stickmantijuana

is there any way for me to tell the ABS system that the front wheel diameter is smaller so the system will operate normally? i have stagger setup with significantly smaller front wheel.... i always locked up the front first and never the back, so i was wondering why and i figured this must be the reason?

thanks all.

G3tR3DDY2GR3DDY

iTrader: (8)

maybe sounds like a leveling sensor in your abs that senses off balance... lower the rear or put blocks in the springs ??? unless the crouching tiger stance is what your going for! lol...

stickmantijuana

mm that's a good point. yea i never adjusted the coilovers so that the overall height would be even. i always matched the wheel to fender gaps instead.

so abs senses the vehicle level as well? it doesn't make much sense to me, but i can take ur word for it

stickmantijuana

so i guess you think if i adjusted the ride height to be the same front & rear, it shouldn't affect the abs function even if i put 18 F and 19 R's?

swoope

iTrader: (5)

just make sure the tire diameter is close. btw, with abs on a base car i dont think it is a big issue.. scott will know.

the car has brake force distribution btw,,

beers

G3tR3DDY2GR3DDY

iTrader: (8)

swoope has more experience than me at this im sure... i just think it makes sense if your car is leaning forward and your ABS is acting up that its probably because it thinks your car is about to flip or is already "braking hard" and squatting the front

stickmantijuana

wait, so what was causing my front to always lock before my rears?
1. contact patch is smaller in the front?
2. vehicle nose is lower than the rear?

basically what i want to get at is whether it'll be okay to put 18" front and 19" rear if i were to adjust the ride height to be even in both front & rear?

thanks all.

stickmantijuana

bump.

want to know why abs system always kicks in the front and never in the back with my staggered set up.

i know if back locks up first, that's bad, but even when i downshift during hard braking, i was never able to lock up the rear... this tells me that rear tires probably got lot more braking grip left in them.

is this because the rolling diameter of my front wheels are smaller than the rear
and if so, is there any way for me to recalibrate the stock ABS for the smaller front diameter?

just wanna fix this issue asap... thanks all.

G3tR3DDY2GR3DDY

iTrader: (8)

pm some of the track junkies like "trackaddict" and "teamrx8" they would know why im sure... sorry i cant help man.. ill stick to selling parts! lol

swoope

iTrader: (5)

first of it the fronts are locking you have a problem that has nothing to do with wheel size... fix that first..

beers

stickmantijuana

i didn't mean it locks up completely... sorry about that. to rephrase, what i meant to say was that the abs is always modulating the fronts when rear tires obviously has more grip left in them.

basically problem seems to be that the front's brake bias is too strong. i wonder if that has anything to do with the smaller rolling diameter.

8rotor8

iTrader: (2)

That's weird, I always thought that the ABS sensors are on the axle and have nothing to do with the wheels at all. The ABS measures the speed that each axle is moving. If your fronts are locking up, you might be braking way too hard, the rears don't lock up because the distrubitation is not 50/50 with the brakes, it's more like 80/20.

Could you give us more information about your set-up? Size of the wheels, weight, tire type, etc.

8rotor8

iTrader: (2)

ABS brakes will always hesitate before they "turn-on". The car has to think that the wheels have stopped spinning to modulate the brakes.

swoope

iTrader: (5)

i would say that is normal... the weight shifts to the front.. that where the traction has to be controlled... less sticky and more narrow tires would cause more anti lock...

but with what i think you are putting on the front and back you will be more than fine...

btw, with what you are doing it is brilliant that you have a base car!!!!!

beers

stickmantijuana

hehe i'm excited too.

can't wait to see u guys and my car soon!!

well before i resign from this question, can anyone with stock tire setup confirm that front gets modulated before the rear under heavy braking?

this brake bias has always bothered me... just didn't think too much of it until i saw some youtube clips of nsx out-braking everyone on the track.

SolarYellow510

If the overall tire diameter is smaller, the ground has less leverage against the brake rotor, making the brakes effectively stronger. Smaller OD in front than in rear moves the balance of brake torque toward the front axle. Matches your observation. If you've also gone skinnier on the front than on the rear, you should have still more grip available at the rear, making it even worse.

Remember, you can only slow down or turn as fast as the tires at the less-effective end of the car can handle the work they have to do for their end of the car.

RX-8 wants to be the same size all around.

stickmantijuana

solaryellow that's really sharp thinking. yea that makes perfect sense to me and effectively addresses my question.

i'm going staggered just because i need the contact patch in the rear for the increased power. i would match the front & rear, but since i drive it on the street primarily i was worried about tramlining on the freeways. they don't really sweep the streets as often as they should over here.

swoope

iTrader: (5)

yes,

silly as big as you can on all four corners... but big and tramlining dont mix.. and not sweeping does not cause tramlining.

beers

stickmantijuana

too many little rocks around. not exactly tramlining but u get the picture...

swoope

iTrader: (5)

so confused..


but ok.

beers

TrochoidMagic

ok...are you guys implying we have 4 wheel ABS? do we?

well, anyways...ur fronts are overloaded as A) the fronts are lower, carrying more of that weight during braking weight transfer. B) the wheels have lower rolling diameter C) the fronts have narrower wheels, again carrying more weight and work load.

if you have A,B, or C or a combination, or all... your car's performance and overall balance is majorly upsetted, and there are no easy cure or a smart one at that.

the fronts may lock up more easily as it may constantly see force or more brake pressures from the front/rear bias. and even if you get a different brake fluid bias switch in favor of a stronger rear bias...the downfall of that may be in asking for a spin-out from easier rear lock-up.

i'm most positive that cars that come with staggered set-up from the factory have a properly tuned front/rear brake bias switch for stronger rears...i.e., the NSX. or even the Z.

the only solution is if you know what you are doing and have readily accessible parts and math and mechanical knowledge. that way you can weed out a decent brake bias switch from another vehicle. maybe even one from the mazda line-up.

TrochoidMagic

even most front wheel drives have a brake bias of 70/30...so staggered set-up on those already front heavy machines can mean disaster.

imagine a front wheel drive car with 2 dummies as front wheels... not cool!

you may want to re-think about your staggered set-up if you want your car to handle properly and balanced again...

or, do some more research and find what tire sizes that you can blend to match out your front and rears.

but remember again, matching front rolling diameter to the rear don't mean jack **** if its only 5 inches wide...

so please, make balanced adjustments to the rears as well as for the fronts.

TrochoidMagic

take what he says...and try to think of your braking system as a large torque wrench... thats what he's basically saying.

Easy_E1

iTrader: (2)

It's always easier to stop a car in a sudden braking issue with the front wheels.
Rear has a tendancy to lift and throw the wieght forward. Thus braking is less effective in the back. Less wieght, less traction, less braking needed. Take a look at the size of your brake rotors front to rear. Notice the larger are in the front. They have to do more work.
Inertia and load shift is the reason your front grabs first. All that wieght going forward, loading the front tires on the pavement. And lifting the back end. More brake pressure is sent to the front wheels.
You wouldn't want the back end locking up and sliding out of control, say on a wet surface.
Therfore more braking force is applied in the front and they will always try to lock first
I have 265/35-18's on all four corners and the front will always lock up first. I don't think the rear has ever skidded.
I'm thinking tire size may have a small amount to do with your situation. But not much.
But all in all, that is simply the way they work.