Couple Of Handling Questions

[33driver]

Hey guys,

Love the car, absolute blast to drive, however now that i've been driving it for a bit, i'm starting to look into its hopefully minor issues.

Issue 1) After full wheel alignment and balance, car still has slight vibration at high speeds - i'm calling shit tyres since the guy at the workshop said the rear's where out of whack and slightly egged just want confirmation.

Issue 2) Car pulls to the left if I let the steering wheel go - car has coilovers but are old and way to hard and i think oversprung, possibilites? castor rods? control arm or something i can adjust?

issue 3) how to tell if car is over sprung - i think it is, had 2 people get in on the passenger side, was sagged and i could 'feel' the damper move and actually work rather than the spring just bounce around like usual - my thinking is with more weight its stopped the spring from moving as much and allowing the damper to do its job. With just me in the car, if i go over a large bump you can hear the springs 'resonate' and clang around.

Issue 1 and 3 i think can be fixed with new tires and a change in suspension, issue 2 i'm not sure about. No obvious viscous fluids so i'm not sure about the castor rods, but my mechanic is away so i can't talk it through with him.

Cheers guys! For once i'm actually looking forward to working on a car!

[salad]

1. is the vibration through the steering wheel or through the seat?

if its through the seat, more than likely its the rear tyres fault as the guy said

2. cars pull with uneven camber and/or castor. they pull to the side with less camber/castor.

to fix the problem get castor rods/bushes. if the camber is uneven too get camber bushes/arms.

all this information will be on you wheel alignment report. both camber and castor should be very close to even.

if there is castor adjustment, wheel aligners will set the left up with 0.5-1.0deg more castor to accomodate for the natural camber of roads (which allow for water drainage)

Edited October 16, 2006 by salad

[33driver]

ok cheers for that, i'll go check the report now. The vibration is through the steering wheel, not the seat. Possibly rack bushes or something?

[33driver]

well there's my answer for the pulling to the left, wheel alignment report shows left at +4.41 degrees and right at +5.57 degrees.

Are the castor rods seperate to the bushes or are they together? Just replace both?

Vibration is the last thing ot worry about i guess, it only happs at about 110km/h plus. Before the alignment it was about 80km/h plus

[salad]

sounds like front tyres still out of balance... alignment wont affect vibration.

rods are seperate to bushes. replace the bushes in the stock rods or replace the whole rod with an aftermarket rosejointed item

bush's are the more street friendly option.

i think you can get enough adjustment out, but im not sure, someone else will have to clarify as i've never had bushes.

rose jointed rods have a lot of adjustment, more than enough, but they're not recommended for street.

[Kinks]

rose joints are illegal on the street, because when they wear out they fall apart.. Having your suspension detach in the middle is generally not a good thing

You don't need that much adjustment on the street. On the track, sure.. especially with semis

If your alignment is fine but the bushes are clapped out just get the bushes replaced. Otherwise get adjustable castor rods and have at it (have seen the noltec ones for a 32 GTR and they make a brick shithouse look like a tent).

Vibration is either caused by out of balance, cheap out-of-round tyres or that your wheels aren't perfectly true on the hubs (you will probably get brake vibration if this is the case because the rotor will be out as well). Edit - if your wheel bearings are on the way out that can cause it too.

If the springs are bouncing around like you say it sounds like the car is oversprung. Personally I think it's foolish to run rock hard suspension on aussie roads, get some nicely matched springs and shocks instead!!

Edited October 19, 2006 by Kinks