X1 Next BMW X1 to go front-drive

[Rainer271]

I like what I can see.

 

[tatoun]

So do I !

 

[Giannis]

Very nice, but FWD, right?

 

[CrunchSlaughtered]

I suppose that most of the X1s will be AWD, so it doesn't matter that much if it is based on FWD or RWD. It’s only the orientation of the engine and the slight difference in load distribution. From technical point of view the best layout for AWD is the car to be based on longitudinal engine and front wheel drive (like Audi A4 and up), because it needs less components, which means less weight.

 

[klier]

Very nice, but FWD, right?

Uhm, you might want to read the thread title

 

[Giannis]

I suppose that most of the X1s will be AWD, so it doesn't matter that much if it is based on FWD or RWD.

Νο, it actually matters and it matters a lot. X1 going FWD means that it will now be underpinned on an FWD engineered platform, which means that now the engine will sit further to the front, on the transverse axis, and all the front subframe will be engineered aroung that. This, in turn, means a bigger front overhand. For those that want just an RWD X1, it's a major let down.

From technical point of view the best layout for AWD is the car to be based on longitudinal engine and front wheel drive (like Audi A4 and up)

Audi's solution is a symmetric AWD system, which has the engine sitting as much upfront as it's possible, so that there's enough space behind the engine for the gearbox, the front and middle differential and the front axles. This is why modern Audi models are very very nose heavy.

Subaru has a similar solution, but the engine practically sits on top of the gearbox, because boxer engines are practically flat.

BMW's solution, which is RWD based, results in a much better weight distrubution (though not optimal in terms of packaging), which is very very important in a car's driving dynamics.

 

[Giannis]

Uhm, you might want to read the thread title

I've read it countless of times in anger. Call this one, Christmas hope for a better tomorrow.

 

[CrunchSlaughtered]

Νο, it actually matters and it matters a lot. X1 going FWD means that it will now be underpinned on an FWD engineered platform, which means that now the engine will sit further to the front, on the transverse axis, and all the front subframe will be engineered aroung that. This, in turn, means a bigger front overhand. For those that want just an RWD X1, it's a major let down.

Mini is also a FWD but it has a short front overhang, so I don't thing this is a issue for the transverse engine, it's above the axle not in front of it. The proportions look more awkward, because less space is needed behind the front wheel resulting in shorter hood. Concerning the weight distribution, I'm not so sure that when adding a front differential to a RWD car it still keeps the perfect 50:50. The X drive system weights 80 kg and all of them are put in the front, while the system for the FWD cars adds weight to the rear axle and makes the car more balanced then from the beginning.
Also if the weight distribution was so important then the in-line 6 would be long gone in favor of the V6

 

[tomazino]

Very nice, but FWD, right?

On which platform is Macan? FWD or RWD?

 

[Giannis]

Mini is also a FWD but it has a short front overhang, so I don't thing this is a issue for the transverse engine, it's above the axle not in front of it. The proportions look more awkward, because less space is needed behind the front wheel resulting in shorter hood.

The original (under BMW) Mini was engineered that way. It was sitting on its own platform for two generations, a platform that could barely be used for anything else.

Yes, typically RWD means much different proportions than an FWD engineered chassis. There are always exceptions. But this is the rule.

Concerning the weight distribution, I'm not so sure that when adding a front differential to a RWD car it still keeps the perfect 50:50. The X drive system weights 80 kg and all of them are put in the front, while the system for the FWD cars adds weight to the rear axle and makes the car more balanced then from the beginning.

The position of the engine is the key here. Have you seen how far back BMW places their engines, let's say in a 3er compared to an A4?

The X-drive system may add 80kg, but how much from that weight is actually ahead of the engine?

while the system for the FWD cars adds weight to the rear axle and makes the car more balanced then from the beginning.

Which system? Torsen? Haldex? The other one from GKN? Which system is that?

And obviously (in most cases) any AWD system will be more balanced compared to an FWD. That's simple physics. The degree of efficiency is a different story, though.

Using the same example again, an Audi A4 be it FWD or AWD it will still be nose-heavy because it has its engine hanging in front of the front axle. That's a fact.

Also if the weight distribution was so important then the in-line 6 would be long gone in favor of the V6

As far as the I6 vs V6 question, there's a thing called engine-balance. I6 engines have a lot of that. V6 engines, not so much. Engines matter a lot.

 

[marley71]

This is really coming together nicely. The only thing I fear is a little Q7 in the lower rear so it looks more wagon than utility vehicle. I can't imagine how they are going to make a SAC out of this, though I look forward to them trying. 2 door, 4door, which will it be?

 

[CrunchSlaughtered]

D

The original (under BMW) Mini was engineered that way. It was sitting on its own platform for two generations, a platform that could barely be used for anything else.

Yes, typically RWD means much different proportions than an FWD engineered chassis. There are always exceptions. But this is the rule.



The position of the engine is the key here. Have you seen how far back BMW places their engines, let's say in a 3er compared to an A4?

The X-drive system may add 80kg, but how much from that weight is actually ahead of the engine?



Which system? Torsen? Haldex? The other one from GKN? Which system is that?

And obviously (in most cases) any AWD system will be more balanced compared to an FWD. That's simple physics. The degree of efficiency is a different story, though.

Using the same example again, an Audi A4 be it FWD or AWD it will still be nose-heavy because it has its engine hanging in front of the front axle. That's a fact.



As far as the I6 vs V6 question, there's a thing called engine-balance. I6 engines have a lot of that. V6 engines, not so much. Engines matter a lot.

Don't get me wrong. I'm trying to say that it's a matter of priorities. Like the case with the smooth running of the I6 and slightly better weight distribution of the V6. IMO for a COMPACT AWD crossover the cabin space and compact outer dimensions are more important than marginal difference in the weight distribution (I don't know what is the weight distribution of 2er AT with AWD, but I expect something like 55%:45%) The first generation of X1 was too cramped inside (my wife was considering getting one, so we intensivly tested it) and the normally perfect looking BMW proportions doesn't suit good to this one.

 

[martinbo]

The weight distribution of transverse orientation FWD-based AWD hardly changes from the typical 70:30 distribution of transverse FWD. The mass location of the rear axle coupling is offset by the additional PTU componentry on the front axle.

For longitudinal applications of BMW xDrive (and 4Matic for that matter), it needs to be appreciated that the engine location is set first (thus ensuring optimal weight distribution) within a RWD-architected platform and then the AWD is added as a "bolt-on" accessory. The same approach is taken with transverse AWD; the layout is first engineered for FWD and then the AWD bits come as a bolt-on. Thus, the weight distribution remains typical of FWD.

The only marques that I can think of which are expressly engineered for AWD first are Audi's MLB and Subaru's Symmetrical AWD models. Even then their weight distributions are superior because the transmissions are located behind the front axle and not upon them as is the case with transverse FWD-based AWD.

 

[CrunchSlaughtered]

A

The weight distribution of transverse orientation FWD-based AWD hardly changes from the typical 70:30 distribution of transverse FWD. The mass location of the rear axle coupling is offset by the additional PTU componentry on the front axle.

For longitudinal applications of BMW xDrive (and 4Matic for that matter), it needs to be appreciated that the engine location is set first (thus ensuring optimal weight distribution) within a RWD-architected platform and then the AWD is added as a "bolt-on" accessory. The same approach is taken with transverse AWD; the layout is first engineered for FWD and then the AWD bits come as a bolt-on. Thus, the weight distribution remains typical of FWD.

The only marques that I can think of which are expressly engineered for AWD first are Audi's MLB and Subaru's Symmetrical AWD models. Even then their weight distributions are superior because the transmissions are located behind the front axle and not upon them as is the case with transverse FWD-based AWD.

It's somewhere between 60-62% to 40-38%

 

[martinbo]

Yeah ok, I'll go with that if we're going by official manufacturer's figures. I need to pull up some old tests where the measured weight distribution was markedly higher (towards the front) when tested independently. But, granted, 70:30 is extreme.

 

[klier]

This discussion reminds me an aweful lot of the LaF/918/P1 discussion
But instead of tire type and asphalt temperature, here it's all about transverse, Haldex, symmetrical AWD and whatever else...

It also keeps coming back, and back, and back.

 

[mickaBZH]

BMW X1 LWB:

http://www.autoweek.nl/nieuws/31448/nieuwe-bmw-x1-als-7-zitter-gespot

 

[Rolf]

It's approaching the X3 in size, it looks considerably bigger than the current X1

 

[Mr Robert]

This car will never be inspiring to drive, nor will it stray from paved road. FWD is fine with me.

 

[mickaBZH]

http://www.autoevolution.com/news/2...uring-winter-testing-photo-gallery-91014.html