Early C4 ABS
Thread Starter
Advanced
Joined: Aug 2024
Posts: 78
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From: Massachusetts
Early C4 ABS
Quick question, is the '86-'87 ABS system stand-alone, or is it managed by the ECU?
And if it is stand-alone, is it a good system?
For background, I have an '85 that I eventually want to retrofit with ABS. Either way the '86-'87 knuckles/hubs/sensors will work, just trying to decide if it's easier or worthwhile to go with a MK60 or just get the C4 ABS module. Any advice appreciated.
And if it is stand-alone, is it a good system?
For background, I have an '85 that I eventually want to retrofit with ABS. Either way the '86-'87 knuckles/hubs/sensors will work, just trying to decide if it's easier or worthwhile to go with a MK60 or just get the C4 ABS module. Any advice appreciated.
Team Owner
Joined: Sep 2003
Posts: 25,394
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There are no new service parts available for any of the C4 early ABS, I would think adding anything that offered serviceability into the future would be more valuable/viable path forward if you're truly interested in ABS.
Drifting
Joined: Jun 2020
Posts: 1,709
Likes: 734
From: Stay dangerous my friends
I removed the ABS from the 1986. Trouble was that if you start to make any power, you have a lot more rear tire slip and the brakes go into ice mode (about 10-20% effective) so you have to wait for a half second before you apply.
It’s a three channel system and it’s standalone. Rear brakes are modulated as one channel only. You also need the wheel sensors and spindles/axles to accommodate.
cheap way to do this is to buy a salvage 1986-1987 car and strip/swap components.
best way would be a new Bosch motorsports ABS system but it’s expensive and would need proper programming. There are other aftermarket systems, but none is cheap. Some have also used the BMW system from earlier M3 M5 but the later of those ABS pumps do a lot more than just antilock, and use steering angle sensors, throttle position sensors, G sensors, etc
It’s a three channel system and it’s standalone. Rear brakes are modulated as one channel only. You also need the wheel sensors and spindles/axles to accommodate.
cheap way to do this is to buy a salvage 1986-1987 car and strip/swap components.
best way would be a new Bosch motorsports ABS system but it’s expensive and would need proper programming. There are other aftermarket systems, but none is cheap. Some have also used the BMW system from earlier M3 M5 but the later of those ABS pumps do a lot more than just antilock, and use steering angle sensors, throttle position sensors, G sensors, etc
Pro
Joined: May 2025
Posts: 614
Likes: 146
From: OK
FWIW there have been a lot of people that have pulled generic Bosch ABS systems off all manner of cars and retrofitted them to all manner of other cars, most of them were pretty well self contained.
I dug around online awhile ago and found a history of Bosch ABS system generations and general info, and they did still seem to offer the standalone adjustable motorsports setup but as was
said it ain't cheap. Odds are if you pulled one from a vehicle that was similar in size/weight to the target vehicle it'd work alright on the street, wouldn't count on it for track use but it's
easy enough to disable. It's been removed completely from my 86 but more because the previous owner was a goober kid that didn't know any better than for good reasons like
AZSP33D had. I notice every single speed sensor connector has turned to ear wax and is falling apart so at a minimum that would need to be addressed if I ever get around to putting it
back on, which is becoming less and less likely. I've very seldom owned cars with ABS, it's cool when it works right.
I dug around online awhile ago and found a history of Bosch ABS system generations and general info, and they did still seem to offer the standalone adjustable motorsports setup but as was
said it ain't cheap. Odds are if you pulled one from a vehicle that was similar in size/weight to the target vehicle it'd work alright on the street, wouldn't count on it for track use but it's
easy enough to disable. It's been removed completely from my 86 but more because the previous owner was a goober kid that didn't know any better than for good reasons like
AZSP33D had. I notice every single speed sensor connector has turned to ear wax and is falling apart so at a minimum that would need to be addressed if I ever get around to putting it
back on, which is becoming less and less likely. I've very seldom owned cars with ABS, it's cool when it works right.
