Bottomed out E53 via INPA susp changes, blew CV.

[jayarc]

Hi there, normally I'm a smarter human than I was today for a period of time. I bought a 4.8is which I love and the dealer manually calibrated the air susp before I left, leaving me with "Inactive susp" message etc...


I managed to install INPA and got things connected and tried many ways of figuring out the calculated ride height, the added feature that you need to drive it a little bit before it adjust got me, bad.



Eventually I noticed resetting the ECU around the suspension and then using the buttons in the car to raise it would work. I got it raised and then attempted to calibrate the car further down off the raised numbers with INPA.


I was happy to see after the "too-high" settings I had calibrated it down a bit. I grabbed my wife so she could come and test drive our new truck with me after a bunch of fixes....


We get out to the main road and it feels good so I give it some gas, the front only of the suspension had been lowering, apparently beyond regular ranges. The front of the X5 bottomed out, causing the tire to grab, the CV still trying to apply pressure blew itself out in particularly loud fashion.


First, I know I'm an idiot who has not paid enough attention and care to another great car. Normally I'm very careful and felt like I was being. Dammit.


My questions are for you guys:


1) If you can imagine the bottoming out, and CV blow out... What would you expect should be replaced. CV only, other things that got hurt in the process?


2) If any of you have more in depth details about the air suspension and INPA please link me. I've searched thoroughly and found information that lead me down the wrong road so now, after my first INPA experience I'm a little scared to proceed.


I'm a software developer so getting the computer things situated was not too hard, I really appreciate any time you take to help out. This forum has been my savior so far in getting this X5 sorted.

[jayarc]

Also, shouldn't there be bump stops to prevent this kind of thing happening? I'm also interested in opinions about doing an air suspension delete for coils/springs.

[crystalworks]

Both sides in the front deflated or just one?

What errors/codes were you getting for the air suspension before doing anything?

[jayarc]

At first after I bought it and the dealer raised it manually (still inactive on) it held ok for about three/four weeks. After that and the cold weather the front left went down. After that I installed INPA and managed to do an ECU reset and air susp activation in INPA which re-enabled the physicial up/down susp button in the car. When that happened I hit the up button and both front wheels elevated to about the same level. The back axle has always been ok, consistent and a high height.


So after my button elevated the front wheels finally I took a test drive and nothing went down, all was good.


Then I tried to go back into INPA and make the heights more perfect. I saw the suggested values for the wheel rim to the wheel well and tried to next, set offsets in the INPA calibration.


This is where I think I went wrong. I have a feeling I'm mis-interpreting the translations for the air suspension. When you're inputting the "offset values" they give you an example equation. This - this = this. It doesn't really seem to be completely clear. You need to set -100 from what I can tell to make the suspension RAISE, a little counter-intuitive.


So after setting the offset values again, I took a drive out to the main road an in that time the front bottoms out and the wheel locks, CV with pressure applied to lock wheel blows things apart. I'm a dolt, I think?


My main concern right now is if people think that my failure here would have potentially ripped apart the front diff. The CV is definitely split where the boot is so I'm hoping that the diff is generally tough enough to deal with the "no movement" jolt it got because of my ineptitude.

[jayarc]

I can see that the front passenger side CV is "blown apart" at the boot. It's separated and I found a large metal bearing like piece in the road. Definitely broken and visibly separated. At this point I'm mostly wondering if I should order just one front passenger CV complete for replacement or I'm being optimistic and should order other parts surrounding my mistake damage.

[crystalworks]

I can't believe it drops so low that it would cause tire to bodywork impact after a bag failure. This is a front bag failure:



Image courtesy of LemansX5

[jayarc]

I have a feeling the bump stops have either broken apart or fallen off. Normally with regular suspensions you have them to prevent this situation. I was pretty surprised myself...

[andrewwynn]

If you hit ice with brakes on the wheel will go from say 20 to zero in milliseconds. If both wheels didn't lock I would expect the diff to take the heat though I'm interested to see what was broken. Photos?

[jayarc]

So both fronts grabbed at about the same time. I'll get down there and take a picture later today as my x-mas present to myself and frame it to remember to be more careful.

[andrewwynn]

If you caused enough torque to break something the weakest link will break and act like a fuse and save the rest.

It kinda sounds like you blew apart a CV axle. If it broke to the point where the axle could turn without the wheel that will free the differential to turn freely if both wheels are stopped.

(The stopped side won't turn the broken side will turn twice as fast)