12-31-2021, 10:38 AM | #1 |
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Testing new car - times, brakes, launch issues?
Hi all,
Just got 2018 M5 (non-comp) - almost fully loaded, 45k km on clock, CCB. Car is fresh out of service (new plugs, oil) & has warranty so doing now rounds of testing to see if I should be addressing something as my old car (G30 540i) had lots of issues that haunted me for a long time. Few things I want to check in with experts (you ) here: 1. Took car to airstrip and tested some 100-200 runs. Car logs 7.6-7.7 at 13C & 122m DA & 75% humidity. To me this is a bit slow - I was expecting 7.2-7.4 max. For americans 60-130 was 8.9 2. Breaks work fine during city driving. But during LC (sport+ all, S3 trans, DSC off - flag showing) with break fully depressed car just crept forward after as breaks couldn't hold it it seems. I get that CCB need temp and was tiny bit wet, but this doesnt seem right no - car was after 15mins of normal driving? Anybody with carbons here can confirm car holds on LC normal? 2.1 Note to that -> braking from high speed (200km/130mph+) the car breaks barely better than my 540 I feel; further looks like something is off 3. During launch - does one need to be in S3? Or does D3 work too? When I tried D3 - car didnt show flag, in S3 it did, but shifted to 2nd at 5000 and then bounced off the limiter at 7200. I thought during LC car should shift itself even in S3 trans setting no? Please let me know to any of these points. I can take car in to get checked. Maybe Im not doing somethign right though. THANKS A TON! |
12-31-2021, 06:57 PM | #2 | |
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2 - the car shouldn’t creep during LC, regardless if it’s wet. If the car is able to engage LC, it means it’s up to temp (and the brakes are gonna be fine too) 3 - yes you need to be in S3 and it should shift itself in LC as long as you don’t take your foot off the throttle kickdown or try to shift it yourself. Then it will act like normal S3 and you may redline it. Sometimes they short shift if the car detects wheelspin unfortunately so there’s nothing you can do about that besides get stickier tires really. On my pilot sport 4s I rarely spin tires so it doesn’t short shift and goes through all the gears. I’d check on the brakes/brake pads for the issue of the brakes not holding you at launch. If you want to try something, maybe do a very brief burnout in rwd when your car’s brakes are cold (so let the car get up to temp and try it, maybe drive it around your airstrip or neighborhood or something but try not to brake if you think cold brakes could be the issue) and see if the car can hold it. You just want to see if the brakes can hold the car while you’re giving it throttle. If the brakes will physically not hold the car still through the burnout then yeah something is wrong. Congrats on the car by the way! Have fun |
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luke1990134.50 |
01-01-2022, 03:50 AM | #3 |
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When you say car crept forward are we talking like the car is continuously moving or it kind of jersey like 1-2cm? That jerk is normal (also just make sure you were actually launching the car because even with the flag showing you can sometimes screw it up and it'll deactivate launch control and I promise you at full throttle those brakes will 99% of the time not hold. Not sure how LC works exactly with the f90, but on the f10 if you pressed the brakes too hard it would deactivated the LC and you'd find yourself flooring it lol.
As for the trans not shifting you have to be passed the click on the gas pedal the whole time or it will deactivate launch control and the automatic shifting. |
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luke1990134.50 |
01-01-2022, 04:59 AM | #4 |
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My 2019 M5C does 7.3 for the 100-200 kmh.
And brakes like no tomorrow
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22 M4 Competition xdrive
19 M5 Competition sold 16 F-Type S AWD sold 11 Audi RS5 Misano Red--sold 08 E92 M3 Jerez Black 6MT--sold 08 E92 335i 6MT traded in for M3 |
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luke1990134.50 |
01-01-2022, 05:12 AM | #5 | |
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@3 - there was a lot of wheelspin - hopefully thats the issue. It shortshifted to 2nd & then bounced off the limiter in 2nd without me taking the peddal from the floor :/. To confirm - if I would be in D3 it wouldn't engage LC (i.e. show the flag), but should be able to brake boost in theory again without creeping right? Will do a test today and see if things changed |
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01-01-2022, 05:15 AM | #6 | |
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For LC my understanding is you need to fully depress the brake and then the gas pedal beyond the kickdown point no? For the shifting - I think I was, but lets see - will try again today |
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01-01-2022, 04:13 PM | #7 | |
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Try doing it without LC, aka put it in d3 flag off, put your foot all the way down on the brake and then mash the gas, if the same exact thing happens you probably didn't activate LC right the first time lol. If it holds on the brakes something else is screwy. During the time where the car is creeping is the flag on the whole time? What about after you let go of the brakes? And another thing your rpm could just be set too high for LC, you can use the cruise control button to set it lower especially if there was enough wheel spin for the car to take itself out of LC mode (again more safety bs) |
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luke1990134.50 |
01-03-2022, 06:50 AM | #8 | |
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In D3 it creeps too - but shouldn't either I think. I tried this again yesterday and crept again - with a flag in S3. The shop says breaks are fine :/ - but we will investigate more tomorrow. During the creep it does it after first maybe half a second - which it shouldn't. I didn't mess with any LC setting and its boosting to less than 3k on stock map. So this simply shouldn't happen. My 540i with 700hp and boosted LC with xHP held on the line with those brakes . Something is off Last edited by luke1990; 01-03-2022 at 10:44 AM.. |
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01-03-2022, 12:26 PM | #9 | |
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Make sure there are OEM carbon pads on there. Aftermarket pads may not adhere to the surface well enough, which could explain the creep and the crap braking. Shawn |
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luke1990134.50 |
01-05-2022, 05:42 AM | #10 | ||||
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