Dinan Stage 2 Suspension

[PNWM3]

Originally Posted by Dave IV

The Stage 2 kit has arrived. Installation is scheduled for Monday.

Really interested in how you like it after you get it installed.

[Dave2]

I took a look at the parts last night. All this stuff is very high quality. I will try to get some photos of the parts and then take some before/after photos of the car.

[Dave2]

The parts:

[GOVCO]

Interested in seeing this as well. I am back and forth between this, and the V3s. Ugh!

[Dave2]

The installation is complete. I have put a some miles on the car and pushed it only a few times. My initial impression is very positive. The car has quicker turn-in and less body roll when cornering.

In contrast to some of the above posts regarding increased understeer with the stiffer front sway bar I have found that the car exhibits less understeer.

The new springs drop the cart by a little less than 1". So far I am very pleased with this mod.

Pictures to follow in a day or two.

[Z K]

I very much doubt you'll feel understeer or oversteer on a public road especially if you have traction control engaged. You'd need to go on a track or autocross with the traction control off to feel that.

[Dave2]

Before Dinan Stage 2

[Dave2]

After Dinan Stage 2

[armyav8tor]

I am also with the camp that says if you stiffen up the front roll bar without doing anything to the rear, you are increasing understeer. Now, maybe the Dinan brand somehow defies physics. Who knows, but as long as the OP is happy then that's all that matters.

[Dave2]

Originally Posted by armyav8tor

I am also with the camp that says if you stiffen up the front roll bar without doing anything to the rear, you are increasing understeer. Now, maybe the Dinan brand somehow defies physics. Who knows, but as long as the OP is happy then that's all that matters.

This is true for double wishbone suspensions and cars with very high spring rates; but not for typical strut suspensions:

A sway bar limits camber changes. The camber is the angle that the tire leans in or out at the top
relative to the chassis of the car. The camber directly impacts the angle at which the tire
cross section meets the road and thus controls lateral grip. As the suspension compresses
the camber angle generally changes relative to the chassis. With a normal Macpherson
strut that hasn't been lowered, the camber goes from positive to more negative as the
lower A arm swings out straight, and then back to positive as it swings up. That swing
up into positive camber is BAD. At that point the chassis is already leaned over so the
tire may be starting to roll onto its sidewall. Changing the camber even more positive
just just nasty. A big sway bar will prevent the body roll in the first place, and
prevent the suspension compression on the outside which causes the positive camber
change relative to the chassis.

http://www.houseofthud.com/cartech/swaybars.htm

[armyav8tor]

Originally Posted by Dave IV

This is true for double wishbone suspensions; but not for strut suspensions:

A sway bar limits camber changes. The camber is the angle that the tire leans in or out at the top
relative to the chassis of the car. The camber directly impacts the angle at which the tire
cross section meets the road and thus controls lateral grip. As the suspension compresses
the camber angle generally changes relative to the chassis. With a normal Macpherson
strut that hasn't been lowered, the camber goes from positive to more negative as the
lower A arm swings out straight, and then back to positive as it swings up. That swing
up into positive camber is BAD. At that point the chassis is already leaned over so the
tire may be starting to roll onto its sidewall. Changing the camber even more positive
just just nasty. A big sway bar will prevent the body roll in the first place, and
prevent the suspension compression on the outside which causes the positive camber
change relative to the chassis.

http://www.houseofthud.com/cartech/swaybars.htm

Good read. Most of my knowledge on this topic is from the FWD community so apparently what I know doesn't translate to the M3.

[Dave2]

Originally Posted by armyav8tor

Good read. Most of my knowledge on this topic is from the FWD community so apparently what I know doesn't translate to the M3.

The article from the linked site provides a good fundamental understanding of some aspects of suspension design.