Transamman25

iTrader: (1)

Im looking to replace my rear-end with a Moser 9" , i dont wanna stay with my stock LT1 rear brakes - i want to upgrade to something that will slow this thing down from 140 mph passes

I have been told i need to use 93-97 wilwood replacements (about 700) jegs
http://www.jegs.com/i/Wilwood/950/140-7148/10002/-1
But are the LS1 brakes any better in wilwood ?
LS1 cars have bigger rear brakes right, so shouldn't they stop better ?

Cap'n Pete

iTrader: (2)

From my experience road racing (and having to slow down from ~135 mph into a corner ) I would recommend staying with your LT1 rear brakes, or going to LS1 brakes at most, with street pads only.

If you want GOOD stopping power, put racing pads on the front, ie: Hawk HT10's or HT14's, or Hawk Blues (Blues are pretty hard on rotors ... the HT10's would probably do you fine).

The reason NOT to put really good brakes on the back is they will cause wheel-hop in the rear, and I actually put my car off the track due to this. It's a common problem, even in cars setup for road racing. If you're setup for drag racing, your car will likely be even more prone to wheel-hop under heavy braking.

The fronts do all the work. The back just keeps the car in a straight line while you're braking .

twitchtwice

iTrader: (12)

going to have to agree, that explains why the front brakes are so much bigger then the rear in the most simple sense, lol.

SimRacer1

You actually want the maxiumin stopping power that you can get, so you want all 4 tires to be on the limit of traction, right before they lock up/loose grip/traction. The rears do a lot of braking, not as much as the fronts but they still do alot. In a public road street car, the fronts are probably setup for 70 percent of braking as you mentioned for saftey, so the front tyres loose grip wayyy before the rears (understeer/push is much safer than oversteer/loose). With 70% in the front though, your going to maximize your front tires grip wayyy before your rears, so your leaving room on the table. In roadcourse racing where perfomance matters most, most cars are setup about 58% (+/- 5%) front braking and about 42% (+/- 5%) rear braking, because when you brake so much weight gets transferred to the front (hence nose dive, rear end lifts up) you will always need slightly more braking power on the front than the rear, but the rear still accounts to about 42% (+/- 5%) of the cars total stopping power, thats quite a bit if you ask me.

Most race cars have an adjustment that can be done that will change the brake bias (f/r brake percentage). Some even have the ability to adjust the brake bias onboard while driving say if the front tyres start wearing and locking up too much they can add half a % or 2% or whatever more rear brake bias or vice versa, or to help cure unwanted handling traits on corner approach/entry like understeer or oversteer, they can simply adjust the brake bias onboard the cockpit through a ****/dial/botton or whatever to help them compensate for how a cars handling traits change throughout the race.

If you were having issues where your rear brakes where loosing control/grip before the fronts then you had too much of your overall braking force on the rears, either that or you have some kind of suspension/chassis set up issue (drag race setup maybe, where suspension is setup so all that matters is straightline acceleration performance).

The rears help massively, just not as much as the fronts, but they still have a huge impact.

Cap'n Pete

iTrader: (2)

Do you have any experience with rear-wheel lock-up / brake-hop?? Myself, and just about every other F-body guy I race with have, and so have many others that I've read about on FRRAX. Some guys have opted to install a proportioning valve on the rears to dial them down. Others have gone with crappy pads on the back, really good pads on the front, and some guys have still had problems and been able to tune them out after extensive suspension tuning. But there's never really a "quick fix", and the whole point I'm trying to illustrate here is, the rear brakes are more than adequate in stock form (if ~42% is what they're required for, apparently they're more than doing their job ).

Now, I suppose for a drag car with skinny fronts and big fat sticky rears, the front tires may not be as good for the job as they could, and the rear tires may have more ultimate grip than I'm used to with a road race car, so perhaps you can setup to use more of the rears than a RR car?? In that case, LS1 brakes do provide better stopping power than LT1's, and if you thought it wouldn't cause problems, then you could probably try a slightly upgraded pad for the rear, ie: Hawk HP+, and have balanced braking in the car. I would still caution that you'd want to be easy on the brakes at initial application, and definitely don't jump on them. I still think the rear would be on the verge of lock-up.

Just so we're clear, I'm not denying that rear brakes perform an important function, but the fact remains, they already perform completely up to snuff in virtually stock condition. Even with RACE PADS on the front and STREETS on the rear, the rears can still lock up .

Major_Lee_Slow

iTrader: (1)

I'm one of those folks who had to put crappy pads on the back to dial out some rear brake. I get very bad wheel hop if I run Hawk HP+ in the rear

SimRacer1

the rear sotckers arent up to the task if your roadcourse racing, they will fade and wont provide u with the stopping power you need, just about no street car has adequate stock brakes for road course racing, and a simple switch of pads wont do it.

koolaid_kid

iTrader: (21)

SimRacer1, I can't discuss roadracing brakes with you, for I have no experience roadracing automobiles. However, in the orginal post, I saw no mention of roadracing.
Therefore, I will contain my opinion to street driving and to drag strip racing, which is more likely the intent of the original post.
Using basic physics, when under braking (assuming near-stock suspension) the bulk of the weight of the vehicle shifts forward. This is the reason that the front brakes are larger; they do the majority of the work. This is assuming straight line braking; side forces coming into play when in or entering into a turn must be discounted for this simple example.
Using your example of a 70/30 bias to the front, it seems obvious that this street vehicle should have the same bias in its brake system, front brakes that are 2 1/3 stronger than the rear. So I would agree with other posters; leave the rears alone and concentrate on the front.
My racing experience is limited to motorcycles, both on road and off. And we use the front brakes to impede motion, the rear brake for control.