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Is the Cactus Mode box a separate standalone item, or does it somehow insert into the ABS unit? It's just a picture of a circuit board, so it was a little tough to tell.
I'll be doing the MK60E5 to Happy Cactus unit then with the Bluegrass motorsports CAN device to be able to send all the data via CAN to my Haltech ECU. I should be able to then see each corner brake pressure live if I want. I'll also be re-doing the entire brake line setup since you need 4 individual lines.
Is the Cactus Mode box a separate standalone item, or does it somehow insert into the ABS unit? It's just a picture of a circuit board, so it was a little tough to tell.
It's a stand alone unit, comes in an enclosure terminated with an electrical connector. I'm still in the planning stages, reviewing the OEM wiring diagrams, but it looks like if you put the Cactus box where the OEM ABS controller was, and locate your Mk60e1/e5 where the OEM ABS pump was, you should be able to re-pin/repurpose the OEM ABS wiring which makes the electrical integration pretty easy.
I went full standalone on mine, so it operates completely separately of the ECU. However, it wouldn't be a pad thing if it talked to the Haltech, and the possibility to use RX8 front hobs (and sensors)
I went full standalone on mine, so it operates completely separately of the ECU. However, it wouldn't be a pad thing if it talked to the Haltech, and the possibility to use RX8 front hobs (and sensors)
With the happy cactus unit, you can use the FD hubs/wheel speed sensors
I bought a set of late model RX-8 sensors to see if they would fit. The rear sensor physically fits in the front, but the connector isn't right.
I think it's the same connector as the stock FD rear sensor, but I'm not 100% certain.
Not sure if it's compatible with the FD ABS, though.
The RX-8 front sensors don't fit at all. The connectors are about the right size, but they aren't the right shape, so I can't splice the two together.
I bought a set of late model RX-8 sensors to see if they would fit. The rear sensor physically fits in the front, but the connector isn't right.
I think it's the same connector as the stock FD rear sensor, but I'm not 100% certain.
Not sure if it's compatible with the FD ABS, though.
The RX-8 front sensors don't fit at all. The connectors are about the right size, but they aren't the right shape, so I can't splice the two together.
They should be Econoseal MkII if I'm remembering correctly from my last harness build. I'm sure someone like Corsa Technic has easily packaged kits.
Turns out the rear sensor does NOT use the same connector. It just looks vaguely similar from a distance.
What do you guys think are the chances that the FD ABS unit will get along with this sensor? Basically zero?
The FD sensor has a litle dingus that hovers over the teeth, whereas the RX-8 sensor just sits to the side of the teeth, but I assume they essentially work the same way.
They probably look different on an oscilloscope, though.
I'm seriously considering retrofitting a MK60E5 ABS system into my FD, and have a few tech questions for those of you that have done this already. My starting point for this project is a '93 USDM FD that had it's ABS pump removed by the PO. He left behind all of the OEM ABS wiring, ABS controller/computer, and all of the ABS sensors, which I verified are all still functional per the ABS wheel speed sensor test procedure in the FSM. And the PO also removed the ABS light bulb in the cluster.
After doing some research on this, and given my starting point, here's my general game plan for the project:
- Find a working used/rebuilt Mk60E5 ABS unit (pump & controller). My understanding is that the Mk60E5 units have integrated pressure sensors, so that avoids the need for the external sensors that the original Mk60 required. Also, the E5 units are more plentiful and cheaper than the older Mk60's these days. Plan is to mount the Mk60E5 in the same space where the OEM ABS pump was.
- Purchase the Happy Cactus Converter box (~$350) which would let me use the FD's existing VR wheel speed sensors as-is with the Mk60E5 ABS unit. This eliminates the need to retrofit a different sensor on the FD chassis and simplifies the electrical wiring substantially. I'd mount the Happy Cactus box where the OEM ABS computer is/was, so I'd have easy electrical access to all the VR wheel speed sensors, power, ground, brake signal, etc. that it will need. Then I would either build a new wiring harness to wire the MK60E5, Happy Cactus, & ABS dash light together OR repurpose the OEM harness by replacing/re-pinning connectors on each end (assumes there are enough conductors in it to suit the Mk60E5)
- Re-install the ABS light bulb back in the dash, so it can be used again by the Mk60E5
- Re-plumb all my brake lines as required (to include the added 2nd line to the rear) with Ni-Cop lines, like this stuff: Fedhill brake line - Where to buy brake line, fuel line, brake line flaring tools, brake line nuts and brake line fittings
On to the questions...
1. What's the overall envelope dimensions of the Mk60E5 ABS unit? Also, does the pump unit need to be installed in a certain orientation (i.e., this side UP or FWD)? Before I buy anything, I want to verify with a cardboard/wood mock-up block that it can be made to fit where I want it to go, and that I'll have enough space for serviceable brake line plumbing & the electrical connections.
2. Recommended sources for used/rebuilt Mk60E5 ABS units? And is there an authoritative list somewhere that tells you exactly which years & specific model BMW's were equipped with the Mk60E5 ABS units that can be retrofitted to cars like the FD, or specific Mk60E5 part numbers that work with the FD? Either would make the search much easier. From what I've been able to glean from the FB Mk60 group, there's a zillion variations of the Mk60E5, and it's unclear which ones to get.
3. I've read conflicting info on FB regarding the need to add an external DSC/yaw sensor with a Mk60E5 retrofit. Wouldn't be too hard to do, and the sensor is relatively cheap, but I'm just wondering if it's absolutely necessary for stand alone ABS functionality and what it buys you?
4. Brake bleeding - Haven't gone too far down that rabbit hole yet, but I've read in the FB group that brake bleeding a Mk60E5 system requires some specialized tooling, akin to plugging in an OBD reader/electronic gadget in and commanding the Mk60E5 into a "brake bleeding mode"? I know how to bleed normal brakes (and normal brakes with typical ABS systems), but this wrinkle is new to me - can anyone elaborate on specifics of the process? What tools are needed, etc.,
Last edited by Pete_89T2; Nov 12, 2025 at 09:46 AM.
I'm seriously considering retrofitting a MK60E5 ABS system into my FD, and have a few tech questions for those of you that have done this already. My starting point for this project is a '93 USDM FD that had it's ABS pump removed by the PO. He left behind all of the OEM ABS wiring, ABS controller/computer, and all of the ABS sensors, which I verified are all still functional per the ABS wheel speed sensor test procedure in the FSM. And the PO also removed the ABS light bulb in the cluster.
After doing some research on this, and given my starting point, here's my general game plan for the project:
- Find a working used/rebuilt Mk60E5 ABS unit (pump & controller). My understanding is that the Mk60E5 units have integrated pressure sensors, so that avoids the need for the external sensors that the original Mk60 required. Also, the E5 units are more plentiful and cheaper than the older Mk60's these days. Plan is to mount the Mk60E5 in the same space where the OEM ABS pump was.
- Purchase the Happy Cactus Converter box (~$350) which would let me use the FD's existing VR wheel speed sensors as-is with the Mk60E5 ABS unit. This eliminates the need to retrofit a different sensor on the FD chassis and simplifies the electrical wiring substantially. I'd mount the Happy Cactus box where the OEM ABS computer is/was, so I'd have easy electrical access to all the VR wheel speed sensors, power, ground, brake signal, etc. that it will need. Then I would either build a new wiring harness to wire the MK60E5, Happy Cactus, & ABS dash light together OR repurpose the OEM harness by replacing/re-pinning connectors on each end (assumes there are enough conductors in it to suit the Mk60E5)
- Re-install the ABS light bulb back in the dash, so it can be used again by the Mk60E5
- Re-plumb all my brake lines as required (to include the added 2nd line to the rear) with Ni-Cop lines, like this stuff: Fedhill brake line - Where to buy brake line, fuel line, brake line flaring tools, brake line nuts and brake line fittings
On to the questions...
1. What's the overall envelope dimensions of the Mk60E5 ABS unit? Also, does the pump unit need to be installed in a certain orientation (i.e., this side UP or FWD)? Before I buy anything, I want to verify with a cardboard/wood mock-up block that it can be made to fit where I want it to go, and that I'll have enough space for serviceable brake line plumbing & the electrical connections.
2. Recommended sources for used/rebuilt Mk60E5 ABS units? And is there an authoritative list somewhere that tells you exactly which years & specific model BMW's were equipped with the Mk60E5 ABS units that can be retrofitted to cars like the FD, or specific Mk60E5 part numbers that work with the FD? Either would make the search much easier. From what I've been able to glean from the FB Mk60 group, there's a zillion variations of the Mk60E5, and it's unclear which ones to get.
3. I've read conflicting info on FB regarding the need to add an external DSC/yaw sensor with a Mk60E5 retrofit. Wouldn't be too hard to do, and the sensor is relatively cheap, but I'm just wondering if it's absolutely necessary for stand alone ABS functionality and what it buys you?
4. Brake bleeding - Haven't gone too far down that rabbit hole yet, but I've read in the FB group that brake bleeding a Mk60E5 system requires some specialized tooling, akin to plugging in an OBD reader/electronic gadget in and commanding the Mk60E5 into a "brake bleeding mode"? I know how to bleed normal brakes (and normal brakes with typical ABS systems), but this wrinkle is new to me - can anyone elaborate on specifics of the process? What tools are needed, etc.,
I'll answer a couple of the questions for now and I'll get to some of the others after I get home from work.
The dimensions look to be pretty close to the factory abs pump (there is likely a 3d scan floating around somewhere)
I got mine off of ebay, the exact part numbers are very annoying to track, but you can always ask on the happy cactus discord, they're pretty friendly and responsive if you give them a few ebay links to check for you.
I got my yaw sensor off of ebay as well for $60, from what I've seen, it is necessary.
One extra thing I saw as I've been going down the rabbit hole for replacing the brake booster with the bosch ibooster v2 from a tesla/Honda accord is that the happy cactus guy recommended to eliminate the proportioning valve (or at the very least use something after the abs pump, since apparently it can cause issues), I need to look into this more though.
I'll answer a couple of the questions for now and I'll get to some of the others after I get home from work.
The dimensions look to be pretty close to the factory abs pump (there is likely a 3d scan floating around somewhere)
I got mine off of ebay, the exact part numbers are very annoying to track, but you can always ask on the happy cactus discord, they're pretty friendly and responsive if you give them a few ebay links to check for you.
I got my yaw sensor off of ebay as well for $60, from what I've seen, it is necessary.
One extra thing I saw as I've been going down the rabbit hole for replacing the brake booster with the bosch ibooster v2 from a tesla/Honda accord is that the happy cactus guy recommended to eliminate the proportioning valve (or at the very least use something after the abs pump, since apparently it can cause issues), I need to look into this more though.
Thanks for the tips!
Hadn't thought about the proportioning valve or what to do with it yet, thanks for the reminder! The OEM FD ABS system had a "proportioning bypass valve" which appears to regulate max brake fluid pressure to the rear wheel hydraulic circuit. That valve has 2 inputs & 2 outputs; the inputs are plumbed to the master cylinder's F & R output ports, and the bypass valve outputs plumb directly into the respective F & R input ports on the ABS pump. I forgot to add, when the PO removed the ABS pump, he added in a Wildwood brake bias adjuster valve, which only has 1 input & 1 output. Don't recall how that is plumbed (away from car now), but I think it's just on in/out on the rear brake circuit?
Hadn't thought about the proportioning valve or what to do with it yet, thanks for the reminder! The OEM FD ABS system had a "proportioning bypass valve" which appears to regulate max brake fluid pressure to the rear wheel hydraulic circuit. That valve has 2 inputs & 2 outputs; the inputs are plumbed to the master cylinder's F & R output ports, and the bypass valve outputs plumb directly into the respective F & R input ports on the ABS pump. I forgot to add, when the PO removed the ABS pump, he added in a Wildwood brake bias adjuster valve, which only has 1 input & 1 output. Don't recall how that is plumbed (away from car now), but I think it's just on in/out on the rear brake circuit?
From what I could find for your brake bleeding question, it looks like people are using the foxwell NT630 (as well as the NT510, possibly others too), so you'll have to have an OBD2 port for it to connect to (I'm just realizing this now, lol). I'm still in the planning phase for my setup (most of the stuff I do have right now though), but another thing I got was Bluegrass Race Electronics MK60E5/MK60E1 to Haltech CAN Gateway to send those pressures (and other info) from the MK60E5 to my Haltech R3.
Also, I just saw you're in Elkton! I'm in Rising Sun, so I'm practically your neighbor . My FD is stripped most of the way down right now, I'll be swapping over my brake lines soon-ish. I ended up getting my brake lines from 4lifetime lines based out of DE. Don't forget, the MK60E5 uses different thread and flaring than the FD, I have all that saved in my google drive, so when you need it let me know if you don't already have it.
From what I could find for your brake bleeding question, it looks like people are using the foxwell NT630 (as well as the NT510, possibly others too), so you'll have to have an OBD2 port for it to connect to (I'm just realizing this now, lol). I'm still in the planning phase for my setup (most of the stuff I do have right now though), but another thing I got was Bluegrass Race Electronics MK60E5/MK60E1 to Haltech CAN Gateway to send those pressures (and other info) from the MK60E5 to my Haltech R3.
Oh joy, more specialized tools to buy! I do have one of those higher end Zurich OBD scan tools from Harbor freight that has ABS functions, so I wonder if that thing can talk to a Mk60E5, at least enough to support brake bleeding? The Happy Cactus box I'll be using (if this project comes to fruition) has CAN, so I can easily feed all that wheel speed & brake line pressure data to my Link ECU. I'm currently running a Link G4+ Fury, but I just purchased a new Link G5 Neo-4 which will be a welcome upgrade. Among the many projects I'll be doing with the FD after I put it into winter hibernation for this year, so the Mk60E5 project is the 3rd job in the queue, so hopefully I can make it happen. This year I'll be taking my FC to Deals Gap, so no pressure to get it all done before then.
Originally Posted by Thehead
Also, I just saw you're in Elkton! I'm in Rising Sun, so I'm practically your neighbor . My FD is stripped most of the way down right now, I'll be swapping over my brake lines soon-ish. I ended up getting my brake lines from 4lifetime lines based out of DE. Don't forget, the MK60E5 uses different thread and flaring than the FD, I have all that saved in my google drive, so when you need it let me know if you don't already have it.
Cool, we are practically neighbors! We should get together sometime & compare notes, feel free to shoot me a PM to coordinate & exchange phone #s.
. My FD is stripped most of the way down right now, I'll be swapping over my brake lines soon-ish. I ended up getting my brake lines from 4lifetime lines based out of DE. Don't forget, the MK60E5 uses different thread and flaring than the FD, I have all that saved in my google drive, so when you need it let me know if you don't already have it.
I do have one of those higher end Zurich OBD scan tools from Harbor freight that has ABS functions, so I wonder if that thing can talk to a Mk60E5, at least enough to support brake bleeding? The Happy Cactus box I'll be using (if this project comes to fruition) has CAN, so I can easily feed all that wheel speed & brake line pressure data to my Link ECU. I'm currently running a Link G4+ Fury, but I just purchased a new Link G5 Neo-4 which will be a welcome upgrade. Among the many projects I'll be doing with the FD after I put it into winter hibernation for this year, so the Mk60E5 project is the 3rd job in the queue, so hopefully I can make it happen. This year I'll be taking my FC to Deals Gap, so no pressure to get it all done before then.