Fifth Ring

The geometry of the front suspension on all Benzes seems to incorporate camber as the wheel turns, leaning into the turn. I've never seen another car with it, which makes me wonder whether it is effective. It seems like a wonderful way to give you negative camber on turns; but perhaps it does not camber quickly enough to make difference?

sdsilverm3

Correct me if I'm wrong but from observing my wheels as they are turned all the way to one side: It seems like only one of the wheels will incorporate negative camber while the wheel on the inner portion of the turning radius actually looks like it leans outwards toward the positive side.

Fifth Ring

Your sig photo illustrates it. Both wheels lean into the turn, so the inside wheel goes negative camber while the outside wheel goes positive camber. In theory, that's the way tires should lean (see NASCAR).

sdsilverm3

Thanks for explaining.

Rafal

This "leaning" is desirable and is achieved by MB unusually large positive caster. Think of a "chopper" motorbike with its forks steeply angled with relation to the steering: that's positive caster in the extreme!

Fifth Ring

That makes a lot of sense. I wonder, then, why other car makers do not do it. I also wonder why people who take their MB to the track often complain about the lack of negative camber in the front suspension. There is little or none while going straight, but when turning, there's plenty.

CynCarvin32

I agreed with everything up until your last statement! Plenty of camber? This car has none!

K-mac bushings just installed in SMGC32's car and all it can have is -2 degrees with a 1/32 of toe in on each side. Caster is set at 11 degrees and spec is between 9 and 10 degrees. MB uses this caster not for camber but for high speed straigh line stability. The more caster the more stuck to going dead straight the car is at speed. We all know the C32 is a great freeway car and that caster plays a big part of it. The oem spec for rear toe is I think .25 inches on each side which is a ton and that also likely makes the car very stable at speed.

I can post picture after picture after picture of tires from the track that are down to the cord after half a day of hard driving. Search back and SMG has put some pretty interesting pictures up for viewing of totally destroyed Dunlop Super Sport Race tires.

After having just spent a night driving the C32 with k-mac bushings front and back I can say the car feels far more sporty, has much more front grip, is very stable, but has a fairly firm ride with very stiff bump impact on all but the softest roads. With these bushings I can say the car still needs more camber for real "hot lapping" but for most track users the 2.1 degrees of negative camber these bushings offer is more than enough.

Also the poly bushings in the k-mac kit reduce suspension play a great deal and the car is far more stable durring extreme driving situations.

If you like your MB ride more than sporty driving these bushings are not a good idea.

I can post pictures of my daily driver 2005 C230k and its front tires will show a complete lack of camber for purely street driving with maybe 1 canyon drive every month for about 20 miles. The PS2 is nearly bald on the side and at about full tread depth on the inside. And mind you this C230k has been alligned for performance with the factory crash bolt, less toe in and the added caster bolt as well.

Zeppelin

Be sure to let us know when they fail. Or if.

Fifth Ring

What I can't seem to reconcile is the fact that the suspension caster creates camber when turning, which is when you need it. But you say there's no camber. With the wheels straight ahead, I agree, there's no camber. But you don't need it then. You need it in the turns.

My only guess is that the camber you get in turns is not sufficient.

I'll see how my tires wear at Summit Point in a couple of weeks. Maybe I'll try the "washer method" if it does not affect driveability. No matter how I cut it, I still drive 99% of the time on the street and 1% on track.

AWDman

CYN...hey where exactly do these busings go? Thrust arms? i'm liking your comments seems there are benefits aside from the camber aspect. the camber is easily adjustable correct? (per JP/carlab) last ? how hard is it to get the k macs in?

also- my experiences (tho limited) with tire wear have not been bad. yes the car wears inside shoulder but flipping side to side evens it out nicely. my worn set of fronts are degraded quite evenly. i'll post pics later. wonder if this is due to tire? seems to me the best tire config for our car is an assimetric non directional (hoosiers, toyo ra1s) next would be assimetric directional (yokes ) then symetric non directional (sport cups).

CynCarvin32

You are correct in stating that connection between Caster and Camber as you turn the wheel. The issue lies in how much camber the caster creats as your turn the wheel and how much steering input you have for taking most corners at the track. Most corners only ask for half a rotation of the steering wheel at most and that steering input does not allow the car to create that much negative camber.

If you are using your car for street driving and you dont see a camber issue I would not worry about it. We all drive at different speeds and maybe your driving style and your local road courses do not stress the front tires as much as ours here in southern california.

The washer method does work to create some camber but the bushings stiffen up the steering response and make the car more stabe due to their stiff nature. If you only want camber and want to keep the nice stock ride skip the bushings for sure since they do stiffen the car up to a point where comfort minded people will object.

Chassis dynamics all comes down to geometry of the suspension. Harder bushings keep the geometry more constant as load increases and allows the wheel to stay in a more ideal angle with respect to the road surface. The W203, with its water filler front thrust arm bushings has a boat load of suspension flex (same in the rear with soft rubber mounts) and all that play means the angels you see on the allignment rack are far different from those you see under load.

I know from having had far too many W203's that every single car, even those driven by other family members, needed more camber even when driven on the street. My C230k bike carrier and work car only sees use on clover leaf on ramps and some moderate drives once in a while and its tire wear is terrible.