Favour to ask of 156 GTA saloon owners

Hi GTA'ers,

I was wondering if somebody would kindly do a simple measurement for me of the ride height of a standard 156 GTA saloon on 17" Rims?
[Edit]The measurement I am looking for is from the top of the wheelarch to the centre of the wheel (for both front and back).
Picture below illustrates the measurement.

This probably needs to be done on flat ground, if left/right sides are the same or thereabouts then thats fine, but I'll take any data I'll get

I'm looking for this info to cross check my Rake angle from back to front against the standard GTA suspension setup. I hadn't recorded the original figured before Autodelta installed their coilovers, am sure they set it appropriately but another garage has recently installed the medium stiffness Autodelta spring set (90Kg) and I just want to double-check everything in case any cumulative error has set in.

[Edit]FYI my current measurements are 330mm front and 355mm rear, which is pretty low, but the AD dampers are very good!

Much appreciated if anybody does this!

Cheers,

TB

A more accurate way of measuring is from the top of the wheelarch to the centre of the wheel as that will eliminate any differences caused by different makes of tyres and tyre pressures.

Good point!
Always trust the opinion of a man whose Avatar is of a car on two wheels

Originally Posted by David C

A more accurate way of measuring is from the top of the wheelarch to the centre of the wheel as that will eliminate any differences caused by different makes of tyres and tyre pressures.

Originally Posted by Trailbraker

Always trust the opinion of a man whose Avatar is of a car on two wheels

It is me in the car too...

Originally Posted by David C

It is me in the car too...

It's better trust no one!

I knew that it was you! Respect

BTW David its my impression that you do a lot of circuit driving and am wondering if you have any suggestions for tyres pressures for a GTA at the track (starting pressure and hot pressure). I had been using 2.6 BAR warm, which meant starting at about 2 BAR cold, but a number of people suggested that might be too high. (225/45/ZR17 Mich PS2's)

Standard Manual recommendation says 2.2 bar cold, 2.5 warm (normal road use).
I tried it a bit lower 2.4 at BAR (but at a 25 degree temp track day which might not have been too clever) and wore the sidewalls a bit too much!
My car has significantly more grunt than a standard GTA and this combined with the LSD mean that any mistakes in pressure on hot days are eating into my tyre budget

Guess I have just hijacked my own thread


Cheers,
TB

Originally Posted by David C

It is me in the car too...

Originally Posted by Trailbraker

I had been using 2.6 BAR warm, which meant starting at about 2 BAR cold, but a number of people suggested that might be too high. (225/45/ZR17 Mich PS2's)

I'd say too soft!

Originally Posted by Trailbraker

I tried it a bit lower 2.4 at BAR (but at a 25 degree temp track day which might not have been too clever) and wore the sidewalls a bit too much!

way way too soft, but I'm guessing you know that!

Originally Posted by Trailbraker

Standard Manual recommendation says 2.2 bar cold, 2.5 warm (normal road use).

The 2.2 & 2.5bar settings in the manual are both cold pressure, the 2.5bar being with the car at full load.
When using normal road tyres on the track the normal practice is to raise the pressures.
If you take the std full load cold pressure of 2.5bar and add the 0.3bar stated in the manual for sustained high speed use you get 2.8bar as the maximum cold pressure.

On no account run lower than 2.2bar cold pressure because you will either pull the tyres off of the rims or you will overheat the sidewalls and get a blowout.

I'd say 2.5bar cold would be a good place to start.

Thanks for the advice David
I knew "higher" was required given the obvious failure of my "lower" experiment but wasn't sure how much.

Cheers,
TB

Originally Posted by David C

I'd say too soft!


way way too soft, but I'm guessing you know that!


The 2.2 & 2.5bar settings in the manual are both cold pressure, the 2.5bar being with the car at full load.
When using normal road tyres on the track the normal practice is to raise the pressures.
If you take the std full load cold pressure of 2.5bar and add the 0.3bar stated in the manual for sustained high speed use you get 2.8bar as the maximum cold pressure.

On no account run lower than 2.2bar cold pressure because you will either pull the tyres off of the rims or you will overheat the sidewalls and get a blowout.

I'd say 2.5bar cold would be a good place to start.

For clarity I edited the first post above to show the ride height measurement I'm looking for more clearly, and added a illustrative pic.

TB

PS: No laughing at my tyres DavidC

Hi Trailbraker
I get 35cm for both front wheels and 36cm for both rear wheels.
(I parked on what appeared to be a flat surface.)
Hope this helps.

Very much appreciated - thanks a bunch!

Appears like I have picked up a little extra rake, my rear is slightly higher relative to the front than standard so.
Will normalise it a bit soon then.

Please do say hello if you see me at Mondello or Kirkistown, I'll keep an eye out for your well polished GTA too

Cheers,
TB

Originally Posted by bmoferrall

Hi Trailbraker
I get 35cm for both front wheels and 36cm for both rear wheels.
(I parked on what appeared to be a flat surface.)
Hope this helps.

Originally Posted by Trailbraker

any suggestions for tyres pressures for a GTA at the track (starting pressure and hot pressure). I had been using 2.6 BAR warm, which meant starting at about 2 BAR cold, but a number of people suggested that might be too high. (225/45/ZR17 Mich PS2's)

TB

Hi TB
I run with the same tyres on my 2.0 Taking the advice from some very experienced guys, i inflate the tyres to 3.0 when driving on the track.

I dont know it this is too high for a V6/GTA though..Good you ask this..probably i would have inflated the tyres on the V6 to the same without thinking any further.

Hijacking your thread even further..:

Those Michelin PS2.. how do you find them in the wet? I got a nasty scare the other day going into a tight curve(about 120 degrees) at the Track. The car suddely lost grip, and drifted sideways across all 4 wheels. Did the same curve a few more times attacking it from different angles best i could, and i can say that on my car, the PS2 seems to have a relative poor grip in tight curves under wet conditions. Going in a straight line or open curves, the grip is excellent, but push it in a curve at 90 degree or beyond, and you may suddely find yourself sliding sideways! I tried deflating the tyres to 2.8, but it made no difference as far as i could tell.

A Friend of mine got a 2.0 156 set up close to identical to my own. He is running with Poteza's, and can do that same curve a helluva lot faster. He recommends the Potenza's for their excellent handling in the wet BTW, so i might go down that road next time. Seems it always rains on TrackDays here

Yes obviously the advice I got for dry days was too much on the low side!
The guys I actually got the advice from that 2.6bar warm was a bit high mostly drive light RWD cars on the track and their front tyres definitely don't increase pressure when warm to the same extent as powerful saloon FWD cars.
One of them also races light FWD saloons competitively very succcessfully but these are equipped with slicks so I guess maybe they didn't have directly relevent experience.

Peter - assuming that you inflate to 3.0bar cold, how high does the pressure go for you when hot?
I wonder is there a point should one consider decreasing the pressure when hot?
i.e IF the pressure kept increasing for every subsequent track session, traction would be compromised at some point.

TB

Originally Posted by Peter K

Hi TB
I run with the same tyres on my 2.0 Taking the advice from some very experienced guys, i inflate the tyres to 3.0 when driving on the track.

I dont know it this is too high for a V6/GTA though..Good you ask this..probably i would have inflated the tyres on the V6 to the same without thinking any further.

Originally Posted by Trailbraker

One of them also races light FWD saloons competitively very succcessfully but these are equipped with slicks so I guess maybe they didn't have directly relevent experience.

Yes, race slicks run much lower pressures than road tyres on the track.
For example Dunlop's recommendation for a FWD Touring Car on slicks is 1.4Bar Front & 1.6Bar Rear (cold), rising to 2.1Bar Front & Rear (Hot).
Their listing for a FWD saloon car on slicks is 1.9bar front 1.8bar rear (cold) rising to 2.5bar F&R hot.

I would think that your pressure is way to high for the wet.
Now hopefully DaveC can confirm/correct this because I have already proved I am not a trusted reference on this topic

BTW Do you know what pressure your friend was using?
And did his tyres have comparable levels of tread with your own?

I saw a very detailed review somwhere of EAgle-F1s and PS2s doing wet and dry laps. The F1s are known to be a very good wet weather tyre, but the wet lap times for the PS2 were only slightly below it and got a very high Wet rating. I'll see if I can track the review down.

I have had 3 wet track days in the last 6 months - my first wet track days.
One was very very wet - Mondello actually said that if the conditions were too extreme for anybody they could come in after 15 minutes and get their money back! Lap times were up to 20s slower than dry.

I actually ran the car with standard cold pressure of 2.2 bar, this seemed to give good traction in the wet.

Suprisingly to me the GTA was putting the power down out of corners efficiently enough to perplex a few japanese 4WD cars (albeit they had less power, but power isn't ciritical in the wet).
Not sure how much this was due to over caution on their part though,
and my LSD certainly helped.

For tight slow corners I found the PS2 grip to be very good, and it was easy to compare directly with other cars because of how close you get to them on these corners.

On corner entry though I have occasionally experienced some some extreme oversteer but in each case I am pretty sure it was triggered by me ( ) ..not being smooth enough with the steering/throttle.
But crikey the GTA could be brought back from crazy angles.

Peter how do you find the PS2s in the wet on the road?
I find them good but I personally drive pretty conservatively on wet roads

Cheers,
TB

Originally Posted by Peter K

Hi TB
Hijacking your thread even further..:

Those Michelin PS2.. how do you find them in the wet? I got a nasty scare the other day going into a tight curve(about 120 degrees) at the Track. The car suddely lost grip, and drifted sideways across all 4 wheels. Did the same curve a few more times attacking it from different angles best i could, and i can say that on my car, the PS2 seems to have a relative poor grip in tight curves under wet conditions. Going in a straight line or open curves, the grip is excellent, but push it in a curve at 90 degree or beyond, and you may suddely find yourself sliding sideways! I tried deflating the tyres to 2.8, but it made no difference as far as i could tell.

A Friend of mine got a 2.0 156 set up close to identical to my own. He is running with Poteza's, and can do that same curve a helluva lot faster. He recommends the Potenza's for their excellent handling in the wet BTW, so i might go down that road next time. Seems it always rains on TrackDays here

Originally Posted by Trailbraker

I actually ran the car with standard cold pressure of 2.2 bar, this seemed to give good traction in the wet.

Yes that is a good place to start in the wet because you have much less side loading on the tyres, probably no more that you would get on a fast A road.

@David & TB

Makes sense what you say. I didnt try to deflate the PS2 that much

Also when i am saying "wet" its after or during a mild shower. I am no where near experienced enough to be racing around in really wet conditions.

@TB

Not sure how the Bridgestone Potenza is build compared to PS2.

My gutt feeling with the PS2's are that the threads in the tire design somehow dont work properly if you try to push the car "sideways". It felt very distinctive to me, that once you try to push it in a tight curve more then 90 degrees it very sudden started to slide sideways acoss all 4 wheels. Up to this the grip was very good even in the wet.(this is hard to explain, hope you know what i mean) but certainly next time i will try to deflate them to 2.4 or so..the wear on the tyres are not so bad when i drive in the wet anyway.

Any chance you guys know of a good place to get some semislicks? Is there any economical sense in getting a set? IE. how long do they last compared to street tyres.

I got some 17" Selespeeds i was planning to make into winter wheels, but i really want some 16" for that, so they might do nicely, and i could use them for both cars.

Thanks again DaveC for the info.

Peter, I'd imagine with being .6 bar over pressure for the wet that your available grip is very much compromised and I would guess that you are not experiencing the normal wet handling characteristics of the tyre.

You mention all 4 the tyres sliding so doesn't sounds just like a snappy cornering transition issue - it sounds to me like you have simply travelled too fast for the wet grip available.

There is only very light wear on road tyres running at 2.2 bar, it wont be an issue. The softer pressure creates more friction allowing the tyres to grip the surface much better, and they obviously wont overheat in the wet.

Wet track days are really really easy on the car, tyres and brakes,
and really really hard on the driver
The concentration required for keeping everything smooth is very tiring.
I flelt knackered on the 30 min drive home after my first really wet full track day.

BTW have you ever considered getting a data logger which logs all your laps and you can analyse them on a computer afterwards?
You can see when you exceed the available grip, and in conjunction with a camera if you have one are really able to analyse any "interesting moments".
I have recently started doing this and its very instructive .
It would also allow you to directly compare tyres scientifically if you had two sets of rims, perhaps you could swop with your mates?
(He might need some convincing after your previous problems though )

Cheers,
TB

I'll be able to tell you soon if there is some economic sense to using track tyres

I was thinking that it couldn't be that much more expensive than abusing high quality road tyres, well at least it will be fun finding out!

I will be giving a set if Michelin Pilot Sport Cups a try shortly, have the tyres but am just waiting for some 235/40/18 alloys that have been delayed in shipment.
They are a road legal competition tyre, but not really meant for any more than slightly damp conditions.

I will only use them for track days and driving to and from the track, maybe keep them on a bit longer if its the middle of a heatwave in Ireland, oh well I suppose I can dream..

Cheers,
TB

Originally Posted by Peter K

@David & TB
Any chance you guys know of a good place to get some semislicks? Is there any economical sense in getting a set? IE. how long do they last compared to street tyres.

I got some 17" Selespeeds i was planning to make into winter wheels, but i really want some 16" for that, so they might do nicely, and i could use them for both cars.