New Springs Fitted - Advice Please!

[jim996]

I've just fitted by 2016 M4 with a set of lowering springs. They are made by a respected tuning firm in the UK. I thought I would share my impressions.

I'm a very experienced motorcycle racer and understand how changing a bike suspension changes the way the bike turns/slides etc. I have much more limited experience of car suspension but have owned a 911 and Lotus in the past so am familiar with powerful rear wheel drive cars. I'm also very open minded on mods. Sometimes I feel that people have to rave about a mod to their car to justify the cost, I will try to be impartial.

The front of the car has a measured drop of 23mm and the rear approx 13-15mm.

I've not had an alignment done yet but these are my impressions.

More road noise at low speed, comfort setting works OK but damping doesn’t keep up over sharp bumps, edges and I quickly change to sport as the pace increases.

The car feels lower at the front and more solid and the steering is heavier. I’m using comfort and sport steering settings now, Sport Plus is too heavy and leads to "choppy" inputs to the steering wheel.

The positives are that the car rock and rolls a lot less through changes of direction and corners much flatter. The front end is very sharp and sensitive to inputs and I'm feeling more feedback generally from the chassis.

The big negative so far is that the car seems to be lacking grip from the rear wheels.

I'm using the standard Continental tyres my car came with, set at 30.5 psi front and rear (measured cold).

I did a 120 mile run through Scottish Borders on Sunday. 7 degrees C and roads covered in shite and slime. Mix of damp and very wet roads. Didn’t really get to see dry roads all day.

The car clearly has a much narrower operating window now. It feels very planted when the road is dry but it will kick the rear out a lot easier in the wet with the stiffer springs and front bias. The traction control also seems to take a little longer than before to catch the slide. It's pretty intimidating and reminds me a lot of my old Lotus Elise, exceptional in the dry but a proper handful in the wet.

I'm having to drive it a lot more carefully than before, making small inputs rather than big changes in throttle or steering.

I thought it might just be the wet roads but I've driven the car on dry roads today and done a number of runs through a long left hand curve that I drive a lot. The tyres were up to 20 degrees C and I drove the corner twice, once in sport plus and once in sport suspension settings. The front is rock solid but the rear started to break away both times as I went through 70-80+MPH. The slide is controllable and predictable but I want to increase the performance of the car rather than drift everywhere.

As I said I'm not a car suspension expert but I think the bigger drop on the front of the car had put too much weight over the front axle and unloaded the rear too much. The balance is too much to the front. If it were a motorbike it would enter the corner well but then not hold a good arc through it. If I had a HAS adjustable kit I would try lifting the front 5mm or so and testing it again.

I reaching out to see if anyone with more car expertise can offer any advice? I'm getting the car aligned on Friday so could it just be a case of the alignment or geometry being out or should I consider taking them off and either going back to standard or considering a coilover? Could the alignment be so far off it's causing the rear to break traction all the time?

I researched the springs carefully and they have been developed with a touring car driver giving feedback, they are not a cheap product and the drive is amazing right up to the point that the rear steps out and it tries to kill me!

Before anyone asks everything is fitted correctly and done up/torqued correctly etc.

Cheers

[jim996]

Just in case anyone is following this. I got the car aligned today after letting the spring install settle for a week and doing approximately 400 miles.

They aligned it to the BMW standard settings with the only difference being +0.04 minutes positive toe on the front wheels (i think standard BMW is +0.10).

What a difference. Driven home on a soaking wet road and the car is stable and grips superbly. In sport setting in the wet the rear slides predictably now instead of snapping sideways and it's night and day to how the car was before.

Very happy with the result now. I'm going to try coding in the CP damper settings over the Christmas break just to see if that makes any difference but the car is very good so if I don't feel any change I will just leave it in the 58.0 standard car settings.

In summary a well designed set of performance springs is a good (cheap) performance upgrade.

[jim996]

Again just for an update if anyone is interested in this. I coded in the Competition Pack VDC damper settings today after getting significant help from Shawn Sheridan.

I've only driven the car around 20 miles today on very cold and damp UK roads (4 degrees C) but I drove the car in near identical conditions yesterday so here are my impressions. My car is fitted with Litchfield lowering springs.

I don't think the CP settings are necessarily any "stiffer" than the standard package (if they are then it is only slight) the difference is that they seem to work much better. My car has more rear traction today than it did yesterday on horrible cold, damp roads.

In my opinion I think that the major change in the CP damper settings is a closer balance between the compression and rebound circuits in the shocks. On the standard settings it felt to me like a very stiff compression circuit was overpowering the weak rebound. The car is a lot less "choppy" and busy over the bumps than it was yesterday and seems to be nicely planted now. I didn't notice it floating on the rebound circuit and it was harder to break traction in second gear when flooring it in a straight line.

The steering felt slightly lighter as well which might be consistent with less compression damping.

Comfort. Decent ride quality and seems to absorb the bumps quite well.

Sport. Slightly smoother ride, less choppy over the bumps and the car feels nicely planted. This is the "go to" setting for me on this car.

Sport+. This is the biggest improvement, I found this setting to be almost unusable on the non CP settings, the compression was so hard that the car just bounced off every bump and quickly lost traction at the rear. The CP settings seem to have improved the compliance in this setting and keeps the tyres in contact a lot better than before. It's still too stiff and broke traction but I put this down to the cold tyres and damp road surface more than any fault of the car. On hot, dry, smooth tarmac this will be amazing.

This is well worth trying if you have a non-CP car and (relatively) easy to do. I'm not particularly tech savvy but managed it with enough time invested to figure it out stage by stage. Cheap/Free upgrade.

[jim996]

Final update on this. I coded the ZCP ICM settings into the car last night. I tried loading the CP DSC settings as well but they kept throwing an ABS fault code, in the end I just settled with updating the DSC from 58.0 to the latest, non-CP DSC settings.

What a difference to the DSC....the car just hooks up now and surges forward, the ABS light flickers a little bit but I couldn't feel it cutting the drive off to the wheels like it did in the 58.0 settings. This is a huge change in feel from 58.0.

I couldn't really tell if the rear diff is doing anything different now but the car seems to hold traction better over broken and bumpy tarmac.

I ran the car for 25 miles over my usual route first in sport and then sport plus settings. The CP sport plus setting is excellent now, definitely softer compression than in the 58.0 version but really works well and the car gripped on cold, damp tarmac.

In summary, I'm much happier with the handling now. It's like a different car, It's taut and predictable and nowhere near as edgy, the springs, dampers, DCT and diff seem to be working much more in sync with each other than they did on standard springs and 58.0. I've also got a sport+ setting that is usable on UK roads.

In my opinion BMW should supply a £60k car like this in the first place. When a major improvement in software becomes available they should get in touch and offer it to customers as an upgrade. I'm not expecting them to do this for free and most people would be happy to pay £150-£200 for the massive improvement in handling. We shouldn't have to rely on forums.

A big thank you to the very helpful members on here who were good enough to answer all my stupid questions and help me with the coding. Cheers.

[M4 CSL]

Nice write up.

I am ready to update to either a ZCP or I may wait until March to see what the LCI offers or even if they do a CS.

So I went and drove the ZCP, even with its extra power its still slower than my Akrapovic fitted standard car,

The ZCP is a much better car than mine. Will transfer Akra and MSR over to it. I 100% agree sport+ is useless on the standard car. This was the first thing I noticed about the ZCP. Sport + is usable.

The steering felt much lighter in ZCP, But hopefully that will firm up when I play with suspension and tyres.

The diff is so much better in the ZCP. Its hardware and software in ZCP.

My car shimmys under power. I can feel the car wiggle from left to right, its aweful. Being a control freak, I start to counter steer everytime it does it.

The ZCP is far more refined and tracks straight. Trying to Hold off for LCI or CS, but getting itchy to grab a ZCP. ZCP is definitly what the M4 should have been.

[jim996]

Try springs and coding. It's only cost me 470 UK pounds all in. I was at the point of going for Ohlins coilovers on my car but tried this first. Your car will handle like a ZCP with the coding done.

I've driven a 14 car which was like a hammer and I thought my 16 car at 58.0 was much better but the latest traction control and damper settings just transform it, 425 BHP driving forward instead of sideways is incredible.

[A47]

Which tuner's springs?Thanks

[jim996]

http://www.litchfieldimports.co.uk/s...sDG0JHp&2NwDQc

[Fblade]

Nice write up OP, I have one of the early cars but have been holding off doing this change as worried about the warranty but i think it's time to do this anyway.
Do you have any tips or things you noticed for a first time coder?

[jim996]

Originally Posted by Fblade

Nice write up OP, I have one of the early cars but have been holding off doing this change as worried about the warranty but i think it's time to do this anyway.
Do you have any tips or things you noticed for a first time coder?

Just don't be in a hurry with the coding. You need to understand what you are trying to do before you do it but I found I still had to learn the hard way with a couple of times.

If/when you fuck it up and your car throws a huge error code and doesn't work any more.......don't panic. There are guys on here who are very helpful and will patiently answer all of your stupid questions and provide a step by step fix.

Good luck!

[elmerzasty]

Originally Posted by jim996

Final update on this. I coded the ZCP ICM settings into the car last night. I tried loading the CP DSC settings as well but they kept throwing an ABS fault code, in the end I just settled with updating the DSC from 58.0 to the latest, non-CP DSC settings.

What a difference to the DSC....the car just hooks up now and surges forward, the ABS light flickers a little bit but I couldn't feel it cutting the drive off to the wheels like it did in the 58.0 settings. This is a huge change in feel from 58.0.

Could you please list the coding changes you did to the ICM and DSC?

[jim996]

I tried to turn on the CP settings in 58.0 but the car threw error codes.

I found I had to code in the latest 60.2 CAFD files to VDC, ICM and DSC before I could get the settings to change to CP.

CODING

VDC - Coded CAFD - M Competition High / Ausgelesen Aktiv - Werte = 01
VDC coded Fahrzeugtyp F82-Comp / Werte 28

Module | Parameter | non-ZCP | ZCP

ICM | IcmKod_I_Karosserie | 0C | 1A MY car is L6CD F13, F82_OD changed to F25L7_F82CP

I couldn’t get the competition DSC settings to work but pack I just flashed the latest 60.2 CAFD Files in instead

DSC | C_Variante_Fahrzeug_e | 00 | 03
DSC | DSC_CODIERDATEN_RDCI_18_18_2 | nicht_aktiv = 00 | aktiv = 01

[aboulfad]

Originally Posted by jim996

Module | Parameter | non-ZCP | ZCP

DSC | C_Variante_Fahrzeug_e | 00 | 03
DSC | DSC_CODIERDATEN_RDCI_18_18_2 | nicht_aktiv = 00 | aktiv = 01

can you please state the Launcher Premium Version and Esys you are using ? I am curious why some of us dont get the unknown parameter named as in your case DSC_CODIERDATEN_RDCI_18_18_2. In my case, I suspect it is the last UNBELEGT parameter with storage info (Start = 18, End=18, Bitmask=11111110) in DSC Group 3008.

Furthermore, doing a "What-If SVT-CAFD" and selecting Option 7MA doesnt show that parameter, comparing both versions of CP and non-CP for DSC shows that the parameter is set to 0.

[CanAutM3]

I would start by getting a GOOD alignment done. That makes a big difference on how well planted the car feels. Without that, there is not much discussion to be had.

Further, without knowing the rates of your new springs, it is difficult to comment.

One observation from mine, is that the base M3/4 has too soft springs in the rear. Installing Eibachs on my car, which increases the rear rates more than the front brought better balance to the car, with more predictable breakaway characteristics. BMW did the same thing with the CP increasing the rear spring rate proportionally more than the front.

So if your aftermarket spring increased the front rates more than the rears, that could explain what you are experiencing.

[inti]

I'm no M owner (yet), but I have a question.
The coding that you've done... I'm guessing that your M4 was not CP originally?
What if you would get CP in the first place and lower it? Would it still need additional coding to get the max out of it?
Thanks.

[gripenM]

Originally Posted by jim996

Final update on this. I coded the ZCP ICM settings into the car last night. I tried loading the CP DSC settings as well but they kept throwing an ABS fault code, in the end I just settled with updating the DSC from 58.0 to the latest, non-CP DSC settings.

quick question OP,

did you try resetting the ICM the first time around right after installing the springs?
that way, the EDC system will know to recalibrate for the newly lowered height.

wondering if coding for the CP setting inadvertently also reset the ICM and that's why you're feeling a big difference.

you can also measure the height before and and after lowering to let the car know to adjust its headlamp to its new height.