Steering weight and feel

[Keeper of The Kitten]

I thought rack preload was about reducing the lash on the teeth and had pretty much no bearing on steering weight.

[S2central.net]

SUspect you are right there Martin... the preload adjustment is just a tweak for wear and tear on the rack.

I also notice the woolier feel with 205/55 tyres on 16 rubber versus my 225/45 on the 18s.

My dampers are well past best now though - not much point in me doing suspension setting investigations until I at least have new dampers all round. Top mounts are fresh, so are trackrod ends, bottom balljoints and new powerflex bushes.

Gonna try and get zero toe on the front to see what that brings though...

[Keeper of The Kitten]

I was joshing a tad - I know preload is only for the pinion and it is not intended as a way of improving feel (well apart from getting rid of dead travel on the steering wheel!) ...surprised that the unplugged servotronic thing hasn't been mentioned much yet?

[Keeper of The Kitten]

Incidentally, I am pretty sure that toe-out, while it will do a magnificent job of improving turn-in, will also make the steering feel more "darty" and I doubt it will make the steering feel heavier, it will probably do the opposite.

More wheel offset to give greater self-alignment would potentially work though.

[S2central.net]

Servotronic was deleted on the S2 circa 92-93... The non servotronic system has better feel by all accounts, but its still not the most connected feeling in the world. In my case its suspension geometry being a bit off... But a stiffer / lighter front end must bring benefits in this area - the geometry of an S2 is not that differnt from a UR for example which feels better planted.

[stiglet]

I was just going to say, toe out gives slightly better turn in response. Very jittery with high offset wheels though.

[Keeper of The Kitten]

Lighter, stiffer, would improve the actual handling characteristic, but again I think that's different from the actual "feel" that the driver experiences from the wheel. I would say more weight at the steering wheel will be created by more reaction from the road wheels, which will be from greater self-aligning effect.

[S2central.net]

So to get good toe 'out' whilst in motion... I thought thats what a static setting of zero toe on our cars would achieve - as the front wheels are driven I mean... doesn't that give some natural tendency to toe out, or have I got is bass ackwards ?

[stiglet]

Oh yes, I see what you mean Paul. I'm not sure because the front wheels are driven, so they pull themselves forward or be pushed by the rears. I set STATIC toe out.

[Keeper of The Kitten]

Any increase in static toe-out will move the dynamic toe more towards outwards, so it will always alter the characteristics of turn-in.

[GazzaG60]

gotta say the steering is crap. even with solid everything its not the best. sharper but still 0 feel. i find i only know its slippery when the abs kicks in. very dull steering and woeful chassis.

i love the gearbox though. need corrado chassis and steering and S2 box and clutch feel

[S2central.net]

SOme quick calcs here...

Stock ABY Coupe front track is 1446mm - that as I understand is width between outside edges of front tyres... Assume measured nominally at centre line for zero skew from toe settings. Thats with 7.5J rims on 205 rubber and positve ET of 37mm.

That means the hub centrelines are 1315mm apart [(1446-102.5)+37] - [102.5-37]

That 1315mm dimension never changes.

Putting 225 rubber (on 8J) as I did with 18" rims on ET of 33 I get the following changes.

Each wheel placed 4mm further outboard and 20mm more tyre footprint each side... Gives me 28mm [2 x (10+4)] more track - which you'd think is a good think - wider stance at centre of wheel and fatter footprint.

Is such a difference significant in wheel alignment terms then ????

[stiglet]

It's mainly the scrub radius that makes the difference. With a smaller offset wheel, you will increase the scrub radius which will mean you will feel things like bumps much more through the steering. Because the stock scrub radius is quite small to start with, a small increase in track (decreasing alloy offset) can make a big difference. I don't know the exact figure, I would guess at maybe 15-25mm? But if you add another 10mm then you've nigh on doubled it!

[S2central.net]

Sorry Stiglet - you've gone and lost me now talking bout scrub radius... I do feel bumps more on these bigger wheels - something I've always attributed to their horrendous weight and tired dampers.

How do I calculate scrub radius then ?

I can feel a google coming on.............

[Keeper of The Kitten]

Scrub radius is the distance from the KPI line to the wheel centreline at the contact patch.