I'm trying to track down an issue with rear end squirminess under hard acceleration..... I've read quite a bit already, but I'm still not 100% sure I know the culprit....

Here are the specs:

2006 E55
Lowered via ELM v2 to 25.25" (ground to fenderlip) at all 4 corners
Suspension set to "Sport 2" Mode
MB Arts Toe Links installed in the rear
Quaife LSD just installed
Michelin PSS - 275/35-18 on CLS500 Wheels (9.5" x 18" - 28mm offset) - REAR (34 psi)
Michelin PSS - 245/40-18 on CLS500 Wheels (8.5" x 18" - 25mm offset) - FRONT (31 psi)

Here's how the car sits visually. It's low, but not THAT low compared to a lot of guys here:



And here's the latest alignment sheet that I just got:

You can ignore the "Initial" values somewhat. I lowered the car just before getting the alignment done, so those values are probably way off as a result. I didn't actually drive the car lowered with those "initial" settings... I wanted to wait until the alignment was done.




I'd be interested to hear what the experts have to say about the "Final" values.... especially related to rear toe. I'm not sure if a positive value on this sheet indicates "toe in" or "toe out"?? but I know that excessive toe can cause the squirminess that I'm feeling now.... however with the adjustable rear toe links, I should be able to set this value to whatever I want now. I doublechecked the jam nuts to make sure that they hadn't backed-off (I've driven about 1000 miles since the install) and everything still feels nice and tight.

I've also seen comments that squirminess can be caused by bad balljoints and/or bad subframe connectors... so I guess that it a possibility also, though I never felt this unusual handling until I lowered the car and got the alignment done.

I also realize that at speed above 68mph in Sport2 mode, the car will lower itself another 15mm (a bit more than 1/2") so maybe between the squatting of the suspension (under hard acceleration) and the dynamic lowering I'm simply getting too low and/or causing alignment changes that aren't visible during a static alignment check?


Any tips or insights would be great. Thanks!

-G

 

You have rear toe in, alot of it too. Think pigeon toed. I would have them adjust the value to something closer to .05 degrees per side. (.10 total toe). This will keep the tires from scuffing and give you more contact patch. I was able to get my lowered CLS55 to minimum toe spec with MB toe bolts.

 

I can confirm on the rear toe-in too. I've also noticed that the bigger the wheels the more rear squirminess it becomes.

 

Thanks Guys,

I was comparing my alignment sheet to one that I think AgSilver posted up a long time ago (it was all in German, but it looks like the same machine was used...the format and layout of the printout is identical)

The most notable differences between his alignment and my numbers above were:

Front Camber: -1.40* vs. mine at -2.4*
Total Front Toe: 0*08' vs. mine at 0.15*
Total Rear Toe: 0*25' vs. mine at 0.60*

So I guess I should probably give the alignment another try and insist that they work harder to improve the numbers.

Any comments about my camber (F & R)? I'm sitting at roughly 2.5* negative at each corner as the car sits now, and I don't think there's much that can be done without buying more parts (Camber Arms, crash bolts, KMAC, etc).

The front seems a bit too aggressive. It seems like MB crash bolts might help me to dial-out some of that negative camber, but my current values might be beyond the scope of what a crash bolt can compensate for.???

KMAC makes kits for front and rear on the W211. I know they are expensive but a set of Michelin PSS tires arent cheap either, and I'm already on my second set..... I'd rather spend the money on adjustable suspension parts, and not worry about corded tires all the time.


-G

 

Ironic. I just lowered my car yesterday and did an alignment but I forgot to take my printout. My rear toe is at 0.15 and 0.17 and I'm pretty much as low as I could go in star. Camber is around -2.5 all the way around. Crash bolts in the front will only bring it to around -2.2. I think I need to get another alignment as mine still pulls for some reason.

 

How's it feel at say, 70MPH when you floor it? Is it straight and calm, or does it wiggle around?

I guess the other variable is that if you are still using the stock toe links, there is going to be some deflection... so you'll go from slight toe-in to maybe 0 toe under power. With the aftermarket toe links (like I've got installed now) it seems unlikely that toe-in values would change at all.

-G

 

I haven't tried flooring it at 70 yet as I was kind of ticked off that it still pulled a little and I had to compensate by holding the steering wheel slightly turned right.

 

Adding more data....

It's not too easy to find published alignment sheets on this forum, but I did find a few (AgSilver and ponyworx). I put them into Excel to compare them to my own sheet as shown below.

NOTE: Some alignment shops measure specs in decimal degrees, and others use degrees / minutes to show the values (60 minutes = 1 degree). In this chart, I converted all of the data to decimal degrees so that it would be easier to directly compare all of the values.

If anyone has an alignment sheet for their car (especially if the car handles either very well or very badly) please send it to me, or post it here and I will add it to the analysis. Someday, this thread may actually end up being useful for someone searching for alignment help!





The "deltas" listed on this sheet are simply the difference between my own alignment numbers and the ones from other members. AgSilver has substantially less negative camber up front than either ponyworx or myself. I was surprised to see that his total rear toe-in isn't really THAT different from mine (0.42 degrees vs. 0.60 degrees).... maybe these cars are hyper-sensitive to toe-in, and even a small amount will make a huge difference? Pretty sure he's running rear toe links like me, so whatever toe-in is there isn't going to change (toward toe-out) under heavy acceleration.

 

With your front caster that far apart from each other, I am surprised it doesn't pull.
One thing to check for rear squirminess are the rear subframe mounts, I have seen some mounts worn causing excessive movement when under load, also make sure they aren't ripped from the chassis

 

Greg, can I PM you an idea I had to try to correct your front camber?

 

The answer is yes.

The K-MAC solution is $485 plus install....

I'd like something cheaper if its legit.


Thanks,

-G

 

I've got some offset lower ball joints for Dodge Chargers that looks like they may work...just haven't had a chance to install and verify yet.

 

My last alignment specs (all in degrees)

Front:
Camber: LF: -1.8 LR: -1.7
Caster: LF: 11.5 LR: 11.5
Toe: LF: 0.08 LR 0.08

Rear:
Camber: LR: -1.6 LF: -1.6
Toe: LF: 0.18 LR 0.18

I have MB Arts Rear Toe links and OEM crash bolt in the front, also I am on coilovers and not ridiculously low.
Also I had K-MAC Front and back and removed them (https://mbworld.org/forums/5377830-post27.html)

 

Thanks for those alignment specs... I will add your information to my Excel sheet and update the image in my previous post. Good stuff!

I'm definitely tired of the wagging. I thought is was only at high-speed (70mph and up) but today I tried jumping on the throttle hard from a dead stop to see what would happen. The car started squirming and weaving so hard that I had to back out of the throttle before I even got to 60mph.

Keep in mind, my car isn't a 500+WHP monster either. It's a very mild stock motor, with a set of MBH headers and an EC tune... Maybe 450WHP total but it is damn scary when I can't keep things going straight and steady.


-G

 

!!! PROBLEM SOLVED !!!!

What an interesting day it's been....

I found a local shop that took pity on me and got me wedged into their schedule so they could take a look at my rear suspension for any signs of obvious damage, loose bolts, etc.

The inspection didn't show anything unusual, so the only thing left to do was hook it up to the alignment machine and see if any of the values from last week had drifted at all.... Boy, did they ever! Take a look for yourself:

NOTE: First column values are the measurements, second column values are "deltas" from previous measurements...



The first column are the values that were given to me when the 1st shop did the alignment. Those were the values I was trying to confirm. The second column is what the car ACTUALLY has on it as of today!!! The car went from a decent amount of toe-in on both the front and rear, to pretty massive amounts of TOE-OUT at both ends. We were scratching our heads trying to understand how this could have possibly happened in only 1 week.

Column 3 ("New Aligment Lowered") are the values that we got today after a bit of messing around with the front and rear toe settings. We knew that there was no chance of correcting the camber, so we didn't even try.... The front and rear toe values went from negative (toe out) to very slightly positive (toe in) and these values are much more in line with the types of values that other members suggested would be "good" for handling and stability. A quick test drive and foot-to-the-floorboards confirmed that the new alignment was a winner! No more squirming, no more drama....just steady hard acceleration with gobs of traction from the new Quaife out back!

Column 4 was a quick test that I did before we rolled the car off the alignment machine. Leaving everything in place with the "good" alignment numbers that we'd achieved, the only change I made was to turn off the ELM and allow the car to return to factory height settings. As the car raised itself about 1" taller, the toe-in settings got progressively more positive (more toe-in)...by almost .25* per side. This tells me a couple of things: first, you can't possibly use the ELM for two different ride heights and expect the alignment to be worth a damn for both settings. You can get one "good" set of alignment values for your preferred ride height, but for anything else you are going to have massive changes in your toe settings.

This lead me to me final hypothesis: I am now pretty sure that the first alignment shop raised my car to factory height to get it onto the alignment rack and then forgot to lower it back down again before starting the alignment.....OR.... it was accidentally turned off at some other point and nobody noticed. That would explain how the car could show such good values on the printout, but end up so much worse as soon as I dropped the car another 1" all around... I am not 100% sure if this is the explanation or not, but at this point I am just thrilled that the car is running hard, and straight as an arrow. As a nice side benefit, it turns out that at least two of the mechanics at this shop are avid road racers, and are very interested in working with me to do the rest of the suspension tuning (eccentric bushings, etc)... most shops don't want to spend the time on anything "non-stock" around here, so getting introduced to a few local enthusiasts was a huge win as well.


-G