Front wheel drive XC60 with VEA engines - traction in wet?

[marchesman]

Originally Posted by Tannaton

A few years ago I had a XC60 D5 AWD, I now have a XC60 D4 FWD and I've got an older XC90 which I've had throughout. I would make the following points:

- the FWD Xc60 is much more prone to spinning the from wheels when setting off quickly, easpecially on corners or roundabouts. The longer, softer suspension travel makes more prone than say in a saloon. You do just get used to this and drive it differently. It is if course just not an issue in the AWD cars. Caravan towers might not like this though....

- tyres is a BIG factor - the FWD XC60's are factory fitted with "Suv" tyres which are much more like summer road tyres. The AWD cars have proper 4x4 tyres like Pirelli Scorpion which I think would be noticeably better in the wet. This is currently the case in the UK market anyway.

- The 4 pot VEA engine is a technical marvel but it feels like what it is - a small, highly turbocharged revvy engine which I don't think suits the XC60 as well as the 5 pot units. It makes a large car drive a bit like a Fiesta diesel.... It is very good don't get me wrong but I much prefer the characteristics of the D5.

What persuaded you to buy the FWD version?

[RoyMacDonald]

For towing I'd say take a look at the XC70 AWD if you don't need the seven seats of the XC90. It has a higher towing capacity than the XC60 and a heck of a lot of room in the boot. Pretty good off road as well.

Tends to get overlooked but out here it pretty popular.

Roy

[Tannaton]

Originally Posted by marchesman

What persuaded you to buy the FWD version?

It's a company car - the emissions on the AWD versions are substantially higher and hence quite a hit on BIK tax. Plus my allowance wouldn't quite stretch to the AWD versions so they weren't an option anyway...

I would have had one otherwise.

[Arianne]

^ makes sense.

Yesterday, we had our dealer's AWD F-Pace out on the road for three hours. It reminded me of the Art of What's Possible with AWD that has a rear wheel bias. In a standing start it is phenomenal. But what I recall is the fact that there was absolutely no wheel spin whatsoever.

If you can afford it then the D5 and AWD is the way to go unless you don't ever seem bothered by the topic under discussion.

Arianne

[Chief inspector]

The wet traction from the FWD VEA is as good as any FWD car and better than any RWD.

I will concede though that it has bad torque steer of a kind not normally experienced on a modern saloon car.

AWD does indeed have a lot more straight line traction, wet or dry, but don't mistake this for cornering grip at speed as it will under steer just the same way as the FWD, as any vectoring at speed is done by braking on the existing momentum on both types. Unless of course you have an F1 type active differential.

Believe me I've done enough conversion training for professional drivers, from RWD to FWD, to 4WD and some now back again to RWD, can't be long till we are on 4 wheel electric power vectoring though.

[RoyMacDonald]

Originally Posted by Chief inspector

AWD does indeed have a lot more straight line traction, wet or dry, but don't mistake this for cornering grip at speed as it will under steer just the same way as the FWD, as any vectoring at speed is done by braking on the existing momentum on both types. Unless of course you have an F1 type active differential.

The AWD is set up to improve steering response.

Since the first Volvo with AWD was introduced, the handling characteristics have been the same. The cars were designed to have a slight "understeer" in extreme cornering situations, regardless of the AWD system's activity. The engineers reasoned that a slight understeer was safer for most drivers whether the vehicle is equipped with AWD or not. But that meant that the rate and amount of power transfer to the rear wheels had to differ in each application. In normal driving, with the AWD system inactive, 95 per cent of power is delivered to the front wheels. Depending on the vehicle, the traction and other factors, the system can transfer up to 95 per cent of the power to the rear wheels.

https://www.volvoclub.org.uk/press/r...5/2547_1.shtml

The controllability of the Haldex AWD system provides the unique possibility to balance and control oversteering and understeering of the car with great precision and stability. The Volvo Performance Concept Car is also equipped with an advanced active chassis system, FOUR-C (Continuously Controlled Chassis Concept). With the unique interaction between Haldex AWD-system and FOUR-C, Volvo has managed the co-operation between two individual systems to provide extraordinary advantages in the performance of the car. Volvo selected Haldex as development partner for the concept car because of Haldex position as a market leader of advanced all-wheel-drive technology, both concerning AWD system performance and engineering development capability. "In this application Volvo does not use the all-wheel-drive for enhanced off-road ability, but for advanced roadholding, dynamic stability and enhanced safety.

Borg Warner are using a new variation of the Haldex unit on the F-Pace. http://www.borgwarner.com/en/News/Pr...fer%20Case.pdf

Version 5 Haldex is what is used on the current XC60...http://www.borgwarner.com/en/News/Pr...new%20XC90.pdf

Roy

[Chief inspector]

Originally Posted by RoyMacDonald

The AWD is set up to improve steering response.


https://www.volvoclub.org.uk/press/r...5/2547_1.shtml

The controllability of the Haldex AWD system provides the unique possibility to balance and control oversteering and understeering of the car with great precision and stability. The Volvo Performance Concept Car is also equipped with an advanced active chassis system, FOUR-C (Continuously Controlled Chassis Concept). With the unique interaction between Haldex AWD-system and FOUR-C, Volvo has managed the co-operation between two individual systems to provide extraordinary advantages in the performance of the car. Volvo selected Haldex as development partner for the concept car because of Haldex position as a market leader of advanced all-wheel-drive technology, both concerning AWD system performance and engineering development capability. "In this application Volvo does not use the all-wheel-drive for enhanced off-road ability, but for advanced roadholding, dynamic stability and enhanced safety.

Borg Warner are using a new variation of the Haldex unit on the F-Pace. http://www.borgwarner.com/en/News/Pr...fer%20Case.pdf

Version 5 Haldex is what is used on the current XC60...http://www.borgwarner.com/en/News/Pr...new%20XC90.pdf

Roy

That's all true Roy, but the AWD doesn't add any more cornering grip, only traction, the 4C is likely to have a modest effect, but its main function is comfort and less sensation of heave.

You do of course have a huge benefit in getting power down, but no ASC system will let you do that against a loaded yaw sensor, you might see the BTCC guys with FWD throwing power down to straighten the car up, but no manufacturer build that in as needs a tight diff that would wind itself up on the road.

I have been extensively trained to train / demonstrate to other professional drivers by BMW, Prodrive, Ford, Mercedes Benz, Maserati, Jaguar Land Rover, Nissan and .....Volvo. Working with Nissan is best, they give you a lambs wool jumper.....the rest only polo shirts....

Each includes a full technical briefing on the technology fitted, how they developed it, how they feel it is best used, what the software and hardware is set up to do and the limitations (usually of the brakes and in the 2wd cars, the driven tyres)

Which car would I prefer not to drive is a sticky situation....a Mercedes ML, the state they get into in tightening corners is as bad as a 70s Range Rover, after it loads up, gives up, and the ASC slams on the anchors you're both sea sick and have lost all your momentum.

I'm not slagging off anyone's choice for AWD, just don't choose it for safety, it's only benefit is traction, which for many is a boon for towing, for marginal grip or steep roads or just for flooring it at roundabouts. It's all to be weighed up against more weight leading to a longer stopping distance.

[RoyMacDonald]

Originally Posted by Chief inspector

That's all true Roy, but the AWD doesn't add any more cornering grip, only traction, the 4C is likely to have a modest effect, but its main function is comfort and less sensation of heave.

You do of course have a huge benefit in getting power down, but no ASC system will let you do that against a loaded yaw sensor, you might see the BTCC guys with FWD throwing power down to straighten the car up, but no manufacturer build that in as needs a tight diff that would wind itself up on the road.

I have been extensively trained to train / demonstrate to other professional drivers by BMW, Prodrive, Ford, Mercedes Benz, Maserati, Jaguar Land Rover, Nissan and .....Volvo. Working with Nissan is best, they give you a lambs wool jumper.....the rest only polo shirts....

Each includes a full technical briefing on the technology fitted, how they developed it, how they feel it is best used, what the software and hardware is set up to do and the limitations (usually of the brakes and in the 2wd cars, the driven tyres)

Which car would I prefer not to drive is a sticky situation....a Mercedes ML, the state they get into in tightening corners is as bad as a 70s Range Rover, after it loads up, gives up, and the ASC slams on the anchors you're both sea sick and have lost all your momentum.

I'm not slagging off anyone's choice for AWD, just don't choose it for safety, it's only benefit is traction, which for many is a boon for towing, for marginal grip or steep roads or just for flooring it at roundabouts. It's all to be weighed up against more weight leading to a longer stopping distance.

Comfort mode does exactly what the title says it is true. The 4C makes a big difference in cornering ability when set to Sport mode though. I much prefer the way AWD feels through a fast corner than FWD or RWD. I've only driven Audi Quattro's and Volvo AWD's though, and of course the Range Rover which used to lower the suspension through a fast corner. Volvo's AWD is set up to be 50/50 on the apex of the bend. AWD can't increase grip above what the tyres can supply of course, but applying power to different wheels during a fast corner can let the car make the most of the available grip and corner faster. You only have to look at how the AWD cars dominated the race tracks as soon as they appeared to see the advantages in fast corners.

Roy

[Gilesme]

How does the Volvo know where the Apex of the bend is ?

[RoyMacDonald]

Originally Posted by Gilesme

How does the Volvo know where the Apex of the bend is ?

Sensors.

Roy