All Things Mk5 > Performance Modifications

TT lower arms and geometry changes

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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  :wink:

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