Wandering wheels

[Pete B]

Upgraded from 17" cups (with half worn non N rated continental tyres) to 18" turbo style with new P-zero assimetricos on. Can't help but feel that the car now suffers more from the wanders. Had the suspension geometry checked and faults in the rear toe-out corrected (that made quite a difference to slow/moderate stability) but on Mways the car is now quite unpredictable. Moderately fast driving on twisty roads produces all sorts of strange effects with the car alternating between perceived understeer to sudden turn-in. All a bit discomforting.
Any thoughts? Car fully serviced and after a 10 minute road test drew no comments from the experienced mechanic, except that it had exceptionally good stoppers!

 

[burrow01]

What year is the car?

I know there you are not supposed to fit 18" wheels to early 993's, and then there is a range of VIN's where you need to add a steering rack brace. This brace was then standard on later cars

Are the offsets of the new wheels the correct ones for a 993?

Cheers

Pete

 

[Pete B]

Hi Pete, its a 95 and I did check the VIN before ordering the wheels - standard offsets - and seemingly ok for 18"

 

[burrow01]

Sounds good - has it got the steering brace fitted?

Who did the alignment? - although it sounds like they knew what they were doing [] - did you get a printout of the current settings?

Do you have your old wheels to put back on? if you get the same effect with the old wheels it would probably be a suspension / geometry problem. If the effect goes away, it could be something to do with your new tyres / wheel combination.

Pete

 

[kennyboy]

ORIGINAL: Pete B

Upgraded from 17" cups (with half worn non N rated continental tyres) to 18" turbo style with new P-zero assimetricos on. Can't help but feel that the car now suffers more from the wanders. Had the suspension geometry checked and faults in the rear toe-out corrected (that made quite a difference to slow/moderate stability) but on Mways the car is now quite unpredictable. Moderately fast driving on twisty roads produces all sorts of strange effects with the car alternating between perceived understeer to sudden turn-in. All a bit discomforting.
Any thoughts? Car fully serviced and after a 10 minute road test drew no comments from the experienced mechanic, except that it had exceptionally good stoppers!

Pete - I had this when I fitted new Pirellis to my 17"'s on a carrera, in the end it was down to the new tyres bedding in......it went away after 150 miles or so.

 

[Gordon Attar]

You will probably need to do a few hundred miles to wear the tyres in, also check the obvious if they are directional tyres that they have fitted them correctly. Lastly suggest you post the results of the geometry test for your felow owners to check!

 

[RichardLW]

And even when the tyres are bedded in you will probably find the car following the tracks and ruts and diving for the kerb if you have any sort of non standard set up at the front.

 

[Melv]

WHAT SETTINGS ARE YOUR ROLL BARS ON?

 

[Pete B]

Thanks everyone for your replies. I'm in the aftermath of a house-move and as soon as I can locate the print-out from the alignment I shall post it. Otherwise the car is absolutely standard. No lowering or different shockers. Before, on the 17" she was rock steady. Sadly they went ebay, together with the Nokian (made from granite) tyres that wore about 2mm down to 5.5mm in 22,000 miles according to the receipts I got from the previous owner!
They were a bit skittish!
Thanks again

 

[kennyboy]

That makes sense Pete - very worn tyres may be 'skittish' but you also get a lot of 'feel' with them on a 993 as there's less rubber between you and the road......perhaps what you're suffering from is losing all the feel with the big (and relatively wobbly) tread on the brand new tyres.

You see we enjoy such a beautiful and wonderfully (or is that annoyingly) sensitive chassis!

 

[Pete B]

Maurice, I watched him adjust front & rear toe/castor but he said (?) that it was not possible to adjust the front camber..although I see that the readings have changed from before to afterwards?

 

[burrow01]

Hi

As Maurice mentioned did he check / adjust the rear kinematic toe setting? I don't see it on the print out?

Where did you have the alignment done, and do you know what machine they used to perform the checks?

Cheers

Pete

 

[Pete B]

Hi Pete, I went to a specialist in Liverpool, recommended by another PCGB member. Place is also used by owner of OPC Chester. Unaware of any other adjustments, esp the kinematic toe setting. I think that a trip to an OPC is needed......

 

[burrow01]

Hi,

Not necessarily an OPC, just someone who knows 993 suspension. The 993 is the only 911 model that has the Kinematic Toe setting, and requires a special tool to measure it, so you need to go to somewhere that is familar with it and has the tool

If you are in the North West there are several specialists who would be able to do the alignment properly - I'm sure some recommendations will be along soon []

Pete

 

[kennyboy]

ORIGINAL: burrow01

Hi,

Not necessarily an OPC, just someone who knows 993 suspension. The 993 is the only 911 model that has the Kinematic Toe setting, and requires a special tool to measure it, so you need to go to somewhere that is familar with it and has the tool

If you are in the North West there are several specialists who would be able to do the alignment properly - I'm sure some recommendations will be along soon []

Pete

they certainly will:
9m in warrington
tech9 northwest somewhere

 

[burrow01]

ORIGINAL: kennyboy

ORIGINAL: burrow01

Hi,

Not necessarily an OPC, just someone who knows 993 suspension. The 993 is the only 911 model that has the Kinematic Toe setting, and requires a special tool to measure it, so you need to go to somewhere that is familar with it and has the tool

If you are in the North West there are several specialists who would be able to do the alignment properly - I'm sure some recommendations will be along soon []

Pete

they certainly will:
9m in warrington
tech9 northwest somewhere

Those were the ones I was thinking of [] but I've not used either myself - I think Tech9 are based in Liverpool

Cheers

 

[delta]

Just to add my own experience from going from 18" to 17" (probably not many people have downsized) but I found the exact opposite and the car was less of a handful and more predictable. I know 18" look better but the sacrifice of lesser handling to me wasn't worth it.