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      03-08-2012, 01:39 PM   #1
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F30 vs E90 Suspension Comparison - Write-up

Exploring the 2012 F30 Suspension and Chassis in Detail and Comparing it with an E90
by Tim Jones on March 2, 2012, 10:40 am



BMW's trademark has always been their sporty handling and ride, especially on the 3 series. With the 6th generation F30 3 series just hitting dealership and in the hands of the early adopters everyone wants to know, has BMW retained it's class leading handling? In a word, YES! Drive the F30 3 series, either in the 2L 4 cylinder turbo 328i or the big brother 3L 6 cylinder turbo and right away you know BMW got it right. Put the car into sport mode and the steering tightens up, the suspension stiffens (with the Adaptive M suspension) and the throttle response quickens. The car has quick turn in, feels rock solid and provides great feedback to the driver.

To figure out what makes the all new 2012 F30 3 series drive the way it does we spent the day at Turner Motorsport's. With factory trained technicians, championship winning race engineers and street car master tuners on we had the skill and resources to break down the entire chassis and suspension on the F30. While at TMS our long term review 328i got a complete workout on the dyno and scales as well, read more about our day at TMS here.

Bimmerfest Long Term Review 328i at Turner Motorsport



The F30 has many improvements over the outgoing E90 3 series, the interior and technology to name a few big ones. However, the suspension on paper is oddly similar to the outgoing E90 3 series. The E90 sedan has a double pivot joint strut front suspension, the F30 has a double pivot joint strut front suspension. The E90 has a 5 link rear suspension, so the does the F30. With all the improvements on the F30, was the suspension overlooked? The car doesn't drive like the suspension was an afterthought, so what changes did BMW make?

BMW F30 Front Suspension
The changes are subtle, perhaps correcting what BMW found to be minor flaws in the front control arms. A tweak here, a thicker arm there, a stiffer bushing over there.



The differences between the E90 lower link and the F30 lower link suspension components are almost indistinguishable. The F30 link is slightly thicker and has a more dramatic bend on the outboard end. That is about it, the length looks dead on. In a pinch could you bolt this E90 link on the F30?



The upper link on the F30 suspension is noticeably different from the E90. Both look like they were grown out of aluminum with their strange organic shapes but the F30 seems more refined. The F30 link is also 25% thicker and benefits from a solid inboard bushing. You can just make out the webbed openings on the inner E90 bushing in the picture. Despite the changes in shape and bushing design the length and ball joint angles are very similar.

The biggest change up front is the steel sub-frame. BMW used an aluminum sub-frame on the E90 to save weight. The front and rear sub frames are the largest single components on the car and probably the heaviest after the engine. Why BMW reverted to a steel sub-frame (E46 generation technology) when weight savings was such a priority on the F30 isn't clear to anyone. Crash protection, cheaper manufacture, something else?

BMW F30 Rear Suspension


The rear suspension of the F30 differs from the E90 considerably. Both are 5 link suspension with the same general geometry but BMW changed the way the links are manufactured. In another bizarre reversion to steel the F30 rear suspension is all steel, the E90 benefited from a lower aluminum arm. The other four links are made of stamped steal, like the E90 but the F30 links appear thinner but also more refined then the E90.



Besides the change to link construction the other big change is the addition of aerodynamic covers for the suspension. BMW spent a lot of time under the car smoothing out the airflow. The rear suspension was a big source of drag so they designed these covers. The covers aren't noticeable from above the car but are really cool looking.

E90 rear suspension reference image 1 E90 rear suspension reference image 2

Oil pan


The biggest shock from our under car tour of the 2012 BMW 328i was the oil pan, it's PLASTIC! I know plastic has come a long way and I don't want to sound like some cranky old timer but this worries me. The oil pan is tucked up behind the sub-frame so it shouldn't suffer any direct impact but something bouncing up into the pan from the road is a real possibility. There is an under tray (under tray pic)that provides some protection but it is a stiff felt like material that is at best 3/16" thick, nothing like the hard plastic under tray of the E90.

On the upside the oil plug appears to be a quarter turn locking style plug so stripped oil plugs should be a thing of the past. How well the plastic oil plug itself holds up is to be determined.

Power Steering Rack


Next on the "oh WOW" list is the variable sport steering rack and it's massive electric motor. Variable steering is a $300 upgrade to the standard rack (both are electric) that changes the ratio of steering as needed. It means you don't have to throw the wheel over as many times for those tight parking lot turns (review coming). So far the steering has been great, but the placement of the rack under the car is not. The rack and the motor sit in front of the sub-frame and are going to be the first thing road debris hits. The motor has has and additional plastic cover but hitting something a speed has the very real possibility of taking out your steering rack. I wonder what it would be like to lose power steering at 60mph after hitting road debris. I have a feeling someone is going to produce a metal skip plate arrangement for the steering rack and oil pan very shortly.

Exhaust


The stock exhaust is actually an impressive, 3" single pipe running from the turbo down pipe back to the rear muffler. There is one mid-pipe resonator and a few crimps for clearance but otherwise it is a clean run. There is a lot of room left for a larger pipe or a true 3" exhaust if tuners can find power with increased exhaust size. TMS also speculated that BMW left a lot of room for the F80 M3 dual exhaust. Leaving this much room for the exhaust means we should expect good things from the next generation M3 motor!



Following the exhaust back to the rear muffler, it is huge! Almost as large as the E46 M3 exhaust, this explains why the 328i is so quite. BMW has ditched the vacuum actuated exhaust flap in favor of an electronic controlled one so there wont' be any 'golf T mod' for the F30. We have yet to try unplugging the flap motor to see what will happen, hopefully it will not set off the check engine light. There was some discussion about the life span of the actuator motor, guess we will have to wait and see.

Drive line and Rear Differential
The entire drive train of the F30 is very compact. About 25% smaller then the E90 especially the 6 speed transmission and differential. As long as the components are built well this should not effect longevity or performance and has a nice weight savings benefit.



A big change that impacts enthusiasts is the rear differential and half-shaft arrangement. BMW has eliminated the bolt on half shafts and drive flanges for the half shafts. It appears the half shafts now spline directly into the differential. While this does save weight it means swapping the diff will be a bigger project. Swapping differentials will require dissembling the outer suspension to pull the half haft out of the diff before being able to drop it down. Hopefully BMW retains the same spline count on all differentials and half shafts so a differential swap does not also require a half shaft swap.

Shifter


I'm impressive with the stock feel of the 328i shifter. The throws are long but less rubbery then the E90 and the transmission has a nice solid engagement feel. That being said a short shifter is on my wish list. With the reduction in size of the 6 speed there is plenty of room in the stock shifter location for a much longer pivot point and some sort of double sheer selector rod. Paging Rob at UUC

Rear Fenders


Something that you might miss unless looking up into the rear wheel wells is the rear fender sheet metal is folded in tight to the outer skin. In previous generation 3 series to fit larger wheels and tires right to the edge of the car you would have to roll the inner fender lip flat to the outer skin. On the F30 the entire inner lip has been eliminated, I believe BMW did this to support offering factory 20" wheels as an upgrade option. Not only does it allow BMW to offer larger wheels and tires they can run more aggressive offsets pushing the wheels right to the edge.

Stay tuned for more information on our long term review 328i. We will continue to dive into the all the details that make up the BMW F30 3 series. Any specific things you want explored on our 2012 328i let us know.
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      03-08-2012, 02:07 PM   #2
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.....Yikes!!!! Looks like the oil pan is plastic.
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      03-08-2012, 02:16 PM   #3
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WTF? I read in a car mag that BMW finally got rid of the Mac Strut front susp for the new 3 series. Not so?
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      03-08-2012, 02:59 PM   #4
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Quote:
Originally Posted by Bartman619 View Post
.....Yikes!!!! Looks like the oil pan is plastic.
BINGO
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      03-08-2012, 03:40 PM   #5
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Quote:
Originally Posted by cvc 22349a View Post
WTF? I read in a car mag that BMW finally got rid of the Mac Strut front susp for the new 3 series. Not so?
Nope, still struts up front.
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      03-08-2012, 06:30 PM   #6
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Excellent information! Thanks for posting.

Yikes about the differential ... that will make things complicated. BMW continues to handicap its non-M cars with open differentials (not that I was expecting any different; after all, they have to sell the M cars). #1 upgrade for a non-M 3'er is the LSD, IMO.
I'll be until the first vendor comes out with a diff upgrade.

Also I'm quite curious about that steel subframe ... why? $$? And using steel in other areas of the suspension ... ?

The F30 does have a slightly wider track than the outgoing E90 so that will help handling, and the new 328i has an advantage since the N20 motor sits further back in the engine bay than the older N52.

REALLY interested in what the M3 will bring to the table.
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      03-08-2012, 09:48 PM   #7
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[quote=CJ421;11506177]Excellent information! Thanks for posting.

Yikes about the differential ... that will make things complicated. BMW continues to handicap its non-M cars with open differentials (not that I was expecting any different; after all, they have to sell the M cars). #1 upgrade for a non-M 3'er is the LSD, IMO.
I'll be until the first vendor comes out with a diff upgrade.

Also I'm quite curious about that steel subframe ... why? $$? And using steel in other areas of the suspension ... ?

The F30 does have a slightly wider track than the outgoing E90 so that will help handling, and the new 328i has an advantage since the N20 motor sits further back in the engine bay than the older N52.

REALLY interested in what the M3 will bring to the table.[/QUOTE]

Very true!
No doubt
Aluminum

The old E9x is looking pretty good right now
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      03-09-2012, 10:29 AM   #8
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I continue to be glad about having a fully loaded pre-LCI sedan! The only two things I am jealous of the F30 are the 4-piston M-sport brakes and the lovely Sport line interior!
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      03-09-2012, 11:28 AM   #9
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The F30 chassis is really not impressive at all. It's almost like they didn't find much to improve on the F30 from the e90. Couldn't hope for more I'm not lusting for the F30 even one bit. Even the engines are poor compared to what BMW used to offer, like the N54.
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      03-09-2012, 05:16 PM   #10
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My impression is that the F30 is a minor refinement of the E90, that is, it's essentially the same.

The E36 and E46 have the same suspension, and now the E90 and F30 have the same suspension. The redesign happened between the E46 and E90.

The F30 rear spring is in the same place as in the E90, and the links & geometry are near identical. It's not a redesign like the jump from E46 to E90, even though they changed how they manufacture the steel links.
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