Unstable

[crossingover]

Hi guys
On my AU ive got 275/35/19inch tyres on rear and on the front ive got 235/35/19 reason being fronts are smaller is guard scrape.My tyres are fairly new ive got 4 shocks new short body and ultra low springs.My swaybars rubbers have all been replaced with noltec rubbers car is tight and very firm.
My problem is sometimes late at night i take it out and give it a squirt when im on the ring road turn offs and bends they are not sharp bends but windy ones,but what happens is my rear end will tend to let go half way through the turn when i say letting go i dont mean a full slide or so but as i put the car in to the bend turns in tight and starts to lightly slide through turn and exits excellent.
Could my tyres being different in size cause the front to dip in more and raise the rear?are 275 tyres to big for this car? At this stage im not sure?prior to my AU i had an vr clubsport with similar setup and it would hold road like glue.Im finding the au is not a good handler or am i wrong ?photos of height and rear rim width

[Casper]

I know exactly what it is. The IRS has not been aligned correctly and is causing it. Take it to someone who knows how to align a lowered IRS setup correctly (not the yahoos at Bob Jane / Goodyear or whatever) and I think you will notice a MASSIVE difference.

Try Rob at Blue Oval Garage, they have all the equipment for specialist suspension and alignment setups and know there stuff (he's a structural engineer!), I'm betting he can sort it in a heartbeat.

[au2sw]

are you saying you dont like her stepping out a little so as to exit the corner at the best angle?!! are you crazy??! but just a question....did the clubsport have traction control? if so that could be the reason why it didnt respond as magnificently to corners as the au does, that and it was a holden!
seriously though, is it such a problem that it worries you? i could understand it if it was a wet road and you did the same thing you probably would end up facing the other way...or worse. a lack of traction could be from various things, poor suspension set-up, to much power - not enough rubber, road surface.....etc etc. as for tyre sizes...well, a lot of high performance vehicles go with the wider rear, for the extra tracton, my thoughts would be with the suspension set up. do you have correct camber set up? you may want a little negative camber to compensate for the ride hight and tyre width. just my suggestion any way.

[Casper]

hang on, I know this car.. its live axle not IRS :

I'm still saying its suspension though. Get BOG to sort it for you.

[JC]

I'm betting it's the WanLi tyres (or similar brand). Throw some Kumhos, Hankooks or even Nankangs at it and you'll notice a different level of grip.

[howesy]

This may sound silly but in a miniscule way it also contributes. Your tyre has a footprint and your suspension setup will give a weight distribution to each tyre. As your go through a left hander for example the centre of gravity shifts slightly toward the front right and so too does the weight distribution. Your weight transferred to the road through the tyre footprint is applied in PSI. Increase the size of footprint while weight remains the same reduces the pressure in psi on the road. In other words, having a larger footprint on the rear than the front ever so lightly lightens the load to the rear end. With hard accelleration the weight and load shift to the back and this becomes null and void as engine power exceeds traction and thats why the wider tyre helps with the launch because the transfer of weight dramatically increases the psi on the larger footprint to give it greater traction. In your case while cruising and shifting weight forward you you reduce weight application to the rear.
This is only one ever so minor contributing factor and not the whole or total cause and this all sounds like garbage then dismiss it but please dont shoot the messenger as this was explained to me once by a tyre specialist. I took his advice and went to 245 and had much improvement. (my problem was the rear losing it in the wet too easily)

[Stav]

I have simlar problems with the wagon since lowering it.I drive extremely slow in the wet.

[GK]

Originally Posted by useless

I have simlar problems with the wagon since lowering it.I drive extremely slow in the wet.

I find it hard to imagine you driving slow in any conditions, especially with that beast of yours! LOL

GK

[GK]

Originally Posted by JC

I'm betting it's the WanLi tyres (or similar brand). Throw some Kumhos, Hankooks or even Nankangs at it and you'll notice a different level of grip.

Crossingover, what tyres have you got on it?

GK

[DJM83]

Hey i seen your car parked opp bunnings in albury last week, it attractted my attention with the T2 front bar ive never seen a falcon with a T2 front bar before very nice mate

[WhiteKnight]

Years ago I put oversized tyres on the rear of an XD 5.8 litre and I found when changeing direction as in "S" curves that the car appeared to squirm on the rear tyres. I eventually discovered that the tyres were too wide for the rims used and I had to go 1" wider on the rear rims which made all the difference.
If you go here (http://www.wheelenhancement.com/tirespecs.php?tireid=18) you will see the recommended rim width for the size of your rear tyres is between 9" and 11 with the "design width" of 9.5" .... are your rims around this size at the rear?
I hope this may help

[rob_liss_lms10]

Originally Posted by JC

I'm betting it's the WanLi tyres (or similar brand). Throw some Kumhos, Hankooks or even Nankangs at it and you'll notice a different level of grip.

For heavens sake, don't use Nankangs. I went from Maxis 245/40/18 to nankang 245/40/18 supposed sports/performance, I never knew my car could drift around a track (Qld raceway) until I got these, and lets not even mention wet weather driving. Will be changing back asap, the Nankangs are harder compound though, so in their defence will last longer and may explain the less grip.

[Stav]

Originally Posted by GK

I find it hard to imagine you driving slow in any conditions, especially with that beast of yours! LOL

GK

Hahha.I got smashed by 2 semis a few years ago and I was going 10kmph,if it were faster Id be hanging out with St Peter lol.. Since the lsd conversion /lowering and replacement of my steering rack my handling isnt as good.Bit strange when you think that everything has been changed .

Its nice to run a quicker car but only when its responsibly done.If a kid ran out in front of me and I ran it over Id never get over it.

[GK]

Originally Posted by useless

Its nice to run a quicker car but only when its responsibly done.If a kid ran out in front of me and I ran it over Id never get over it.

Quite true!

GK

[AUXRVIII]

Originally Posted by crossingover

Hi guys
On my AU ive got 275/35/19inch tyres on rear and on the front ive got 235/35/19 reason being fronts are smaller is guard scrape.My tyres are fairly new ive got 4 shocks new short body and ultra low springs.My swaybars rubbers have all been replaced with noltec rubbers car is tight and very firm.
My problem is sometimes late at night i take it out and give it a squirt when im on the ring road turn offs and bends they are not sharp bends but windy ones,but what happens is my rear end will tend to let go half way through the turn when i say letting go i dont mean a full slide or so but as i put the car in to the bend turns in tight and starts to lightly slide through turn and exits excellent.
Could my tyres being different in size cause the front to dip in more and raise the rear?are 275 tyres to big for this car? At this stage im not sure?prior to my AU i had an vr clubsport with similar setup and it would hold road like glue.Im finding the au is not a good handler or am i wrong ?photos of height and rear rim width

Have the rear lower trailing arm bushes checked, it's common for the rubber in the bush to separate from the outer part of the bush which allows the arm to move.
Sometimes it is forgotten to back off & retorque the bolts in suspensions when it's sitting in its lowered positon which results in them failing.

[Sapper]

Originally Posted by WhiteKnight

Years ago I put oversized tyres on the rear of an XD 5.8 litre and I found when changeing direction as in "S" curves that the car appeared to squirm on the rear tyres. I eventually discovered that the tyres were too wide for the rims used and I had to go 1" wider on the rear rims which made all the difference.
If you go here (http://www.wheelenhancement.com/tirespecs.php?tireid=18) you will see the recommended rim width for the size of your rear tyres is between 9" and 11 with the "design width" of 9.5" .... are your rims around this size at the rear?
I hope this may help

I reckon this might be the problem. When you go wider tyres on the rear you change the angle of the sidewalls and so they flex differently to the front tyres. Incorrect alignment like Casper said would be my next guess. I'm guessing in this that you have the same tyres front and rear.

[HLC]

Originally Posted by rob_liss_lms10

For heavens sake, don't use Nankangs. I went from Maxis 245/40/18 to nankang 245/40/18 supposed sports/performance, I never knew my car could drift around a track (Qld raceway) until I got these, and lets not even mention wet weather driving. Will be changing back asap, the Nankangs are harder compound though, so in their defence will last longer and may explain the less grip.

maxxis tyres are rubbish : we have them on my dads BA XR8. absolutely shocking :

[rob_liss_lms10]

Originally Posted by HLC

maxxis tyres are rubbish : we have them on my dads BA XR8. absolutely shocking :

I didn't say maxxis were any good, just that the Nankangs are worse.

[GK]

Originally Posted by HLC

maxxis tyres are rubbish : we have them on my dads BA XR8. absolutely shocking :

I would suggest that it depends on which type of Maxxis. I have MAV1's on both my AU's and they work fine in the wet and dry. They have only done a few thousand kays though, so we'll see in another year or so I guess!

They make more noise than I would like, but that's not too bad really!

I say they are fine, but I'm not trying to break traction with them or anything. My AU's (both I6's on gas) are hardly tyre shredders in any case! LOL!

GK

[crossingover]

Originally Posted by TE50 056

Hey i seen your car parked opp bunnings in albury last week, it attractted my attention with the T2 front bar ive never seen a falcon with a T2 front bar before very nice mate

Thanks for the comment,I went to nsw to see some friends and dropped into the sports store in albury opposite bunnings,I love Albury always spend time there when crossing through.

As for my unstable condition i finally worked it out.Ive now replaced rear tyres with 245s and fitted a adjustable front stabiliser bar.Seems alot better and feels alot more stable and yes most of the problem was having 275 rears with 235 fronts.My tyres are hankook ventus.

[GK]

Originally Posted by crossingover

I love Albury always spend time there when crossing through..

Or should you say crossing over! LOL!

Originally Posted by crossingover

As for my unstable condition i finally worked it out.Ive now replaced rear tyres with 245s and fitted a adjustable front stabiliser bar.Seems alot better and feels alot more stable and yes most of the problem was having 275 rears with 235 fronts.My tyres are hankook ventus.

Glad you got to the bottom of it!

GK