TT lower arms and geometry changes

[Carrera2RS]

Okay out of interest I found somewhere quiet to explore understeer/ oversteer. With my current settings the chassis is performing very well indeed ( making me wonder if I should fiddle much more ! )

Turning in aggressively loads up the front tyres quickly, it is actually quite hard to force the car to push wide, but it will. If you apply too much lock too quickly and unsettle at speed the poise is upset and it will push wide, but the bite is still quite respectable and it will regain and track again quite quickly. Turn in smoothly and quickly and the feel is actually a lot better than expected, weight is good and feel very informative.

Load up and turn in sharper and the balance moves to the front, you can feel the limitation of grip is now more front heavy. lift off and it stops tucking in and 'pulling' round in a tight arc, but no oversteer, just a shift of weight to the rear. I am sure I could provoke lift off oversteer, but I would have to try harder. Drive smoothly and the car is remarkably well behaved, change direction when loaded up and it response in a very settled balanced competent way with competence and accuracy.

I would like a nat's less front loading but this is probably driving RWD for the last 20 years where I suspect the balance with no throttle would be very similar (or possibly a tad more understeer), but the ability to balance understeer and oversteer with entry position and throttle is a familiar RWD thing that I am going to have to re educate myself to FWD characteristics

All in all, quite impressive tbh, but no scary oversteer.

My bars are currently Neuspeed 25mm full hard rear, 25mm soft front

[berg]

what tyre pressures have you settled on as best?

[fuscobal]

Being I'm on my 19" rims now, I'm using 2.6bar (38PSI) F and R. These 19" have very little grip as expected. Strange is that with both bars on soft the car was quite neutral and I thought...hey, if I'm putting them both on Hard the ration should be about the same but it seems that somehow the BSH 27mm RSB got much harder than the H&R 26mm FSB. The back gets loose when I'm accelerating hard during the corner (pretty unbelieveable for a FWD) and of course while turning in aggressively ! Drove an OEM ED30 the same day with 18" and while it was far from having my grip it was much more predictable and understeering !

[Carrera2RS]

Interesting, I am wondering if your rear bushes are worth checking, I agree I can see no obvious reason why the balance would not stay consistent on full hard all round ( unless the diff in spacing or bar mount/construction means there is a greater difference on full hard.

In any event the sort of overseer
Sounds like rear toe out. Perhaps worn bushes under load flex or your rest toe in is marginal moving to toe out undr load.
I'd get her up in the air and do the good old scaffold bar test....

Load up the suspension with the lever from underneath choosing lever points carefully and see how much wheel movement you have under load ( you might be surprised ) this will show geometry flex under load.

Interesting all the same !

[danishmkvgti]

As Fuscobal has H&R front and BSH rear arb, and BSH being the stiffest rear ARB there is, you cannot compare hard front and hard rear. the front on hard may increase torsion strength by for example 40% and the rear on hard 120%. i don't think that there will be any advantages by setting the rear on max. unless the front ARB is upgraded to a similar stiff item as the rear.

Just my 2 pence 

[rex]

Carrera2RS what speeds did you do the tests at?
What are your ARB?

With my H&R 26/24 bars I had oversteer quite a few times. Some of the times the road surface had a kink in and that unsettled the car. But on some occasions there was nothing wrong with the road surface... My car just oversteered... I was either mid corner with no throttle or on exit with a little throttle. Once I hit the gas and counter steer on exist the car would settle.

Fuscobal I bet that the weather in Bucharest is not sunny and warm. I also think that you did not have the chance to heat up the rear tires. If you remember our first trip to Hungaroring, in the first corner I had a monumental oversteer (not intended...) because of the cold tires. I think this also played a part in your experiments.

[Carrera2RS]

My roll bars are Neuspeed 25mm f and 25mm rear

The speeds were not very high speed corners as there are very few places you can load up to that point. I doubt you would find any opportunity to load up higher on the road.

I also doubt anyone would get the car beyond the limit at higher speeds without notably exceeding the limit, so realistic for what you might expect on the road.

It may behave differently on the track at higher corner speeds. I think your tyre temp point is a good one !

[fuscobal]

Yes, of course I keep in mind my tires were not heated. Can't do it around town. Another thing I don't like is my steering rack is starting to make cluncking noises over the bumps and responds with a delay wich increases with the speed ! Might have to replace it soon and this is not cheap. Unless I find one on a totalled car, It will delay my plans of getting the polepositions !

[Carrera2RS]

what tyre pressures have you settled on as best?

With my set up, I have settled on 33.5 R 35F warm. This is after a non sporting drive in traffic this morning 12 miles, the outside tem 10 degrees. The cold temps were 31.5R, 32.5F

I hope this helps 

[laurent.d]

You shouldn't drive hard a car with coilover set on soft and sway bars set on hard.
Keep in mind that sway bares act like strings. If dampers are set too soft they can't absorb the sway bars energy and then you can get very brutal oversteer.

[fuscobal]

I'll keep that in mind and will play with the hardness soon !

[Carrera2RS]

I actually think the PSS10 for the Golf is quite heavily damped. settling at 3F, 4R sounds soft, but the rear at 5 is heavily enough damped on rebound that the back of the car will 'land' on the ground before the suspension has the chance to recover from compression.

It's also interesting that BSH advise fitting the 27mm bar alone as a method to reduce stock GTi understeer.

I may well be very wrong but my guess is that soft/worn rear bushing with perhaps low rear toe figures are possibly the cause. I keep thinking about increasing the roll bars to full hard with 26/27 and I simply see no reason why the balance would be that bad in comparison to my car. 25 hard rear, 25 front soft, 3f, 4R, stock toe rear, parallel front 1.5 deg camber rear and 2 front.....

I take other points of view but would check alignment and rear toe ?

[Carrera2RS]

Here you go......

I tried full hard all round, better feel and weigt and turn in, but chassis balance to forward. It feels very safe and grippy but it's just how much and when it will push wide.

Added a tad more front camber (10-15 mins) and now 5 min toe out and back to soft front ARB. 

Now very happy indeed. Better feel than before with soft ARB, feels very balanced and just as neutral mid corner better turn in and accuracy. Not fidgety in my book with 2 deg 10 mins of front camber and 5 mins toe out, feels nice and less blunt and dull. Nice steering weight and feel.

Not sure if the ultimate grip is any better (certainly no worse) than the settings last time round, but the feel is better and precision improved.

[fuscobal]

Carrera, best way would be to have a track nearby and test the stiffness settings on PSS10. I'm afraid that we as drivers can be fooled into thinking certain settings are faster while they may not be in reality. We are not professional racing drivers and don't have the experience to say a car is or is not faster just by the feel. For this we'd need a track and access to a ramp nearby where we can play with Suspension, ARBs and geometry !

[the bruce]

Yes, it's very easy to get fooled by your self.