4.8is Ride Height Calibration

[sockethead]

Yes it will go lower but remember, when you reach a certain sped, I can’t remember the mph exactly, it will go back to the normal ride height

[jayarc]

I think I've heard the speed is 25mph. Recently a new car to me was calibrated with INPA and I drove out my neighborhood to test only to have the car bottom out after I reached 25, locking a front wheel and blowing the front right CV clean apart. I was surprised that even if there's a ride height sensor problem the car would be able to bottom out like that. At this point I suspect the PO/Dealer did strut work and did not replace the bump stops. Check for these and be careful!

[SlickGT1]

Originally Posted by jayarc

I think I've heard the speed is 25mph. Recently a new car to me was calibrated with INPA and I drove out my neighborhood to test only to have the car bottom out after I reached 25, locking a front wheel and blowing the front right CV clean apart. I was surprised that even if there's a ride height sensor problem the car would be able to bottom out like that. At this point I suspect the PO/Dealer did strut work and did not replace the bump stops. Check for these and be careful!

This is the first I hear of this on the forum. I’ve had air out of my springs and I am 100% sure I could drive the car around. I’ve also heard of quite a few bag failures and the car just becomes ultra bumpy and bouncy, but still drives no problem.

So I have to agree. Someone did some stupid shit to your car and failed at putting it back together. I replaced my bags with complete Arnott units with the shock, so not sure where the bump stop it.

[jayarc]

There were other things found that a PPI wouldn't reveal that make me cringe as well. So the only time I've actually seen a front bump stop on an air suspension was doing research. This video you can see the orange rubber bumpstop:


https://youtu.be/gbd_EUJojyQ?t=9


On other cars these prevent bottoming out. I don't have my new parts yet for the CV/stops but I'll post pictures of what I find when I do.

[X5M-ISH]

Labor Day Resurrection:


I came across the ride height debate in another thread: https://xoutpost.com/bmw-sav-forums/...sing-inpa.html . Being the second owner of the 4.8is I have, the thread I linked poked my interest and after looking at my truck parked on level ground, the ride height appears to be off. Further investigation with a tape measure and finding this current thread via a search in Google, has proven to me that my eyes are not lying. The front end looks like it's got a slight lift kit.



However, I have followed everyone's advice on measuring and data input but get an error message when inputting my newly calculated values into INPA. What's more is that the software is reading "current" measurements that are way off the OEM specs that are provided within INPA on the calibration page. As we all know for the 4.8is sport suspension (in mm) the:
front axle = 707
rear axle = 709



INPA is reading my truck at:
LF = 596 RF = 455
LR = 432 RR = 515


However, these measurements don't make sense because my personally measured numbers are:
LF = 717 RF = 725
LR = 703 RR = 709


Following the INPA V.5.0.6 work flow I select:
e53>chassis>two-axle air suspension>F6>F5
which brings up the electronically measured numbers above and displays the OEM ride heights where they need to be all on the same page. I then select calibrate, which brings up a small window instructing me to subtract the current measurement from the OEM recommendation. My assumption is that I take the electronically measured number (current) say LF = 596 - 704 = -108. I then put -108 into the field, click ok. I get an error message stating the value is invalid.


Am I to use my physical measurement with the tape measure (as my current) minus the required (OEM) and input this into the fields and ignore the electronically measured numbers? Before doing that, let's back up a step: how I am to baseline the suspension to factory?


The final goal is to drop the entire truck around 25 mm, maybe 30 mm in the front.

[LVR]

Hi mate...

Firstly I'm better with ISTA on this than INPA, but when I was playing around with it I made a similar mistake. I didn't read the explanation CLOSELY and got incorrect errors.

The software needs to generate offset values as all cars and components are different, or put another way, because it's measuring voltages in the ride height sensors it needs to know which voltage measurement is the correct one so it can raise or lower to the right point.

It then applies an offset value to get it there.

Read the calculation sentence again and follow it precisely. From memory it is the other way around to your calcs..... actual height (your measurements) minus the nominal height (INPA)

[X5M-ISH]

That did it. I was able to zero all four corners, then dropped the entire truck 30 mm. This process took about five minutes. To summarize the work flow for future lurkers:


For using INPA v.5.0.6 and SPORT SUSPENSION:


*Park on a flat surface
*Check inflation levels for all four tires: doesn't matter what they are so as long as they are the same
*Measure from the absolute bottom of the rim to bottom of fender molding: lining up your measuring device along the center of the roundel and note the length. Measure as vertical as possible.
*Make sure you properly measure: If you tend to read the left side of your tape measure this is fine for one side of the truck, but the opposite side must read from the right side of your tape measure else your measurements are off by up to 3/16".
*Convert everything to mm and round to the nearest significant figure: If you have 709.5, then it is now 710. If you have 709.4, then it is 709. Rounding a tenth of a mm is just fine for spatial resolution.
*Subtract your measured numbers from the OEM numbers. If you have a negative value, you must put a minus sign into INPA later on.
*Interface computer to truck
*Start engine
*Close all doors
*Select "e53"
*Select "Chassis"
*Select "two-axle suspension"
*Press "F6"
*Press "F5"
%Input calculated numbers for Rear Right and Rear Left
*Click "OK"
%Input calculated numbers for Front Right and Front Left
*Click "OK"
*INPA will indicate the system is calibrating at the bottom left of your INPA window
*Once completed manually raise and lower your truck via the button near the steering wheel
*Measure all four wheels again to verify
*Repeat all steps as necessary

%To lower your truck, you simply input your desired drop in mm during the data entry phase of this process. I did a 30 mm drop so I input "30" in all four fields. If I desire to change this back to stock ride height I will then put "-30" in all four fields. The numerical input is inverse of the output.


...now if only I can figure out how to entry-access lower the truck when the key fob unlocks the doors!

[gtiownr]

I just did this using ISTA Plus. It worked a little different than everything I have read before.

I connected and chose the appropriate section.

It asked me for rim size in inches and then the measurement in mm. It separates front and rear measurements. I selected fronts and put the appropriate measurements in. Then it directs you to the rear.


My truck was off right to left on both axels by an inch in front and 1.5” in the rear. The first go, the program said the front was in parameters and didn’t allow a change. The rear was far enough out..

I went back to the front and fudged the numbers to get it to level.

Then, I wanted to drop it 30mm...

After the initial calibration, I started the truck exercised the suspension through all three settings and then returned to the middle ride height. The ride height was 711mm all the way around (this is what it went to after calibrations).

Then, to get it to lower, I fudge the numbers left-to-right. First, I chose front axel and put LF at 741Mm and RF 711mm. Then the same for the rear. I hit continue and allowed the truck to take the difference. I started it again and ran it through as above.

Then, you go back in and do the same but switch the 741/711mm numbers. The overall result is a lowered truck at the middle position (really all positions)

I measured everything and it ended up being 27” from the bottom lip of the rim to the fender. The RF was 26.8” and that is due to me fudging the numbers in the beginning because the 1” was w/ in tolerance.

Overall the truck looks amazing and is slammed when I put it in the lower position when parked.