Car Unstable Especially At High Speeds

[Thelen]

Hey SAUers, I'm not sure how best to describe or if others will understand, but I'll try!

At high speeds, 100kmh ie, even going along straight the car seems.. unstable. Not that it jumps whole lanes, but it feels to me at least like a spider on a hotplate or on ice.

And yesterday after driving in St Kilda for a while on REALLY bumpy roads, it was even happeningish at lower speeds. Once I almost sideswipped a car next to me (I was inside lane, thank god it didn't go over to oncoming traffic), the car just suddenly started going left and I had to turn the wheel right.

Anyway, it is at mechanics, hopefully they find a bush missing or something extremely loose, but does anyone have any ideas?

I realise it is a GTR and has tight suspension and so on, but it seems to me that it isn't just being sensitive to the road.

Cheers!

[Hadouken]

I believe your hicas is playing up! Do you have a lock bar?

[vorse]

+ for hicas freaking out get that checked out pronto

[Thelen]

Don't know about lock bar, but I'll relay that it could be HICAS.

Definitely makes sense that it would be HICAS, as it is definitely some sort of weird steering thing that doesn't affect the steering wheel itself.

Oh another thing, it also seems to happen more not just from going over bumpy things, but by fanging it. IE 1st 2nd to 100kmh, it definitely feels wobbly.

[Hadouken]

Search for hicas problems and you will get your answer. Now that we have told you what your problem is, get a lock bar and see ya later

[89CAL]

Are your wheel bearings OK? Jack the rear of the car up and have a look for bad bushes as well. Hicas is probably the issue but good excuse to check everything out

[D.I.Y. Mik]

Hicas eliminator is good because it eliminates the outer tie rod ball joints.

More expensive than a lock bar but cheaper than tie rods and ball joints

Those outer rear hicas ball joints are expensive and hard to find.

[Thelen]

I think the bearings are ok. Both rears were replaced like 6 mo ago. Bushes should be OK, lots were replaced 6 mo ago as well when I replaced much of the rear.

I'll see what they say then perhaps think about lock/eliminator. I don't really plan on racing or whatever so I'm not sure the pros or cons of having it in for the street, but if it isn't much more then I guess I can go for it.

[GTSBoy]

The cons are simply that HICAS delete bars are defectable. The pros are that HICAS sucks arse and has no place on any car, let alone one that is intended to be fun to drive.

Edited June 1, 2012 by GTSBoy

[Thelen]

Meh I'd rather avoid defects to keep life simple.

What does it really do to the driving experience? My mate loves my car and he's got a massive single turbo 1JZ MKIII supra with a crazy diff (only goes to 45kmh in 1st lol) although i suppose his suspension is older and not as good.

[GTSBoy]

Mk3 Supras are a little crude in the rear suspension, but not terrible.

HICAS is intended to produce slip angles at the rear as you turn in, to make the car more responsive to changes in direction. It is also supposed to make continuous small tweaks to the rear steering throughout a corner to keep the car on line. In reality, whilst it may enhance turn in (desirable), what it really does when you are fanging is make the rear do things that you were not expecting. Makes it very uncomfortable to drive fast. And that is while the system is still working properly. Once it starts to f**k up, all bets are off.

[Thelen]

They found right rear camber nut was completely loose, explains everything

Haven't had chance to drive on the highway so not sure if its really fixed, but seems better.

How much for elimination kit?

[R TUNE]

Could also be a wheel alighment, had a 31 that was all over the road, front toe was out.

[Thelen]

They re-aligned it.

It seems better, but still is a massive problem. Twice tonight on the way home along royal parade the car had a mind of its own and decided to 'jump' to the right. Thankfully they are only smallish ones and I react in time, but... damn.

[R32GOJIRA]

What size / width tires are you running? Wider tires with a lower profile tend to "tramline" or follow the grooves in the road. Wide semi slicks are notorious for doing this, and the car feels like it pulls randomly when it hits a different angle on the road surface. Wide street tires tend to have the same effect.

[Hadouken]

But not at 100km/h

Hicas kicks in at 80 or something

[Thelen]

I'm not sure I will check but they aren't low profile. 265R19 I do believe.

I'm starting to think its gotta be something in the suspension and steering rather than the wheels because sometimes when I break (sometimes heavilyish) the car will pull to the left/right and the steering wheel will actually turn a fair amount as well if I let it.. perhaps?

[rehab2010]

They re-aligned it.

It seems better, but still is a massive problem. Twice tonight on the way home along royal parade the car had a mind of its own and decided to 'jump' to the right. Thankfully they are only smallish ones and I react in time, but... damn.

Can you post how much toe in they dialled in - I had my car aligned too when I just bought it, felt shocking to drive - tramline central, then I went back to the alignment place and checked the toe in, which was left at 0 - now its 1mm or something like that, sensitive but much better.

265's wouldn't help much either - tramlining you all over the place.

[ima_slap_joO]

I had the same issue with the hicas, after 70km or so it would just kick the ass out but always the same way, i believe the drivers side rear...would slide to the right, very scary, i had the whole system removed and the lock bar installed. I would have rather keep it, but just way too dangerous.

[GTSBoy]

These symptoms (or at least the one posted above this post) are usually caused by the steering angle sensor....and more particularly by not having a boss that drives the steering angle sensor.