DrZiplok
Member
- Joined
- Nov 25, 2015
ABS is nice to have on track. If you disagree, you're welcome, but this thread is not for you. 8)
The Bosch ABS-II unit that was fitted to late-model 240s is a lot better than nothing, but it's dumb, it's slow, and it doesn't modulate the rears independently. It would be nice to have something better...
A very common swap for BMW E30s (which incidentally also used ABS-II) is the Teves MK60 as fitted to the E46 (2001+) M3. Actually, this unit is a common swap into many platforms, as it runs standalone and can be flashed with some fairly interesting software. Even stock, however, it's a much better, smarter unit.
Most of the swap is prettymuch the same as for any other MK60 swap, but we encountered some 240-specific issues.
Rear reluctors: the 240 ABS system uses a single reluctor & sensor in the differential. The MK60 needs individual rear wheel sensors. Happily, if you are prepared to ditch the parking brake, there's a nice machined surface on the axle in that area outboard of the axle seal.
We sourced these from reluctorrings.com - if you call and ask they should have our measurements on file. Installation involves nothing more complex than a torch to heat the ring enough to expand it, and then it just drops into place (once you have removed the bearing, of course). If you want to make your own, the rear reluctors need to be made with 48 teeth (same as the front).
EDIT: see post #24 below for a better rear sensor option.
The rear BMW sensor has a long strain relief on the cable that needs to be carefully trimmed off, so that it can be tucked in under the parking brake drum. I can't say whether this would fit under the standard rear rotor, as we have S60 rotors on the car - you might need to shrink the ring or find another sensor to work with.
Shown here with a 3d-printed prototype mount, the sensor mounts using existing holes from the handbrake mechanism and a bracket fabricated using 1.5" L stock.
The front BMW sensor is a nice fit in the stock ABS knuckle, but it's not long enough. Here we copied the E30 guys and trimmed the sensor back. It looks terrible, but it works.
Engine compartment: ignore the M52, nothing to see here. The MK60 is normally mounted very close to the master cylinder in OE applications, but this is only required for DSC purposes. ABS-only installations work with it prettymuch anywhere.
Wiring is very straightforward. You can wire the stock brake light wire into the ABS unit; the warning light is a bit trickier as the output from the ABS unit is pulled to ground to *disable* the warning light. Either use an LED with a series resistor, or a relay.
Image taken from a mostly helpful document produced by facebook.com/bmwm3motorsport. Note that in other applications the MK60 is driving a bulb directly; I tested one on the bench as drawing ~100mA, meaning that if you want to use a brighter LED, you can use a much lower-value resistor. We see good results with a super-bright BA9 LED and a 680R resistor.
The DSC button input is not useful and can be left disconnected. Make sure to tie the fluid level sensor input to ground (or wire up a fluid level sensor...). DSC sensor box is installed under the driver's seat in the correct orientation (connector forward, mounting surface up). The steering angle sensor is not required for ABS purposes, so we pitched it.
Note that we don't have an ignition switch - you might choose to route pin #4 differently in a car that does.
The Bosch ABS-II unit that was fitted to late-model 240s is a lot better than nothing, but it's dumb, it's slow, and it doesn't modulate the rears independently. It would be nice to have something better...
A very common swap for BMW E30s (which incidentally also used ABS-II) is the Teves MK60 as fitted to the E46 (2001+) M3. Actually, this unit is a common swap into many platforms, as it runs standalone and can be flashed with some fairly interesting software. Even stock, however, it's a much better, smarter unit.
Most of the swap is prettymuch the same as for any other MK60 swap, but we encountered some 240-specific issues.
Rear reluctors: the 240 ABS system uses a single reluctor & sensor in the differential. The MK60 needs individual rear wheel sensors. Happily, if you are prepared to ditch the parking brake, there's a nice machined surface on the axle in that area outboard of the axle seal.
We sourced these from reluctorrings.com - if you call and ask they should have our measurements on file. Installation involves nothing more complex than a torch to heat the ring enough to expand it, and then it just drops into place (once you have removed the bearing, of course). If you want to make your own, the rear reluctors need to be made with 48 teeth (same as the front).
EDIT: see post #24 below for a better rear sensor option.
The rear BMW sensor has a long strain relief on the cable that needs to be carefully trimmed off, so that it can be tucked in under the parking brake drum. I can't say whether this would fit under the standard rear rotor, as we have S60 rotors on the car - you might need to shrink the ring or find another sensor to work with.
Shown here with a 3d-printed prototype mount, the sensor mounts using existing holes from the handbrake mechanism and a bracket fabricated using 1.5" L stock.
The front BMW sensor is a nice fit in the stock ABS knuckle, but it's not long enough. Here we copied the E30 guys and trimmed the sensor back. It looks terrible, but it works.
Engine compartment: ignore the M52, nothing to see here. The MK60 is normally mounted very close to the master cylinder in OE applications, but this is only required for DSC purposes. ABS-only installations work with it prettymuch anywhere.
Wiring is very straightforward. You can wire the stock brake light wire into the ABS unit; the warning light is a bit trickier as the output from the ABS unit is pulled to ground to *disable* the warning light. Either use an LED with a series resistor, or a relay.
Image taken from a mostly helpful document produced by facebook.com/bmwm3motorsport. Note that in other applications the MK60 is driving a bulb directly; I tested one on the bench as drawing ~100mA, meaning that if you want to use a brighter LED, you can use a much lower-value resistor. We see good results with a super-bright BA9 LED and a 680R resistor.
The DSC button input is not useful and can be left disconnected. Make sure to tie the fluid level sensor input to ground (or wire up a fluid level sensor...). DSC sensor box is installed under the driver's seat in the correct orientation (connector forward, mounting surface up). The steering angle sensor is not required for ABS purposes, so we pitched it.
Note that we don't have an ignition switch - you might choose to route pin #4 differently in a car that does.
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