ABS kicking in too quickly?

[kkim388]

Anyone else find the ABS kicking in way too easily? I can activate it just by braking hard into a turn if the wheel is slightly off straight ahead.

Is there an easy fix for this? Seems to me like the brake bias is off and the front tires start sliding which the reason for the ABS coming on.

Thoughts?

Car is a 07 Si sedan.

[Highrev1]

Get better tires, and only brake in a straight line! :)

Your ultimate stoping power will allways be determined by your tires.

[noahrexion^2]

^ good advice +1

To the OP: yes I notce it in my 07' Si Sedan as well. There is no fix other than what highrev said. Braking in turns should only be done via engine braking to pull your nose back in. Anyhow it is semi annoying to have the pedal feel lose itself when ABS kicks in, however it does still slow you down and thats the main point

[kkim388]

225 Kumho MX tires, so I doubt it's the tires. Yes, in a perfect world/track braking should all be done in a straight line, but there are times in the real world where that advice does not work. I 've been driving the same mountain road for the last 30 years with a host of hi performance cars, so it's not the technnique that's lacking, it's the ABS sensitivity.

[CZ-75]

http://www.teamassociated.com/racerh...andling.2.html

http://www.dur.ac.uk/r.g.bower/PoM/p...ml#figtraccirc


EBD should be changing your brake bias somewhat, but you can switch to aftermarket pads (like PBR/Axxis Ultimates) in both front and rear, since most cars are biased toward the front brakes, both in size/torque and in the quality of the front brake compound compared to the rear.

[Highrev1]

Pads won't help..

Your brakes arnt the Weak point.. its the tires. Lets see you can activate abs now so your brakes are fine If you can do that with these tires than the brakes arent the issue. The tires traction is. How much you can brake is determind by how much traction your tires can!

"Also the way you use the brakes will influence your how much your abs engages.... such as if you "pounce" on them. I.e. going to 100% brakeing instantaniously. what happens in such casese is weight doesnt have time to transfer to the nose before you reach 100% brakeing... meaning the front tires wont be makeing enough traction for the amount of brake force given so you end up Locking them up (ABS going off) momentairly, giving you crappier stopping distances."

[kkim388]

Agreed, pads aren't the problem, though I already have axxis ultimates all around.

And yes, the corners that's activating the abs are downhill smooth tight turns that require me to be on the brakes through an S configuration. I'm already on the brakes and as I turn the wheel into the turn, the abs will activate. Any sort of "drop" in the turn will turn them on. I just think it's way too sensitive and that would mean the rears aren't doing as much work as they could. Again, I think the bias is off front to back. I wonder if they are using the same biasing as the coupe and the longer wheelbase of the sedan is causing the problem?

[Highrev1]

Also get all your braking done in a straight line. EBD would correct some sort of bias issue.

[CZ-75]

Originally Posted by Highrev1

Pads won't help..

Your brakes arnt the Weak point.. its the tires. Lets see you can activate abs now so your brakes are fine If you can do that with these tires than the brakes arent the issue. The tires traction is. How much you can brake is determind by how much traction your tires can!

"Also the way you use the brakes will influence your how much your abs engages.... such as if you "pounce" on them. I.e. going to 100% brakeing instantaniously. what happens in such casese is weight doesnt have time to transfer to the nose before you reach 100% brakeing... meaning the front tires wont be makeing enough traction for the amount of brake force given so you end up Locking them up (ABS going off) momentairly, giving you crappier stopping distances."

Pads will help by decreasing front bias, at least as long as you use the same material front and rear (or something of higher friction coefficient in the rear - not recommended).

http://www.stoptech.com/products/BBK/balance.shtml

[Highrev1]

Those same guys from stoptech "Brakes stop wheels, Tires stop cars." :)
Pads will not help because he is already at maximum traction for the tires on the car. If he didn't have abs the wheels would be locking up so it is lack of traction from the TIRES.

http://www.teamscr.com/grmbrakes.htm

"In summary, brake system modifications have their place to help make your ride more consistent, predictable, and user-friendly; however, if your ultimate goal is to decrease your stopping distance, look no further than the four palm-sized patches of rubber connecting your ride to the ground."

[CZ-75]

Originally Posted by Highrev1

Those same guys from stoptech "Brakes stop wheels, Tires stop cars." :)
Pads will not help because he is already at maximum traction for the tires on the car. If he didn't have abs the wheels would be locking up so it is lack of traction from the TIRES.

http://www.teamscr.com/grmbrakes.htm

I've read it before. Your article notes that the tires don't contribute the same amount of traction to stopping the car because of load transfer, so if one can shift brake bias rearwards, you can even that out a bit more and utilize more of the rear tire, as opposed to over-utilizing the front tires.

[TommyD]

This has been a common thing with every Honda I've owned with ABS except the S2000 but I can get it to turn on in that pretty easy as well.

[Highrev1]

Maybee it isn't abs your feeling. EBD doing its job? Especially if your braking mid turn as you say you are :)

The electronic brake distribution (EBD) feature helps control vehicle braking by adjusting the rear brake force in accordance with the rear wheel load before the ABS operates. Based on the wheel sensor signals, the control unit uses the modulator to control the rear brakes individually. When the rear wheel speed is less than the front wheel speed, the ABS modulator-control unit retains the current rear brake fluid pressure by closing the inlet valve in the modulator. As the rear wheel speed increases and approaches the front wheel speed, the ABS modulator-control unit increases the rear brake fluid pressure by momentarily opening the inlet valve. This whole process is repeated very rapidly. While this is happening, there is kickback at the brake pedal.

[kkim388]

Originally Posted by Highrev1

Maybee it isn't abs your feeling. EBD doing its job? Especially if your braking mid turn as you say you are :)

The electronic brake distribution (EBD) feature helps control vehicle braking by adjusting the rear brake force in accordance with the rear wheel load before the ABS operates. Based on the wheel sensor signals, the control unit uses the modulator to control the rear brakes individually. When the rear wheel speed is less than the front wheel speed, the ABS modulator-control unit retains the current rear brake fluid pressure by closing the inlet valve in the modulator. As the rear wheel speed increases and approaches the front wheel speed, the ABS modulator-control unit increases the rear brake fluid pressure by momentarily opening the inlet valve. This whole process is repeated very rapidly. While this is happening, there is kickback at the brake pedal.

That sounds like exactly what's happening. I'll read up on the EBD system in my service manual. Thanks for the tip... I didn't even know these cars had EBD.

Mahalo

[Highrev1]

Tires :)

This system is composed of the ABS modulator-control unit, the wheel sensors, and the system indicators in the gauge control module. The ABS modulator-control unit controls the anti-lock brake and the brakes distribution functions.

Without ABS, when the brake pedal is pressed while driving, the wheels sometimes lock before the vehicle comes to a stop. In such an event, the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if the rear wheels are locked, creating an extremely unstable condition. With ABS, the system precisely controls the slip rate of the wheels to ensure maximum grip force from the tires, and it thereby ensures maneuverability and stability of the vehicle. The ABS calculates the slip rate of the wheels based on the four wheel speeds, then it controls the brake fluid pressure to reach the target slip rate.

The control unit detects the wheel speed based on the wheel sensor signals it received, then it calculates the vehicle speed based on the detected wheel speed. The control unit detects the vehicle speed during deceleration based on the rate of deceleration.

The control unit calculates the slip rate of each wheel, and transmits the control signal to the modulator unit solenoid valve when the slip rate is high.

The hydraulic control has three modes: Pressure intensifying, pressure reducing, and pressure retaining.

The ABS modulator consists of the inlet solenoid valve, the outlet solenoid valve, the reservoir, the pump, the pump motor, and the damping chamber. The modulator reduces the caliper fluid pressure directly. It is a circulating-type modulator because the brake fluid circulates through the caliper, the reservoir, and the master cylinder. The hydraulic control has three modes; pressure intensifying, pressure retaining, and pressure reducing. The hydraulic circuit is an independent four channel type; one channel for each wheel.

The electronic brake distribution (EBD) feature helps control vehicle braking by adjusting the rear brake force in accordance with the rear wheel load before the ABS operates. Based on the wheel sensor signals, the control unit uses the modulator to control the rear brakes individually. When the rear wheel speed is less than the front wheel speed, the ABS modulator-control unit retains the current rear brake fluid pressure by closing the inlet valve in the modulator. As the rear wheel speed increases and approaches the front wheel speed, the ABS modulator-control unit increases the rear brake fluid pressure by momentarily opening the inlet valve. This whole process is repeated very rapidly. While this is happening, there is kickback at the brake pedal.

[Sirbelch]

I just ran my favorite twisty road which as a lot of quick elevation changes at all different points of a lot of corners. This changes weight over different wheels very quickly and as long as i wasn't too hard on the intial pedal press, the abs never kicked in. However, if i was to hard, the abs would kick in. I could still control the car just fine when the abs did kick in. I could even trail brake to get the car to rotate better without the abs kicking in. Just try to be a little smoother getting on the brakes.

[kkim388]

Originally Posted by Sirbelch

I just ran my favorite twisty road which as a lot of quick elevation changes at all different points of a lot of corners. This changes weight over different wheels very quickly and as long as i wasn't too hard on the intial pedal press, the abs never kicked in. However, if i was to hard, the abs would kick in. I could still control the car just fine when the abs did kick in. I could even trail brake to get the car to rotate better without the abs kicking in. Just try to be a little smoother getting on the brakes.

Thanks... I feel I'm already pretty smooth on the brakes. I've driven this road repeatedly with many different cars and this is the first to lose traction so easily in the corners when braking. Looks like I will have to modify my driving... or change cars.

Curious... is your car an SI sedan?

[kkim388]

Originally Posted by Highrev1

Tires :)

Don't quite understand. MXs are pretty sticky tires... there are better, but not by leaps and bounds.

[Chase]

Originally Posted by kkim

225 Kumho MX tires, so I doubt it's the tires. Yes, in a perfect world/track braking should all be done in a straight line, but there are times in the real world where that advice does not work. I 've been driving the same mountain road for the last 30 years with a host of hi performance cars, so it's not the technnique that's lacking, it's the ABS sensitivity.

Subject Matter experience here...

With My Kumho MX's I experienced the same problem... Same with the ASX Kumho's that I had on for a week. ABS in all the time with just normal braking.

I have Nitto Neo Gen's on right now and The problem is not as severe, The ABS only starts up with hard braking.

I don't ever recall My ABS starting up during a turn, but then again I don't brake in turns unless its absolutely necessary, use a lower gear!

[Sirbelch]

Originally Posted by kkim

Thanks... I feel I'm already pretty smooth on the brakes. I've driven this road repeatedly with many different cars and this is the first to lose traction so easily in the corners when braking. Looks like I will have to modify my driving... or change cars.

Curious... is your car an SI sedan?

No its a Coupe. This is also my second FWD VTEC powered honda. I had a GSR. Come to think of it, the Si is easeir to get the ABS to kick in when compaired to the GSR. So Just get use to it. Don't give up your Si.
I want you to go out there and give me 20 (times up mountain) :) By then you'll have it down. Is this your first FWD on that road? I have Kumho ESCTA XT 235/40/17 if that helps. Your MX are supposed to be sticker i think.