CVH

Was booting the car round a roundabout last night and suddenly the steering went realy light as if front wheels were off ground, just had some cheap tyres fitted to the front so was wondering if this was the cause?
It felt like when a bikes front wheel lifts under full throttle.
Wondered if anyone else has felt this?
Sti uk 05 blobeye.

AdamNI

iTrader: (1)

Were you on or off the throttle? I've the same car and get exactly the same feeling with the dccd in auto, but only when you're off the throttle, as the diff isn't doing it's thing, you have to keep your foot in, then when the front loses grip the torque gets sent to the front and pulls you round like you're on rails. Never fails to put a smile on my face.

On the other hand it could be your crap tyres

Get some RE070s on her quick!

nez-wrx

i had the same problem on my 1994 wrx when i had 18s on a cheap tyres i now have pirellis and differant rims and ok

The rookie

iTrader: (1)

Interesting idea, if completey wrong!

The DCCD is rear biased, so as the rear looses grip (and therefore starts to spin faster than the front) the LSD effect takes over and sends more torque to the front.

It could be your cheap front tyres, it could be that as the back started to step out slightly the steering went light (as it will as you're no longer having to apply the effort to create as big a slip angle at the front).

Simon

CVH

Thanks for the replies never had the back end on a scooby step out before thought they always hung on, dont know if i was on or off throttle cos i was going through the gears just better take care i think.

AdamNI

iTrader: (1)

The manual itself talks about distributing torque front to rear, hence my wording. I've only noticed it working when going round a corner and gradually accelerating, the front starts to understeer, but it you keep your foot in and keep accelerating you can feel the front tyres starting to dig in and pull you round. It doesn't feel like the rear is losing grip, maybe it is. I shall go and read up a bit more of how the DCCD works.

CVH

Wondered if had something to do with lift as in the front of the car making steering go light as i have seen kits for subarus called anti-lift?

The rookie

iTrader: (1)

Indeed, but understeer does not necesarily mean the fronts are slipping in traction, as you keep accelerating the rear torque bias of the DCCD diff incraeses the torque and therefore slip angle at the rear reducing understeer.

DCCD is a much misdescribed animal, made needlessly compicated, so heres a short paragraph...

The DCCD is a plate type limited slip diff that happens to have (but doesn't need to) a rear torque bias, the preload on the plates is set statically very low so the limited slip function is minimal, in responce to a control input (thumbwheel or controller) an electromagnet is energised that progressively increases the preload on the diff and therefore its limited slip function.

Thats it, nothing magic, no changing torque bias or anything like that!

When I said the rear stepped out, I did not necesarily mean into oversteer, but an increasing slip angle (between line the tyres pointing and the track its taking) will decrease understeer and therefore the front slip angle and lighten the steering.

CVH (yuk, horrible engine!) all Subaru's have prolift on the front suspension, in that the geometry means that traction effort forces the front wheels down, the whiteline 'anti-lift' kit, INCREASES this pro-lift making it more pronounced...

Simon

CVH

Some explanation simon thanks.
So would you recomend the anti-lift kit to counteract this problem?
chris.

The rookie

iTrader: (1)

As I've never driven a car before/after ALK I can't say, although as it adds castor angle it should improve the steering 'weight'.

Not sure I'd call it a problem, more a charactristic, my XR4x4 (rear torque bias) used to do similar.

Simon