Hey all,

Wondering if you have any tips/tricks regarding STAR lowering. I only have one shot at this as Ill only have access to STAR and the alignment rack once. With that said, I want to make sure i get it done correctly. Would absolutely hate to be done and have the heights change and end up with a backwards rake or have the height change after a short drive as that means my alignment was a waste.

My questions are:

1. Should i raise/lower the suspension up and down while doing it to make sure it sets correctly?
2. Keep the car running the whole time?
3. Should the driver be in the car so the ride is set with the correct weight on the drivers side?
4. Is it the final angles, as measured by Romess, that actually set the heights? How crucial are these angles?
5. Any special instructions when doing an alignment after lowering? Will the MB alignment machine know to compensate for the lowered stance? I know camber/caster are not adjustable, so i'd like to set my toe to a perfect 0 to lessen the tire wear.

Any and all info is greatly appreciated. I will post the procedure and results for anyone interested.

 

1. Should i raise/lower the suspension up and down while doing it to make sure it sets correctly?
-not necessary. So long as you drive it onto/into the location where you plan on adjusting the height. If, however, you lifted the car via the jack pads and then lowered it, the car will sit several inches high until you drive it again.

2. Keep the car running the whole time?
-not necessary

3. Should the driver be in the car so the ride is set with the correct weight on the drivers side?
-eh...you could weight the seat if you wanted; it isn't necessary but it won't hurt.

4. Is it the final angles, as measured by Romess, that actually set the heights? How crucial are these angles?
-negative. It is the angle referenced to the sensor voltage. Example: Rear sensor voltage should be between 2.3 (highest height) and 3.0 volts (lowest height).
-I calibrated my suspension to raise the car to correct terribly negative camber and an uneven front suspension. Sounds like you are wanting to lower the car so the rear sensor (for example) is reading 2.9 volts. You can then measure the axle angle but you will enter a false value that corresponds to a "tall" ride height. i.e. rear axle measures -2.2 degrees, but you enter -1.2 degrees. The computer is now mis-calibrated and keeps the car at the lowered level. A negative measurement on the rear axle means the outer end of the axle is higher than the inner end of the axle.

5. Any special instructions when doing an alignment after lowering? Will the MB alignment machine know to compensate for the lowered stance? I know camber/caster are not adjustable, so i'd like to set my toe to a perfect 0 to lessen the tire wear.
-you have to measure and adjust alignment. The toe is the most important; you DO want toe in on the rear tires! This acts much like the fletching on an arrow and adds stability. Toe out will have the car trying to swap ends. I set mine to 1.5mm toe in on each side. Front is only 0.5mm toe in; zero will work but toe out will make the car "darty"; that may be fine on a Miata for autocross but most certainly what I do not want on my road cruiser.
-camber adjustment up front is limited to about 0.5 degrees plus or minus the initial starting point although you can swap caster for camber (which creates other issues). Rear camber is non-adjustable unless you use KMac on the inner bushing or SPC adjustable bushings on the hub. The SPC bushings will only work with non-AMGs. The non-AMG hubs use M12 bolts, AMGs use M14 bolts; not enough material to allow the use of the SPC parts on the AMG hub without risk of catastrophic failure. On non-AMGs should be fine.

 

#4 - It sounds like I shouldnt use the Romess and that I should just enter 3.5 in the front and -1.1 in the rear in order to keep the lowered stance (I see those values referenced when talking about lowering in a few threads here).
Am i understanding that correctly? Use F4, F6 and F8 to achieve desired height, then enter 3.5 and -1.1.

Once complete, sounds like i wont need to drive the car and i can just go ahead and start the alignment.

#5 - Lastly, you gave me MM toe measurements. Any idea what that will equate to on the alignment rack in degrees? Would like to set-up per your recommendation.

 

Front toe range:
0.03 to 0.13 degrees.

Rear toe range:
0.05 to 0.29 degrees.

Error in my above post; just checked my maintenance logs and I set the rear toe to 1mm toe in on each side. With my wheels that is close to 0.17 degrees toe in. Tangent(0.17 degrees) x 495mm (the physical diameter of my wheel at the edge of the rims).

 

The person doing the alignment should know this ,look for a guy who does lowered cars

 

My buddy is doing this with me. He's a good MB tech but he is one of those guys that believes that anything other than stock is wrong.

 

Here we go with them guys lol

 

Hey bbirdwell,

wondering if you can confirm the above for me.

Thanks for all the help!

 

Yes, that will work so long as the sensor voltages are in the range specified in the diagnostic system. i.e. rear sensor 2.3 to 3.0 volts the system will accept a -1.1 degrees even if it is a true -3.2 degrees (I'm exaggerating here). If the sensor voltage is 3.05 or 3.22 volts, the car will not take the angles you enter; you must be in the voltage range specified. Sort of a "fail safe" mode.

 

So lets say my angle range is 3.05 to 3.22, should i pick the very middle angle (3.13) so that my desired ride height is directly in the middle, as sort of a neutral? Similarly if the rear angle range is -2 to -1, i'd put -1.5. Is that correct?

Im still trying to understand this fully. From what i gather, and correct me if im worng, you adjust height using a measuring tape and the F keys on STAR. Once set, you input ANY angle value, and what that does is tricks the computer into thinking that the angle is, for example, 3* at the specified voltage. Being that the angle is within acceptable range, the specified ride height is now stored as the default height and the computer thinks that you are sitting at normal height. The computer on its own cant measure the angle so it doesn't know that your angle input is false.

Am i making sense? Am i getting it?

 

Two different things.
-Sensor voltage range, rear axle: 2.3 to 3.0 volts. So long as the voltage reads in that range, the next step of the process will accept your axle angles. If the sensor voltage reads 2.2 or 3.1 volts, the next step will *not* accept your axle angles.

-Axle angles, rear axles: -0.9 degrees to -1.5 degrees. As you lower the car, the angle goes more negative.

Example: My car's rear ride height was 25 3/8" at the fender roll. Axles reading -2.8 degrees on side, rear camber -2.3 degrees each side; I raised the rear of the car 1 1/2" to 26 7/8"; axles reading was -1.2 degrees per side, rear camber -1.7 degrees each side.

Voltage value went from ~2.8 at the lower height to ~2.4 at the higher height. I didn't car about the voltage so long as it was between 2.3 and 3.0. I stepped into the next screen, entered -1.2 degrees, pressed "yes" to perform level calibration, and it was accepted. The computer now calibrated to accept ~2.4 volts as equivalent to an axle angle of -1.2 degrees.

If I'd left the car lowered with the voltage at ~2.8, and then entered -1.2 degrees, the car would accept that as calibrated (albeit incorrectly) and I could continue to drive around with a car with extreme camber and 1 1/2" lower than what I have now.

 

Gotcha!

Since I am only looking to lower 0.50", i shouldn't have any issues with getting out of the angle or voltage range.

Ill lower 0.50" all around by dropping the voltages. Once at desired height, ill go to the next screen. I will proceed to measure the control arm angles and input them as I measure them with Romess. Once again, I shouldn't be out of range since i'm only going down half and inch.

And at that point I hope to be sitting pretty at 25.75" all around. Most importantly, I hope its level all around. My right side has always been 0.20" taller than the left and has been driving me mad

 

V Amg make sure you drop a tad more up front to give it the take look like I did .front fender is cut higher then rear

 

I want to be at 25.75" from fender arch to floor on all 4 corners, which will mean that front will be dropped a touch more than the rear.

Really looking forward to it. Doing it tomorrow night.

 

I checked again with a new tape 25.25 front 25 rear I'm ver happy

 

Amazing photo. I'll post mine when its all done

 

Thanks v Amg

 

Update on my attempt to lower:

Goal was to set it at 25.75" from fender to floor on all 4 corners. Car kept on weirdly changing heights on us. We'd adjust it all perfectly level then hit vehicle raise then lower and usually end up 0.25" off. Most of the time end up with 0.25" higher than measured and front passenger 0.50" higher than measured.

After numerous attempts we set it where we thought it was finally level after raising and lowering. I drove home and when i parked, left side is perfect but front passenger is 0.25" lower and the rear passenger is 0.50" lower. So its all over the place.

After 3 hours all i can say is shoot me... afternoon wasted, car doesnt sit level and the alignment is clearly going to need redoing.

How'd you guys do it? Any ideas what happened with me tonight?

 

Hysteresis. The system has a +/- 10 mm tolerance before it will adjust height. That's over 3/4".

i.e. you measure it when it is -7mm from calibrated value, drive it, the car for whatever reason goes to > -10mm low, car suspension system adds air, targets the calibrated ride height, but overshoots slightly. You park the car and measure it at +8mm from calibrated value. Difference between your first and second measurement is 15mm (8mm -(-7mm)). That's over 1/2". See attached.