How To Tell A Quattro?

[InvaderGIR]

Surely after 18 months of driving you would be able to tell if it was FWD or not..?

My brother has been driving for years and was shocked when I told him his Toyota Corrolla (N reg) and almost all new cars are FWD.

 

[Dolph]

That isnt possible with haldex unless the front wheels are loosing grip. The rear power is taken of the front diff so it can only share what the front diff has not transfer more power aft than what is given to the front. If all wheels have grip the max is still only 50/50.

The link I provided shows you're wrong.

The max split via haldex is not 50/50, even when all four wheels have grip, because the simple act of putting power to the front wheels creates slip, and as the loading on the wheels changes (especially under hard acceleration), haldex can happily put 60-70% of the torque to the back wheels without actual wheelspin from the front. Under normal cruising conditions, 40-45% of torque is going to the back.

The other issue that suggests this is the case is that the tyres on my S3 (which need changing) have all worn equally. If there was a heavy front bias to power, as well as steering, the front tyres would wear much more quickly.

 

[Wayn0r]

That isnt possible with haldex unless the front wheels are loosing grip. The rear power is taken of the front diff so it can only share what the front diff has not transfer more power aft than what is given to the front. If all wheels have grip the max is still only 50/50.

correct, to a point. the gen 2 haldex which was fitted to the mk4 r32 wouldnt allow more than 50% power to the rear wheels.

however, the gen3 haldex thats on the mk5, coupled with the haldex controller thats available allows 3 modes - stock, sport and race. race mode makes the car permanently rear wheel biased.

you can read about it here : http://www.hpamotorsports.com/haldex.htm

 

[JediFragger]

Hi Guys. Just so we're clear please do not post for someone on their behalf when they're suspended/banned as it kinda defeats the object

I'm not gonna start handing out holidays, this is Motors after all and not GD. We expect a higher class of moron here

 

[pdw8]

I have an A4 3.0 Sport Avant which is Quattro. It was debadged on the boot when I got it but there is a Quattro badge on the passenger side of the dash and another badge on te grill on the front.

 

[Dandle]

correct, to a point. the gen 2 haldex which was fitted to the mk4 r32 wouldnt allow more than 50% power to the rear wheels.

however, the gen3 haldex thats on the mk5, coupled with the haldex controller thats available allows 3 modes - stock, sport and race. race mode makes the car permanently rear wheel biased.

you can read about it here : http://www.hpamotorsports.com/haldex.htm

The system cannot send more power to the back wheels than is available at the front. The haldex unit taps the power of from the front diff it can only ever share that power. Torque bias can be greater than at the front but only when the front wheels are unable to put all the power available to them onto the road, then the rears have more grip and hence more torque at the rear wheels. With the haldex clutch packs fully closed then the front and rear axles are directly connected together in effect. The HPA controller acts more agressively than the standard controller and has the 3 different modes to make it act in varying degrees of agressiveness but again it can only share what is sent to the front diff. It cannot send more power to the rear wheels because of the way its designed and where it taps power from, to do that you need a centre diff to distribute power. The HPA controller makes the car act with more rear bias than standard but it cant make the car more rwd biased than front.

Mk4 R32 uses gen1 Haldex same as the original S3 and Audi A3s. The gen2 haldex was fitted to all 8P A3s and S3s up until the face lift when the Gen 3 system was fitted. Most mk5 R32s will be gen2 and im not sure if they fitted gen 3 to them at the same time they did the Audis.

 

[Dolph]

The system cannot send more power to the back wheels than is available at the front. The haldex unit taps the power of from the front diff it can only ever share that power. Torque bias can be greater than at the front but only when the front wheels are unable to put all the power available to them onto the road, then the rears have more grip and hence more torque at the rear wheels. With the haldex clutch packs fully closed then the front and rear axles are directly connected together in effect. The HPA controller acts more agressively than the standard controller and has the 3 different modes to make it act in varying degrees of agressiveness but again it can only share what is sent to the front diff. It cannot send more power to the rear wheels because of the way its designed and where it taps power from, to do that you need a centre diff to distribute power. The HPA controller makes the car act with more rear bias than standard but it cant make the car more rwd biased than front.

Mk4 R32 uses gen1 Haldex same as the original S3 and Audi A3s. The gen2 haldex was fitted to all 8P A3s and S3s up until the face lift when the Gen 3 system was fitted. Most mk5 R32s will be gen2 and im not sure if they fitted gen 3 to them at the same time they did the Audis.

Do you think you understand how Haldex works better than the people who created it? Because your explaination of the system and it's capabilities seems to share very little with theirs

 

[Dandle]

The link I provided shows you're wrong.

The max split via haldex is not 50/50, even when all four wheels have grip, because the simple act of putting power to the front wheels creates slip, and as the loading on the wheels changes (especially under hard acceleration), haldex can happily put 60-70% of the torque to the back wheels without actual wheelspin from the front. Under normal cruising conditions, 40-45% of torque is going to the back.

The other issue that suggests this is the case is that the tyres on my S3 (which need changing) have all worn equally. If there was a heavy front bias to power, as well as steering, the front tyres would wear much more quickly.

Your quote is a little wrong. Its under normal cruising up to 40-45% of torque can be sent to the back(this would be under very hard acceleration, where the is maximum torque split) . While normal cruising 10-15% is sent to the back. All I am pointing out is that the Haldex system is front wheel biased and under normal driving the car cannot be rwd biased.

 

[Dandle]

Do you think you understand how Haldex works better than the people who created it? Because your explaination of the system and it's capabilities seems to share very little with theirs

Dolph I know very well how the system works and was having the agruements on here about the torque split before you had your S3.

 

[GreenMint]

OP, if you're that unsure, go somewhere like Elephant and do a quote using your reg number, wouldn't that show if the car is a quattro or not And you can do it in the warm!

 

[Dolph]

Dolph I know very well how the system works and was having the agruements on here about the torque split before you had your S3.

That just makes you persistant, not correct.

How do you explain the direct conflict between your position and that of haldex regarding how much torque can be transferred to the rear?

Or are you claiming it's a limitation of the early haldex controllers on cars like the MK4 R32 or the old S3?

 

[Django x2]

Jack up complete rear of car. Turn one wheel one way, the other wheel should rotate in the opposite direction. Ergo, Quattro or 4WD at least. (or rear wheel drive even).

Poole Audi are many things, liars is probably one of them

 

[Dandle]

That just makes you persistant, not correct.

How do you explain the direct conflict between your position and that of haldex regarding how much torque can be transferred to the rear?

What conflict? there is nowhere they say the car can drive around with rear bias. I have already agreed that under hard standing starts when the weight of the car shifts to the rear that the will be more torque transferred to the rear but due to the fact the front wheels aren't putting all of there torque down(that doesnt mean wheelspin)that will very quickly move back towards the middle as the car moves off and weight transfer is reduced. As the car gains pace or the acceleration is reduced the amount of slip between front and rear axles will be reduced opening the clutch pack and reducing power transfer. The system cannot decide to send more power aft you can only have more aft torque transfer if the front wheels are unable to put their power down fully.

 

[swyllie2000]

How would you not know if your car is 4wd after 18 months?

 

[s0ck]

Why is fox suspended anyway?

OP: I'm really interested to hear the outcome, do post back

 

[Siliconslave]

the haldex is electronic isn't it? wouldn't it have a fuse maybe....

 

[mjt]

HUGE can of worms all over my desk, they've gone all over the place!

I always put the newest tyres on the front, simply because a FWD car requires more grip at the front end so you can turn and still put power down without understeering in the wet.

I prefer oversteer to understeer and if your car has ESP then its a no brainer FWD = newest on front, RWD = Newest on back.

yeh, mine's 4wd tho..
i was talking to some colleagues about this today, and they'd rather put the new ones on the front here, as going up hills in ice/snow with knackered tyres on the front is never going to happen [fwd].

i agree with you though. i'd much rather control oversteer than understeer into a ditch

 

[Banny]

I thought new tyres on the front would be better, but I got two new tyres today and he swapped the rears to the front and put the new ones on the back.
I wanted Goodyear Hydragrips what I had, but never had any, so had to settle for NCT1s, as he said they would be fine.
As for oversteer, its pretty non existant in a ESP equipted A4 and I have tried, even put a RS4 rear anti-roll to stiffen it up, seems ESP does a good job of keeping car in straight line.