M Track Mode enabled on Z4MR
- Thread starter Meeko
- Start date
Caddyshk said:
If you consider the maximum grip that a tyre can yield is explained by the theory of "circle of friction" then you can understand that the DSC will intervene around the point where the loss of traction on the driven wheels under power, coupled with rotation of the car around a vertical axis (i.e yaw) will make the car spin unless the power to the driven wheels is reduced/stopped.
As you know, a tyre has only so much grip that it can give, so braking in a straight line is required when braking from high speed before a turn, to permit maximum front wheel grip for the direction change, otherwise you get loss of traction, which is experienced as understeer. As you know, it's also possible to use trail braking, where you continue to brake whilst initiating the turn, but because the tyre only has only so much grip it can give, you must apply much reduced braking forces in the turn, so that the tyre can use most of its grip for changing direction.
The same thing applies at the rear wheels with RWD. When the car changes direction at maximum grip levels, continuing to apply full power to the driven wheels whilst it commences to change direction, will exceed grip and this will allow the rear of the car to break free, creating yaw.
The maximum grip of tyres whilst turning requires the tyre to use the maximum slip angle, and the DSC does permit this to happen without intervention, but the sliding feeling that you get when driving at the limit of grip with the car at maximum slip angle of the tyres is not creating yaw, because the car is turning and not rotating.
Therefore, to prevent DSC intervention at maximum grip levels on turns, you need to set the car up so that you get to maximum slip angle without exceeding maximum grip, by lifting off the throttle instantly before you turn, so that the rear wheels can use their maximum grip without power applied, so that 100% of their available grip can act as "brakes" during the initiation of their change of direction. In this scenario, the rear tyres are not being used for traction, and so the rotational speed of the rear wheels can only get slower, so they cannot continue to break traction. Even if they momentarily lose grip during the change of direction, they will soon recover grip. Once the car has become balanced immediately after the change of direction of the whole length of the car, you can reapply the throttle progressively to maintain the speed around the bend and you should then find that you'll be able to feel for maximum grip with maximum slip angle.
I find that by turning sharply off-power into a corner probably 2 metres earlier and not braking as hard as the "slow in, fast out" technique, gets the car to change direction quicker and nicely set up allowing me to reapply power earlier in the turn at higher cornering speeds. At the same time there's no DSC intervention because any yaw that results from lift-off oversteer occurs when there's no power to the rear wheels. Hope this helps.
Thanks. I did find that going slower allowed for going faster at our slower loop last week. Not leaving braking as late and smoother power on at exit. That said; I need to do an alignment and reset the steering angle sensor to be sure DSC is functioning correctly. At times it has felt like the car has gone into limp mode. Replaced all the Coil Packs a couple of weeks back due to some misfire codes #5 & #6 and that has made a world of difference in everything from startup, idle to full power. Our Diffs (wear) can be the culprit too; especially if the fluid was changed to the Castrol SAF-XJ with the FM Booster (HD Friction modifiers). I've purged the Diff twice with Motul to remove the Castrol. The only thing left is the Steering angle sensor reset because my DSC intervention is highly unpredictable right now. I do love the idea of the M Track mode too. Once inTgr8r has this ready its being installed on my car for sure!exdos said:Caddyshk said:
If you consider the maximum grip that a tyre can yield is explained by the theory of "circle of friction" then you can understand that the DSC will intervene around the point where the loss of traction on the driven wheels under power, coupled with rotation of the car around a vertical axis (i.e yaw) will make the car spin unless the power to the driven wheels is reduced/stopped.
As you know, a tyre has only so much grip that it can give, so braking in a straight line is required when braking from high speed before a turn, to permit maximum front wheel grip for the direction change, otherwise you get loss of traction, which is experienced as understeer. As you know, it's also possible to use trail braking, where you continue to brake whilst initiating the turn, but because the tyre only has only so much grip it can give, you must apply much reduced braking forces in the turn, so that the tyre can use most of its grip for changing direction.
The same thing applies at the rear wheels with RWD. When the car changes direction at maximum grip levels, continuing to apply full power to the driven wheels whilst it commences to change direction, will exceed grip and this will allow the rear of the car to break free, creating yaw.
The maximum grip of tyres whilst turning requires the tyre to use the maximum slip angle, and the DSC does permit this to happen without intervention, but the sliding feeling that you get when driving at the limit of grip with the car at maximum slip angle of the tyres is not creating yaw, because the car is turning and not rotating.
Therefore, to prevent DSC intervention at maximum grip levels on turns, you need to set the car up so that you get to maximum slip angle without exceeding maximum grip, by lifting off the throttle instantly before you turn, so that the rear wheels can use their maximum grip without power applied, so that 100% of their available grip can act as "brakes" during the initiation of their change of direction. In this scenario, the rear tyres are not being used for traction, and so the rotational speed of the rear wheels can only get slower, so they cannot continue to break traction. Even if they momentarily lose grip during the change of direction, they will soon recover grip. Once the car has become balanced immediately after the change of direction of the whole length of the car, you can reapply the throttle progressively to maintain the speed around the bend and you should then find that you'll be able to feel for maximum grip with maximum slip angle.
I find that by turning sharply off-power into a corner probably 2 metres earlier and not braking as hard as the "slow in, fast out" technique, gets the car to change direction quicker and nicely set up allowing me to reapply power earlier in the turn at higher cornering speeds. At the same time there's no DSC intervention because any yaw that results from lift-off oversteer occurs when there's no power to the rear wheels. Hope this helps.
Only fair that I report back after trying 'M Track Mode'... I was at Donington last night for an evening track day. Conditions were dry and temperatures typical for UK summer at around 20 degrees. I'm running an MC with Bilstein coilovers, AP Brakes, E46 Anti Roll bars, a strut brace and Michelin Supersport tyres.
Bottom line is that running M Track mode is FANTASTIC on track - far less intervention than when traction control is fully engaged. It *does* intervene eventually, even in the dry, but you've got to be doing something a bit daft for that to happen (like miss a braking point for example!)
It also allows the rear end to move about a bit more and you can really feel the differential working which is excellent.
Of course, the ultimate Nirvana is everything off, but when you are learning a car like the Z4, then full-on 'I'm going to kill you' mode doesn't inspire confidence, especially when trying out new mods (for me, AP brakes and new anti roll bars) so M Track really gives more confidence to push on just a wee bit harder.
It will be interesting to try out in the wet! :evil:
Bottom line is that running M Track mode is FANTASTIC on track - far less intervention than when traction control is fully engaged. It *does* intervene eventually, even in the dry, but you've got to be doing something a bit daft for that to happen (like miss a braking point for example!)
It also allows the rear end to move about a bit more and you can really feel the differential working which is excellent.
Of course, the ultimate Nirvana is everything off, but when you are learning a car like the Z4, then full-on 'I'm going to kill you' mode doesn't inspire confidence, especially when trying out new mods (for me, AP brakes and new anti roll bars) so M Track really gives more confidence to push on just a wee bit harder.
It will be interesting to try out in the wet! :evil:
I just completed mine. First thought: every Z4M should have this. It's great! Initially I thought it didn't allow much slip, but when I was hooning around a bit I realised it is fantastic. Just enough slip to make it fun, yet the electronics intervene when things become challenging. Love it!
The process itself was painful though - as the documentation and availability of tools is spread over different forums and websites. I'll try to describe what I bought / did to make it work.
I bought the K+DCAN adapter of eBay for €29.90 + shipping. Good value, yet the cable initially didn't work
. The Z4M needs a D-CAN cable with pins 7 and 8 shorted. Mine didn't have this hardware modification, so I soldered the bridge between both pins myself. I forgot to take a picture, so you'll have to work with the instructions on e90post.com.
Once the cable was modded I downloaded the USB Driver and dcan_tool from osefactory, where http://www.one-stop-electronics.com is referring to (note: one-stop-electronics also sells a K+DCAN cable with pun 7&8 adapter, but I didn't knew that at the time I bought mine).
Install the tools that come with the adapter. Mine were version 5.0.1 of INPA and 3.0.4 of NCSExpert. Those are not recent enough, so you'll have to find a package with INPA v5.0.2 and NCSExpert v4.0.1. My NCSExpert package came with datenfiles v54.3. As a reminder, don't forget to set the communication interface in
to
with x being the COM port of your cable (mine was COM3 - see the device manager). I also had to change
and set Interface to
(was: REMOTE in the original file).
Next, install the USB Driver and connect the K+DCAN to the USB port and the ODB port to your car. I have been using VMware Fusion 7.1.2 on a Macbook 12" running El Capitan Beta 4, which worked like a charm. Set the mode to 500 kbit/s D-CAN & PT-CAN (you need to do this within 60 seconds after connecting the OBD port - while the LED is orange / red).
Now you should have everything working to follow the steps of @Meeko to code the M-track mode. A few more things I struggled with:
- I took "Expertenmodus (OFFEN)" as profile in NCSExpert. EXPERT MAN doesn't allow you to select MK60.C20
- The generated FSW_PSW.TRC file says "m_roadster" as value for BAUART_MK60. This upset me initially
but some Googling and common sense taught me that this is probably the right value for all E85/E86 (especially since this value is read over the OBD interface if I'm not mistaken)
- @Beedub: the whole process works like a charm on a Mac using VMWare Fusion. PM me when you need details!
The process itself was painful though - as the documentation and availability of tools is spread over different forums and websites. I'll try to describe what I bought / did to make it work.
I bought the K+DCAN adapter of eBay for €29.90 + shipping. Good value, yet the cable initially didn't work
. The Z4M needs a D-CAN cable with pins 7 and 8 shorted. Mine didn't have this hardware modification, so I soldered the bridge between both pins myself. I forgot to take a picture, so you'll have to work with the instructions on e90post.com.Once the cable was modded I downloaded the USB Driver and dcan_tool from osefactory, where http://www.one-stop-electronics.com is referring to (note: one-stop-electronics also sells a K+DCAN cable with pun 7&8 adapter, but I didn't knew that at the time I bought mine).
Install the tools that come with the adapter. Mine were version 5.0.1 of INPA and 3.0.4 of NCSExpert. Those are not recent enough, so you'll have to find a package with INPA v5.0.2 and NCSExpert v4.0.1. My NCSExpert package came with datenfiles v54.3. As a reminder, don't forget to set the communication interface in
Code:
C:\EDIABAS\bin\OBD.ini
Code:
Port=COMx
Code:
C:\EDIABAS\bin\EDIABAS.ini
Code:
STD:OBDNext, install the USB Driver and connect the K+DCAN to the USB port and the ODB port to your car. I have been using VMware Fusion 7.1.2 on a Macbook 12" running El Capitan Beta 4, which worked like a charm. Set the mode to 500 kbit/s D-CAN & PT-CAN (you need to do this within 60 seconds after connecting the OBD port - while the LED is orange / red).
Now you should have everything working to follow the steps of @Meeko to code the M-track mode. A few more things I struggled with:
- I took "Expertenmodus (OFFEN)" as profile in NCSExpert. EXPERT MAN doesn't allow you to select MK60.C20
- The generated FSW_PSW.TRC file says "m_roadster" as value for BAUART_MK60. This upset me initially
but some Googling and common sense taught me that this is probably the right value for all E85/E86 (especially since this value is read over the OBD interface if I'm not mistaken)- @Beedub: the whole process works like a charm on a Mac using VMWare Fusion. PM me when you need details!