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Old 10-10-18, 11:29 AM
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Rear ABS

I am trying to source rear ABS hubs, sensors and ABS tone rings.
The car is a S4 turbo that did not come with ABS. I have sourced front ABS sensor and hubs from a S4 GXL but the car was not equipped with rear ABS.
My understanding is that on S5 some models carried ABS as an option.
What about rear ABS? Did that only come as option on S5 Turbo? I have seen that the hubs on S5 cars have the mounting holes but unless optioned for ABS would not contain the ABS tone rings.

Rear ABS seems to be difficult to obtain hard parts as most cars either didn’t come equipped with or people have scrapped the stock ABS all together.

I am am looking for clarification specificly on finding actual ABS hard parts for the rear.
I have a post in the “for sale” if anyone has rear ABS parts or knowledge.
TIA

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Old 10-10-18, 05:13 PM
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S4 Option GXL/Turbo
S5 Standard Turbo

Quit a job installing into a non ABS vehicle.
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Old 10-10-18, 06:30 PM
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On the GXL was ABS on all wheels or just front?
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Old 10-11-18, 05:21 AM
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All 4 wheels. All models the same.
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Old 10-11-18, 07:32 AM
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Keep in mind that on both S4 & S5, the ABS was a rudimentary 3 channel ABS system. So your front brakes had individual ABS functional control, but the rears shared a common hydraulic circuit ("T" in the lines), so if either rear wheel locked, the ABS system could only modulate line pressure to both. The FD and pretty much every car made with ABS since that time use 4 channel systems.
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Old 10-11-18, 10:31 AM
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I understand the FC abs pump/computer is not very good and I won’t be using it.
My plan is to use more modern sensors, pump and computer.
Possibly FD or Miata, S2k etc.
Sourcing the hard parts will give me a jumping point to adapt another system to the car.

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Old 10-11-18, 03:37 PM
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Originally Posted by 25XP View Post
I understand the FC abs pump/computer is not very good and I won’t be using it.
My plan is to use more modern sensors, pump and computer.
Possibly FD or Miata, S2k etc.
Sourcing the hard parts will give me a jumping point to adapt another system to the car.

You do realize that all of those cars are very different from the FC in terms of weight, F/R weight balance, and a bunch of other factors that can affect braking right? Even if you do manage to make all these donor car ABS components fit & mechanically function on an FC, the resulting braking performance will be a huge unknown. For example, the ABS algorithms running in the bowels of an FD's ABS computer won't have a clue how to effectively stop a bigger & heavier FC.

If you really want ABS on an FC, your best bet is to just restore the system as Mazda designed it. Or just do the plumbing bypass and get rid of the ABS gear.

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Old 10-11-18, 04:24 PM
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I appreciate your input.
The fastest FDs in autox use the stock computer and have silmilar weight (2050-2150 lbs) and balance that I have.

Yes it will be a bit of a challenge to adapt the parts but my goal would be to graft and entire FD or Miata parts to the FC application.
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Old 10-11-18, 09:44 PM
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You must have put your FC on one hell of a diet to get it that light! Curb weight on an unmodified FC varied roughly between 2600 to 3000 lbs, depending on year & model. The stripped down early S4 base models & GTU-S models were lightest, and heaviest were the S5 convertibles. There are more accurate curb weight figures in the FAQ stickies.
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Old 10-12-18, 08:02 AM
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Yes. Pretty slim.
This is what I am trying to avoid.


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Old 10-12-18, 09:15 AM
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Originally Posted by 25XP View Post
I understand the FC abs pump/computer is not very good and I won’t be using it.
My plan is to use more modern sensors, pump and computer.
Possibly FD or Miata, S2k etc.
Sourcing the hard parts will give me a jumping point to adapt another system to the car.

the 90's-early 2000's Acrua Integra ABS was stand alone, its on its own wiring harness. its also 4 channel
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Old 10-12-18, 10:59 AM
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That’s for the info.
The FD rear tone rings are pressed onto the axle. The FC appears not to be from the pics on the FSM. I believe the FC tone rings on the rear are between the dust shield and rotor. Can anyone confirm? While a ring may be machined to fit the FC axle it wasn’t designed to carry a ring. I will check into the Acura system.
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