devenh

Just completed the Silver State Classic Challenge with my 2005 SL65. The SSCC is an open road race where a highway (NV318) is closed and one can legally exceed the speed limit. For more info on this event, please see sscc.us.

Some observations on the SL65 at 100mph and above under dry road conditions and minimal wind. These comments reflect what I'm comfortable with, and others, with more skill, may have different opinions (my background is autocross and track day driving, skill level average).

100mph: Easy and comfortable to drive for sustained periods.

110mph: More attention required, but very manageable for sustained periods.

120mph: Car is feeling a little less stable and complete attention is required to drive for sustained periods.

130mph: At this speed and above I would not drive the car for sustained periods. This speed is fine for short bursts on straight roads. Would not go through any turns at this speed.

140mph: Car continues to get lighter. This is usually where I stop accelerating. At this speed and above you are doing everything very gently.

150mph: Only briefly ventured here. Every time I've hit 150 the car stopped accelerating (loss of power). Is there a SPEED LIMITER? I don't see any mention of one in the forums. In any event, I don't think I'd want to exceed this speed.

Again, these are just my observations and reflect my average driving skills. Your mileage may vary. Of course I do not condone nor encourage driving above the posted speed limits. Driving these speeds should only be done under controlled conditions with the proper safety gear.

Deven

kittyandgary

The 'stock' SL55 has a 155 speed limiter. There is another one at 186 mph, IF the lower one is removed via re-flash. In Europe, some of the second ones have been removed, supposedly allowing full top speed (MB tested it at Nardo and reached 203 on that large round/oval track. Eurocharged can remove the 155 limiter, and some have reported they did it via STAR.

I've reached 135-140 mph at Watkins Glen track (uphill backstretch) at least 50 times in 2 days of driving, and did not feel any of the lightness you indicate - stable as could be, but since the next corner was 75 mph max, it was time to clamp the brakes!

aeroman

Hmmmm. My SL65 is a 2007 and yes does have Renntech lowering module but I have been over 150mph on middle setting and it feels firmly planted. Now before I discovered the sport setting I was a little taken back by the suspension shifting around under hard acceleration from zero all the way up. BUT with that on its a lot different. I will never see 200mph but I could see bombing along at 150 on a lot of freeways.

RaceHorse

The car is probably hitting its speed limiter at 155 mph and or having heat soak issues if the intercooler pump is totally dead. There are many things that come into play with speed. I'm no expert but some of the simplest should not be over looked. The correct tire size, condition of the tire, speed rating and proper inflation are very critical. A slightly over inflated tire will get real floaty as it heats up and the pressure becomes even higher. The surface of the road along with dips may also create a floaty feeling. I know our cars are very different in design, but I had no problem bringing my car up over 170 mph a few times. Its limited real estate that is the biggest problem when trying to safely stop these heavy cars. The weight probably helps it feel more stable.

Benz-O-Rama

I once or twice, have traveled at 180+ mph in my SL600, in the great country of Mexico. Car is lowered, and on 20" wheels with low profile meat. 255/30/20 and 305/25/20. While my heart was jumping all over the place, the car felt rock solid. I don't start getting butt puckered until about 150 in that car. Really has nothing to do with it's stability, I'm just afraid of a Mexican deer jumping out in front of me or having to hand over my watch to The Federales.

devenh

My car is stock with new Potenza S-04 tires that were properly inflated (btw, the safety people at the SSCC are sticklers about tires, and rightfully so). Road surface was good, but not perfect, so that may have contributed to the "floaty" feel.

The cut out at ~150mph sounds like the speed limiter -- close enough to 155mph. I now doubt that it was mechanical as it happened at the exact same point at both my tries.

Deven

Sauveur

What happens if you exceed the speed rating on tires? On a couple occasions I went around 135 in my C300 and found out after the fact my tires are H rating, which theoretically means I can't exceed 130 mph.

AMG-Driver

Hi Deven,

the SL65 AMG is a VERY stable car at higher speeds. I have experience with many different Cars on the German Autobahn without any speed limit.

Fastest up to date with my car was 337 KM/H = 209,4 MPH measured with GPS on a even road.

Of course the surface and bumpiness of the road is most important for the driving feeling.

Also important is that your ABC-Suspension is in a good shape. I am changing my accumulators from the ABC-Suspension at the moment, because they go out after time, although my car has only 45.ooo KM on the clock. Then the car gets a lot stiffer and looses nearly all of its damping.

When the ABC-Suspension is in a good shape the SL65 AMG is perfectly stable at higher speeds.

In my opinion much smoother and safer feeling, in comparison e.g. to a Porsche Turbo or Lotus Esprit Turbo where I experienced the lightness in the front of the car on the Autobahn, because the motor is in the back or in the middle of the car. Completely different feeling above 250 KM/H = 150 MPH between these cars.

Cut-off at 155 MPH sounds like normal speedlimiter. Keep in mind that you reach 155 MPH in 4 gear, and the car has one more gear to go...

devenh

I checked my ABC fluid and it looks good -- just like the video in this thread:

https://mbworld.org/forums/cl55-amg-...me-change.html

Are there any other signs to look for that the ABC system may need service?

Also, how does one go about removing the speed limiter? I assume a dealer won't do this?

Deven

devenh

You shouldn't. Google "exceeding tire speed ratings." Tire Rack has a good article on the subject.

Deven

AMG-Driver

The problem is you never can really tell if your ABC needs service, because it has a subtle wear in the system over the time. When you get error codes or something is not working correctly normally the repair starts...Some change the fluid and filter every 30.000 KM, but some say never change a running system. After changing fluid some cars started to drop more than before. It is a complex system, but when o.k. the car drives very well.

I would compare the ride of your SL65 with another good shape SL65 in your area and then you know if your car drives like it should from the factory.

A reputable tuner can remove the speed-limiter in your car. Maybe you get a good, safe tune at the same time. It is worth it.

sound 8

I drive my SL65 on a daily basis and quite often exceed 150, I did do
180 in my 63 TT. It's all pretty usual driving at these speeds, I think the
more you drive at high speed the less you notice these differences.
I will say since I had it lowered with links it feels slightly lighter at high speed but it may be in my mind ever since I was told it would lift because
of lowering.

devenh

Really? I would think that lowering would reduce the airflow under the car and thus reduce the "floaty" feeling.

Deven

MJ50

fyi, u can version code it to remove speed limiter...

sound 8

I think you need a certain amount of air under the car, to suck it down,
mind you I could be wrong.
I think the problem is when the car reaches 60 the car lowers itself which
may be too low. When the car moves up and down like a pair of bellows I
think this may push all the air out then when it comes up from the bump
air rushing in might lift the front, someone who knows about this may want
to comment.

devenh

Not familiar with "version code it." Could you explain?

aeroman

What you may be feeling is varying air pressure below the car front to back.

Quadcammer

use the SDS or STAR diagnostic system to change it with developer mode. From my playing around with it, that will allow you to raise it to 186 mph, but not remove it entirely.

aeroman

So does my Renntech Tune remove it completely?

Quadcammer

I don't believe it can ever be fully removed, even with a tune. The tune, through the ECU, moves it to an unreachable point, like 300mph.

The STAR coding is actually done through developer mode in the instrument cluster control unit.