Under steer in Octy 4x4

EddyH · 19-04-2005, 12:04

In general I'm very happy with the handling of my 4x4 and if accelerating through corners it's very planted and on roundabouts it's very easy to induce a little over steer to power round with.

However last night on a very long bend, exit slip road which is almost a full circle I got to the point where I couldn't apply any more power and had to hold a constant throttle. At this point I think the haldex disengaged and the car felt a little twitchy and like it was about to under steer.

Any ideas if there's any mods I can do excluding coilovers which could improve this. Current chassis setup is: H&R springs, R32 front ARB, Powerflex bushes up front, uprated dogbone and upper engine mount, 18x8 wheels with 225/40/18 Goodyear Eagle F1 GSD3 tyres.

I would really like a rear ARB but AFAIK there isn't one that'll fit the 4x4 due to the spare wheel well. A little more feedback would be nice as well, after fitting the F1's grip is much better but there is a little less feedback than the Ultrac's.

***DGW*** · 19-04-2005, 12:06

Have you sorted the Haldex ECU out yet, Eddy, or is it still showing a memory error? (Just wondering if the Haldex is working as advertised).

***ColinD*** · 19-04-2005, 12:11

Correct Rear ARB is unique to the Octavia. StuartJ was / is looking to get one made.

Haldex as you know works on slip detection. I had a huge understeer with mine on Pembry. Was slighlty off line and just went, classic understeer onto the kerbs. Jon (TaviaRS) had some flow charts I was using to tweak the setup when I was on coilovers. I got it (standard arb's) to the point of almost being oversteery...

I think you have to take stock of where you were, speed and what you have. On a recent Porsche chase upto about 120 before a sharp right hander 40 max we were doing well...where the prosche went round the corner like he was rails I had odd smells and flashing ESP lights and a hint of the rear end on my mirror...no way I could follow the porker round that bend at the same pace. Have to take my meal ticket and get in line, no way the Octy will do what that porker did.

Did it actually understeer? IIRC on mine if it got to that point I could lift slighlty to upset the balance then apply, the logic being that the esp and haldex would kick in.

EddyH · 19-04-2005, 12:13

Quote:

Originally Posted by DGW

Have you sorted the Haldex ECU out yet, Eddy, or is it still showing a memory error? (Just wondering if the Haldex is working as advertised).

No, not sorted yet,

and something that did cross my mind. Hoping to get this sorted soon but I'm waiting on responses from others before it can be moved on.

EddyH · 19-04-2005, 12:24

Quote:

Originally Posted by ColinD

Correct Rear ARB is unique to the Octavia. StuartJ was / is looking to get one made.

Haldex as you know works on slip detection. I had a huge understeer with mine on Pembry. Was slighlty off line and just went, classic understeer onto the kerbs. Jon (TaviaRS) had some flow charts I was using to tweak the setup when I was on coilovers. I got it (standard arb's) to the point of almost being oversteery...

I think you have to take stock of where you were, speed and what you have. On a recent Porsche chase upto about 120 before a sharp right hander 40 max we were doing well...where the prosche went round the corner like he was rails I had odd smells and flashing ESP lights and a hint of the rear end on my mirror...no way I could follow the porker round that bend at the same pace. Have to take my meal ticket and get in line, no way the Octy will do what that porker did.

Did it actually understeer? IIRC on mine if it got to that point I could lift slighlty to upset the balance then apply, the logic being that the esp and haldex would kick in.

It wasn't going 'that' fast so was a little suprised at the car feeling twitchy, it didn't actually under steer, I just held it at that point but it felt like it was ready to break away. ESP didn't kick in at all. However this is the time I've experienced this, thinking back prehaps the bend had adverse camber. I certainly wasn't worried that I was about to loose control just I'd like to improve this characteristic if possible and take similar bends with a little more speed.

stathap · 19-04-2005, 12:45

Eddy,

Won't a stiffer front ARB than standard without a rear ARB to match make it understeer more

? I'm sure you don't want to take the R32 one off though

***Neo_VR*** · 19-04-2005, 12:49

What about one of those fancy EIP haldex controllers?

SkodiRS · 19-04-2005, 12:57

Quote:

Originally Posted by stathap

Eddy,

Won't a stiffer front ARB than standard without a rear ARB to match make it understeer more

? I'm sure you don't want to take the R32 one off though

I'm sure this is too simplistic an explanation?

I always thought if the front was a lot softer relative to the rear you were more likley to understeer.....i.e there is more give and then physics kind of take over and a lot stiffer rear lends itself to oversteer.

Or something like that.

EddyH · 19-04-2005, 13:09

Quote:

Originally Posted by Neo_VR

What about one of those fancy EIP haldex controllers?

I'm considering one but I don't think it will help on this type of corner as it will still only engage if the fronts are spinning or if I put my foot down.

stathap · 19-04-2005, 13:19

Quote:

Originally Posted by SkodiRS

I'm sure this is too simplistic an explanation?

I always thought if the front was a lot softer relative to the rear you were more likley to understeer.....i.e there is more give and then physics kind of take over and a lot stiffer rear lends itself to oversteer.

Or something like that.

Adrian

Did you just say

Softer front than the rear = Understeer
Stiffer rear than the front = Oversteer

Am I missing something ?

EddyH · 19-04-2005, 13:24

Quote:

Originally Posted by stathap

Eddy,

Won't a stiffer front ARB than standard without a rear ARB to match make it understeer more

? I'm sure you don't want to take the R32 one off though

If the rear is 'rolling' and the front isn't then yes you're right. That's why I want to stiffen the rear up. I'm gonna find out if uprated ARB bushes are available for the 4x4 in an attempt to improve the rear in the absence of an uprated ARB.

EddyH · 19-04-2005, 13:25

Quote:

Originally Posted by stathap

Adrian

Did you just say

Softer front than the rear = Understeer
Stiffer rear than the front = Oversteer

Am I missing something ?

I noticed that too!

My understanding is stiffer front = understeer, stiffer rear = oversteer (but usually only induced by lifting off).

SkodiRS · 19-04-2005, 13:29

Quote:

Originally Posted by stathap

Adrian

Did you just say

Softer front than the rear = Understeer
Stiffer rear than the front = Oversteer

Am I missing something ?

Yeah....I know where you're heading with this Pete...but it's not as simple as that.

Difficult to describe....and not that I fully understand it

..where's that damn flow chart I got from Jon.

stathap · 19-04-2005, 13:51

Quote:

Originally Posted by SkodiRS

Yeah....I know where you're heading with this Pete...but it's not as simple as that.

Difficult to describe....and not that I fully understand it

..where's that damn flow chart I got from Jon.

I wasn't good at dynamics at school Adrian but I like this concept of tire lateral load tranfer distribution

"..... one might even assume that a firmer anti-roll bar, which leads to better camber control, would lead to better traction. If we add a firmer anti-roll bar to the front, traction loss diminishes, so understeer is reduced, right?

Wrong. Let's evaluate more closely the meaning of TLLTD--tire lateral load transfer distribution. Stated another way, we might describe TLLTD as the relative demand of side-to-side energy control that is placed upon the tires. Because a firmer anti-roll bar allows less deflection, it will transfer side-to-side energy (lateral loads) at a faster rate.

As the rate of lateral load transfer increases, additional demands are placed upon the tire. So if we install a firmer anti-roll bar in the front, then we increase the distribution of lateral load transfer toward the front tires. This increases the front TLLTD value, which will result in additional understeer, holding all else constant.

The same logic also holds true in the rear. A firmer anti-roll bar in the rear will increase the rate of lateral load transfer, placing more demand upon the rear tires, accelerating lateral traction loss and creating more oversteer, holding all else constant.

This is why blindly adding parts to your car may not produce the desired results. A wise consumer consults with--and buys from--knowledgeable experts that have the tools to make informed tuning recommendations...."

the full story is here ARBs

Now I now a lot of stuff on the net is pap

but I still think that

stiffer ARB on front = increased understeer
stiffer ARB on back = increased oversteer

but i would love to be wrong

**TaviaRS** · 19-04-2005, 13:55

Was it a right hander per chance? If so, I reckon it wpould be the change in wheelbase that did it (hint, when the wishbone bush is FUBAR, the wheelbase will change as the wheel will move back and forward as well as up and down) HTH

Adrian, do you mean this or this?

EddyH · 19-04-2005, 14:01

It was a left hander. I'll have to try it again when the wishbone bush is sorted.

SkodiRS · 19-04-2005, 14:02

Quote:

Originally Posted by stathap

I wasn't good at dynamics at school Adrian but I like this concept of tire lateral load tranfer distribution

"..... one might even assume that a firmer anti-roll bar, which leads to better camber control, would lead to better traction. If we add a firmer anti-roll bar to the front, traction loss diminishes, so understeer is reduced, right?

Wrong. Let's evaluate more closely the meaning of TLLTD--tire lateral load transfer distribution. Stated another way, we might describe TLLTD as the relative demand of side-to-side energy control that is placed upon the tires. Because a firmer anti-roll bar allows less deflection, it will transfer side-to-side energy (lateral loads) at a faster rate.

As the rate of lateral load transfer increases, additional demands are placed upon the tire. So if we install a firmer anti-roll bar in the front, then we increase the distribution of lateral load transfer toward the front tires. This increases the front TLLTD value, which will result in additional understeer, holding all else constant.

The same logic also holds true in the rear. A firmer anti-roll bar in the rear will increase the rate of lateral load transfer, placing more demand upon the rear tires, accelerating lateral traction loss and creating more oversteer, holding all else constant.

This is why blindly adding parts to your car may not produce the desired results. A wise consumer consults with--and buys from--knowledgeable experts that have the tools to make informed tuning recommendations...."

the full story is here ARBs

Now I now a lot of stuff on the net is pap

but I still think that

stiffer ARB on front = increased understeer
stiffer ARB on back = increased oversteer

but i would love to be wrong

Aha....now this make sense and would eplain why on standard set-up the car understeers and then when adding the ARB understeer is reduced.

But going overly stiff at rear, as in stiffest setting on Neuspeed ARB, produces oversteer.

Cheers.

stathap · 19-04-2005, 14:05

Quote:

Originally Posted by SkodiRS

Aha....now this make sense and would eplain why on standard set-up the car understeers and then when adding the ARB understeer is reduced.

But going overly stiff at rear, as in stiffest setting on Neuspeed ARB, produces oversteer.

Cheers.

Adrian you've battered me, you win

Stuart_J · 19-04-2005, 14:07

Mine tends to have tooooo much understeer, The Front ARB mod I have also been told hasent helped, It did Improve when Powerstation tracked my car & I specifically told them to dial out as much as they could

SkodiRS · 19-04-2005, 14:09

Quote:

Originally Posted by stathap

Adrian you've battered me, you win

SkodiRS · 19-04-2005, 14:10

Quote:

Originally Posted by TaviaRS

Adrian, do you mean this or this?

Yep...those are the ones.

EddyH · 19-04-2005, 14:13

Quote:

Originally Posted by Stuart_J

Mine tends to have tooooo much understeer, The Front ARB mod I have also been told hasent helped, It did Improve when Powerstation tracked my car & I specifically told them to dial out as much as they could

Stuart - Any update on the rear ARB?

Doesn't look like uprated bushes are available for the standard rear ARB, AFAIK the standard rear ARB is 13mm, powerflex only offer bushes for the TT/S3 which has a 14mm rear ARB.

***ColinD*** · 19-04-2005, 14:18

Eddy, see if you can find koni inserts for KW v2....if you can then forget what I said in pm about price...or half it

Unless I can find half a set of rear KWv2's for the vRS...you mayaswell get use out if them

EddyH · 19-04-2005, 14:36

Colin you've confused me!

I've sent you a PM to try figure out what you mean!

Stuart_J · 19-04-2005, 14:51

Quote:

Originally Posted by EddyH

Stuart - Any update on the rear ARB?

Doesn't look like uprated bushes are available for the standard rear ARB, AFAIK the standard rear ARB is 13mm, powerflex only offer bushes for the TT/S3 which has a 14mm rear ARB.

Couldnt be done echonomically as far as I could find, Jabba were trying to get the std one tweaked but that couldnt be done either by their contact so have sort of given up on it.

Re Colins post KW V2 Will certainly help, ask Bengie about how he finds them

19-04-2005, 12:04	#1
EddyH Briskodian Join Date: Jun 2004 Location: West Yorkshire Posts: 4,908 Members Car: Audi S8 Thanks: 41 Thanked 27 Times in 27 Posts	Under steer in Octy 4x4 In general I'm very happy with the handling of my 4x4 and if accelerating through corners it's very planted and on roundabouts it's very easy to induce a little over steer to power round with. However last night on a very long bend, exit slip road which is almost a full circle I got to the point where I couldn't apply any more power and had to hold a constant throttle. At this point I think the haldex disengaged and the car felt a little twitchy and like it was about to under steer. Any ideas if there's any mods I can do excluding coilovers which could improve this. Current chassis setup is: H&R springs, R32 front ARB, Powerflex bushes up front, uprated dogbone and upper engine mount, 18x8 wheels with 225/40/18 Goodyear Eagle F1 GSD3 tyres. I would really like a rear ARB but AFAIK there isn't one that'll fit the 4x4 due to the spare wheel well. A little more feedback would be nice as well, after fitting the F1's grip is much better but there is a little less feedback than the Ultrac's. __________________ EddyH Audi A6 Avant 2.7 TDI Audi A3 2.0 TDI Sport

19-04-2005, 12:06	#2
*DGW* BRISKODA Staff Join Date: Oct 2002 Location: Cambridgeshire Posts: 17,294 Members Car: Octavia 1.8T 4X4 Estate & Fabia vRS Thanks: 51 Thanked 207 Times in 156 Posts	Have you sorted the Haldex ECU out yet, Eddy, or is it still showing a memory error? (Just wondering if the Haldex is working as advertised). __________________ Denis 2002 Octavia 1.8T 4X4 turbo Estate - rebreathed on by Jabba ... 31.93mpg 2007 Fabia vRS - CC, ESP and full leather trim by Seat Surgeons ...48.57 mpg...

19-04-2005, 12:11	#3
*ColinD* Site owner Join Date: Oct 2002 Location: Hill & Mountains of North Wales Posts: 10,297 Members Car: Roomster Scout Images: 3 Thanks: 26 Thanked 171 Times in 80 Posts	Correct Rear ARB is unique to the Octavia. StuartJ was / is looking to get one made. Haldex as you know works on slip detection. I had a huge understeer with mine on Pembry. Was slighlty off line and just went, classic understeer onto the kerbs. Jon (TaviaRS) had some flow charts I was using to tweak the setup when I was on coilovers. I got it (standard arb's) to the point of almost being oversteery... I think you have to take stock of where you were, speed and what you have. On a recent Porsche chase upto about 120 before a sharp right hander 40 max we were doing well...where the prosche went round the corner like he was rails I had odd smells and flashing ESP lights and a hint of the rear end on my mirror...no way I could follow the porker round that bend at the same pace. Have to take my meal ticket and get in line, no way the Octy will do what that porker did. Did it actually understeer? IIRC on mine if it got to that point I could lift slighlty to upset the balance then apply, the logic being that the esp and haldex would kick in. __________________ ColinD 1.9 Scout Roomster - Standard www.BRISKODA.net :: Site Owner E-Mail : webmaster at briskoda dot net Got a comment to make about the site? Please feel free to use the feedback form here, we welcome your views.

19-04-2005, 12:45	#6
stathap Briskodian Join Date: Jan 2003 Location: north Posts: 1,220 Members Car: Thanks: 0 Thanked 0 Times in 0 Posts	Eddy, Won't a stiffer front ARB than standard without a rear ARB to match make it understeer more ? I'm sure you don't want to take the R32 one off though __________________ "Classic" Black Magic

19-04-2005, 12:49	#7
*Neo_VR* Om nom nom nom Join Date: Feb 2003 Location: Manchester Posts: 12,455 Members Car: A White Car Thanks: 78 Thanked 176 Times in 125 Posts	What about one of those fancy EIP haldex controllers? __________________ ColGod the UberMod ,___, [O.o] /)__) -"--"- ORLY??

19-04-2005, 13:55	#15
TaviaRS Dinosaur Join Date: Oct 2002 Location: North of the Watford Gap Posts: 14,942 Members Car: Merc E class & SLK Thanks: 19 Thanked 42 Times in 38 Posts	Was it a right hander per chance? If so, I reckon it wpould be the change in wheelbase that did it (hint, when the wishbone bush is FUBAR, the wheelbase will change as the wheel will move back and forward as well as up and down) HTH Adrian, do you mean this or this? __________________ A jolly sensible Mercedes E class saloon in a rather fetching bluey grey colour. No it isn't fast, no it isn't modded, and yes, it will still eat your Fabia for breakfast. Official mobile chicane for Briskoda trackdays

19-04-2005, 14:01	#16
EddyH Briskodian Join Date: Jun 2004 Location: West Yorkshire Posts: 4,908 Members Car: Audi S8 Thanks: 41 Thanked 27 Times in 27 Posts	It was a left hander. I'll have to try it again when the wishbone bush is sorted. __________________ EddyH Audi A6 Avant 2.7 TDI Audi A3 2.0 TDI Sport

19-04-2005, 14:07	#19
Stuart_J Briskodian Join Date: Jan 2003 Location: Winchester Posts: 5,708 Members Car: Nissan 350Z Twin Turbo Also Octavia 1.9 TDI L&K & Superb td 140 Thanks: 39 Thanked 85 Times in 78 Posts	Mine tends to have tooooo much understeer, The Front ARB mod I have also been told hasent helped, It did Improve when Powerstation tracked my car & I specifically told them to dial out as much as they could __________________ Speed is an addiction for which thankfully there is no cure

19-04-2005, 14:18	#23
*ColinD* Site owner Join Date: Oct 2002 Location: Hill & Mountains of North Wales Posts: 10,297 Members Car: Roomster Scout Images: 3 Thanks: 26 Thanked 171 Times in 80 Posts	Eddy, see if you can find koni inserts for KW v2....if you can then forget what I said in pm about price...or half it Unless I can find half a set of rear KWv2's for the vRS...you mayaswell get use out if them __________________ ColinD 1.9 Scout Roomster - Standard www.BRISKODA.net :: Site Owner E-Mail : webmaster at briskoda dot net Got a comment to make about the site? Please feel free to use the feedback form here, we welcome your views.

19-04-2005, 14:36	#24
EddyH Briskodian Join Date: Jun 2004 Location: West Yorkshire Posts: 4,908 Members Car: Audi S8 Thanks: 41 Thanked 27 Times in 27 Posts	Colin you've confused me! I've sent you a PM to try figure out what you mean! __________________ EddyH Audi A6 Avant 2.7 TDI Audi A3 2.0 TDI Sport

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