Insights from Rooks Fabulous Training Manual...

[ersatzS2]

Imagine, real data!

Biggest revelations for me:

The underbody tray is pretty amazing. Interesting they highlight the brake cooling flow pathway. It's a feature that is irrelevant except on the track or maybe the occasional canyon run so it's cool they think it's important.

I wondered about that regenerative braking system. Basically under hard braking it turns off the fuel system, and unleashes the voltage regulator. I guess the alternator is designed for high output in short spurts. However I assume it is still belt-driven all the time so wondering what the savings really is. Interesting that it requires a gel-cell battery. All in all sounds like more marketing than substance or at best a lot of technology for a tiny gain?

Suspension diagrams are great, wish they diagrammed the sport suspension since the text suggests there are significant differences.

[atr_hugo]

Nah, I suspect the alternator is probably clutched like the A/C compressor - simple idea really, just needed appropriate battery technology and some software to make it work right. For example, long stints on the freeway may drain the battery enough that the software will need to re-enage the alternator. Just my thoughts, but that's how I'd make that happen.

[mikeo]

Yeah, and the front swaybar is tubular, man, tubular.

Nice details like this make you appreciate BMW engineering. I was blown away years ago when I learned my '69 911T lugnuts were titainium.

[Crowley]

Originally Posted by mikeo

Yeah, and the front swaybar is tubular, man, tubular.

LOL

[ersatzS2]

Originally Posted by atr_hugo

Nah, I suspect the alternator is probably clutched like the A/C compressor - simple idea really, just needed appropriate battery technology and some software to make it work right. For example, long stints on the freeway may drain the battery enough that the software will need to re-enage the alternator. Just my thoughts, but that's how I'd make that happen.

Yep I assume the same thing, but there is still HP lost to belt and pulley friction. All I'm saying is that _all_ cars charge the battery (if it needs it) under braking, it's just that they also do it under power (if it needs it) This seems to be a minor refinement such that it charges less under power by using a system that tolerates more battery depletion and has a quick charge alternator... No big deal, it's a nice refinement as long as the marginal complexity doesn't carry unforseen unintended consequences!

[atr_hugo]

You're absolutely correct, most cars do a constant charge via the alternator - BMW appears to have done a very intelligent approach to it as you have pointed out.

[larryn]

The biggest things for me are:

- We now know that we do get hydraulic steering racks (not electronically assisted)
- We know that the eLSD is real, and unique to the 1 series coupe

- Much of the suspension is identical to the e90 (that I already have some mods for, which might fit).

- Cones are going to sliiiiide under the car, if I happen to nail any on an autocross run. :smile: Very slick belly.

- We confirmed ballast in the rear bumper to bring the car closer to 50-50 weight distribution... It's got to be substantial to make some difference. I doubt they would bother for 20 lbs (since petrol would cause more weight than that). Wonder what the car would handle like with it removed, if you could remove some weight from the front, or gave the front a bit more bite.

[Drawarms]

The belly of the car for me is insane. Thats what BMW is known for. If you look under other cars its like they use rusted and old parts on the car.

[ersatzS2]

Originally Posted by larryn

- We confirmed ballast in the rear bumper to bring the car closer to 50-50 weight distribution... It's got to be substantial to make some difference. I doubt they would bother for 20 lbs (since petrol would cause more weight than that). Wonder what the car would handle like with it removed, if you could remove some weight from the front, or gave the front a bit more bite.

Oh yeah forgot about that one. Shades of the '60's 911s which had lead ballast in the front. Ultimately they gave up and just lengthened the wheelbase. BMW is obviously working hard to get this thing close to 50/50 which was an extra challenge with that big long lump up front offset by _less _wheelbase... Kind of a bummer for all those guys eager to add cf this and ti that when you can lose ~Nlbs simply by unbolting some cast iron from behind the rear bumper.

[adc]

Originally Posted by ersatzS2

Oh yeah forgot about that one. Shades of the '60's 911s which had lead ballast in the front. Ultimately they gave up and just lengthened the wheelbase. BMW is obviously working hard to get this thing close to 50/50 which was an extra challenge with that big long lump up front offset by _less _wheelbase...

Hardly. The balance is actually 48/52, so I think BMW wanted more bite in the rear than the front. So clueless drivers aren't killed by unexpected oversteer.

Removing that dead weight might remove some of the understeer too.

[larryn]

Originally Posted by adc

Hardly. The balance is actually 48/52, so I think BMW wanted more bite in the rear than the front. So clueless drivers aren't killed by unexpected oversteer.

Removing that dead weight might remove some of the understeer too.

adc, are you positive about the rear weight bias? I saw that at one point, and it was refuted as yet another typo in some documentation.

[Mpulse]

The way a regular alternator works is that it charges only when electrically excited by a voltage regulator. If you totally disconnect the wiring, it will basically free spin and not be a drag on the engine.

What BMW has done is to control the alternator from a computer instead of a on/off switch. But this way it doesn't get its maximum charge all the time, only when the dynamics of the system allow. Their will be no drag on the engine when the engine needs to produce power.

Current lead acid batteries don't like to be partially charged in spurts. They will not last if not fully charged. So this new battery we're getting is both necessary and a good thing. It's a better battery.

[adc]

Originally Posted by larryn

adc, are you positive about the rear weight bias? I saw that at one point, and it was refuted as yet another typo in some documentation.

Yes, 100% positive. From the BMWUSA website, 135i Specifications page:

Weight distribution, front/rear – Manual Transmission
47.7/52.3 %

Weight distribution, front/rear – Automatic transmission
47.6/52.4 %


Once I read about the trim weight, I immediately connected it with the rear weight bias (and part of the understeer issue). Otherwise, how can you explain rear weight bias when the longer 335i Coupe has a 52/48 weight distribution???

Now contrast this with the 335i reviews which wondered about the (relative) lack of understeer - but perhaps not if you consider the front bias of that car.

[turbomg]

Originally Posted by adc

Otherwise, how can you explain rear weight bias when the longer 335i Coupe has a 52/48 weight distribution???

With a typo?

I hope you're right, but I'm not counting on it.

[moff]

Originally Posted by adc

Yes, 100% positive. From the BMWUSA website, 135i Specifications page:

Weight distribution, front/rear – Manual Transmission
47.7/52.3 %

Weight distribution, front/rear – Automatic transmission
47.6/52.4 %


Once I read about the trim weight, I immediately connected it with the rear weight bias (and part of the understeer issue). Otherwise, how can you explain rear weight bias when the longer 335i Coupe has a 52/48 weight distribution???

Now contrast this with the 335i reviews which wondered about the (relative) lack of understeer - but perhaps not if you consider the front bias of that car.

Great theory, and one I think could be true.

The question is though, why would BMW stick ballast in the 135 and not in the 335?

I am sure that there is a much more complex explanation, but it's a good starting discussion.

I read that increasing the size of the rear sway bar could also increase front grip (from BimmerFile.com)- but I am not techie enough to really get it??

[atr_hugo]

It's a typo guys - honest. Look at how much of the engine hangs ahead of the front axle centerline. They added ballast in back to keep it from being a 54/46 weight split. If it was 50/50 they wouldn't have added ballast to make it 48/52,

[larryn]

LOL!! I'm waiting for Advevo to start flipping us off for people beginning to ask him to corner weigh his car! :wink:

[Troyn]

Originally Posted by larryn

LOL!! I'm waiting for Advevo to start flipping us off for people beginning to ask him to corner weigh his car! :wink:

Hahahaha!

[Yoot1]

Originally Posted by adc

Hardly. The balance is actually 48/52, so I think BMW wanted more bite in the rear than the front. So clueless drivers aren't killed by unexpected oversteer.

Removing that dead weight might remove some of the understeer too.

Adding weight in the back increases the tendency oversteer. Adding weight in the front increases stability.

[abc]

Originally Posted by larryn

The biggest things for me are:

- We now know that we do get hydraulic steering racks (not electronically assisted)
- We know that the eLSD is real, and unique to the 1 series coupe

- Much of the suspension is identical to the e90 (that I already have some mods for, which might fit).

- Cones are going to sliiiiide under the car, if I happen to nail any on an autocross run. :smile: Very slick belly.

- We confirmed ballast in the rear bumper to bring the car closer to 50-50 weight distribution... It's got to be substantial to make some difference. I doubt they would bother for 20 lbs (since petrol would cause more weight than that). Wonder what the car would handle like with it removed, if you could remove some weight from the front, or gave the front a bit more bite.

is there any pic of the dead weight?

[abc]

Originally Posted by turbomg

With a typo?

I hope you're right, but I'm not counting on it.

i though the 3series was 50/50, it's not?

[atr_hugo]

Originally Posted by abc

is there any pic of the dead weight?

We're going to have to wait (pun intended) until someone removes the bumper cover. Who wants to bet it's by accident or by design? ; -)