GregMB

Did the installation of the "RennTECH" (aka Marcus ELMv2) a couple of days ago and everything seems to be pretty good.

I'm taking a methodical approach to get the car at a ride height that looks good, but I'm running into a bit of an issue.

Here are my initial "stock" measurements before the ELM install:

Tire Pressures:

Front - 32 psi
Rear - 35 psi


Fender Heights:

LF - 26.250"
RF - 25.875"
LR - 25.750"
RR - 25.750"

As you can see, even from the factory the car seems to sit slightly "off" from corner to corner. I checked these numbers a few different times on level pavement to make sure they were consistent.

So here's where it gets interesting.... with the ELM installed, am now sitting at the following values (number in parenthesis are my current ELM settings)

LF - 25.250" (-1.6")
RF - 25.250" (-1.6")
LR - 25.000" (-0.4")
RR - 25.500" ( n/a ) <- Only one setting is available for the both rears.

Most of you know that the rear suspension only uses a single height sensor, so there seems to be no way to address the fact that my right rear fender is sitting about 1/2" higher than the other side...... or is there?

I found an old post from Finny that indicated there might be a way in STAR to airdown the bags and reset them which might make it sit more level. Failing that, I'm not sure if there's a way to increase pressure in one of the Airmatic struts to level things out? I'm concerned about adding too much additional pressure to a single corner and introducing "cross-jacking" effects (kind of like a badly corner-balanced car setup)

My guess is that I'm not the only one who's come across this phenomenon, so I figure someone might have a solution. Obviously up front I can set each corner perfectly, but out back it's a bit tougher to understand how I'm going to resolve this.


Thanks!

-G

GunMoto

I adjust the front corners to articulate the diagonally opposing rear corners, but since both your front sides are even, there isn't really any other way to independently adjust each rear side unless you confirm STAR can actually "reset/re-calibrate" the airbags.

Subscribed...to see if there's a practical solution to this issue.

taurran

The rears on most of these cars are very slightly uneven. I stopped worrying about mine long ago.

GregMB

How far off do you run your settings on the ELM? (Left vs Right drop values?)

I played with a few more at lunchtime, drove around for a bit after each adjustment to settle the suspension before taking the measurements.

I left the rear set at -0.4 and only adjusted the front airbags.

Experiment #1:

LF (-1.4") = 25.375"
RF (-1.8") = 25.500"
LR = 25.000"
RR = 25.875"

That one was pretty bad, I had 7/8" variation across the back wheels, so I tried pulling one front down and pushing one up to see if I could affect it.

Experiment #2:

LF (-1.0") = 25.750"
RF (-1.8") = 25.500"
LR = 25.500"
RR = 25.625"

In this one, I was able to get the rears REALLY close to the same but I had to trade-off a little bit up front to get it.

As a side note, it does seem like I'm using an awfully large "correction" value on the front corners to get things to sit level.... more than 3/4" difference between the LF and RF wheel settings.

Seems excessive to me, but I'll keep messing around with it.



Thanks.

-G

GregMB

I'm kind of surprised at how inaccurate the values on the display are relative to the amount of change I "actually" get with the settings.

I haven't full dumped all the settings, but it seems like there's no way I'd get 2" lower (the max setting) all around. Even at -1.6 the true change is only 1" at the fenderlip.

Do you guys set your ELMs in "Comfort" mode, "Sport 1" or "Sport 2" mode? So far I've been doing everything in Comfort since that's where I typically drive anyway.

I was also wondering if using the "Raise Vehicle" button could be useful to help settle the suspension between changes.....or maybe just turning the ELM "off" so that everything returns to factory height before making the next set of adjustments? Hmmm......


-G

saleen01

u may have to start over....turn off the ELM set up the factory ride height again (or even Star lower it a bit) and then see what happens, my rears are off a tiny bit also...just decided to live with it.

GregMB

I just got a text from Bruce @ T/T/M.

He says that the right front always seems to sit high on these cars for some reason... interesting.

So it seems that if I fight to make the two fronts match, I am going to push the problem diagonally to the rear of the car. I guess I feel a little better knowing that the fender heights are always "off" even from the factory. With that information in mind, I will probably set the rears level, and allow any discrepancies to stay up on one of the front wheels.....


-G

HeissRod

I hate the uneven sitting of these cars. It never looks right as I'm walking away.

1badassbenz

Left side should be slightly higher so that when your in the car it will be level. I got someone to measure when I was in the car to see what the height changed to and made the left side that much higher when out of the car. I'm 180lbs and it does make a difference.

GregMB

For sure the driver's weight makes a difference (I'm pushing 195Lbs!)

However, the system is adaptive on the fly. This morning when I arrived at work I kept the engine running and stepped out of the car. I was watching the LF fender as I shut the door and within a couple of seconds it dropped roughly 1/2" to the ride height I'd programmed it for (25.5").... my stepping out of the car caused the car to sit higher, but the car made the adjustments for that within a few moments.

I've collected a few more data points since yesterday, I will post them up a bit later on today. It seems that the more I lower the rear of the car, the less it is affected by the changes up front. I'm actually getting pretty good numbers at all 4-corners now.


-G

GregMB

Well, I think that I'm finally dialed-in!!!

I dropped the rear setting from -0.4" to -0.8" and that seemed to help the front values to stay more consistent as a result.

The ELM settings that I am happy with are as follows:

LF: -1.4" (25.250")
RF: -1.8" (25.250")
REAR: -0.8"
LR: (25.250")
RR: (25.375")

That puts me within 1/8" across the rear fenders, and perfectly even across the fronts. These front ELM settings are 0.2" lower than yesterday, which helped me to get the stance just the way I wanted it. It seemed just a touch too high at the front fenders, and this final tweak seemed to put everything "just right" aesthetically.

I'll drive it around a bit more over the weekend, and keep checking the fender heights with a tape measure to make sure that the values don't drift or change... assuming they don't it looks like I have a winner!

The next step is to drop the car off at T/T/M on Monday where Bruce will work his magic on the alignment and hopefully there will still be enough adjustment left in the car to give the car a good "performance-oriented alignment" at this ride height.


-G