Baffling suspension issues

[malteser]

Hi guys,

As some of you may know, I've had some 16x7 BBS RS on my VR6 for some time now. Ever since I've put them on, I've been experiencing some weird handling characteristics from my car.



The day I put them on, (with 5mm spacers on to clear the front calipers) I took the car for a test drive on the M4, and at about 100km/h, swerving from left to right, the car just felt extremely loose and continued swerving about a second after the initial turning. My initial reaction was, "Oh crap, I didn't tighten the rear bolts", but after taking it back home and checking the bolts, they were plenty tight.

So then, I thought that the new wheels, which are much smaller offset (ET43 stock, ET35 previous and ET23 BBS) were just amplifying the problems with the steering and suspension.

I then needed to get the steering rack reconditioned as well as some other things like bushings and sway bar links changed, however, even with new Brigestone Potenzas it still has the high speed weave. It never seems to be completely planted and on a winding road with different camber, the steering weights up on the straight from left to right and it doesn't always feel like you have complete control.

My theory is that the offset change is just too large and that's stuffing the steering geometry up. I would really love to keep the BBS, so my bright idea was to change the barrel to make the wheels 8" wide rather than the 7" it is now. I could keep the 205/45R16 Potenzas and have some nice stretch at the same time. The other option is to put the 5 spoke 15 inch wheels back on with some sticky rubber.

Does anyone have any other ideas on what this gremlin could be or have experienced this before?

(On a side note, I may not have to worry about handling too much anymore as I'm sure a MegaSquirt'ed supercharger strapped to the engine will produce ample torque steer to cancel out even the best wheel alignment...
S/C + stock injectors + stock ECU = FAIL
S/C + 30lb/hr Red Tops + MegaSquirt = WIN)

[The_Hawk]

Damn you and your super charger (I'm just jealous )

Have you considered trying the stock wheels just to see how different it feels, especially if you can do it one after the other to feel the difference.

[malteser]

Haha Aaron, the charger has lag at the moment. Not enough fuel getting to the engine despite using 13L+/100km. If it gets around 150kW and 300Nm of torque I'll be very happy.

I'll have to put on the old wheels at ET35 compared to stock offset of ET43 or so cos I don't have any stock wheels. I just need to get some new tyres for them as they've worn through to the belts!

It's just extremely strange that offset can affect the handling so much, where other cars seem to benefit from bigger offsets. Maybe the VR is just sensitive and set up differently...

[rayray086]

I've used lower offsets before and I never got that high-speed weave you're talking about. If changing the wheels fixes the problem, perhaps try different tyre pressures?

[malteser]

I've only got spacers on the front, but I wanted to try it without them, just to see. I don't think I can at the moment as there's still not enough clearance to the calipers.

I reckon the only thing to do is get some tyres for the old wheels and try them for a bit. It does seem weird that it only affects my car though...

One thing I have noticed is that when I back out of my driveway, I often hear a clunk sound from the front of the car which hasn't been rectified with all of the suspension work. I wonder whether it could be something to do with the subframe.

I must say though, that the Bridgestone Potenzas have almighty grip and are well worth the extra cost.

[malteser]

mine had this clunk, from memory it was something like the top of the spring rotating, eventhough I could feel it through the steering rack.

Yeah, that's sort of what mine sounds like...

Ray, what sort of offsets were you running?

[kiasu]

sell me those wheels and it'll fix your problem :p

[Ben J]

some bigger lips will solve all of your problems haha

[rayray086]

I had 15x8 ET25 on the front, and 17x8 ET20 on the fronts before too. The 15's had 195/50 Falkens and were sweet, the 17's had 195/40 Pirelli Pzero Neros and were bloody awesome. In the rain, on the highway to Melbourne, it just stuck to the road. Very stable, low road noise. I was driving at decent speed too. Both examples I didn't have any problems with loose steering or twitching. Both examples had different suspensions too, ranging from shock and lowered spring setup to full coilovers. I experienced tramlining though but only on horrible roads (Parramatta Rd) but on smooth sections of the M4, they tracked beautifully.

How many kilometres have the tyres done? Any uneven wear?

[malteser]

sell me those wheels and it'll fix your problem :p

Lol, despite the poor handling, I will get these to fit and work on my car! They're not leaving my sweaty grip for a long time

some bigger lips will solve all of your problems haha

I'll actually be going in the other direction if the other old wheels work out and putting wider barrels on.

How many kilometres have the tyres done? Any uneven wear?

Well, that the thing. Its got brand newies on and all the camber issues have been fixed... So as the thread title goes, I'm simply baffled.