TT lower arms and geometry changes

[vRSAlex]

There is nothing wrong with running the extra camper.  You don't get extra wear issues as long as the toe is set correct.  I run 2.5 degs negative front and 2 degs negative rear with no wear problems.  I do 50 miles per day too.  There are a few m3s we look after that run 4 degs negative at the front!

[Top Cat]

Extra camper. 

I have been runnng well over 2 degrees of camber and have no sign of extra tyre wear whatsoever.  What i tend to do though is not slow down for roundabouts and the occasional right hand sharp bend. 

[berg]

Berg,

I'm at wheels in motion tomorrow, any guidance would be appreciated. 

unfortunately, i had to get my father in law to take car in as cant have any time off work at mo so i did not get much out of the visit

[Carrera2RS]

A useful hour or two

The car has now moved to matched front camber at just less than 2 degrees, it was close but slight differences between left and right. Toe now straight ahead and a small correction to rear toe.

Rear camber adjusted down to 1.5 degrees neg (to reduce understeer). The ride heights measured at 335F and 322R. I will probably lift to 340F and 325R this was my target but adjisting cambe then affects ride heights. The geometry will not be affected by a few mm of ride heigh adjustment.

I will also continue to experiment with damper settings and also try different roll bar settings.

The settings of Front ;

2 degrees neg (1 deg 55 mins)
zero toe (parallel)
8 degrees 23mins caster
PSS10 3/10
Roll bar soft

Rear

1.5 degrees neg (1 deg 29 mins)
13 mins toe in (L 6 mins, R 7 mins)
PSS10 4/10
Roll bar hard

All other checks showed the car close to spot on (set back, lateral offset etc)

So far the car feels a little less fidgety, better balanced and less 'front fighting back'. Les understeer and better directionality and confidence.

Not perfect yet, but getting there 

[berg]

The settings of Front ;

2 degrees neg (1 deg 55 mins)
zero toe (parallel)
8 degrees 23mins caster
PSS10 3/10
Roll bar soft

Rear

1.5 degrees neg (1 deg 29 mins)
13 mins toe in (L 6 mins, R 7 mins)
PSS10 4/10
Roll bar hard

So compared to your settings mine are 


1.47 and 1.33 negative front camber
0.05 toe both sides
8 degrees 36 min caster (LF) and 8 degrees 23 minutes caster (RF)

Rear

1.44 degrees neg and 1.42
10 mins toe in (L 5 mins, R 6 mins)
 

Fairly similiar in some respects but you are running the more negative camber whic I will need to do to get the benefits from the TT wishbones I presume?

[RedRobin]

the clearance is there, the trouble is the stock inner fenders doesn'r "rest" in the wider fenders and as such are getting "adjusted" by the tyres 

....When you say "stock inner fenders" don't you mean the stock wheel arch linings?

I know this is something I have asked you about and you haven't done anything yet to mod them to fit/join the carbon fenders. Surely not a difficult mod?

[danishmkvgti]

the clearance is there, the trouble is the stock inner fenders doesn'r "rest" in the wider fenders and as such are getting "adjusted" by the tyres  

....When you say "stock inner fenders" don't you mean the stock wheel arch linings?

I know this is something I have asked you about and you haven't done anything yet to mod them to fit/join the carbon fenders. Surely not a difficult mod?

You're right RR, it's the stock wheel arch linings, actually i have a plan  
I'll buy 2 new wheel arch linings, split them longitudinal, use the outer parts, the old ones will get the outer 10-15% removed and then cut across to app. the middle, then the new ones will be put in and marked against the old and then both parts will be put together.  

[Carrera2RS]

I have experimented a little with tyre pressures, currently running 36F, 34R

The combination is very good, balance is now very close to neutral. I am currently having no arch problems cornering hard. I might put the order of a set of 8x18 ET 50's on hold (5 mm further in per side than my current ET45's)

I will experiment over the weekend a little, I may try adjusting ride platforms a little up 1/2-1 turn F, up 1/4- 1/2 turn at the rear this will add 2-3mm front and back. This should put the heights to 340F, 325R.

Then given my rear toe was 2mins total, I am wondering how reducing toe a small amount from 13 mins on the current set up might feel (should increase oversteer a touch) I'll talk to Tony and see what he thinks.

I'd be interested to those who have settled on a set up have the car set to. The other option might be to add 15mins of camber at the front and back to 2 deg 15 mins F, 1 deg 45mins back.

I like the balance of feel, weight and stability at the front with parallel tracking. I have more confidence at higher speeds than a touch of toe out on the previous setup.

[rich83]

IIRC a straighter rear setup should loosen the rear up.

My rear toe is a little straighter than yours being the same as bergs... 10mins total.

[fuscobal]

Carrera, what brakes do you have ? 8x18 is good but is ET50 enough if one wants to go with some Ap racing 356mmx32 6 pots ? Wouldn't ET45 be better in this respect (maybe succed to avoid spacers) ?

I'm running like -2.3 camber in front and close to 0 toe and -1.5 camber on the rear and 10mins toe in. Also don't have any uneven tire wear problems !

[Carrera2RS]

You make a good point regarding brake clearance.

I am currently running ET45 8 x 18 TD's al round. As I have not had any arch problem over the last week, I have put my order on hold for two ET50's

I am awaiting VWR to restock their 352/32 six pot kit. I would prefer AP Racing or Bembo but the VWR size equivalent is cheaper. I will continue to experiment with tyre pressures and ride heights. At the moment the balance when settled mid corner is extremely good and close to Neutral.

The feel straight ahead is better, the initial turn in still needs more weight and precision for me. I am wondering if another 15-20 mins at the front might help ? I am also wondering if I reduce the rear toe in to say 10 mins. Plus I may try putting the front roll bar on full hard to improve feel then perhaps I can achieve better turn in and feel and keep the mid corner balance ?

Fuscobal what ride heights do you run and suspension set up ?

[the bruce]

Setting the front ARB to hard will help initial turn in and may increase traction issues at corner exit. 

Don't go too low on rear because you need travel. With only 325 mm I'd strongly recommend a
stiff rear to prevent hitting the bump stops. This would cause oversteer.

[fuscobal]

Don't know the current height (especially ince I lost some weight) but I'm using the PSS10 at 7F/7R on the track and 2F/2R on the street. Sways are on stiff both but at the last Hungaroring session they were on soft both + 5F/5R for the suspension. Height is however close to equal F/R (about 64cm from the ground to the wheel arch) !

[Carrera2RS]

I have jus measured my floor to arch looks like 640ish front and 630ish rear. I suspect the 'lost' 5mm between wheel centre measurements and floor measurements is down to the position of the wheel centre and arch.

I have settled on 33 psi front 32.5 rear cold (well warm weather, but no direct sun on tyre) after a drive they come in 34.5-35 F and 34-34.5 R

I am very happy with this set up. I tried experimenting with damper settings and I have settled again on 3F, 4R. I was going to drop the rear pressures a little, but the balance is now very good indeed, it's extremely balanced around roundabout, so I thought leave it alone !

The car is currently the best I have had it.

[fuscobal]

Well, Carrera, it seems we are both running on the same height and pressures. I measured the height to be 635-645mm (not the same everytime because I need a straight plane wich I don't have here...maybe when I go to my mechanic). The pressures I'm using on the track are also between 32 and 34PSI. Tried softer but my car is too heavy and they got overheated. As for the suspension, have you tried harder on the track ? I used 5/10 both F and R but I would try like 7/10 F and 8/10 R next time !

My car had the following weight evolution :

- 1715Kg in Aug 2010 when I was on street tires + OEM arms and I had my lady with me ! > pulled a terrible 2'29''
- 1636.5Kg in Oct 2010 when I was on R compound tires + TT arms and did not have the lady and the rear seats anymore ! > pulled a good 2'18''

On the future events this year I should have something like this > 1636.5 - 80 = 1556.5 Kg. For next year, I'm planning to get to about 1450Kg with me inside !

What's your weight Carrera ?