GregMB

Guys,

I'm on the verge of insanity and need some objective feedback.

Ever since having my Quaife LSD and MBArts rear toe links installed this summer I've been chasing what I call a "wiggle" in the back end under hard acceleration.

Basically, in either 1st or 2nd gear if I really romp on the throttle, the car seems to have a slow "wiggle" or "squirm" in the back end. Ever since installing the Quaife LSD my ESP triangle barely blinks anymore in these situations, and I feel like I'm getting much stronger acceleration and grip. I can't help but wonder if what I'm feeling is simply the rear tires grappling for traction, with perhaps a small bit of tire spin that is causing the rear to feel slightly loose?

In the last few months, I've gone through quite a few alignments in an attempt to correct the "wiggle". It seems like rear toe-out is a real contributor to the issue, although with the aftermarket rear toe links I know that I should have better control over "power induced toe-out" than a typical E55....

Here is the latest alignment (performed yesterday) by the dealership.




I completely disabled the ELM (Factory Height!) and the tech put my car on the machine, and used STAR to reset all of the factory ride height sensors to spec before doing the alignment.

They noted that the RF wheel couldn't be brought into spec without installing a set of crash bolts, but since I already bought a complete set of K-MAC bushings (still need to get them installed) I didn't want to waste money having the crash bolts installed.

I believe this alignment shows that I have a small amount of rear toe IN (0 degrees, 22 minutes) ... positive values mean toe IN, correct? On previous bad alignments, I've seen this value as a negative number (Toe OUT) and that seemed to correlate to really squirrely handling, even up into 3rd gear and not even at WOT..... it was pretty scary.

So my question is: Do you guys with LSDs notice this type of "wriggle" under full throttle launches? Is this nothing more than the power of the engine overwhelming the rear tires? In the days before the LSD, the ESP would interfere so aggressively on a WOT launch that these types of issues might not have even been detectable......


The car is basically stock, except for a set of MBH longtubes and a box ECU/TCU tune from EuroCharged. Air temps in New England now are crisp (mid 40s), so I'm getting a TON of extra power these days... so I'm guessing it IS possible that a rolling 20-30MPH romp of the throttle in 2nd gear could cause me to break traction. I guess I'm just looking for some feedback on how an E55 with a Quaife is SUPPOSED to feel when it's trying to lay down power at WOT....... perfectly poised and straight, or just a bit more "informative" about the punishment that the rear tires are receiving?



-G

E55Greasemonkey

What brand of tires? Does it feel different with esp off?

E55Greasemonkey

I think you are feeling the esp doing its job, and applying the appropriate brake on whichever rear wheel is needed.

GregMB

I'm running Michelin PSS's on all 4 corners. Stock size up front and in the 275 width in the rear on a 9.5" wide CLS wheel...

Honestly, I'm a bit nervous about turning ESP off and just hammering the throttle to see what happens, but I agree.... that would probably be a good data point to compare. Guess I could also try "Dyno Mode" too to really be sure that the electronic nannies aren't playing a role in this....

-G

chiromikey

This is NOT related to LSD or ESP...unless you have a rear flat tire, this is a suspension issue...PERIOD!

A few bone stock cars had this problem early on and had a hard time getting it sorted out, mostly related to bad rear toe alignment. My car was highly modded (back in the day) and tracked perfectly straight under any acceleration, stayed perfect after I lowered the car, stayed perfect after I installed my Quaife, but became seriously dangerous after I started trying to mitigate tire wear with suspension parts. The problem started with the Kmac bushings. It got better with MBArts but I gave up on the car for other reasons before getting it fully sorted out. If I had it to do all over again, I'd deal with tire wear or not lower my car quite as much!

HeissRod

I have the same wiggle with a completely stock rear end, suspension & all.

Newzchspy

Wiggle as in what?? If the car is under hard acceleration and BOTH tires are spinning or attempting to get traction (because of the Quaife) , the back end is going to try and "swing" or wiggle as you call it from side to side. You probably didnt see this before the Quaife as there is generally only one tire spinning when ESP kicks in to stop the action. One way to test this is to go out to a empty parking lot where you can "lay down a strip" and from the digg, do a quick run and you should see in the tire marks in black which way the car is trying to "wiggle" as you call it.

Newzchspy

Do it in an empty parking LOT or on a less traveled road and see what you're looking at from the digg?? ESP is just going to try and shut it down, so try it with ESP off.

AUS-E55

^^^^^^^^^^^^^^

X 2 What he said

get your toe adjusted on your MB ARTs arms, jusy ahve them set it to 0 deg toe and you will feel the difference, it was really bad on mine after I installed the K-Mac bushings that kept moving all the time.

chiromikey

it's not a lack of traction wiggle...it's a wiggle where the back end starts pushing or wandering from side-to-side as if the suspension is deflecting under torque. it can happen at freeway speeds under hard acceleration with enough power. before I messed with aftermarket suspension, it didn't matter if my tires were spinning or getting full traction with drag radials...my car went dead straight. this was both before and after the quaife. it's definitely alignment and suspension related.

GregMB

I remember studying your old posts (and AgSilver) when I first started trying to understand the toe and camber issues....

I seem to recall that you both had a small amount of toe-in (~ 0*, 25 min total toe)... and whenever I can seem to find a posted alignment sheet on MBWorld that seems to be consistent for guys who claim their cars run straight and true....

Any idea how long the heims should last on the rear MBArts toe-links? I've only got about 3000 miles logged on them so far, but I could imagine that once they get worn out the rear toe is going to get sloppy and unpredictable.


-G

Newzchspy

X2 Mikey, BUT if its suspension related, he can still use the "lines" he makes with some photos to help explain to the tech what the vehicle is doing. I had to do this on my Roush Stage III with the 3.73 LTD Slip because they wanted to see what the car was doing under accelerative load. Solution was: Control Arms for about $200 bucks. Less HOP, less "wiggle" and firmer launches.

RedBullJnky

This^^^^

And I've felt that "wiggle" at 100+ That'll tighten your anus!

ajm55

I had the exact same issue following the installation of my Quaife LSD. I even corresponded with Quaife UK about it. They indicated that they'd never before experienced these symptoms. The problem eventually resolved itself although only after a tire change, as I recall it.

justinwrock

Had the toe links + P030 LSD in my E55...

Noticed with cheaper tires (V12 Vents), I could break them loose and keep it going straight all day long. 36* morning, ESP off, WOT from 20mph roll, and it would track straight as an arrow!

Put some PS2s and/or NT01s on, and @s$ would be dancing to it's own beat!

IMO, the problem lies with ESP and toe settings... If the tow isn't zeroed out, and the traction control is trying to do its thing with the LSD, the rear is going to step out, and pull in the direction that the wheel with the most power is pointing...

Makes sense (prolly not, but I had to try explaining)

SterlingE55

I've had no issues with either my CLS wheels with V12s or my stock wheels with PSSs. I'd wager to think the toe links are flexing or have loosened and toe'd out. It does have the characteristics of a toe issue.

AgSilver

And here's my $.02 - - - Make a run with the ESP off. The LSD and ESP may be creating a conflict. One way or the other, it will eliminate one scenario. And also, as already emphasized by others, alignment must be correct.

GregMB

Well that was interesting....

On the way home I turned ESP off and as I headed up the hill to my house I rolled into the throttle in 2nd...as soon as the boost came on the tires broke loose and the car swung slightly left, then more sharply right. Things got dicey in a hurry and by the time I backpedaled it I was in the other lane heading for the shoulder. Yikes!

I'll try to find a flatter spot with lots of space tomorrow to try again, but at this point at least it seems more alignment related than ESP related.


-G

chiromikey

I'll try to find my notes but I do seem to recall a minimal amount of toe in.. However, I'd try to get back to factory settings above anything else.

I never got to put that many miles on my MBArts stuff so I don't know how long they'll hold up.

HeissRod

From your alignment printout, you are within factory specs. In fact, you're within .02' of perfect factory total rear toe.

try m3

My car does the same exact thing at anything under 50mph. It kicks out hard to the left yet it tracks straight under normal driving and no uneven tire wear. I'm not sure whether it's the stock diff or alignment. OP I'm pretty sure your issue is alignment related I have 2 other cars that I track frequently which have LSD's and they don't kick out.

AMGPilot

The MB Arts stuff is crap.

Get the Chassis square camber wise and your problem should go away

aeroman

Yup. Me to. I have always attributed it to tire wall flex under extreme horsepower lay down.

AgSilver

I have Evo's toe-links installed. Quite frankly, they look like they came off of a NASCAR Grand National. Subsequent to their installation, the improvement in stability under hard acceleration was significant. But again, proper alignment is critical and do not forget the importance of quality tires.

GregMB

What are you suggesting for camber? 0.0* at each corner, or just a lot less than I have now?

I'm tempted to bring the car to my local shop and have them set the rear to 0 toe as an experiment....

My thought is this: The stamped factory part with its rubber bushings deflects under power creating toe-out, so perhaps that's why the MB alignment spec calls for a slight amount of toe-in? The net result (under hard acceleration) would be zero toe.

Obviously with a rigid, heim-jointed toe link there isn't any deflection so I've got toe-in under all conditions.

Just a theory.


-G