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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > STILL understeering at limit - there is more in the car I know it



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      02-17-2012, 01:11 PM   #67
subieworx
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Not what I meant I guess. Sure, it can be measured without a spring in place and compressing the suspension will give you a measurement of what it will be at a specific ride height. However, dynamic camber is MUCH different when you start to turn the wheel as caster and SAI play into the amount of dynamic camber that is added to the wheel. One could setup a scenario where multiple points are measured, but to get an accurate idea of what the suspension is doing under load many points would need to be measured.

Alternatively, one could measure all suspension components and plug the numbers into suspension modeling software to determine all values....I don't have that.
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      02-17-2012, 01:49 PM   #68
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Quote:
Originally Posted by subieworx View Post
Tire temps indicate that -3.2* is reasonable in the front given what I put the car through.

I am running AST 4100's so only rebound adjustability, but have gone through a few different iterations of the valving with my local shop all of which have made positive changes.

Depending on what kind of driving I am doing in what time frame the alignment changes regularly. I typically run .1* total toe in front as less than that tends to eat tires quickly. I run .14* total toe in rear which any less makes the car really twitchy at high speed.

There is no way of measuring dynamic camber without some serious equipment as you know so that is out of the question. The car is not very low however and by the evaluation of the suspension at my current ride height I am not in the danger area of poor geometry for a macpherson strut equipped car.

I think my main issue is really the need of an aftermarket LSD, but given mine is welded the expense is quite great as you guys know. Not running any deals currently are you?
No, no current specials. We can hardly keep these things on the shelf and the machine shops(Yes, we got two machine shops working) is working overtime on the machine work on the ring gears.
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      02-17-2012, 01:50 PM   #69
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Quote:
Originally Posted by vwong View Post
Not exactly. I've done something similar a while back. Here is how I did it.

1. while the car is still on the ground, measure the distance from the center of the wheel to the top of the fender arc
2. put the car on jack stands, make sure the car is leveled
3. remove wheel, remove the spring only, disconnect the swaybar
4. put the wheel back on
5. use the floor jack to compress the suspension to the distance you measured in step 1
6. measure the camber, this will be your static camber
7. continue to compress the suspension, stop at every 1/2" or so and measure the cambers, these numbers will be your dynamic camber
8. stop until the suspension is fully compressed

This is a simple way of measuring when you don't have the sophisticated equipment.
That works to an certain extend, but does not account for bushing deflection and the degrees of body roll.
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      02-17-2012, 02:12 PM   #70
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Quote:
Originally Posted by DaFish
Well, I thought I would start a thread on the amount of AT THE LIMIT understeer still in the car after the following:

1) Dinan Stage THREE - Dinan Front sway, Dinan springs/shocks all round, and the Dinan camber plates - PLUS

2) M3 Tension rods and M3 Wishbones (I added those)

I must be running over negative 2 degrees of front camber

3) 1 size up on NON RFTs - Bridgestone Pole Position tires (235/265 - on 19" stock 230 rims)

I guess it is stilll good that the car understeers not oversteers, but I certainly feel there are more G's can be pulled in this car that what I can currently do. I noticed in a long tight on ramp - 270 degrees, the front is losing traction still and pushing.

COMING: Rear subframe bushings, REAR Dinan Sway Bar, Wavetrac LSD

My questions to the communitity are as follows:

Q1) How much difference will there be when I add the three items listed above?

Q2) Do you believe the front strut bar would be a good addition to my Mods? Why?

Q3) Stagger: I think the Stagger is really increasing the amount of understeer and the weight of the car is overwhelming the 235 front tires - regardless of the mods.

What will give me the biggest bang for the buck to get some more G's?
LSD will make the biggest difference.
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      02-17-2012, 03:45 PM   #71
vasillalov
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Originally Posted by The HACK View Post
Well, yeah. You're from Denmark. The land where they ALL know how to properly control a drift through a corner. Aren't like all of you people born to be World Rally Championship drivers anyway?

Or am I thinking of Finland?
Finland... not Denmark! Denmark is the country with the highest suicide rate in Europe!
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      09-30-2012, 06:26 PM   #72
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Originally Posted by Yankees 2010 View Post
You are on point and this is what I was taught during my HPDE classes.

Personally I think understeering is all relative to speed, acceleration and grip. When I was going into a turn too fast the car understeered like crazy. When I went in a little slower and keep my foot on the gas to keep traction on the back tires I blew threw the turn and was able to keep it tight. You have to be very smooth with your hands because any abrupt movments will unsettle the car. Quick hands are for stunt driving and smooth hands are for racing. Driving on the road and track are two different worlds. I never knew what my car could do until I went racing.


The turn im talking about is at 3:36 and please watch in 720HD
Great video, thanks for posting. What kind of camera mount was that?
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