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If you look at the photos there... the one on the left is the unicorn 817.3, but the other two are distinctly not.
I wonder where the other ones come from and if they're flashable. I think an email to the contact person, Mario (info@mk-rennsporttechnik.de) might be informative.
That might reveal good info. There are several types of units, and I'd have to check my notes to remember what the common belief is. Many can be flashed with the CSL load. Some come with the CSL load. And some can be flashed with a motorsport load. I have part #s of those somewhere.
My understanding with the Mk60 was that unless certain components were connected via CAN, (I believe it was the steering angle sensor), the Mk60 would not send CAN data like pressures. I believe it was earlier in this thread that someone suggested that AIM data loggers somehow provided a solution to this. I'd like more info, if anyone has it.
If by certain components you mean other BMW control boxes/electronics, that is if you're running BMW OEM firmware. I really hope you're not doing this, because... first it is all set up for the characteristics of the specific BMW car (weight, track, wheelbase, piston sizing, F/R brake bias, tires circumference, etc.) And second it is a 3 channel street setup.
When you get custom firmware flashed, it is made for your specific car and its parameters. It is 4 channels and it doesn't check for presence of other devices on the CAN bus in order to start transmitting.
If by certain components you mean other BMW control boxes/electronics, that is if you're running BMW OEM firmware. I really hope you're not doing this, because... first it is all set up for the characteristics of the specific BMW car (weight, track, wheelbase, piston sizing, F/R brake bias, tires circumference, etc.) And second it is a 3 channel street setup.
When you get custom firmware flashed, it is made for your specific car and its parameters. It is 4 channels and it doesn't check for presence of other devices on the CAN bus in order to start transmitting.
I know nothing about the MK60 and when/how/if CAN works when the MK60 is used standalone. But if I'm reading your post correctly, you imply that the OEM BMW firmware on the MK60 is 3 channel. I'm pretty sure, positive, that it's 4 channel.
I know nothing about the MK60 and when/how/if CAN works when the MK60 is used standalone. But if I'm reading your post correctly, you imply that the OEM BMW firmware on the MK60 is 3 channel. I'm pretty sure, positive, that it's 4 channel.
The hardware has 4 channels. That doesn't mean the ABS software is set to control the rears independently. Read the paragraphs about the ABS in the BMW workshop manuals.
The hardware has 4 channels. That doesn't mean the ABS software is set to control the rears independently. Read the paragraphs about the ABS in the BMW workshop manuals.
A link, or document name would be nice.
I have read, although I can't find where, that the E36 (not MK60) 4-channel was 3-channel for ABS, 4-channel for traction control.
A link, or document name would be nice.
I have read, although I can't find where, that the E36 (not MK60) 4-channel was 3-channel for ABS, 4-channel for traction control.
BMW E46, Teves Mk60, ABS rear wheels logic: "Select Low", front wheels logic: Individual
"Select Low" means the wheel with the lowest traction is used as a basis to pulse both left/right valves together.
Same about the E46 Mk60 dynamic brake system (where the unit can do auto braking for the driver in emergency situations). Front individual, rear together (select low):
BMW E46, Teves Mk60, ABS rear wheels logic: "Select Low", front wheels logic: Individual
"Select Low" means the wheel with the lowest traction is used as a basis to pulse both left/right valves together.
And yet, on the very next page, the manual discusses CBC. Emphasis is my own.
If the control unit detects transverse acceleration in excess of 0.6g and the brakes are applied, CBC prevents a build up in brake pressure to the inside rear wheel. This prevents the vehicle from entering into an unstable situation that can lead to Oversteer.
The MK60 accomplishes this by closing the Inlet Valve, thus not allowing brake pressure to increase at the brake caliper.
The difference in braking force between the two rear wheels creates a yaw force that opposes the oversteer and allows the vehicle to handle neutrally.
If by certain components you mean other BMW control boxes/electronics, that is if you're running BMW OEM firmware. I really hope you're not doing this, because... first it is all set up for the characteristics of the specific BMW car (weight, track, wheelbase, piston sizing, F/R brake bias, tires circumference, etc.) And second it is a 3 channel street setup.
When you get custom firmware flashed, it is made for your specific car and its parameters. It is 4 channels and it doesn't check for presence of other devices on the CAN bus in order to start transmitting.
I'm using a Mk60 unit purchased from 3DM Motorsport, flashed with the CSL firmware. Others are running just the standard E46M3 firmware, on non-E46 platforms and it is plenty good enough.
Is your assertion about 3-channel just based on your reading of that doc?
Pretty interesting. I can't keep track of all the functions the MK60 does in its OEM application, and I can't keep track of exactly which functions only in work stand alone. It's a complicated little device. But from the text above, sometimes it's 4-channel, sometimes 3. I'm guessing, maybe in a straight line applying ABS to only one rear wheel could upset car dynamics more than applying to both, even if one tire is higher in slip than the other. They may activate rear ABS much earlier in slip percentage than the front. Put another way, maybe you want the rear further from lock-up than the front, at all times, and because of that, it's better to regulate both rears at the same time. All blabbering conjecture. Anyway, I'll be emailing Doug early next week to follow up on something, and might ask him.
Same about the E46 Mk60 dynamic brake system (where the unit can do auto braking for the driver in emergency situations). Front individual, rear together (select low):
Question, is the document you're referencing specific to the E46 *M3* MK60?
I'm finding E46 traction control service docs, etc, that list a lot of models, but none that list the function of the MK60 as programmed for the E46 M3.
Yea, just guessing here, but the document I found that matches the text and pictures from the posts above is dated Jan 2003. This is *prior* to the updated MK60 into the E46 M3. Major changes were made to the E46 M3 ABS systems in 2003 (I don't know the exact model yr/month update), but I'm guessing...quite possibly...the documents being quoted don't accurately reflect the function of the MK60 units from E46 M3's (post 2003 update).
I was told by an ABS engineer who works with these units that the street tune does the rear wheels at the same rate (based of the rear wheel having least traction), when the Mk60 ABS engages, because for a street car the goal is for the average street driver (who most of the time has no idea about performance driving or doesn't care about chasing lap times) is to safely stop the car without spinning and that most of the time is some emergency situation.
The motorsports tune on the other hand is made to achieve minimum possible brake distance by using all the available tire grip with the goal of faster lap times, thus ABS is independent for all wheels. Controlling the rear ABS at different rates (to maximize all available grip) can cause instabilities in the rear in some situations and it is assumed the driver is skilled enough so they compensate along with steering just fine while achieving maximum possible deceleration.
I was told by an ABS engineer who works with these units that the street tune does the rear wheels at the same rate (based of the rear wheel having least traction), when the Mk60 ABS engages, because for a street car the goal is for the average street driver (who most of the time has no idea about performance driving or doesn't care about chasing lap times) is to safely stop the car without spinning and that most of the time is some emergency situation.
The motorsports tune on the other hand is made to achieve minimum possible brake distance by using all the available tire grip with the goal of faster lap times, thus ABS is independent for all wheels. Controlling the rear ABS at different rates (to maximize all available grip) can cause instabilities in the rear in some situations and it is assumed the driver is skilled enough so they compensate along with steering just fine while achieving maximum possible deceleration.
That all makes sense. I just wonder, if, the lawyers for the E46 M3, or the E46 M3 CSL, allowed a different approach. Would be interesting to find the same documentation for those specific cars.
And yes, a Motorsport load changes everything!
I'll ask Doug Wardell next time I email him, likely next week.
If you narrow the definition of ABS to exclude the clearly-four-channel CBC described in the documentation. True, CBC does not apply during ABS regulation (see earlier post). My definition of ABS control follows the BMW description, which includes CBC as a submodule of ABS.
Regardless, the system is fantastic on track, even without the "race map" that allows you to parameterize everything. I don't have a crazy number of sessions with it, but I have enough to feel comfortable saying that.
I'm finding some interesting papers on ABS and vehicle control, and am starting to piece this together.
It's pretty interesting. Thinking of the MK60 as a 3-channel in ABS is a bit simplistic. Put that aside, and think of how the optimum F/R bias changes as weight transfers to the front of the car under braking. This is fundamentally why "select-low" is used in straight-line braking, it's effectively a dynamic bias valve, and yes, is more stable than regulating just the side that's near traction loss. But at lateral G's more than 0.6G, select-low is no longer used, and ABS is true 4-channel. This approach seems to be pretty common.
UPDATE, MK60 working!
I'm nearly certain it was the BLS switch that I had hooked up incorrectly. But, I did change a few things.
Compared to the last day where the pedal was very inconsistent, I:
- Connected BLS correclty
- Changed front M/C
- Set bias bar such that the ABS MCU wouldn't error on the pressure senors.
And all was good.
I then adjusted the bias bar and pushed bias further to the front, and the ECU started reporting the pressure sensor error, but the ABS continued to work fine.
There may be some detail in some mode that changes when that error occurs. Maybe I'll notice once I get some time with it, but I'm calling this a win.
I will say, that with no booster and with dual M/Cs, you do clearly feel the ABS working in the pedal, including when you're really into the ABS and the pressure/pump function is doing it's thing.
Thanks for all the help and ideas from this forum!!!
Do you feel the Mk60 doing things when the anti-lock function is not intervening, e.g. releasing the inner rear wheel during trail braking?
Congrats and enjoy!
I could feel it regulate the inner rear during trial. I was playing with bias quite a bit, and just in general gaining confidence in the system. I got back to where I could put the back end of the car where I wanted by using the brake pedal. Which, isn't the fastest way around but it can be a lot of fun! And the opposite was true, when I got serious, I could plant the front of the car with light pressure on the pedal, and feel the dynamics.
I'll be at my bumpy track this Friday. There's a bump that's just in that perfect place that caused my previous ABS system to react when the car gets light, and then pause..pause...oh crap...pause...turn off. I'll see if this system gives me the brakes back earlier after an "air time" event.
06-30-2021, 09:14 PM
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Would be interesting to find the same documentation for those specific cars.
