Sway Bars VS Camber plates

[!kid]

so if sway bars were put on an e30 at stock ride hight would this still apply ?

[Wh33lhop]

so if sway bars were put on an e30 at stock ride hight would this still apply ?

This is exactly the setup I'm currently running. Camber curve is certainly more favorable at stock height (I haven't inspected the LCA angle at stock height, but it probably gains camber for an inch or two of compression, then loses afterwards) you will still benefit from a bigger front sway to alleviate some camber-sapping excessive body roll. I definitely noticed a lateral grip increase.

[T Verdier]

think about this. the if the front sways are stiff and the rears loose then the rear will sag to one side under power and lift the front tire. that means 1 front tire has very little contact right. creating understeer?

[7pilot]

think about this. the if the front sways are stiff and the rears loose then the rear will sag to one side under power and lift the front tire. that means 1 front tire has very little contact right. creating understeer?

Porsche 911s do this all the time..Even if the inside front is off the ground, you'll still have good front traction.
Because you are accelerating, there is very little vertical load on the front suspension. Most of the weight transfer is on the outside rear, then inside rear, then outside front.
There is the possibility of understeer, but your right foot should be well trained enough that you get to the limit of front traction and stay there until the steering is straight. You ideally will be taking lock out of the steering as you accelerate out of the corner anyway. If you don't, it is driver induced understeer. You are more likely to see understeer if you are running a staggered set up, where you'll have excess rear grip.
Generally, the current popular swaybar set up in BMW tracking is little or no rear, big front.

m

[Nonspec325]

!kid,

This is the simple of it... The first thing you need to do is get a good alignment. Alignment is the biggest "performance" upgrade you can have. I'm sure there are guys on here that can give you a better idea of what alignment can be done with a e30; I just changed to an e30 from another autox car so my experience with the e30 in particular is limited.

Also, if you are getting under steer the simple solution to bringing the car close to neutral are to stiffen up the rear in a rwd car. This will get you back end to rotate better and should eliminate most if not all of your understeer.

Camber/Castor plates are great but it is normally an upgrade to be had after springs, struts, and sway bars are sorted.

If you have the $$$ for castor plates you should be able to get yourself a nice rear sway bar, alignment, and a set of springs for about the same price. That would be the way I would go...

and remember the best autoX upgrade is to adjust the nut behind the wheel. :D

[nando]

However, with our macpherson struts, at a lowered ride height we lose negative camber the more our front suspension is compressed (camber curve has decreasing negative camber slope), so as previously stated, a lowered car needs all the roll stiffness it can get..

you would have to lower your car to the point that the angle between the strut and the control arm was greater than 90 degrees to lose camber. Only the stanceworks kids are that low (I hope).

[JGood]

you would have to lower your car to the point that the angle between the strut and the control arm was greater than 90 degrees to lose camber. Only the stanceworks kids are that low (I hope).

I think he was trying to say the camber curve becomes less "curved" as you go down. So the negative camber gain per inch of drop would be a smaller amount every inch that you go down. Although I don't see this being relevant, as e30's without serious suspension modification (custom control arms, etc...) need all the negative camber they can get. You won't see more then -3 or so with stock size springs, and maybe -4 with 2.5" coilover springs.


LOL @ the stanceworks comment

[nando]

yeah, you do gain less as you approach the 90 degree point, but you definitely don't lose any. and if you do get past that point your suspension geometry is pretty well fucked anyway (bump steer, travel, roll center, etc). :p

[Hallen]

Sorry, but that's incorrect. On e30's, as well as many other cars, a thicker front bar will actually increase front end grip, giving less understeer, due to increasing the front tires contact patch.

You need to add "up to a point". After that, then the car will start behaving in the normal way, eg, more front sway bar = more understeer.

It is important to note that the front sway helps at controlling the front induced camber from body roll (I think I am saying that right). Like you said, increases the front tires contact patch by helping to keep more of the tire in contact with the pavement across with width of the tire.

Camber plates will also do this, so in that way, they are comparable. Thicker sways will also make the car a bit more twitchy over bumps.

TO the OP: Another point will be that if you add camber plates, you will get more grip out of the front end and that will induce more body roll. You'll probably be wanting the sway bars pretty quickly thereafter. ;)

[Wh33lhop]

I think he was trying to say the camber curve becomes less "curved" as you go down. So the negative camber gain per inch of drop would be a smaller amount every inch that you go down. Although I don't see this being relevant, as e30's without serious suspension modification (custom control arms, etc...) need all the negative camber they can get. You won't see more then -3 or so with stock size springs, and maybe -4 with 2.5" coilover springs.


LOL @ the stanceworks comment

Well, as I said I haven't really inspected the LCA-strut angle at stock or lowered height, so I made an assumption that the geometry was similar to my old car. But at any rate, yes, at the very least, the slope of the camber curve decreases the further you compress the front suspension, whether it be gaining less negative camber or losing negative camber. Sorry for the misinformation.

[Wh33lhop]

think about this. the if the front sways are stiff and the rears loose then the rear will sag to one side under power and lift the front tire. that means 1 front tire has very little contact right. creating understeer?

Basically, the more load on a tire the less efficiently it performs.

With a big sway bar you're using the tires on that axle to heavily combat body roll, so with a big front sway you're loading the outer front (outer is much more important than inner in a corner) quite a lot, whereas both rear tires are planted with similar force to each other since they're not resisting roll as much. So, the front axle has less grip than the rear.

That's the typical "perfect geometry" behavior.

[JGood]

Well, as I said I haven't really inspected the LCA-strut angle at stock or lowered height, so I made an assumption that the geometry was similar to my old car. But at any rate, yes, at the very least, the slope of the camber curve decreases the further you compress the front suspension, whether it be gaining less negative camber or losing negative camber. Sorry for the misinformation.

Well, I'm still learning, I've never actually measured the front camber gain nor have I seen any charts of it. Just going off of info from sources I would consider reliable :)

Did e30m3performance.com have info on front camber gain? Here is a chart for stock rear (15 degree), but I haven't seen anything for the front...

http://www.e30m3project.com/e30m3performance/tech_articles/susp-tech/rear_curves/page-2.htm

[guibo09]

anyone know the kingpin inclination on an e30? visually, it looks so aggressive that i dont think bump camber loss is too significant a problem. it usually isnt a problem for rear wheel drive cars that have less packaging issues up front and dont have to worry about torque steer.

on my impreza however, bump camber loss was a significant problem, being AWD.