BMW Negative camber

[mechanicx]

Originally Posted By: IndyIan
BMW is kind of unique though with having a double a-arm rear suspension(that can increase camber with wheel travel) and lots of static camber to start with. Usually static camber is used on mac struts that have little dynamic chamber change. I'm sure they have their reasons, it is an easy way to make the car understeer more, but alot of them now have mac struts on the front so they should help promote understeer already when driving hard?


Good points. For all they cost BMW doesn't even give you upper and lower control arms front suspension. If you are the ultimate driving machine you'd think you'd start off with control arms and monotube shocks. Cadillac CTS gives you that. A little better reliability would be nice too. But struts and an inline 6 while effective, is the most cost effective way they could build the platform. BMW must be making a lot of money on their cars.

 

[OVERKILL]

I know eh? with all that mickey mouse suspension they are lucky they can turn corners. Jeeez! BMW needs to talk to GM and learn how to do it right!

 

[mechanicx]

But there's nothing novel about that suspension. Lot's of cars have double lower balljoints to alter scrub radius. The Camaro does have that same setup lol.

 

[OVERKILL]

Originally Posted By: mechanicx
But there's nothing novel about that suspension. Lot's of cars have double lower balljoints to alter scrub radius. The Camaro does have that same setup lol.


I'm just busting your balls

There are plenty of ways to get a car around corners. For whatever reason, this is the approach BMW has taken.

 

[mechanicx]

I know we do that to each other all the time

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BMWs are nice cars, maybe not as great as some claim. I like their styling even if it's hard for the average person to tell the year or model. I just think they'd be even better if they weren't so pricey. Also a little better reliability and a little more simplisticy would be good. There's genuis in simplicity sometimes.

 

[OVERKILL]

I don't think the Germans know how to do "simple"

 

[OceanDoctor]

Everyone is doing neg. camber now, esp. run of the mill front drivers. When the Mazda3 came out, it was noticibly cambered when driving from behind (the entire line up is, even the beam axle 2), then the Koreans joined in, the Chevy Cruze and other contemporary GM models are cambered.. pretty much everyone is doing it now. Next time y ou're stuck behind a newer car, just check it out

 

[IndyIan]

Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

I guess they had to compromise, a simple front suspension so they can cram more engine and drivetrain gizmos up there. All those split water cooled ECU's and stuff...

 

[OVERKILL]

Originally Posted By: IndyIan
Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

I guess they had to compromise, a simple front suspension so they can cram more engine and drivetrain gizmos up there. All those split water cooled ECU's and stuff...

EXACTLY!

 

[mechanicx]

Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

But good engineering is about making things effective yet simple (and reliable). Just like the ultimate driving machine is hype so is "German engineering"

.

 

[OVERKILL]

Originally Posted By: mechanicx
Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

But good engineering is about making things effective yet simple (and reliable). Just like the ultimate driving machine is hype so is "German engineering"

.


Coming from a family of Engineers... who also have German heritage, I don't think I can agree with that, LMAO

 

[d00df00d]

Porsche uses strut suspensions, too. Guess they are just as clueless about handling and engineering as BMW.

 

[mechanicx]

Originally Posted By: OVERK1LL
Originally Posted By: mechanicx
Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

But good engineering is about making things effective yet simple (and reliable). Just like the ultimate driving machine is hype so is "German engineering"

.


Coming from a family of Engineers... who also have German heritage, I don't think I can agree with that, LMAO

American Germans are better engineers though

.

 

[SteveSRT8]

I will agree with the German fans about the quality of the driving experience. The Germans bring a unique blend of driver involvement and handling prowess with a smooth ride and low NVH that is seldom found in an American car.

BUT, the downside is ridiculous complication that often makes long term ownership problematic and expensive. My good friend has a beautiful 2008 E63 AMG that is a perfect example.

One of the nicest cars my butt ever rode in, but now with a few miles on it it has more squeaks and rattles than my Chrysler does! His auto trans is shifting funny and he has strange electrical gremlins that the dealer cannot seem to diagnose.

 

[IndyIan]

Originally Posted By: d00df00d
Porsche uses strut suspensions, too. Guess they are just as clueless about handling and engineering as BMW.

Well, you would never end up with the engine behind the rear axle, or mac struts, if you were designing the "ultimate driving machine" on a blank sheet of paper...
I'm sure they pick their compromises very carefully though! And I would love to take even a strut impaired BMW or Porsche for a rip on the track.

 

[mechtech2]

We also have to consider that neg camber can HELP tire wear.
It depends on how much and how fast you turn.

 

[d00df00d]

Originally Posted By: IndyIan
Well, you would never end up with the engine behind the rear axle, or mac struts, if you were designing the "ultimate driving machine" on a blank sheet of paper...

Says who? I don't think any of us knows enough about chassis design to make this statement.

Moreover, "ultimate driving machine" is subjective, anyway. That's why there are so many different kinds of cars with so many different characters, even within any given genre.

You mention the rear engine layout as a liability. It has advantages: it puts the CoG near the rear axle for good traction under acceleration, makes for good weight distribution under braking, and allows the car to run narrower front tires for better steering response and feel. In exchange, the higher polar moment of inertia reduces the car's agility. This doesn't mean the 911 is gimped, and that all 911 owners are somehow accepting a sub-optimal layout for some unknown reason. It's just a case of different strokes for different folks.

You said it yourself: you'd be happy to take a strut-equipped BMW or Porsche to the track. Many people would agree with you, and I think that says it all. Looking at one trait (like the design of the front suspension) in isolation doesn't tell you anything. You have to look at the end result of the whole package. In this case, the end result is that strut-equipped BMWs and Porsches have been topping their respective classes for decades, particularly in terms of handling. That is mutually exclusive with the idea that they have poorly designed front suspensions.

Yes, there are compromises. Everything is a compromise between one thing and another. Reducing everything to "better" or "worse" might make it easier to think about, but it's not a good way to understand what's really going on.

 

[calvin1]

Originally Posted By: OVERK1LL
I don't think the Germans know how to do "simple"

LOL, I think simple went out the window after the E30.

 

[rslifkin]

Originally Posted By: mechtech2
We also have to consider that neg camber can HELP tire wear.
It depends on how much and how fast you turn.


Very true. In the case of the Jeep in my sig, it absolutely kills the outsides of the front tires unless I corner like a grandma (and this is with a solid axle, so body roll can't effect camber). This is due to having zero camber up front, and not enough caster. Giving it a tiny bit of negative camber and a bit more caster would help greatly to counteract the sidewall flex in harder cornering, which would lead to more even wear.

The rear tires on the Jeep wear fine with zero camber though (not adjustable in any way). It's all a balancing act of suspension dynamics to get the desired end result. There's lots of different parts and setup combos that can achieve this.

 

[IndyIan]

Originally Posted By: mechtech2
We also have to consider that neg camber can HELP tire wear.
It depends on how much and how fast you turn.

The problem with alot of static camber on the drive wheels is that you can wear the inside edge of the inside tire. I find this with my Neon and R-comps as I run a fair amount of front camber, and if its a cooler day I'll abuse the front tires a bit for the first couple corners to get some heat into them, not smoking the inside tire but forcing some understeer under power. If we get a lot of cool days during the season I can cord the inside edges first, but I don't want to reduce the front camber as its needed to balance the car...
If I had a nice double A-arm setup the static camber setting would be much less of a compromise.