suspension: how low is too low?

[nomuken]

When I recently went to a suspension shop to have my new suspension installed the man working on the car warned me not to drop the car too low. He said that while it's desirable to have the lowest center of gravity possible, the suspension must also have some room to travel. My question is how is the minimum "travel room" determined? How does the performance of the suspension suffer as the travel distance approaches and breaches this minimum?

[AZhitman]

Hoo boy. Great question, nomuken.

Dennis is gonna have a field day with this one.

[corn322]

heh. also, how much suspension travel does the 240 have stock?

[Q45tech]

Pretty much all Nissan have the same shock travel = 7".Some are offset from the ideal 50/50= +-3.5"2 200 pound people in the front will drop the body 0.7", the full 900 pound load might drop the rear 2.5" inches.

Unless you move the suspension pick up points [totally redesign and custom make every part] to redefine the camber curve 1.000000000000000000000000000000000000" is the practical limit. If you want the car to behave anywhere close to what the factory designed.

Once you get below 1" you start hurting performance and don't gain anything.

If anything most Nissans don't have enough wheel travel and could benefit from an 1" more.........but special custom shocks would need to be designed and produced.What you want is with your weight in the drivers seat is for all 4 shocks to be perfectly at 3.5"..........shim the spring seats to level the car............ideally you would weigh each wheel load and select differing springs or change body components around to have a perfect 50/50 side to side.

[AZhitman]

Based on Dennis' comments, the Eibach ProKit would be a nice safe setup for the 240 - But we already know that.

SWA has a rippin' deal on them for NICO members.

[Altiman94]

If you are looking for a good performance based setup with a small drop. I would go with the Tein S Tech springs and kyb AGX struts. The drop estecially is minimum, but the performance of this unmatched to pretty much any spring/strut set up. These tow components seems to be well balanced together.

[nomuken]

Quote »Pretty much all Nissan have the same shock travel = 7"[/quote] is this shock travel pretty straight forward to measure? will sitting on the corner of the car's trunk make the suspension travel the distance?

p.s. AZhitman and Altiman94, thanks for the suspension recommendations, but i already have HKS installed.

[MrFox]

Like Q45 said, what is needed is ride height that can maintain the designed camber/bumpsteer geometry, else your handling will go to hell. The height to look for is where the LCA becomes parallel to the ground - around 1.5" IIRC.

[PROJECTRB240SX]

SO IF I WERE TO GET A FULLY ADJUSTABLE COILOVER SETUP, WITH ADJUSTABLE FRONT PILLOW BALL MOUNTS, ADJ T/C RODS, AND IN THE REAR ADJ UC ARMS, ADJ TOE LINKS, ADJ T/C BAR. COULD I LOWER THE CAR 3" AND ADJUST THE CAR TO BEHAVE LIKE STOCK? OR MORE AGRESSIVE THAN STOCK?

ALSO CAN I GET AWAY WITH LITTLE TO NO BUMP STEER?

[Q45tech]

You can change the front suspension [struts] but the rear arms attachment points are fixed to subframe..........ideally you would lower the attachment points which means designing a BRAND NEW rear subframe...........when dropping the rear more than 0.8" to 1.0"!!!!!!!!!!!!!!!!!!!!!!!!!

[s13sr20chris]

yay, brand new subframe coming boys! i cant wait. whos gonna make it?

[MrFox]

ALSO CAN I GET AWAY WITH LITTLE TO NO BUMP STEER?

Bumpsteer is dependent on the location of your steering rack and tie rod attachment points. There really isn't a geometry that gets you perfect zero bumpsteer, but it can get pretty close. There's probably not enough room under a 240 to do much relocating with the steering rack though.

[toki]

2" is too low. i'll put it that way. i think i may actually even be 2.25" dropped, not sure. either way. it's too low. 1.5-1.7 would be much nicer.

[Q45tech]

"There's probably not enough room under a 240 to do much relocating with the steering rack though."

Have special offset tie rod ends forged, but that doesn't solve the low arm angle, or the tension rod angle.

[MrFox]

I haven't really looked at the bumpsteer geometry on these cars. It only needs to be moved so little? Would eccentric steering rack bushings accomplish the same then?

Regarding the original question, suspension travel is less of an issue than the geometry on (mildly) lower cars, since you'll be using stiffer springs anyway.

[Bart1]

check out a software analizing company called Performance Trends, just do a search for them and you should find them.I have the soft and its pretty good, even if you want to sort out just the bump steer, you just make adjustments in the soft prgm, either lower or raise rack/tie rods and then you do a bump test, 3" travell even though it wont see 3" in real life, and see if the wheels toe in or out etc.

Good learning tool.

[7thGear]

if you have time to read this 600 post thread, please do

http://forums.vwvortex.com/zerothread?id=621342

i know it deals with vdubs but i think the theory will still be beneficial, since they have macphearson struts they have their world of problems as well, and the general conclusion was that on mk3's + almost ANY drop hurts handling unless stiffer springs are added which hurts ride quality