4-Channel ABS vs. 3-Channel - Hyundai Forum: Hyundai Performance Forum
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post #1 of 5 Old 12-16-2004, 12:11 AM Thread Starter
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4-Channel ABS vs. 3-Channel

Okay I understand the difference between the two. Essentially, the 4 channel system monitors and pumps each wheel according to the conditions of the vehicle speed and how fast that individual wheel is slowing down. And on a 3 channel...both front wheels have a seperate channel each, as they do in the 4channel system...but only 1 channel is used for both rear wheels so they are pumped at the same time. Now that I know what each system is. Does anyone know why some manufactues use 4channel and some use 3? I was always under the impression the 4channel is better because each wheel is modulated according to their conditions where as on the 3channel both wheels do the same action no matter what. But then I was looking around on Acura's website and I was looking at the Acura RL...you know there new 300hp superluxo sedan with SHAWD. Well...their $89,000 RL uses a 3channel system, where as their $26,000 TSX is fitted with a 4channel system. :??: WHAT? Why would they fit a superior system on a more inferior(sp?) model? Does anyone know why? Does anyone know if there are advantages of a 3channel over a 4channel? Thanx.

[Edited by tranceokido on Dec 15, 2004 8:15 PM]

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post #2 of 5 Old 12-18-2004, 04:13 PM
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Re: 4-Channel ABS vs. 3-Channel

Probably to save some on production costs, although it truly doesn't make sense like you said.

From what I know, a 3-channel system has the rear speed sensor on the rear axle while the 4-channel has one in every wheel.

Theoretically, 4-channel is far more superior because in 3-channel both wheels have to start locking up for rear ABS to kick in. Also, when the road is uneven traction-wise, it might be possible to lock up one of the rear wheels :dead:.

This is the reason you get a BMW, Mercedes-Benz or Audi for that amount of money, far less compromises.

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post #3 of 5 Old 12-18-2004, 07:11 PM
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Re: 4-Channel ABS vs. 3-Channel

Any front engine, front drive car will have 4 sensors, even when there is only 3 channels (except rear ABS like on some pickups/SUVs where the sensors + ABS are on just the rear wheels). They say there are some advantages to having both rear wheels pulsing instead of pulsing them individually, especially for drivers that expect ABS to make up for their poor driving habits. 4 sensor, 4 channel will usually outbrake a 4 sensor 3 channel system because it can squeeze every last bit of traction out of a rear wheel with any grip available. The handling with 4 sensor 4 channel systems is supposed to be less forgiving for the extra reduction in stopping distance it may achieve.

It is not possible however, to lock up one side on any ABS system. The axle sensors that you spoke of are on either side of the rear differential (two of them), and the sensors tell the computer to pulse the single rear solenoid. If either rear sensor (on the axle or at the hub) detects lockup, the pulsing continues until both wheels are rotating again.

As to why Acura decided to go with a 4/3 system on that car, cost cutting was definitely not a factor. It might even tie into stability or traction control in a better way, but I would have to read up on it - strictly a guess.

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post #4 of 5 Old 12-18-2004, 09:54 PM
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Re: 4-Channel ABS vs. 3-Channel

In general, 60-80% of braking performance is done by the front brakes of a car, due to weight transfer. Having that extra channel on the rear is not going to significantly increase braking performance on most production cars and isnt needed in general. Also, it does cost more money to produce a true 4 channel system than a 3 channel, as you have to account for that extra wheel in the engineering and tuning phase of design. Not all costs are simply manufacturing.

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post #5 of 5 Old 12-20-2004, 05:57 PM Thread Starter
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Re: 4-Channel ABS vs. 3-Channel

Quote:
Originally posted by MonzaRacer
[body]
Probably to save some on production costs, although it truly doesn't make sense like you said.

From what I know, a 3-channel system has the rear speed sensor on the rear axle while the 4-channel has one in every wheel.

Theoretically, 4-channel is far more superior because in 3-channel both wheels have to start locking up for rear ABS to kick in. Also, when the road is uneven traction-wise, it might be possible to lock up one of the rear wheels :dead:.

This is the reason you get a BMW, Mercedes-Benz or Audi for that amount of money, far less compromises.
[/body]
Correction: Only 1 wheel has to lock up in the rear for the ABS to kick in on a 4-3 ABS system. Just like on me corsica. One wheel locks then both of them start pumping away.

I see your guys point. There isn't really a right answer...i was just looking for your guy's thoughts. Thanx.

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