[Rumbloki]

Originally Posted by landapanda

I removed the seats and ran the car in that configuration for almost two years before putting in a custom made half cage. There was no negative impact to handling, but I did have the car corner balanced after the seats were removed and the MPS installed. Here is a video I did in my half cage install.

Great info. Thanks!

[bentom2]

Originally Posted by pal

Thanks landapanda! It sounds like removing the rear seats may not be as bad for handling as I am thinking. I'll give it a whirl at the next event.

M2guru, looking forward to your feeeback as well.

There’s no downside. Grab my keys next time we’re at the Ridge.

[booya_45]

Originally Posted by SEAT TIME RULES

I've had mine in since Jan 2020 love it.

Also installed the ARC Brace with safety net.

https://f87.bimmerpost.com/forums/sh...ight=arc+brace

Any info you can provide as to how you made your antigravity battery work? What needs to be done in order for it to work in our cars?

It’s not plug and play right?

The weight saved by switching to a lighter battery should be added to the list too.

[SEAT TIME RULES]

Originally Posted by booya_45

Any info you can provide as to how you made your antigravity battery work? What needs to be done in order for it to work in our cars?

It’s not plug and play right?

The weight saved by switching to a lighter battery should be added to the list too.

Its PNP...I had a tech try to register it with the car but he wasn't able to. I've had the battery in for about 1.5 years now. No problems to date

[Hawkdriver]

If my wife is displeased... I know I'm doing something right. Thanks for posting progress!

[M2guru]

Removed OEM front seat belts, related parts and b-pillar trim: 9.6 pounds (saved 1.2 pounds relative to Schroth 6-point harnesses). Updated spreadsheet.

[TargaM2]

Couple of new weights of items I have fitted for the list (wasn't able to edit as it was in 'read only' format)...
Aluminium GTS hood : 9.9 kg
Cobra Nogaro seats: 10.2 kg each (Carbon version are 5.3 kg each).
Lithiumax battery: 3.3 kg.

[Rumbloki]

Loving this thread.

[M2guru]

Adding:

Headliner and related pieces - 10 pounds
Side curtain airbags and a-pillar trim - 6.7 pounds
Subwoofers - 7.3 pounds

Kicking myself for not weighing my half-cage/rollbar before I reinstalled it after painting it. Guessing it was 50-60 lbs.

[EDWYER]

M2guru The speadsheet link didn't work for me.

[M2guru]

Originally Posted by TooSoonJunior

M2guru The speadsheet link didn't work for me.

Try it again please.

[EDWYER]

Originally Posted by M2guru

Try it again please.

Works now, thanks!

[swampfox94]

Any pics of the gutted interior? Crazy amount of work you've put in!

[kart driver]

The problem of weight saving measures in the rear side of the car (antigravity battery, rear seat delete, etc) is that the rear end is struggling to find proper grip even being stock. And when you take off the weight from the rear the car will become even more unbalanced.

[bentom2]

Originally Posted by kart driver

The problem of weight saving measures in the rear side of the car (antigravity battery, rear seat delete, etc) is that the rear end is struggling to find proper grip even being stock. And when you take off the weight from the rear the car will become even more unbalanced.

In theory, this makes sense, but as a counterpoint, I consistently run my fastest lap times when the fuel light is on and I’m carrying a minimal fuel load. So in my case anyhow, less weight on the rear axle appears to be helping more than it hurts.

[M1500Z]

Originally Posted by bentom2

In theory, this makes sense, but as a counterpoint, I consistently run my fastest lap times when the fuel light is on and I’m carrying a minimal fuel load. So in my case anyhow, less weight on the rear axle appears to be helping more than it hurts.

I also tend to be quicker with a lower fuel level. However, I don't believe the fuel level is going to have a significant effect on the overall balance of the car. The tank is low, wide and in front of the rear axle.

I tend to agree with Kart Driver here, not necessarily because of traction (managing weight shift and tuning suspension/tire can often resolve that) as in overall static balance—switching to a lightweight battery or a titanium exhaust back-box are pulling weight from where it has the most leverage and may not be as easy to compensate for with corner balancing. Unfortunately, it appears easier to remove weight from the rear of the car vs. the front where it may be more beneficial.

[bentom2]

Originally Posted by M1500Z

I also tend to be quicker with a lower fuel level. However, I don't believe the fuel level is going to have a significant effect on the overall balance of the car. The tank is low, wide and in front of the rear axle.

I tend to agree with Kart Driver here, not necessarily because of traction (managing weight shift and tuning suspension/tire can often resolve that) as in overall static balance—switching to a lightweight battery or a titanium exhaust back-box are pulling weight from where it has the most leverage and may not be as easy to compensate for with corner balancing. Unfortunately, it appears easier to remove weight from the rear of the car vs. the front where it may be more beneficial.

The OP for this thread is a friend and as mentioned in the original post, bought some scales, we should be able to get corner weights with a full and empty tank to address the fuel load impact on weight balance.

Agree an equivalent change in fuel weight probably has a different impact than the battery, exhaust, or a carbon trunk lid. Also agree there are a few more options to remove weight in the vicinity of the rear axle than the front, chasing the lightest weight possible is certainly shifting weight balance forward, but my point with fuel is that perhaps you gain more benefit toward lap time reduction with the lower weight than you lose by shifting weight balance forward.

If balance were more beneficial than total weight, I’d expect nose heavy race cars would get ballast added (beyond what’s necessary to meet the class rules for minimum vehicle weight), but I do not believe that is the case. If anyone is aware of some exceptions, they would be interesting to hear about.

[NISFAN]

Light weight and balanced is clearly the optimum, but if only allowed one choice

Light weight > balance

[pal]

Here's my thread around weight reduction and corner weights.

https://f87.bimmerpost.com/forums/sh....php?t=1819724

I don't plan to go as extreme as M2guru here, and am focusing on the "bolt on/bolt off" large weight reduction rocks with the M2. I am at 3370lbs with a full tank of gas and an empty car. Below is my list of mods so far and weight change estimates. The only other thing I'd like to do is an M Performance hood that I am hoping will be good for somewhere between 30 and 35 lbs reduction. And, at some point I'll get a carpet made for the rear seat base and remove that for a net decrease of around 10 more. And on track days, I usually run 513Ms which are around 12lbs lighter than the 437Ms.

Akrapovic exhaust -10
Rear seat back delete -35
Recaro Sportster CS front seats -24
- VAC floor mounts for the seats
- Recaro sliders
Remove engine bay foam piece -4
- Replace engine cover with Turner carbon
AntiGravity 60Ah battery -40
ER intercooler & charge pipes +14
KW Clubsport coilovers +4
Bigger PSS tires on 437M +6

[EDWYER]

Originally Posted by pal

Akrapovic exhaust -10
Rear seat back delete -35
Recaro Sportster CS front seats -24
- VAC floor mounts for the seats
- Recaro sliders
Remove engine bay foam piece -4
- Replace engine cover with Turner carbon
AntiGravity 60Ah battery -40
ER intercooler & charge pipes +14
KW Clubsport coilovers +4
Bigger PSS tires on 437M +6

Mine as well have no cover.

[M2guru]

Photo of interior facing forward. Note the custom idrive controller and drive mode button mount.

[M2guru]

Better picture.