Please help me fix the understeer issues with my SL 55

Chuck Finley

Chuck Finley

205
Hi everyone,

instead of giving you insides in my tunes I ask you for help this time. I just discovered the Mercedes SL 55 AMG as a really fun car to drive. The only thing that really bothers me is the huge understeer problem of this car. Especially since it is fully tuned.

Right now I am driving the Deep Forest Raceway to Grind in Aspec because it pays out quite nicely. But I have to use the e-break for pretty much every corner and slide through them what works well as long as I stay fast enough to slide. But as soon as I get some traction the heavy understeer shows off.

Does anyone know how to fix the understeer while not loosing to much fun at the same time? I hope someone gets the idea what I mean here. I dont know ho to become more precise because I am not a native speaker (as some may have recognized :) ).

I would really appreciate every help.

Here are the fact:

Mercedes SL 55 AMG
fully tuned
Racing Softs

want to fix some understeer while not loosing to much drift fun when using the e-break.
 
Default suspension, your attempt to tune? More details... but generally try dampers down on front and rear to increase the roll and maneuverability; and rear anti-roll up to for more oversteer.
 
You could try softening the front suspension too, like the spring rate. Or stiffen the rear but softening the front on that car gave me exactly what I wanted. I also slammed the car as low as it would go. Seemed to drive fine after those two changes.
 
Remember its a heavy car so your usual driving style may not suit it. The suspension tuning on Mercedes tend to be understeer more, so slow in and fast out would be much better then speeding into the corner and trying to force that heavy front end to point towards the apex.
 
Also need to know where & when it understeers.
Entry, center, exit? On throttle, off throttle, on brakes, etc etc etc.
 
Hello everyone,

first of all thank you all for the willingness t help me.

I start with the actual setup:

Downforce
- standard

Transmission
- Top Speed : 370 km/h

Adjustable LSD (Front/Rear)
- Initial Torque : -/25
- Acceleration Sensitivity : -/35
- Braking Sensitivity : -/16

Suspension (Front/Rear)
- Ride Height : -20/-20
- Spring Rate : 6.7/5.6
- Dampers (Extension) : 5/5
- Dampers (Compression) : 5/5
- Anti-Roll Bars : 4/4

Wheel Alignment (Front/Rear)
- Camber angle : +0.0/+0.0
- Toe Angle : -0.00/+0.20

Brakes (Front/Rear)
- Brake Balance 5/5


Like I was trying to say. I really like the fact that I have to use the e-break for going into corners. And as long as I am sliding the car is perfectly controllable. But as soon as I get some traction during the acceleration out of corners the massive understeer sets in. I would like to correct only a little bit of the understeer problem while not lossing the controlability during the slides/drifts.

I hope I was able to explain it properly.

Thank you for your help.

CF
 
tighten the front up to about 10 or 11 and the rear the same, compression on dampers set to 6 for both and ARB to 5, initial torque set to 10 or so to give some more kick under throttle, especially around the corners and a little bit of - toe in the front if you want some more steering sensitivity.
 
Poppins
tighten the front up to about 10 or 11 and the rear the same, compression on dampers set to 6 for both and ARB to 5, initial torque set to 10 or so to give some more kick under throttle, especially around the corners and a little bit of - toe in the front if you want some more steering sensitivity.
Click to expand...

Nice! I will try as soon as possible. Cheers!
 
If what Poppins says doesn't work for you I would go back to your custom settings and try raising your Rear Spring Rate slightly. I would say up it to around 6.0-6.3. It sounds like your problem is weight transfer. When your on your brakes, most of your cars weight is on the front tires, allowing you to steer into the turn. I think what your problem is that when you get on the gas, most of your cars weight is going to the rear, causing a lose of traction to the front wheels, thus creating Understeer on corner exit.


BTW is the name a reference to Burn Notice?
 
Yeah I think the same thing as well, overall just a bit too loose so the weight transfers a bit much and causes some problems when trying to make sudden reactions.
 
I see two possible problems. Most obvious is zero camber. A bit less obvious, I think the suspension is way too soft for a car this heavy. As an experiment I would try doubling your spring rates and bump up the dampers to 7 or 8 and see what happens.
 
Last edited:
I thought about the Camber issue, but since he's getting good Corner Entry I didn't think it was such a problem. If your going to test for Camber I would take your SL-55 to a track like Trial Mountain. I find a you can go up to a Camber setting of -2.0 without experiencing negative effects on your acceleration.

Also I agree with oppositelock, after reviewing my tune of my AE86, I found that even with a car that weighs 825ks I'm still running a Spring Rate of 10.8 in the Front and 10.0 in the Rear. So crank up your spring height up, this should make your car more responsive, as well as improving overall cornering ability. Just keep in mind, A higher Spring Rate in the Front with Front Engine-Rear Wheel Drive cars.
 
oopssorryy
I thought about the Camber issue, but since he's getting good Corner Entry I didn't think it was such a problem.
Click to expand...

Actually, I find low front camber angles are good for turn-in. The problem is that once the weight transfers and the car starts to lean then you get the tire rolling over onto the sidewall which could explain the mid-corner understeer he's getting. The trick is finding a camber angle that walks the fine line between the two.
 
Agreed, finding the right Camber angle to suit both your car and your driving style is all important. I hope we haven't overwhelmed you with info, and I hope this helps you out!
 
here's my sl65 amg's suspension

rh -20/-20
sr 11/11
ext 6/6
comp 7/7
arb 5/5

camber at 1 for both front and rear, -0.10 for toe on front.
 

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