ABS Brake Conversion?

[lil289]

Is it possible to convert an old 60's non-ABS car to ABS brakes? What would be involved in such a conversion?

[Noob]

alot....

individual wheel speed sensors, a computer of some sorts, ABS in line valve just to start off.. no aftermarket systems are known to me.. you'd best be served by removing a system off a modern car and retrofitting. No one said this was easy.

[Masher Manufacturing]

The most direct route would be to install a rear anti lock from a pickup truck. These consist of one speed sensor for the rear axle, a solenoic dlock and a electronics package.

These operate by first blocking further increases in line pressure then bleeding pressure if the wheel is still locked.

[dwilliams]

I'm doing this to my 1979 Mazda RX7. I have a complete ABS system from a 1990 Corvette. I picked that one because I like how it works, it's separate from the rest of the car's electronics, and its software is flexible enough to handle radical chassis and tire changes without freaking out.

Different OEMs program their systems differently. Some go into "ABS" mode well before the tire nears lockup. Some have very low cyclic rates.

1) pick a system that is standalone in its application (separate ABS computer)

2) drive a car with the same system to see if it works like what you want.

Some of the 1990s Delco systems on small GMs were so horrible I can't imagine how GM never recalled them or got sued. Some other systems basically do nothing at all. So the drive check is important.


Anyway, you'll need the computer, the wheel sensors, the lateral G sensor if the system uses one, and the reluctors ("tone rings") for the hubs.

If you're lucky you can retrofit the hubs and/or axles from a later model car. Otherwise, the reluctors and mounting are the main hassle. In my application I was unable to adapt any reluctors from anything else, so I have four chunks of steel ready to meet the rotary table, which is a tedious task I'm not looking forward to. It would be trivial on a CNC machine.

Anyway, though the reluctors are usually made of sintered ferrite material, plain old mild steel will work. The exact number of teeth isn't critical as long as the count is the same at both axles. The GM application I have used 47 teeth; doing 48 teeth will be much easier to make.

The master cylinder and brake booster are the same as the manual bits. You'll need to run a lot of new brake lines. The Corvette mounted the ABS module behind the driver's seat. Most other Detroit systems mount the module in the engine compartment. It doesn't really matter.

[lil289]

dwilliams, Thanks. Lots of good info there. Let us know how it turns out.

[David Redszus]

Bosch has announced the introduction of a retrofitable racing ABS system.
If you are interested in more details, you can pm me and I'll talk to my contact at Bosch engineering.

[Driver_10]

Im actually doing this to my 95 Camaro. The original car had 3-channel ABS from the factory. Im swapping a 92 Corvette IRS into the car which gave me the option to upgrade to the 4-channel C4, Bosch 5.0 ABS system. As it turns out, the 4th gen F-body and C4 vette use the same front and rear 47 tooth relucutor rings on their wheel hubs.

The only engineering snag is TCS function. The system uses throttle position, brake switch and wheel speed input. I dont particularly need TCS so Im excluding the "engine retard module" and throttle position input from the swap.

Its unknown territory so I dont know how this will impact the ABS control. Im hoping that input from the 4 wheel-speed sensors and brake switch will be enough.

[Unkl Ian]

Is it possible to convert an old 60's non-ABS car to ABS brakes? What would be involved in such a conversion?

Find a donor car, ideally with a rear end the right width,
and swap over everything possible.

I would swap the spindles too, so you get better brakes and ABS.

First choice is 4 wheel discs.

[Driver_10]

OK did some more research on this. I talked to a buddy at FRRAX.com who had swapped in a 4-channel ABS network into a customer's road-race F-body.

"...I started with a C5 EBCM and a wiring harness, Ken got them off of Ebay. I'll get you the part numbers. I needed the wiring harness only for the connector that plugs into the EBCM - it is a unique, multi pin connector.

The C5 ABS combines the hydraulics and electronics in the EBCM, so just the one module to mount. I replicated the C5 mounts, with 3 studs that engage rubber donuts in the EBCM, and located it near where the OEM Fbody ABS hydraulic module is located.

The ports on the C5 EBCM are labeled with function

For plumbing, I installed new LS1 Fbody front hardlines, they have a flex section at the ABS end, and the bubble flare fittings are compatible with the C5 EBCM, so just had to bend the hardlines up a bit, and plug them in.

I fabbed up new rear hardlines from the EBCM back to the axle, and used Global West chassis to axle flex lines. I fabbed new axle hard lines.

I put a new LS1 MC and booster on the car, and using a new set of LS MC hardlines as a starting point since the MC fittings are oddball, fabbed new hardlines from the MC to the EBCM. The rear line goes thru a Wilwood bias adjuster.

Electrical:

Red +12V thru a 25A fuse to the alternator
Blk, Blk/Wh Ground to chassis
Brn ign to switched side of ignition circuit - I put a dash switch with pilot light on this connection so the driver can turn the ABS system on/off on the fly.
Lt Blu stop to switched side of stop light circuit
a twisted pair from each wheel sensor:
left rear: Red/Blk
right rear: Wh/Brn
right front: Tan/Grn
left front: Yel/Blu

I salvaged the front hub harnesses, axle wiring harness and the rear bulkhead connector from a 4channel Fbody chassis, made up the rest of the rear twisted pairs.

That's it - no connection to a PCM, so this could go on anything, carb or EFI or whatever

There is no ABS ERR or ABS ACTVE indicators, nor any diagnostic port - those would need to be wired thru a compatible PCM.

Bleeding - connect everything, bleed, leak check, drive it a bit in the paddock, carefully activating ABS, use some water or gravel if necessary, then bleed again. Rinse and repeat. It is important to get the system bled - air in the ABS system will try to kill you - ie pedal stuck to the floor with both fronts locked up. Do not drive it on track or on the street until you are satisfied that the system is fully bled of air..."

Assuming you can weld on a set of exciter rings to the hub of you car (don"t really think the tooth count is important as long as they're the same front and rear), you should be able to use a C5 EBCM on virtually any car.