2009 Ford Focus ST [XR5T]

[culver]

The differentials you seem more familiar with are simply of a mechanical operation rather than electronically controlled. These newer systems may even be put down as variable diff's.

I can't think of any differential that doesn't follow the general kinematics that I mentioned. Even the computer controlled LSDs would do the same. Basically any dif that uses gears would do the same thing. A system might use a computer to control a LSD clutch pack in a dif but it still has the fundamental property that the average of the output speeds equals the input speed.

I am aware of many of clutch packs or viscous type systems used instead of center difs on AWD cars. I haven't seen those commonly referred to as a "differential". They do some of the job of a dif but again, they are more like variable control that sends some amount of torque to an axle.

Can you give me an example of the sort of newer dif you are referring to? I certainly could have missed some new type of dif.

[syko]

I guess looks are subjective but i've always liked the way the car was proportioned.

[Ferrer]

I dont understand why anyone would buy this when the RS is being released.

For the same reasons people buy GTIs instead of R32s.

[fpv_gtho]

I can't think of any differential that doesn't follow the general kinematics that I mentioned. Even the computer controlled LSDs would do the same. Basically any dif that uses gears would do the same thing. A system might use a computer to control a LSD clutch pack in a dif but it still has the fundamental property that the average of the output speeds equals the input speed.

I am aware of many of clutch packs or viscous type systems used instead of center difs on AWD cars. I haven't seen those commonly referred to as a "differential". They do some of the job of a dif but again, they are more like variable control that sends some amount of torque to an axle.

Can you give me an example of the sort of newer dif you are referring to? I certainly could have missed some new type of dif.

Ive mainly just been using the Acura everybody is talking about as an example. I did pull this from Wikipedia though when looking for more examples:

Active differentials
A relatively new technology is the electronically-controlled active differential. A computer uses inputs from multiple sensors, including yaw rate, steering angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like understeer. Active differentials used to play a large role in the World Rally Championship, but in the 2006 season the FIA has limited the use of active differentials only to those drivers who have not competed in the World Rally Championship in the last five years.

Fully integrated active differentials are used on the Ferrari F430 and on the rear wheels in the Acura RL.

The second constraint of the differential is passive – it is actuated by the friction kinematics chain through the ground. The difference in torque on the tires (caused by turns or bumpy ground) drives the second degree of freedom, (overcoming the torque of inner friction) to equalise the driving torque on the tires. The sensitivity of the differential depends on the inner friction through the second degree of freedom. All of the differentials (so called “active” and “passive”) use clutches and brakes for restricting the second degree of freedom, so all suffer from the same disadvantage – decreased sensitivity to a dynamically changing environment. The sensitivity of the computer controlled differential is also limited by the time delay caused by sensors and the response time of the actuators.

[culver]

I think there are still differences. I haven't looked at the Ferrari dif but I suspect it has some sort of gearing that still maintains the kinematic relationships even if it does use computer controlled clutch packs or something else to control the distribution of torque.

I tried to find a picture of the ATTS dif used in the Prelude but with no luck. The back of the RL doesn't appear to have any differential that I can spot. It looks like, based on computer command, the system could effectively disconnect both wheels from the prop shaft.

Mitsubishi S-AWC vehicle dynamics control system - motiontrends.com car magazine - Car technology section
If you look at the rear dif on this Mistubishi you can see it has a real gear differential in the back (its a planetary dif) as well as a buch of other stuff. It uses clutches in the rear end to control the transfer of torque.

The front of the Mitsubishi also has two "conventional" difs (though the packaging is hardly conventional) and uses a clutch pack to control the transfer of torque.
http://www.carbuyersnotebook.com/ACD_01.jpg

For all the complexity I see in the Honda system:
http://www.autoreview.ru/archive/200...nda/800/08.jpg
http://www.autoreview.ru/archive/200...nda/800/07.jpg
http://www.autoreview.ru/archive/200...nda/800/09.jpg

I do not see a rear “dif” (as I’ve defined it). It really does appear that power is send to a spool and complex electromagnetic clutch-planetary gear systems take the power from the spool and send it to the wheel. It does appear the computer could, if programmed to, simply disconnect the rear wheels. It is a very clever system using planetary gear sets to presumably allow the axle to spin even faster than the output of the spool. The same results could be achieved (though with unacceptable mechanical friction and power losses) by making the rear axle try to spin slightly faster than the front then using a traditional wet clutch as might be used in place of a center dif on a soft roader type AWD system.

Edit: BTW, I was actually mistakenly thinking of the system used in the MD-X not RL
The MDX version is simpler and what I was thinking of when I went hunting for pictures:
http://www.forum-auto.com/uploads/20...ura_dif_ar.jpg

Again, no dif in the back. Just two slip capable clutch couplings.

And even better, Honda's tech talk!
http://www.vehicledynamics-expo.com/...day2/honda.pdf
(took me a bit to find this one!)

Still, no “dif” and the system can apply 0 power to both rear axles simply by disengaging both clutches.

[Cotterik]

For the same reasons people buy GTIs instead of R32s.

because they have a much better price-quality ratio? I cant see the RS being that expensive. Atleast certainly not like the R32 is compared to the GTi.

[Clivey]

I guess looks are subjective but i've always liked the way the car was proportioned.

The proportions themselves aren't really the problem IMO - the styling is just very bland (pre-facelift like the one in your avatar), but attaching a squinty-eyed nose to an otherwise dull shape doesn't exactly sort the problem out.

The car could do with being around the same size as a Golf, though. I've also noticed that the latest Mondeo is huge for it's class. I don't know why Ford are making their new cars so large as space is at a premium in Europe, where these things actually sell. The only thing is that it then becomes "good" value for money in terms of size and space, but with more stress on engines.

Back to that interior pic: Unfortunately, it looks as if they've just sprinkled some shiny plastic around, rather than fixing the parts of the interior that were sub-standard. Maybe the next Focus will be better, as the new Mondeo / S-Max / Galaxy all seem to be satisfactory.

[Cotterik]

Yeah I know what you mean. Manufacturers seem to think bigger is better even in the small -car range. The new corsa looks like an Astra with a few inches taken off. Put it next to the old corsa and you suddenly wonder are they doing this to make their super-mini's sell more? The mondeo is big to say the least. The boot is big enough to fit 2 weeks worth of food shopping in it.

I think people are somehow overestimating what ford describes as the 'new' and 'updated' focus that they're calling this. It really is just a facelift. They do it to every version of their car after 2-3 years. They change the headlamps, put a few more knobs in the dashboard and pretend its completely new. Some people actually fall for it too. But it has to be said. They are brilliant cars. Hard to find a fault in them otherwise.

[Ferrer]

because they have a much better price-quality ratio? I cant see the RS being that expensive. Atleast certainly not like the R32 is compared to the GTi.

Well we don't know yet, but I'd say that a pair of extra wheels driven and about 60bhp more (according to the rumours) is enough to not make the ST pointless.

[Clivey]

For the same reasons people buy GTIs instead of R32s.

Precisely. A base Focus ST costs just £17,795 - I'd expect a 280-300 BHP AWD RS to cost between £25-30k.

[Ruggy]

Here's a quick pic of the new RS

Click on the link and scroll down about half way

Forums @ The Ford RS Owners Club

[Sauc3]

Here's a quick pic of the new RS

Click on the link and scroll down about half way

Forums @ The Ford RS Owners Club

Welcome to UCP.

In order to view the picture, one has to register for those forums, and I daresay most people won't want to do that for just once picture. Would it be too much to ask for you to attach it to a post on these forums? Would make life a lot easier for all of us.
Thanks

(P.S. If you're not aware how to attach something on these forums, click the Post Reply button and then scroll down to the Additional Options box, where there's a Manage Attachments button. Fairly self-explanatory from thereon.)

[Ruggy]

Here you go, sorry forgot you had to log into rsowners club. Might be worth mentioning that this is the only picture they have released of it

[Ferrer]

Isn't it the same as before, just brighter?

[Ruggy]

There's more pictures of the rs in top gear magazine