They say, 70% of braking is Front Brakes, but?

[Brosho]

I have a Question.

Since it is said that 70% of braking comes from the front brakes. Suppose if your rear brake calipers and rotors are twice as big as the front setup. Will the rear brakes contribute now 50% or more of the total braking of the car or truck? Or would the rear brakes just simply lock up and slide the rear of the car, while the front brakes still do most of the braking?

Im sure a Anti-Locking brake system is braking percentages would be different, but do people use anti-braking systems in offroad racing?

[SimonSays]

do people use anti-braking systems in offroad racing?

no they cause more troubles then they help.. instead of locking them up and scrubbing off speed.. your peddle just goes to the floor and vibrates and u hit it at full speed...

[loufish]

Or would the rear brakes just simply lock up and slide the rear of the car, while the front brakes still do most of the braking?

You kind of answered you own question...Yes.

[Ramsey_ElWardani]

Since it is said that 70% of braking comes from the front brakes. Suppose if your rear brake calipers and rotors are twice as big as the front setup. Will the rear brakes contribute now 50% or more of the total braking of the car or truck? Or would the rear brakes just simply lock up and slide the rear of the car, while the front brakes still do most of the braking?

The reason most braking force is realized up front is because of weight transfer under braking to the front of the veicle. Of course it take traction for this to happen, so where the weight is in the vehicle (front engine or rear engine) has a big effect on brake force distribution. Traction also plays a significant role; narrow tires up front and wide tires in the rear will shift braking distribution towards the rear - think of a Porsche. So, everything is somewhat different off road as traction is quite different and buggies are rear weight biased and have bigger tires in the rear. Most off road racers perfer more rear brake as it can be used to set the car up better entering a turn and the car is less likely to "push" through the turn.

[zjohnson]

Plus if you lock up the front tires, you can't steer the car . . . The rear bias induces an oversteer, allowing the car to become more responsive.

[Zambo]

While many people like the way a car handles if the rear locks up first, one drawback to this is the increased shock loading that you send thru the drivetrain, especially with a manual trans that doesn't have a torque converter. Just depends on your vehicle and preference.

You can buy a brake bias valve that goes inline to your front or rear brakes. It has a knob which lets you decrease brake pressure down to 50% of normal. You can find one at summit for pretty cheap.

[SimonSays]

While many people like the way a car handles if the rear locks up first, one drawback to this is the increased shock loading that you send thru the drivetrain, especially with a manual trans that doesn't have a torque converter. Just depends on your vehicle and preference.

You can buy a brake bias valve that goes inline to your front or rear brakes. It has a knob which lets you decrease brake pressure down to 50% of normal. You can find one at summit for pretty cheap.

we couldnt ever get that thing to work right so we took it off and threw it in some box somewhere in the shop....

[Zambo]

Really? Seems pretty simple to me, I just put it in the brake line and we turn the knob to adjust the brake bias. I'm trying to imagine what problems there could be, seems like a pretty straightforward device.

[SimonSays]

Really? Seems pretty simple to me, I just put it in the brake line and we turn the knob to adjust the brake bias. I'm trying to imagine what problems there could be, seems like a pretty straightforward device.

no it was installed corectly... wasnt a problem of it not doing what its supposed to do...it adjusted the rod just fine... its just that we would play with the knob and it didnt make a difference... with it all the way adjusted one direction or the other still stopped exactly the same...

[Zambo]

Wow, we had a much different experience. Our truck used to get all sideways if we hit the brakes a little too hard, after I put the valve in the rear it made a huge difference immediately. Stops straight ahead and we don't reverse load the manual tranny now.

[SimonSays]

Wow, we had a much different experience. Our truck used to get all sideways if we hit the brakes a little too hard, after I put the valve in the rear it made a huge difference immediately. Stops straight ahead and we don't reverse load the manual tranny now.

well our brakes feel fine the way they are so its no big deal that it didnt work for us...just kinda wierd that it didnt work like everyone says it should...

[WoodyW]

Simon I think Zambo is talking about an inline bias adjuster while you are thinking of a balance bar adjuster that works on the pedal assy. The inline adjuster is much more effective at creating bias than the marginal amount of change you get with the adjustment available in the balance bar.

[gadjeep]

Doesn't reverse loading of a drive train only happen when the power delivery end (engine) loads the driveline (compression braking)? when you are on the brakes, you wouldn't be reverse loading the trans, drivetrain, etc like you would if you downshifted at high rpms. One of the other positive side effects of motorcycle slipper clutches is decreased wear on the coasting side of the teeth on the gears in the tranny.

[la2baja]

We run an inline bias adjuster and I think it is a must kave. If you have more than one driver in the car and they have different driving/ braking styles into the corners it is a life saver. It is in reach of the driver on the dash. If you are suffering from brake ware, you can also cheat the bias to get some of the load off the failing brakes.

[bajaxp]

I have an inline rear brake bias adjuster on my 96 Ranger and it works great! I have a 9" with huge disk brakes off of a lincoln and they are too effective without the adjuster.

[Brosho]

Thanks for all the great info. I originally asked the question, because I wandering, if its even worth it to install bigger rear rotors and calipers in the rear, since regardless, the front will still do most of the braking anyway. Larger rear brakes, seem they might only add more weight, than the extra stopping power, we are in search of.

[Zambo]

Gadjeep, I think I said what I meant the wrong way. You're right, whether you're accelerating or hitting the brakes, the stress on the teeth in the gears is on the same side. When you downshift it puts the stress on the other side.

What happens with a manual tranny is of course if the wheels lock up and you aren't on the clutch, you kill the motor. Not a good thing obviously and it leads to guys tending to use engine braking rather than the brakes to slow the truck. That causes the reverse loading in the drivetrain. With the brake bias valve in the rear we can use some brakes without locking up the rear, which means way less use of the clutch, which leads to less chance of burning it up, and also it leads to less engine braking, which also makes the tranny last longer.

[redmist]

no it was installed corectly... wasnt a problem of it not doing what its supposed to do...it adjusted the rod just fine... its just that we would play with the knob and it didnt make a difference... with it all the way adjusted one direction or the other still stopped exactly the same...

You havent got 4 WD with a locked center diff do you? If so (in regards to feel) it won't matter which way you bias the brakes. The drive train will transfer the additional braking load fore or aft. You'll obviously want to balance the brakes to ensure as little load is transfered to the drivetrain as possible.

[SimonSays]

You havent got 4 WD with a locked center diff do you? If so (in regards to feel) it won't matter which way you bias the brakes. The drive train will transfer the additional braking load fore or aft. You'll obviously want to balance the brakes to ensure as little load is transfered to the drivetrain as possible.

no that was on our race truck its a 2x

on our 4x4 it has the stock ranger master cylender and power brake booster... no abs.. f150 4x4 front brakes and 79 lincoln mark Iv rear brake calipers.... it has a 50/50 weight distribution and the brakes work really well...