F30 340i - Pt.5 - Drivetrain and Handling Mods

After the recent upgrades in suspension, wheels and tires, we are on the hunt to further chase that ///M feeling and find ways to efficiently put the power down to the ground with the least amount of parasitic loss possible.

The F8X M cars received a great amount of chassis stabilization and handling parts from factory such as:

• Front Chassis Bracing System (which we did in the last segment)
• Mid Chassis Bracing
• Solid Rear Subframe

With that being said, we are looking to tighten up the rear suspension by addressing the parts that twists and shifts under load and cause the rear suspension to feel loose and lack precision. 

After a lot of research, the parts we have chose are:

• 034 Motorsports Engine Mounts
• 034 Motorsports Billet Subframe Bushing Inserts
• 034 Motorsports Billet Rear Differential Bushing Inserts
• TURNER Motorsports Rear Differential Brace
• Rolls Performance F30 Mid Chassis Brace

First we started with the 034 Motorsports Engine Mounts. The factory engine mounts are made of a low durometer rubber with fluid filled voids to help dampen and eliminate noise, vibration and harshness (NVH). This is good for comfort, however the fluid filled rubber tends to crack and collapse over time due to its design. The 034 Street Density option is a full rubber high durometer option with no voids that will be stiffer with close to no NVH. This part is not listed to fit xDrive vehicles, however we found a work around for this and it fits perfectly. These upgraded mounts are supposed to decrease engine movement under load, reduce drivetrain slop, more direct power transfer, and improved shifting feel.

034 Motorsports Billet Subframe Bushing Inserts

Next we tackled the 034 Motorsports Billet Subframe Bushing Inserts. The purpose of the inserts is to fill the voids in the bushings and in turn limits the movement of the rear subframe previously caused by deflection. This helps maintain proper suspension geometry when cornering, launching and accelerating. By doing this, it will eliminate slop providing better gear shifts, as the differential is connected to the subframe. 

TURNER Motorsports Rear Differential Brace

Continuing in the rear, a must-do modification would be the TURNER Motorsports Rear Differential Brace. By fixing the Rear Differential to the rear subframe, it will now improve the transfer of power to the ground, improve high speed stability and also reduce the wear on the input bearing and differential bushings (which are prone to failing even stock).

034 Motorsports Billet Rear Differential Bushing Inserts

Taking this one step further, we did the 034 Motorsports Billet Rear Differential Bushing Inserts. Since the OEM bushings were still in good condition, we decided that the inserts will be more than enough, as the Turner Differential Brace will be doing its job in keeping the differential in place. These inserts will do the same principle as the subframe inserts, which is to eliminate deflection that will rob and delay the power we can put to the ground.

Last but not least, we installed the Rolls Performance Mid Chassis Brace. The F30 did not get the OEM V Brace that came on F22/F31/F32/F33/F36 and we think the decision was made due to a matter of comfort since the F30 was designed as a luxury sedan. Although you can retrofit the OEM one, we opted for this one as it is powdercoated and made of thick forged aluminum compared to the bare stamped steel original. This brace starts from the tunnel and 2 arms then connect to 2 points on the rear subframe. This brace is designed to reduce chassis flex, improve handling and keep the rear end more stable.

To conclude, these modifications made a tremendous amount of changes to how the car now handles and put the power down. All of these upgrades in this segment work together in synergy. The shifts feel much more crisp, improved turn in and out handling, better launches, increased and faster power transfer to the ground on acceleration and a faster response to throttle input.