New alignment settings

K

kerstien

Member
A while back I upgraded my suspension system to the KW v3 setup and was very pleased. Next was to try different alignment settings. I took EXdos' advice and tried the following: zero toe front and back
-1.3 camber front & -1.0 camber rear.
Before continuing I better mention that the roads in Malta are complete rubbish with no grip whatsoever.
I have driven the car this way for a few months in order to determine if I like it better or not. The car definitely turns in alot better than the standard settings. However I feel you need to use the complete width of the road road to get the best of the car in these settings. Using both lanes you can turn the steering wheel much less and the car responds. Turn too much and the back just comes out. She's definitely much more sensitive and i fear that with our bad roads the car just wants to drive sideways. This is something I usually enjoy, however I just cannot get the power down. Even in a straight line the car comes loose at the rear.
I basically want to change the settings to keep the sharp turn in at the front but I need to make the rear less sensitive. Would adding more negative camber at the rear help this? I think the more neutral setting of camber at the rear is making the car come loose on our bad tarmac. Does this make sense? do i also need to change toe settings?

thanks

kerstien
 
I would think that more negative camber in the back would give more grip in the corners but wouldn't think it makes much difference in straight line acceleration... That would probably require some toe-in in the back?
 
Increase rear toe-in just a little, but not camber, to reduce the tendency of the backend from stepping out. If your roads are really bad then getting grip on a powerful RWD car will always be a problem - think rally car on a gravel road
 
exdos said:
Increase rear toe-in just a little, but not camber, to reduce the tendency of the backend from stepping out. If your roads are really bad then getting grip on a powerful RWD car will always be a problem - think rally car on a gravel road
Click to expand...

When you say increase toe-in slightly, by what amount? Would 0deg 4' like the csl be good? why wouldn't more camber at the rear help grip? after I had changed my suspension i felt much more confident driving the car, now it's like I have much less control. Funnily enough I also had to change my rebound and bound settings after I changed the alignment. I stiffened the front up much more and made the rear softer.

So the front settings can remain the same?

thanks kerstien
 
If I'm you, definitely increase rear toe a bit eg: 0.20 and increase rear camber to -2.00

Most rwd BMW runs an aggressive rear camber from factory.
 
kerstien said:
exdos said:
When you say increase toe-in slightly, by what amount? Would 0deg 4' like the csl be good? why wouldn't more camber at the rear help grip? after I had changed my suspension i felt much more confident driving the car, now it's like I have much less control. Funnily enough I also had to change my rebound and bound settings after I changed the alignment. I stiffened the front up much more and made the rear softer.

So the front settings can remain the same?

thanks kerstien
Click to expand...
Click to expand...

When adjusting suspension and geometry, you have to use "trial and error" to find the sweet-spot in handling. If you keep written notes of all your settings and adjustments and always drive the same test-route to asses changes, then you will be able to find the optimum settings and not get "lost" and be able to return to the best settings if you go too far in the wrong direction with adjustments.

So, try, 0deg 4' and see if that improves the handling. If it works, you can then try reducing it a little to see if that works better, and so on.

Setting a car with static -ve camber is only done to account for the change to camber in the dynamic situation, where bodyroll makes the outer wheel roll over the tyre contact patch. Since the outer tyre takes more load when there is bodyroll, you want the optimum contact patch in this situation across the full width of the tyre, therefore a car with static negative camber should have 0 camber when fully loaded due to bodyroll. So if you have too much static -ve camber, the contact patch will never be optimum when driving straight or when cornering and the tyre will always be loaded mostly on the inner side thus traction and grip will never be optimum.

The Z4M does handle better with stiffer front suspension than the rear, but if you find the car handles better with setting the rear even softer, you should also try setting the front a little softer too, so that you preserve the overall front-to-rear suspension balance. You can easily change it back to the previous settings if things don't improve.

As you've discovered, suspension settings are very much related to the geometry, so you have to adjust them all to account for each other until you find the sweet spot. Likewise, there's no "one-size-fits-all" settings which give optimum performance to suit all occasions, so for everyday driving in the way that suits the roads that you drive and your driving style, you have to decide settings and geometry that give the "best compromise". For me, I like my "fast road" settings to be able to account for the worst roads that I drive on, because with such settings, the car also performs extremely well when I'm driving on better roads. OTOH, if the settings are optimum for good roads and track, then the car will behave horribly on the worst roads that I drive. If you've been using KW's recommended settings, then I found that for my Z3MC with KWV3 suspension, that their recommendations are far too stiff for bad roads, and it's only by ignoring their recommendations and adjusting the settings to suit me that I have been able to get my cars to handle optimally to my liking.

IMO, setting suspension and geometry isn't much different to setting up your car stereo system to produce the optimum sound, where you can adjust volume, balance, fade, bass, treble etc. You just keep trying little changes, one step at a time, until you find what suits you for the type of music you like. What suits me, might not suit you, and vice versa. You'll get there in the end! :thumbsup:
 
Have to say that Exodus is bang on the money here. Type of car, type of roads, driving style / preference - all mean you've got to play and learn / try again!

All my previous cars have had chassis tweaks and I've found the Z4M the most difficult to get 'just right'...
... my current set up, I feel the spring rate I have is too high for the 'worst road' situations and only really comes into it's own on the 'smoothest' surfaces - which aren't all that often!

For what it's worth, I thought I'd share my current settings, if only so the OP can have another set to try.
Front Camber -2 deg, Rear Camber -1.5 deg
Front Toe; 0 deg
Rear Toe IN; 0 deg 2'

Hope that helps... I've been lurking on here / stealing all your info, so thought it was about time I shared some of my experience too!
 
How are you liking those camber plates? I heard that those particular ones rattle a bit? Post a review damnit! :lol:
 
ga41 - sounds like you and I read a lot of the same reviews on the GC stuff, from the US z4 forums?
- I have no complaints about the quality of the GC stuff, and no rattles from the camber plates as I believe they changed the design to remove this
- I was also considering KW kit and I do wish I'd gone for that in the end, there's nothing 'wrong' with the GC stuff but I feel people are 'happier' with KW

I think both Beedub and Exodus have hinted at this, but I'm not convinced linear springs on the rear of the Z4M are necessarily the right set up.
GC didn't offer anything other than linear springs when I was looking at the options, but I know KW spec a progressive rear spring, even on the Clubsports...
 
thank you all for the help. One last question....is there a way I can align the car myself without having to take it to a shop? I fear that going to and fro to the shop is going to cost alot :(

thanks

kerstien
 
kerstien said:
One last question....is there a way I can align the car myself without having to take it to a shop? I fear that going to and fro to the shop is going to cost alot :(

thanks

kerstien
Click to expand...

Yes. I do my own geometry settings and I've posted about it in these links: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=43082&p=612286&hilit=exdos#p612286 and here: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=43082&p=612878&hilit=exdos#p612878

It's easy enough to do: you just need to be methodical and patient.
 
You must log in or register to reply here.
Back
Top Bottom