MK20 -> MK60 Swap

[CrookedCommie]

Gotcha, yea the fronts I am using are also the 345mm. But again that begs the question of how something like a 355mm StopTech for example works with the MK20 ABS. Or older cars like the E36 which has 3-channel ABS, lots of people run BBK of various types on those cars. Just kind of spitballing here. Sounds like you looked into this a lot so I just wanna soak up some secondhand info.

MK20 will work, I have an AP 9668 and AP rear kit. Problem is, the pedal has no feedback, and when you get into the abs, it destabilizes the whole car. On the E46M MK60 race cars I drive you can feel exactly what the front tires are doing through the pedal. That was on Falkens that we run in WRL races. On slicks I expect the MK60 with race map to be even better.

[eacmen]

I don't know what the MK60 motorsport versions get you specifically, but the Bosch M4 Motorsport kit lets you do precisely that

https://www.bosch-motorsport.com/med..._m4_ait_en.pdf

Contintental has this: https://conti-engineering.com/domain...otorsport-abs/

Apparently based on the "MK100" stability control modules. Perhaps in the past there was a listing for an MK60 variant, but I cannot find them now. Honestly at $7k for a full kit new with software support and tunability... I think that'd be well worth the expense over a $3-4k mk60 "race" kit if I were actually building a race car.

Where things could get interesting is if the consumer variants of those newer modules can be flashed with the respecitve motorsport software without having to pay some guy in Germany a few grand to do it. Contintental RSX = MK100 (and various variants are like $60 on ebay), bosch M4 = bosch 8.1, bosch M5 = bosch 9.0. The bosch 8.1 apparently has an MPC555 CPU, so that might actually be feasible to flash even for us mere mortals if we can get the software dump.

But I digress. Sorry for taking thisthread off topic.

Hopefully CrookedCommie can verify this when he gets his kit. Anxious to see what tuning parameters you get with the motorsport ABS flash!

Tuning ABS could be a dangerous proposition, Done poorly could be unsafe.


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[Nate047]

MK20 will work, I have an AP 9668 and AP rear kit. Problem is, the pedal has no feedback, and when you get into the abs, it destabilizes the whole car. On the E46M MK60 race cars I drive you can feel exactly what the front tires are doing through the pedal. That was on Falkens that we run in WRL races. On slicks I expect the MK60 with race map to be even better.

Right on, thank you for this. I sent you a DM to see if I can pick your brain and not clutter up OP's thread.

[heinzboehmer]

Problem is, the pedal has no feedback, and when you get into the abs, it destabilizes the whole car.

I felt this a lot on the track, even with stock brakes. Car would get super unstable and squirm around a ton under heavy braking. Thought it was a sticking caliper or bad rotor at first, but I checked that and it was all good. Hoping the MK60 makes the car more stable under ABS braking.

I also agree with what you say about feeling what the front wheels are doing through the brake pedal with the MK60. I've gone out a couple times when the streets are empty to test out higher speed braking (~80 -> ~40) and that was the main difference I noticed. It's hard to describe with such limited exposure to the sensation, but the feedback just feels tighter and crisper. Anyway, I'm sure I'll have more to say about this in a week or so after the track day.

[heinzboehmer]

Right on, thank you for this. I sent you a DM to see if I can pick your brain and not clutter up OP's thread.

Nah, feel free to keep the conversation going here. Feels like there's little talk about the difference in feel between the two systems besides "MK60 is better", so it's good to be able to read through some of these impressions (even though they're subjective).

[Nate047]

Cool, yea I have tracked my E36 a lot and experienced what sounds like a similar lackluster, borderline out of control ABS feeling. I'm just assuming the MK20 E46 must be kind of like that? I have only tracked my E46 once so far and I'm just starting to get my build planned out. So TBH, the whole "buy a MK60 car" is not completely off the table. But I kinda don't WANT to do that. I feel like this mod might be inevitable down the road, and I have definitely thought about it a lot before today. But maybe I don't need to come hot out of the gate and do it first. I'm just really not confident in my own ability to putt off a retrofit like this unsupervised. I have an awesome friend who can definitely do this, but that's a biiiig favor to ask someone who's very busy with customer cars.

[bigjae46]

I felt this a lot on the track, even with stock brakes. Car would get super unstable and squirm around a ton under heavy braking. Thought it was a sticking caliper or bad rotor at first, but I checked that and it was all good. Hoping the MK60 makes the car more stable under ABS braking.

I also agree with what you say about feeling what the front wheels are doing through the brake pedal with the MK60. I've gone out a couple times when the streets are empty to test out higher speed braking (~80 -> ~40) and that was the main difference I noticed. It's hard to describe with such limited exposure to the sensation, but the feedback just feels tighter and crisper. Anyway, I'm sure I'll have more to say about this in a week or so after the track day.

I have an 818.3 unit and it seems to have a pretty high limit. I have yet to overstep the limits of the ABS or let's say the ABS has a higher limit that me at this point.

My buddy has an MK20 equipped car. I can always out brake him even when the cars were similar. He had a 4.10 diff and I was a little lighter (no cage or anything crazy at that point). Power was about the same.

[heinzboehmer]

I have an 818.3 unit and it seems to have a pretty high limit. I have yet to overstep the limits of the ABS or let's say the ABS has a higher limit that me at this point.

My buddy has an MK20 equipped car. I can always out brake him even when the cars were similar. He had a 4.10 diff and I was a little lighter (no cage or anything crazy at that point). Power was about the same.

Nice, sounds like I should notice a big difference then. Excited to try it out.

I also signed up for an autox in a month or so. Will be nice for messing around with m track mode and all that.

[thegenius46m]

Mk60 vs MK20 is drastic. Id venture to say its the end of 1990s tech vs 2000s to the teens as E9x and later used newer variants of an already drastic upgrade. I haven't driven an MK20 car but have friends with them and the big one is the ability to programmed for brake bias change due to a bbk and/or rack ratio change. Buddy and I both have zhp racks and with M track I can push very hard in the canyons, onramps, on track, etc and the system works very well with little intervention. Friend's MK20 car if he starts to push the car on a simple cloverleaf onramp dsc kicks on full force because of a rack change. So you have those issues and then just the inferior ABS system even with dsc fully disabled, I'd venture to say MK60 is a huge drivability upgrade. Large reason in the early days when I bought my M3 an MK20 car was not an option.

[heinzboehmer]

Have done some more street driving and a track day now with the MK60, so I'll give some driving impressions. This is all subjective and I'm just some random dude on the internet, not a professional driver, so keep that in mind when reading. I'll split the impressions up into the three separate functions of the system and will mostly focus on comparing it against the MK20.

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Traction Control:

This is the bit that I felt was most similar between the two modules. Traction control seems to come on at about the same threshold and allows about the same amount of spin. The one difference is that the MK60 intervention seems a bit more gradual. On the MK20, you can feel the entirely drivetrain clunking and jerking around whenever power is cut. This feeling is still there with the MK60, but it's less aggressive. Hard gear shifts with cold tires still result in the same level of annoyance when you forget to turn DSC off, though.

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Stability Control:

I'll start with my impressions about the system fully on. It seems like the slip threshold is pretty similar to the MK20. Doesn't really allow you to get sideways at all, but is much more subtle about it. The pulsing felt through the pedal is of lesser magnitude and the system seems to intervene at a higher frequency but less aggressively. All of this yields to less upsetting of the car in a turn. Biggest difference is probably that it feels like the system is intervening less, when in reality it's doing about the same. This is great because it lets you focus more on your driving inputs vs trying to work around the stability control. That being said, the system will still be just as jerky if you truly try to get the car sideways (say, when you take a sharp turn from a stop and break traction), but that's to be expected.

When M track mode is enabled, the slip threshold increases, but not as much as I thought. It seems like it works mostly on wheel speed delta between the front and rear axle. It won't let you get the car super sideways at lower speed, but it will allow slip in corners at higher speeds. I've found that the biggest difference isn't so much in the amount of oversteer it allows, but instead in the amount of understeer. With the MK20, pretty much any steering input with the front end loaded up resulted in the system activating. The MK60 with everything on is much less aggressive at this, but still intervenes a bit (especially at the track). M track mode makes it so that you reaally have to be pushing the front end a lot before it starts intervening.

I've booked an autox in two weeks, so I'll get a chance to test M track mode a bit more there, but that's been my experience so far with it. I will say that I didn't find it super useful on track. It would start getting in the way as soon as the tires warmed up. However, it was nice for catching mistakes in the first couple laps when I thought the tires had warmed up and they hadn't.

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ABS:

This is where I felt the biggest difference (and it was especially huge on track). I do have to give a disclaimer and say that I wasn't the best of scientists, though. I changed three variables at once (MK60, tires, track), so it wasn't truly a fair comparison. Regardless, I felt the difference was big enough that it was worth writing about.

I will probably book a track day at the track I'm most familiar with (Thunderhill East) and take the wheels + tires I was using before (PS4Ss) to run a couple sessions with. This should yield the most direct comparison, but for now, my bad science will have to do.

I can't speak to stopping distances, but I can say that hard ABS braking feels MUCH more controlled with the MK60. When the MK20 was on and I got hard into ABS braking, the entire car would get unsettled and I would have to actively counter steer to keep it going straight. With the MK60, this is no longer the case. I can stand on the brake as hard as I can and the car will come to a stop in a much more calm and controlled manner, no steering input required at all. The system even handles ABS braking with the steering wheel turned surprisingly well. Not that you ever really want to be doing that, but I was messing around with it on track and the car just slowed down as it turned, instead of squirming around all over the place.

Additionally —kinda like with the stability control the feedback in the pedal is significantly improved. MK60 makes the pedal shake at a lower amplitude and higher frequency than the MK20. It's a lot more confidence inspiring and gives the impression that just the unsprung bits are experiencing the effects of ABS and not the entire car. Feeling is much more refined, which makes it feel like you can tell what each tire is doing through the pedal. Probably just something I'm imagining, but it definitely feels like that.

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In conclusion, I'm happy with the swap. The ABS improvements alone make it worth it to me. If anyone close to me has a similar weight MK20 car on PS4Ss, we could do some brake tests to see which one stops better. I have a feeling MK60 will win, but it would be nice to have concrete data

[bigjae46]

ABS:

This is where I felt the biggest difference (and it was especially huge on track). I do have to give a disclaimer and say that I wasn't the best of scientists, though. I changed three variables at once (MK60, tires, track), so it wasn't truly a fair comparison. Regardless, I felt the difference was big enough that it was worth writing about.

I'm glad that you can notice a difference and it aligns with my opinion. I can't speak about traction control, I always turn it off before I deleted it.

The system even handles ABS braking with the steering wheel turned surprisingly well. Not that you ever really want to be doing that, but I was messing around with it on track and the car just slowed down as it turned, instead of squirming around all over the place.

I would suggest rethinking this. You can brake and turn...you SHOULD brake and turn if you want to run a fast lap. The MK60 has done very well for me. I have gained up to 1 second in some turns where I'm in the brakes aggressively and turning at speeds over 80mph. It opens a world of possibilities on some tracks. In fact I think this is the one reason to keep ABS vs going to manual brakes.

[heinzboehmer]

I'm glad that you can notice a difference and it aligns with my opinion. I can't speak about traction control, I always turn it off before I deleted it.

Oh yeah I ended up turning everything off after some laps, it definitely gets in your way if you're pushing even a little hard on track. It was interesting to mess around with though.

I would suggest rethinking this. You can brake and turn...you SHOULD brake and turn if you want to run a fast lap. The MK60 has done very well for me. I have gained up to 1 second in some turns where I'm in the brakes aggressively and turning at speeds over 80mph. It opens a world of possibilities on some tracks. In fact I think this is the one reason to keep ABS vs going to manual brakes.

Thanks for the tip! I still have a long way to go in terms of driving skill, so I'll have to experiment with this a bit more. The most I do now is start my turns with the brakes still depressed, but it sounds like I might be able to gain some time if I further overlap the two. Have something to work on for my next track day!

But perhaps I should have elaborated a bit more when I said that. Didn't mean it to sound like that's something you NEVER want to do in a car, but you should probably not do it the way I was doing it. When I tried this I was basically trying to be as stupid as possible. i.e. Sharp and not smooth turn of the wheel and hard slam on the brakes. Was just trying to upset the car as much as possible to see how the system responded. To my surprise it did pretty well.

[terra]

When M track mode is enabled, the slip threshold increases, but not as much as I thought. It seems like it works mostly on wheel speed delta between the front and rear axle. It won't let you get the car super sideways at lower speed, but it will allow slip in corners at higher speeds. I've found that the biggest difference isn't so much in the amount of oversteer it allows, but instead in the amount of understeer. With the MK20, pretty much any steering input with the front end loaded up resulted in the system activating. The MK60 with everything on is much less aggressive at this, but still intervenes a bit (especially at the track). M track mode makes it so that you reaally have to be pushing the front end a lot before it starts intervening.

I do wonder if the real CSL/ZCP module's M-track is any different in this regard. I should have done some scientific testing when I made the switch myself.

For that matter, I wonder about the ABS difference too with the real CSL/ZCP module. I have always read claims that it's different, but I just don't have enough seat time at the limits to say if there's a real difference.

With the ABS difference being that pronounced between the MK20 and MK60, that makes me even more curious about the MK60e5, MK100, and the actual race modules. Especially since one of the innovations with the MK60e5 is supposed to be "analog" control of the abs solenoids, which coupled with the independent pressure sensors makes me think the ABS behavior during turns could be even better

[Nate047]

Right on, good impressions. My reaction to all this is that I try my best to stay out of ABS if at all possible on track, including when I'm trail braking. Maybe I'm not getting every last 1/10th of a second though. I'll differ to the experienced racers on that, and in fact I'd like to hear what exactly is better about being in ABS vs being at the threshold just before it kicks in.

[eacmen]

Right on, good impressions. My reaction to all this is that I try my best to stay out of ABS if at all possible on track, including when I'm trail braking. Maybe I'm not getting every last 1/10th of a second though. I'll differ to the experienced racers on that, and in fact I'd like to hear what exactly is better about being in ABS vs being at the threshold just before it kicks in.

My data seems to suggest that if I stay IN abs and commit to it I stop faster than if I stay out of ABS. But most of the time if I hit ABS my instinct is to back out of the pedal.

There were a few times I intentionally went into ABS and made myself commit to it and it was better. Can’t comment on how it effects rotor and pad life.


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