2021 AMG C 63 S Sedan classed in FS?

[Todd Giencke]

Barb says that the BMW M2 Competition is too masculine for her liking.

I'm thinking 2021 AMG C 63 S Sedan is classed in FS. Correct?

(clarification: We are looking at the coupe version due to wheel width as discussed below.)

[Faust]

Out of curiosity, I looked at the 2021 SCCA Solo rules, and it looks like they don't list any 2021 models yet. It does say "C63 AMG (non-Black Series) (2008-20)" in the F street section, so that seems promising.

That car would be an interesting transition from the Miata!

[Todd Giencke]

Out of curiosity, I looked at the 2021 SCCA Solo rules, and it looks like they don't list any 2021 models yet. It does say "C63 AMG (non-Black Series) (2008-20)" in the F street section, so that seems promising.

That car would be an interesting transition from the Miata!

It's for Barb, I'm still in love with the RF.

[Shane86]

going to have issues getting enough rubber under it to be effective in class.
8.5" and 9.5" stagger's pretty rough for a car with 503hp and that much weight.
The coupe's got 9 and 10.5 respectively, which will help.. but good lord it weighs 4100lbs... shockingly the sedan is only 3900..

[Todd Giencke]

going to have issues getting enough rubber under it to be effective in class.
8.5" and 9.5" stagger's pretty rough for a car with 503hp and that much weight.
The coupe's got 9 and 10.5 respectively, which will help.. but good lord it weighs 4100lbs... shockingly the sedan is only 3900..

I didn't notice the difference in wheels. Thanks!

The whole weight thing is something I just can't avoid with current cars. So... FS is looking better... Even "the FS car to have" 2011 BMW M3 is 3,700Lbs on the same width wheel (I think).

Our requirements for Barb's car are:

1. Must have 4 seats with the rear seats folding down.
2. Must be rear wheel drive (only).
3. Must have an automatically shifting transmission without a torque converter e.g. dual clutch transmission, AMG MCT, Porsche PDK, etc. These are popular with German brands, and rare otherwise.
4. Must have an actual limited slip differential (not using the rear brakes to "torque vector").

I actually really like the BMW M2 Competition (classed in BS). Yes it is still a lot of money, but compared to others that meet the requirements it's a steal.

[Shane86]

The whole weight thing is something I just can't avoid with current cars. So... FS is looking better... Even "the FS car to have" 2011 BMW M3 is 3,700Lbs on the same width wheel (I think).

Almost. 2011-2013 M3 ZCP wheels are 19x9 and 19x10.

Our requirements for Barb's car are:

1. Must have 4 seats with the rear seats folding down.
2. Must be rear wheel drive (only).
3. Must have an automatically shifting transmission without a torque converter e.g. dual clutch transmission, AMG MCT, Porsche PDK, etc. These are popular with German brands, and rare otherwise.
4. Must have an actual limited slip differential (not using the rear brakes to "torque vector").

I actually really like the BMW M2 Competition (classed in BS). Yes it is still a lot of money, but compared to others that meet the requirements it's a steal.

BMW sold the ZCP package in the Sedan in 2011, and there was an option for a fold down rear seat. That's going to be the car that's competitive in FS that will check all your boxes. The rear seats are actually very usable in the coupe of the same gen, as it's effectively the same wheelbase with longer front doors.

The F80/82 Non-CS would also be in B-Street, has a competition package (Not the CS, but the wider wheels are important) and should be in the hunt in BS. Would likely be better accepted and again, checks all boxes. https://f80.bimmerpost.com/forums/sh....php?t=1214853

BMW's out of the box shock tuning on comp-pack cars have been awesome, most people in FS are just on factory shocks (including champions) leaving the only mods needed are smaller/lighter wheels and a front sway bar.

There's a lot of factors in looking at stock class cars a lot of people gloss over. how much front camber can you get out of a merc? what are your tire options on the wheel sizes available? are there any feature packages that are big give/take.

I basically went through this same exercise 2 years ago when i moved to LA, with the same specs (except the seat) and the E92 M3 was the only one that checked the boxes and was still actually fun to drive, and in the budget.

[Shane86]

and FYI, I drove a M4 Comp in Germany a few years ago.. it was really, really good.

[Todd Giencke]

There's a lot of factors in looking at stock class cars a lot of people gloss over. how much front camber can you get out of a merc? what are your tire options on the wheel sizes available? are there any feature packages that are big give/take.

Well I went through all of the tire math and here is the autocross tire package:

Yokohama Advan A052 Front: 275/40-18 (down-size 1" diameter, should fit over the brakes because this is an OEM diameter option) Rear: 285/35-20

The RPM ratio front to rear is <2% different from stock so the traction control should be happy.

The tire package is $1,422.25 total with tax. To put this in perspective the same tire on the MX-5 is $803.47 total with tax. A 77% increase (Ouch!)



The front suspension is double wishbone so I am hopeful that front camber isn't going to be much of an issue (maybe on concentric bolts like the MX-5?). The rear suspension is multi-link.

[Todd Giencke]

Well…. It is good to look at all the small details. Thanks again!

We want the S trim for certain modes that the electronics do (9 stage driver selectable traction control (reminds me of a GT3 race traction control), launch control for ProSolo, etc.). But with that, the 15.4” ceramic brakes with 6 piston mono-block calipers come stock. Ummm, yeah I don’t think I am going to get an 18” wheel over that. The rear brakes are iron 14.2”. I guess this is what you get when you develop a car on the Nordschleife.

So… I guess OEM width tires are going to be needed… Nordschleife comes to mind again.

The front tires are going to be:
A052 255/40-20 (increase in diameter by 1” from OEM). The diameter is almost identical front to rear, and within 2.5% front/rear ratio from OEM so the traction control should be happy.

At least the tire price decreases $53. Yeah, still a lot on consumables.

[Shane86]

We want the S trim for certain modes that the electronics do (9 stage driver selectable traction control (reminds me of a GT3 race traction control), launch control for ProSolo, etc.). But with that, the 15.4” ceramic brakes with 6 piston mono-block calipers come stock. Ummm, yeah I don’t think I am going to get an 18” wheel over that. The rear brakes are iron 14.2”. I guess this is what you get when you develop a car on the Nordschleife.

For street class use, I'd say this package isn't worth the cost and limitations it puts on setup. Those rotors are $$$, the traction control is practically useless for autox use, and launch control? look into the restrictions on it. Some cars will have limits around mileage between launches, time, or other equipment variables making them only functional for the first launch in a prosolo round. But to restrict your wheel/tire package options that badly, i'd say the value isn't there.

Ask around in Merc circles if tire OD stagger is actually a problem. BMWs don't care as they recalibrate on the fly, and again, opens more options. if you can get to the same size front and rear, even if pinched can help you cut tire costs huge..

Multilink/double wishbone is helpful, but rarely is the dynamic camber curve anywhere near what you're looking for. knowing what the factory sweep is would be good data.

"Nürburgring designed" is so much marketing fluff it hurts.

TBH, as an FS driver, nothing I've seen about this vehicle in class would make me worry about it being at the top of the class, and I'd be surprised if it trophies nationally.
Sure it has more horsepower than the currently dominant E9x M3s, but considering you're already talking about putting it on less tire than the M3s you're not going to be in any advatage putting it down. Trust me, i can pretty much light them up anywhere i want. Stack on top of that over 550lbs.. feels like you're buyin an also-ran before it leaves the line.

Hell, the Camaro SS is in the same class.. 455hp, 3685lbs. (120lbs more than m3).. 20x8.5 and 20x9.5 stock wheels.. They fall on their faces. Yes, you could get it done, but there's functions of the stock vehicle you just can't change (ABS has been a big complaint, lack of front camber, and imho throttle mapping in "competition" mode) in street class that you cannot legally correct that make them not only underdogs, but just straight frustrating to drive. Sure it's good on paper, but if you can't get it there, and you hate every minute of trying.. why do it?

[Shane86]

Just because i was thinking about it on my.. ehem... constitutional i took after writing that..
9 speed gearbox.. have you run the numbers on what per-gear redline looks like for autox speeds? with your planned tire sizes?

I have a feeling you may find that you're between gears in the 30-70 range pretty regularly. Yes, it's a DCT that "Shifts lighting quick" but where you have to shift can be a problem, and a lightning quick DCT downshift can still put your ass around if you're trying to do it at the wrong place. (ask me how i know.).

It's worse in this case being a traditional manual box, but it's the exact thing that makes 6-speed NB miatas pretty terrible for autox use. second's too short, 3rd's too long, and you're working between them a lot.

[Faust]

https://www.reddit.com/r/Autocross/c...8s_prodigious/

looks like a handful! I think I would enjoy listening to it drive the course.

[Todd Giencke]

Maybe Saturday morning I’ll have some time to write.

Just a couple of points.

The car is for Barb not me. She isn’t looking for a national trophy. We are planning to move to Houston and be a part of the autocross gang there and members at MSR Houston. Barb likes driving DCTC track style. Barb is trending to not being a momentum type of driver. The traction control is always going to be on. And I think it’s going to a heck of a lot of fun trying to keep up with her at MSR with the RF.

But I like the process and maybe others like to read this stuff. I don’t know. Got to run!

[Todd Giencke]

(Smiling inside) Barb said to me today that she wouldn't feel comfortable in the AMG on any track; and maybe we should get the BMW M2 Competition.

Yeah I said that probably would be a good thing. And we could install the Ohlins Road & Track shocks revalved for the OEM springs (and softer blow-off valve), and have the piano black center console & center dash replaced with mahogany wood. Barb said yeah that would be nice. Once we move out of MN. Yes honey. :-)

[phile]

https://www.reddit.com/r/Autocross/c...8s_prodigious/

looks like a handful! I think I would enjoy listening to it drive the course.

The flexing of the camera mount makes me queazy.