is it true

[blondiechick]

i heard somewhere that cops get the most accurate reading of your speed when u press ur breaks passing them? Is that true? Because people have told me to just simply release the pedal when u see them and it's more difficult to get a reading..

[93rollaracer]

probably not true. they come after you when you punch the brake because they see the car of your nose dive and they know you were speeding (or at least think they know) because you slowed down so quick

[blondiechick]

well yea, but i don't no if it changes ther accuracy on there radars or not

[lwpat]

By the time you see the officer he probably already has a readout on your vehicle. The only situation would be where you are in heavy traffic.
Don't slam on your brakes but slow down as quickly and safely as possible to the speed limit.

Continuing to speed will only assure you of a ticket rather than a warning. In addition he may decide to chose another vehicle rather than yours.

[TRD2000]

if you're nose dives that much fix your suspension!

[RandomTask]

Originally Posted by TRD2000

if you're nose dives that much fix your suspension!

Completely ignorant--

To say nose dive is a result of bad/poor suspension is borderline stupid. All vehicles will nose dive, and its not a bad thing. A car nose dives because weight from the momentum is being transferred to the front of the car. This has purpose. Here's why: Its the suspension tranferring the lateral forces into a vertical force to give you more traction on your front tires (because there is NO way you can transfer those lateral forces to the rear tires). Usually you run about a 60%front to 30% rear breaking power. Ever wonder why front rotors are always bigger than the rear? Every race car i've set up runs as such. Watch any race on T.V.-- Nascar, SCCA, Ralley (on pavement), and you will see nose dive.

Secondly- A cop gets a reading no matter what. However, hes more prone to pull you over if he sees you break for the fact that you've shown the officer that you know you were speeding and are trying to get out of it. Either, A: Don't speed so heavily as to apply the brake, rather than just lift the accelerator. B: If you know you're hauling ass, don't just mash the brake, lightly apply it. If the officer wants to pull you over he will, but hes more likely to pull you if you just slammed hard. (Because this also opposes a risk to drivers behind you) The only reason you would be slamming your brakes also is because you know you're going faster than surrounding traffic, or way too fast on the posted speed limit.

[TRD2000]

borderline stupid.... i realise that the weight has to transfer when you change the way you accellerate (in any direction) note i said if it dives "that much". weight transfer does not have to be reflected by significant body roll... its not desirable when cornering and nor should it be when braking. harder suspension will transfer the weight (that has to happen as you said) but will not dip and dive. think about it before you call people stupid.

one more think about slamming the brakes on... if its safe to do so... it's possible to scrub off speed before he clocks you, so if hes gonna get you anyway he might not get you for as much. i think it would also depend on how much you're speeding by, you can't go past at twice the limit and get off by saying "sorry officer i didn't realise, didn't you notice i didn't brake?"

oh and as far as brake bias goes... my car actually has larger rotors on the back... and it's recommended that if you upgrade you upgrade the back first to make the bias even further to the back... as enlightened as you are, i figure you'll know as well as i do why....

[classicstangracer]

ok lets stop all the name calling now and state the facts. first off hitting your brakes as you get hit by radar does nothing because the laser bounces off and back so fast your breaks can't help you. Now on to the whole discussion of brakes and setup here is a basic rundown for ya. You run larger brakes and bias to the front of the car because as basic vehicle dynamics tells us and as randomtask said as a vehicle deccellerates the nose dives it all has to do with the moment develop by the brakes. Think of it as dragging a pin on a desk, under acceleration the bottom is pushing forward which is why the nose of our cars lift when accelerating. Under decceleration the opposite occurs, the bottom of the pin is slower than the top causing the top to roll over. This is why the nose dives, the body is rolling over the suspension. Now on to the concerns of vehicle setup, rollbars are not in effect in braking at a straight line. Sway bars are only used to control side to side roll, springs and shocks are used to control the pitching of the car. To setup a car properly the main idea is to use the minimal spring needed to control pitching as to gain optimal camber gains and weight transfer, you them use swaybars to control body roll in corners. Most people screw up and think super stiff springs are the way to go, the result in a car is a skating effect causing the car to slid in turns instead of sticking around the corners.

[RandomTask]

http://www.stoptech.com/whitepapers/...erformance.htm

Read that

I don't know who you've talked to about brake setup- Please refer me to somewhere that says you should upgrade your rear brakes first. Again, with the front brakes doing more of the braking, why would you upgrade the back first? I've helped set up dozens of cars for racing-- circle track, craftsman truck series, Auto-X, ralley.

http://www.corvettemuseum.com/specs/2005/specs.shtml
And don't forget that the actual surface area for the pads are different too. I have NEVER heard of a car coming with bigger brakes in the rear than the front. Please, what type of car do you drive? Unless of course you're talking about disc brakes up front and drum brakes in the rear, in which case, drum brakes are not as nearly as efficient as disc.

I'm saying nose dive is inherant. When you set a car up stiff, it doesn't allow for as much transfer of the loads from lateral to vertical. That doesn't give you as much traction and as such-- reduced braking ability.
So, you would sacrifice stopping ability just so you could have reduced nose dive? You have nose dive from the suspension compressing. Jounce and rebound, read on it. This theory that the stiffer the suspension the better the handling is false. All high performance/race cars have plenty of suspension travel.

I never said just blow by the cop at mach10, I said DON'T SPEED. Usually, by the time you see a cop, hes already clocked you. This whole thread would be avoided if you DON'T SPEED... Yes, I have speed passed cops, at quite considerable speeds before too. I can remember one on I-95, I was going 102 in a 65, I gently applied the brake and said a prayer. I was pulled over. His words were "At least you knew I had you clocked and you didn't think you could brake hard to get out of it" He told me to slow it down but he let me go with a warning.

"Dives, THAT MUCH" anyone that looks at a car can see it dive. Its not too difficult to tell. Body roll has little to do with braking for the fact you SHOULD NOT BE BRAKING WHILE IN THE MIDDLE OF A TURN. Go find something on how to drive for that.

So again, I'm calling you stupid...

[TRD2000]

... i am not disputing the forces involved purely the amount of "nose dive" i realise what the roll bars are for.. but think of it this way, what will counter the moment in a shorter distance, and resultingly minimalise body movement, if you replace the springs with solid steel blocks or if you replace them with marshmellows?! the marshmellows will dive more.

i drive a 1990 toyota Mr2 turbo, and i'm pretty sure that the rear rotors are about 2mm larger in diam than the fronts. I thought it would be an easy principle to understand, if you move the weight within the car you can change the degree of brake bias, the Mr2 has the engine further back and as a result gets more braking done on the back than a car with the engine in the front.

i also realise that your suspension can be too hard... i'm not saying weld it solid here... just that i don't think the nose dive should be what gives you away to a cop, as i said originally, if it dives THAT much theres something wrong...

[classicstangracer]

Remember that when all that weight goes to the front that the tires then have my tractive force thus you can add more stopping force at the brake. The opposite is true for the rear since there is less force acting down on the tire, less braking force can be applied. The general idea of braking is ofcourse to have all the wheels lock at the same time. With the extra force in the front more stopping force is required. Also the force still occurs even when there is no suspension the braking force creates a moment about the car resulting in more nose weight

[TRD2000]

yeah more nose weight... but the movement is determined by how much "give" there is.

mine like locks the front way earlier, even with the (slightly) bigger rear brakes, hence i guess why they say upgrade the rears first... or all 4 but not just the front which you can do with many cars...

[classicstangracer]

you could have spent 40 bucks on a proportioning valve and had it fixed. if the front still out brakes the rear then there is prolly something wrong with them. Yes the movement is determined by the "give" but even when there is no seen movement there are still added force in the front that the tires absorb and is seen in sideway deflection

[TRD2000]

http://www.dba.com.au/dba_catalogue_...Out/Toyota.pdf

check out the SW 20 mr2, the rear brakes are bigger, i don't think i need to fix it, most that have been crashed have lost the back end, consequently i guess they were cautious on the back brakes...

[classicstangracer]

that is the first time i have ever seen any place where larger brakes are used in the rear. i have been building and racing cars for 7 years and have never seen or heard or anything like that. the only thing i guess they are doing is adding larger rotors but keeping the single piston calipers while the front has dual calipers. even with the larger rotors i'm sure the dual piston calipers create more braking power