general are not nearly as responsive as a car set up for slalom or auto cross. Some days you just don't react as you should either.

I don't see this or seatbelts as being subjective, all the opinions in the world don't change what happens. If you need to get out of a burning car, just unbuckle your seat belt first. You might have to unlock the door too. If you had a horrific crash you are not going to get out even with your belt off if all your bones are broken and your head is smashed.

Just don't drive in a manner that involves locking the brakes. If you can't help it, it is better to have the car still aiming in the direction of travel when you do get off the brakes. Having the fronts lock first give you the best chance of this. It is easier to make the problem worse than it is to make it better.

I agree with the fronts locking first. Dan you being from snow country I'd think you would defently be in agreeance here. I was born and raised in snow country, so don't let the Florida tag fool you. Once the rear starts to come around even if you get off the brakes completly it takes time for the rear to find the center again and if you lucky it would snap to the other side. Keep in mind that using the brakes during the time will only extend the time it takes to correct the problem. The problem being the rear chasing the front. With the front locking the only thing needed to do is release some brake pressure. I can modulate the brake pressure many many times faster than sterring lock to lock or even one 3/4 turn each way which is what you'll be doing if the rear starts coming around.
Ever watch Nascar. When the rear comes around they back it into the wall. I have never seen a driver recover from the rear breaking loose, unless ofcourse he hits another car and it rights him.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

holy crap, I didn't know I was going to start a religious war with this one...

So it looks like my basis is correct: Rears lock up first = un-predictable oversteer, fronts lock up first = understeer and the car keeps going wherever it was headed when the wheels locked.

Based on my experience, having the brakes bias slightly to the front is the most predictable way to drive, and provides the best stopping power, and it looks like a lot of you agree.

I just don't buy that still having steering is a benefit to locking the rears up; you can still steer, but who knows where you're gonna go. Good luck countersteering while you panic. Like another poster said, I can modulate the pedal faster than I can countersteer and the correct, even with power steering.

Perhaps my comparison with the Dart (fronts slightly first) and my satellite (rears significantly first) wasn't quite right, but I have Polara where the rears lock up first, but a lot later than the Satellite. It's still scary, particularly when it's wet.

I toldjya how to fix it in the very first reply in this thread...with a part number and everything!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've got the wheel cylinders in the garage and an adjustable proportioning valve if it needs it ... it's not that I don't know how to fix it. Why do you think my Dart stops right? It certainly didn't when I got it.

I was asking for a discussion of braking dynamics with reasons, and simply gave those cars as examples.

Speed and road conditions change everything a great deal, and no set up will behave the same under all conditions. Mixed brake types are the worst in this regard. If you have disks front, and drums rear, then the proportion of braking will change most dramatically with road conditions. As traction goes down, so does the grip of the drum lining on the drum. This is because the slight rotation of the linings inside the drum as it begins to take hold increases the friction between the drum and the lining. This behavior is more intense the better the traction between the tire and the road.

On wet pavement, the drum' shoes simply don;t apply lock up force as quickly as on dry pavement. The disk brakes do not share this quality. The sqeeze factor of the caliper does not care what the traction of the tire on the road is doing. For this reason, a disk/drum set up that is biased perfectly for dry pavement will go into dangerous front wheel lock up in the wet. If you have this set up, I recommend biasing the rears for slightly early lock up on dry pavement. If you have disk/disk, or drum/drum, shoot for even, four wheel lock up. Of course the load in the trunk plays a part in this, and your speed, as the car will pitch forward under high speed panic stopping conditions. There is no perfect situation here, but biasing the rears a slight amount protects you from unexpected consequences more than the other way around.

In this way, you will not be AS surprised in the wet weather or when that deer darts across the road when you are hitting 80 MPH on the expressway.. It was such a deer that prompted me to put disk brakes on the rear of my car.

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Is there a book that anybody can recommend on the subject of brake caliper sizing, bias, master cylinder sizes, etc? I would like really understand this subject.

Thanks,
Greg

My five cents (inflation and based on experience):

I had an 80 mustang turbo and got the SVO rear axel with BIG rear disks, way bigger than the fronts. it was heavily rear biased. that combinded with the big two stroky power band made for some really really fun (and predictable) driving in the wet. but lots of practice was required. And a couple of sets of tires.

I would say if you are a paniker (and by that i mean STAND ON THE BRAKE AND HOLD HTE WHEEL STRAIGHT) then there is no point in having stearing, except to say, by the laws of physics, you are beter off NOT locked up as you will go faster locked than you will at 99% NOT locked. Coeficients for static friction (rotating wheels have a static contact patch) are always higher than those for kinetic friction (wheels not rotating have a kinitic contact patch if the car is moving). For you people, drive slower or buy a car with ABS or some other braking management system. I also like to look at the car in front of the car infront of the car in front so I am not surprised and panicked.

If you want to read a more intense debate about this subject (and yes, that is possible) log onto any motorcycle forum. With motorcycles you have individual control over front and rear. Locking the front means falling off (washout) or if your weight is badly placed, going over. Locking the rear means whiping out. EIther way, its bad and we spend a lot of time arguing how to slow down. If you are hard enough on the fronts hte rear will not be touching the ground anyway, at this point touching the rear brake will mean not having countrol when your wheel touches the ground again. On a bike I tend to ignore hte rear. But the point is, you should NOT be locking up no matter what, you should NOT be panicking. Go out and practice. Make it stop as hard as you can witout locking it up. Find 99% and find it in lots of conditions.

if you are a practicer, find an abandoned airstrip and get a proportioning valve.

In a car I prefer slightly rear bias, which i find by throwing my car down a hill and lcoking them up. Fist I find front bias and then rear bias referenced from there. I do it on a flat straight away, then up a hill. On a bike I tend to ignore the rear brake. wierd HUH?

I am bracing myself for the flames I just fanned. I hope it helped (someone)

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63 valient 4 speed over drive, holly 390, dutra duals, power steering, ac, hydraulic roof, KH 4 piston disks, kyb gas adjust all round, sway bars front and rear, 8 3/4 rear axcel and the ugliest green you ever saw

Based my experience, i still prefer a very slight front lockup. It seems that no matter how careful I am, I still can't predict w/ 100% accuracy what the people in front of me are going to do, particularly when it's wet. I'm also running 20:1 manual steering in my driver Dart, which makes it a little bit slower to counter steer. Those put together make things to where I'd rather have the car keep going straight in the rare situation where a panic stop is required. I also used to drive a '77 911S Porche which was an oversteer monster, so that probably has made me a little over-cautious. I went end-over-end and oscillating back and forth a few too many times for my taste in that car. The sway bars were adjusted, and the tires changed to try and reduce the oversteer, but turning around and waving "Hello" to the traffic behind you can be a pretty sobering experience.

I don't have a bike yet, so i can't comment on that at all, but I will be getting my motorcycle license at the end of the month. We'll see if that changes my opinion on this.

After checking out this thread, I went and checked my 1973 Swinger, stock front single piston disc setup, 1976 8 1/4 rear end with 10" drum. One leaking rear wheel cylinder was replaced last year. The backs locked before the fronts. Is there a "best" way to fix this on this car?

The back was coming around before the fronts locked, I let off, so I didn't get the fronts locked at all in the test. It has a shimmy on hard braking, so I plan on getting the rotors turned and replacing the pads, even though there is a fair amount left. There are new shoes on the back (about 3,000 miles)

Yes, and you've quoted it. A pair of WC37696s.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I didn't know if the Satellite and Dart had interchangeble Wheel cylinders, thanks.