How much do the LCA eccentric bolts effect toe in/out - PeachParts Mercedes-Benz Forum

bgkast · #1 10-30-2008, 11:07 AM

I would like to adjust my eccentric bolts to give a few degrees of negative camber to help reduce understeer. I have just rebuilt my front suspension and had an alignment done a month or two ago. Currently both eccentric bolts are right in the middle of their adjustment range. I am planning to turn them about 1/4 turn which looks like it could increase the toe out slightly. Will this cause a negligible amount of toe out, or is it something I should be concerned about?

DeliveryValve · #2 10-30-2008, 05:27 PM

Having a small negative camber will cause a toe out, but not sure how much toe out a 1/4 turn would cause. In theory, a toe out would make your steering quicker with the possibility of compromising straight line stability.

Scott98 · #3 10-30-2008, 09:28 PM

It will cause a TREMENDOUS amount of change in toe. I align my own cars and have aligned my Benz several times. Don't do it unless you know how to align your car with jack stands or smart strings. I speak from much personal experience.

Scott

jt20 · #4 10-30-2008, 09:32 PM

this change can be deduced mathematically. I can probably give you a an estimate within ~1/2 a degree if you take the time to measure some of the components.

turbobenz · #5 10-30-2008, 09:35 PM

Since i had the LCA off and didn't mark the bolt position, mine is incredibly out of alignment. I have noticed the steering is much more responsive but that may be due to the fact that I eliminated all the worn parts. A small change in the bolt posistion makes a HUGE change in the LCA posistion. I really don't think you can just adjust it, its not that simple.

Scott98 · #6 10-30-2008, 09:41 PM

Quote:

Originally Posted by jt20

this change can be deduced mathematically. I can probably give you a an estimate within ~1/2 a degree if you take the time to measure some of the components.

There is a lot of suspension travel in a Mercedes and I find this car much more difficult to align than others. I'm not trying to sound mean here, but there is no way you are going to get this with a mathematical calculation. Theory does not always play out in real life situations. I have to reset the suspension each time I make a change (and no, I am not jacking the car in the air) and recheck my measurements because there is always a change after making an adjustment and resetting the suspension. To get your toe set correctly, you need to accurately measure 1/32 of an inch. These are finite adjustments and there is a tremendous amount of change going on here. Castor has a huge effect on camber and toe, camber has a huge effect on toe. Suspension geometry is different on all cars and Mercedes has its own idiosyncrasies. Again, I have aligned my car MANY times (due to piecemeal suspension work). Don't change your camber unless you are prepared to measure and reset your toe and know what you are doing.

Scott

Scott98 · #7 10-30-2008, 09:43 PM

Quote:

Originally Posted by jt20

this change can be deduced mathematically. I can probably give you a an estimate within ~1/2 a degree if you take the time to measure some of the components.

BTW, factory specs are a 1/4 degree of toe on each side. 1/2 degree wouldn't cut it.

Scott

jt20 · #8 10-30-2008, 10:11 PM

if measurements are accurate that may be reduced.

It sounds like the OP wants a rough estimate.

Scott98 · #9 10-30-2008, 10:13 PM

Quote:

Originally Posted by DeliveryValve

Having a small negative camber will cause a toe out, but not sure how much toe out a 1/4 turn would cause. In theory, a toe out would make your steering quicker with the possibility of compromising straight line stability.

Toe out is generally desirable in cars used for autocrossing. The car will be "snappier" and more nimble. However, you sacrifice stability at higher speeds.

Scott

jt20 · #10 10-30-2008, 10:21 PM

Quote:

Originally Posted by Scott98

There is a lot of suspension travel in a Mercedes and I find this car much more difficult to align than others. I'm not trying to sound mean here, but there is no way you are going to get this with a mathematical calculation. Theory does not always play out in real life situations. I have to reset the suspension each time I make a change (and no, I am not jacking the car in the air) and recheck my measurements because there is always a change after making an adjustment and resetting the suspension. To get your toe set correctly, you need to accurately measure 1/32 of an inch. These are finite adjustments and there is a tremendous amount of change going on here. Castor has a huge effect on camber and toe, camber has a huge effect on toe. Suspension geometry is different on all cars and Mercedes has its own idiosyncrasies. Again, I have aligned my car MANY times (due to piecemeal suspension work). Don't change your camber unless you are prepared to measure and reset your toe and know what you are doing.

Scott

I didnt catch this post.. I'll take your word for it.

babymog · #11 10-30-2008, 10:22 PM

Yes, a daily with toe-out is tremendously sensitive to cross-winds and ruts, a pain to drive straight.

To reduce understeer, you might consider a stiffer rear sway-bar.

bgkast · #12 10-30-2008, 10:25 PM

Hmm...it sounds like it will have a large effect on the toe. I guess I will just wait for my next alignment.

bgkast · #13 10-30-2008, 10:29 PM

Quote:

Originally Posted by babymog

To reduce understeer, you might consider a stiffer rear sway-bar.

I have one.

I was hoping I could easily add a bit of negitive camber to the front to help stop wearing out the outside edge of my fronts from hard conering rolling over the tall 14' tires.

Scott98 · #14 10-30-2008, 10:42 PM

Quote:

Originally Posted by bgkast

I have one.

I was hoping I could easily add a bit of negitive camber to the front to help stop wearing out the outside edge of my fronts from hard conering rolling over the tall 14' tires.

If you are experiencing outer tie wear AND the problem is due to camber, you have a lot of positive camber. We're talking way out of factory spec. Factor spec is + - .3 degrees camber - which is basically zero camber. You probably need to have way over a degree - more likely 1.5 degrees positive camber or more to cause outer tire wear. If your tires are off this large amount, it will be readily noticeable by simply looking at the front of your car (stand back about 20 feet) and see if the tires are cocked out.

Scott

babymog · #15 10-30-2008, 11:06 PM

I've found that (the 124 body anyway) will rise up slightly when toed-in and eat the outside shoulders, toe-out will lower the front and eat the inside shoulders. Could be a toe problem. Do your tires' tread blocks wear with a slight sawtooth feel when you drag your hand from inside to outside of the tire's tread?