Has anyone here actually weighed their vehicle?

[Obioban]

The factory battery weighed 49lbs in my car, so you may not get 40-50lb weight savings. My lithium battery is 19lb for a 30lb weight savings, for example.

The Braile GU1R I've been running for the last 11 years is 6 lbs.

[Bry5on]

Full tank. Lithium battery is worth another 40-50 pounds so you aren’t too far off. Within a reasonable margin of error for sure on the scale.

Also my “lightweight” 19 lb wheels with Hankook RS4 brick tires felt pretty much as heavy as my ZCPs with lighter Michelin PS4S .. could be a nonzero factor if you have heavy tires

The factory battery weighed 49lbs in my car, so you may not get 40-50lb weight savings. My lithium battery is 19lb for a 30lb weight savings, for example.

[Bry5on]

Is there a downloadable version of that spread sheet? Seems like the spread sheet is for a normal e46, is there one for an e46 m3?

Sheet is attached to the post (had to edit to make it show for some reason), and as stated it is accurate for an M3 as the only material difference is front and rear track width. I have a touring, but the numbers don’t care which body you are running

[Obioban]

Did you ever end up doing a write up on the Stereo project? 50lbs is quite a lot to delete. Also how is the sound quality with just two speakers?

I am running PS4 tires so pretty light tires compared to some other brands.

What was the latch removal?

Latch is the child seat anchors. It's not that much weight :P

Sound quality with two speakers, powered by the head unit amp, isn't amazing. That said... I almost entirely listen to podcasts, and it's plenty good for that. I didn't do a write up, but... it is what it is. Remove everything, install what you're using. The chassis to stereo harness plug is right behind the head unit, so you can get power/ground/ibus there, and then just connect the speakers to the head unit and.... done. The PITA part of the project is pulling the entire interior and all the wiring.

[repoman89]

Yeah, that's what is disappointing. I pretty much have the same mods. I also have SAP delete and I have lighter wheels. I do not have a lithium battery yet but I was still at 3341lbs. Again that was with a full tank of gas.

How much gas did you have when you weighted the car?

Full tank. Lithium battery is worth another 40-50 pounds so you aren’t too far off. Within a reasonable margin of error for sure on the scale.

Also my “lightweight” 19 lb wheels with Hankook RS4 brick tires felt pretty much as heavy as my ZCPs with lighter Michelin PS4S .. could be a nonzero factor if you have heavy tires

[bmw m3 s50]

Street car, AC, Avon Avant 4 with factory amp..everything else audio and nav related in the trunk were removed, dashcam hardwired with parking mode.



Honestly not much feedback to give since I’ve only driven the car like 200 miles after the swap. I generally keep the battery hooked up to a charger. I’ve left it without charger for 1-2 weeks before with no issues.

Last Dec the battery was draining quickly, and I think it’s been resolved with a new hood sensor. I can confirm that the battery’s restart feature works, and the car will start up without any problems.

I removed the OE battery tray and used a lighter setup. This is the mount I used. Bolted it up to an aluminum plate, then secured the plate using the mounting points for the OE tray. Ignore the terminal covers in the pic…was waiting for proper covers to arrive.

Wow, so you definitely have alot of electronics still hooked up. I glad to hear that the battery has been holding up.

I plan on having the battery hooked up to a battery tender the entire time the car is in the garage. When the is used it will be driven then put back into the garage. It will never be a daily driven car.

Thank you for posting that tie down option. I have been looking for something to help with the tie down of that battery.

How much did that bracket weight?

[bmw m3 s50]

This excel sheet might be useful to you to help track your weight savings. Enter your corner weights, then add/remove weight by part and enter the x,y,z coordinates of the parts added/removed to recalculate your new corner weight targets. My car is an M3 converted (except body/muffler) touring and I'm at 3420lb in full street trim (seats, sunroof, HK stereo, trailer hitch, etc) with a half tank and damn near 50/50 weight balance (slightly rear biased, which is best). The coupe and touring have the same wheelbase and my numbers are setup for M3 track width, so this sheet doesn't need modifications to be used on an M3. It will also calculate body roll and some other suspension parameters, and show the difference between your as-weighed setup and your weight-reduced setup (perfecting still a work in progress).

The TLDR is: Prioritize removing weight from the front and top of the car, above ~ the top of the tire height particularly.

Is there a downloadable version of that spread sheet? Seems like the spread sheet is for a normal e46, is there one for an e46 m3?

[bmw m3 s50]

If you're going to have speakers, IMO you should just run the factory door cards.
Big ticket weight loses on my car with specific amounts as accurate as my memory is:
Roof (CF), 44 lbs
Seats, 62 lbs
battery, ~50 lbs (lithium ion-- I'm on year 11 with the battery, and no issues yet!)
Stereo project, ~50 lbs (my stereo is an Xtrons head unit with two (light) speakers plugged directly into it-- entire factory harness removed, all the modules, and the scaffolding that holds them. Completely gutted/removed the factory stereo harness)

And then a bunch of little stuff that is probably another 50-100 lbs total-- LATCH removal, middle seat belt removal, CF trunk full exhaust (but with not super light muffler), BBK, wheels, tires (people never mention this, but huge variety here), CSL intake, SPAL fan in place of aux and clutch fan, second air pump, small/relocated washer tank, battery cable, CF cabin air filter housing and strut tower brace, aux water pump, tool kit, mobility kit, suspension, hollow sways, fog lights, bla bla bla. There's lots of other little things but that's all I got off the top of my head.

But, no roll bar weight adder.

If I ever get in a front end collision, I'd like to do CF fenders. I'd also like to do the CF door skins at some point. And, I have a notion of doing LED headlights to take some weight out of them, as my car is currently front heavy and they're on the nose.

Did you ever end up doing a write up on the Stereo project? 50lbs is quite a lot to delete. Also how is the sound quality with just two speakers?

I am running PS4 tires so pretty light tires compared to some other brands.

What was the latch removal?

[bmw m3 s50]

When I got my car ( lcrain's now) corner balanced it came out to 3410 with 160 lb weights in the driver's seat and a full tank. So around 3200 with no driver and a half tank. That was with the CF roof, 996 brakes, Ohlins suspension, Nogaros, lithium battery, CSL intake, SAP delete etc. Stock ZCP wheels, OEM muffler and OEM non-lightweight CSL trunk too.

Yeah, that's what is disappointing. I pretty much have the same mods. I also have SAP delete and I have lighter wheels. I do not have a lithium battery yet but I was still at 3341lbs. Again that was with a full tank of gas.

How much gas did you have when you weighted the car?

[bmw m3 s50]

For sure, the rear seat bottom cushion isn't a heavy item on it's own but everything adds up. You'll find a balance that works for you. Would definitely look cool with some sort of block off plate.

Yes, for sure. Definitely will be removing the rear bottom cushion and replacing it with a carpet wrapped carbon fiber or aluminum shelf to reduce a few extra pounds. Also planning on pulling the OEM rear carpet since I will be using fixed back seats. I will possibly replace it with a lightweight carpet so it looks decent.

It's all a work in progress at this point. Not planning on ever selling the car so it will be done little by little.

[bmw m3 s50]

Interesting thread with a lot of great information.

If you decide to swap your OEM CSL bootlid with one from Karb, I'd be interested in purchasing the OEM piece. Feel free to PM me.

Honestly, I probably will not sell the OEM CSL Trunk and just hoard it. OEM CSL parts are becoming much harder to find today.

I will be selling the bimmerworld CSL race ram air intake airbox (with headlight ram air), the full set of Stoptechs BBK from the car, and the 19" Forgeline GW3R wheels from the car.

[SQ13]

On a dedicated track car or street driven car? Still have audio, AC, ...?

Street car, AC, Avon Avant 4 with factory amp..everything else audio and nav related in the trunk were removed, dashcam hardwired with parking mode.

Could you provide some more details and you experience on the ATX30 battery.

Honestly not much feedback to give since I’ve only driven the car like 200 miles after the swap. I generally keep the battery hooked up to a charger. I’ve left it without charger for 1-2 weeks before with no issues.

Last Dec the battery was draining quickly, and I think it’s been resolved with a new hood sensor. I can confirm that the battery’s restart feature works, and the car will start up without any problems.

I removed the OE battery tray and used a lighter setup. This is the mount I used. Bolted it up to an aluminum plate, then secured the plate using the mounting points for the OE tray. Ignore the terminal covers in the pic…was waiting for proper covers to arrive.

[Bry5on]

This excel sheet might be useful to you to help track your weight savings. Enter your corner weights, then add/remove weight by part and enter the x,y,z coordinates of the parts added/removed to recalculate your new corner weight targets. My car is an M3 converted (except body/muffler) touring and I'm at 3420lb in full street trim (seats, sunroof, HK stereo, trailer hitch, etc) with a half tank and damn near 50/50 weight balance (slightly rear biased, which is best). The coupe and touring have the same wheelbase and my numbers are setup for M3 track width, so this sheet doesn't need modifications to be used on an M3. It will also calculate body roll and some other suspension parameters, and show the difference between your as-weighed setup and your weight-reduced setup (perfecting still a work in progress).

The TLDR is: Prioritize removing weight from the front and top of the car, above ~ the top of the tire height particularly.
CG location change_332it.xlsx

[repoman89]

When I got my car ( lcrain's now) corner balanced it came out to 3410 with 160 lb weights in the driver's seat and a full tank. So around 3200 with no driver and a half tank. That was with the CF roof, 996 brakes, Ohlins suspension, Nogaros, lithium battery, CSL intake, SAP delete etc. Stock ZCP wheels, OEM muffler and OEM non-lightweight CSL trunk too.

[Nate047]

Thank you, sir.

Yeah, I was pretty happy the prior owner didn't really go crazy and strip the car.

I think you nailed it honestly. It is difficult to get that clean OEM look as well as the light weight design. I am trying to do like a CSL / GTS or GT3 / GT3 RS type of build. Anti Gravity ATX30 Battery and Pole Position ABEs (hopefully in CF) is definitely happening which should cut close to 70-80 lbs. Also going to remove the rear seat bottom cushion and build a lightweight shelf in it's place. I know the trunk still has the NAV system and the bracket that holds the radio and NAV components. I may get rid of the NAV system since it is kinda useless. I figure between the NAV system and the bracket that should like like 10-12lbs right there.

For sure, the rear seat bottom cushion isn't a heavy item on it's own but everything adds up. You'll find a balance that works for you. Would definitely look cool with some sort of block off plate.