Interior weight reduction but keeping things a bit civilised

[Muzzman]

I've bought a 325ti, chucked in a m54b30 along coilovers etc etc. 3rd car, will be driven to track but not much else road use.

I live in Essex and apart from Brands/ Snett everything is a bit of a drive away in the UK, I.e. I've booked Anglesey in July. I will also be driving to Nurburgring etc.

Thing is I'm a bit older now, I'm not sure i can take the whole fully stripped out scenario, however this is only going to be a track car.

I keep on flipping between go the whole hog or not. I had a fully stripped 172 Cup with cage etc about 12 years ago, it didn't bother me too much then and took that to Spa/ Ring etc.....hmmm but then I do recall at times wishing I hadn't gone the whole hog and condensation on the roof used to annoy me.

I'm thinking maybe just:

Remove rear seat
Swap front seats for fixed back seats
Lightweight door cards
Air con delete
Remove radio/ speakers

I've also seen those Dead weight batteries weigh 3.8kg down from 22kg so might be worth considering.

Whats your thought? Anything else I can remove and still do relatively long journeys. I appreciate the sounds deadening and tar weighs a tonne but then you might as well go the whole hog.

Edited by Muzzman on Sunday 21st March 08:45

Edited by Muzzman on Sunday 21st March 18:00

[Tommie38]

Can you get comfortable in a fixed back seat? If not going for cage, harnesses etc you might not need it. There seem to be some nice intermediate examples like the Recaro CS Sportster (which is not cheap).

Also AC is something I’m less keen to give up, not just for the drive to the track but for on track time as well. If you are doing tourist days in the summer, at the ‘ring you’ll miss it whilst queuing.

A little extra noise has never really bothered me.

[Muzzman]

Pretty sure I'm okay in fixed seats, had Pro 2000's before

[motorhole]

Good fixed seats will be fine. Can remove head unit, speakers etc if you're happy doing that. Would be tempted to keep the air con!

Lightweight battery is super easy.

Back seat removal is a cheap win too. The other thing that might be worth doing is lifting all the carpets and removing the insulation underneath and the bitumen sound deadening stuff (heat gun and scraper). You'd be surprised how much weight is there. Then put the carpet back in to keep things civilised.

The other easy wins will be carbon/fibreglass bonnet (metal bonnets weigh a sh*tonne) and perspex rear 3/4 windows.

Depending how comfortable you are with doing it, can also remove the front/rear bumper crash structures and reattach the bumper skins with custom mounts. Bear in mind though you will lose a lot of damage mitigation from low speed bumps.

[MrC986]

Hi, I’ve a half share in a 325ti Sport which we’ve owned for about 2.5 yrs. I’ve done the work to make it more useable as a track car....removing the rear seats/seats belts, parcel shelf & the spare wheel /carrier is the the main work as well as fitting Cobra Suzuka seats. The removal of the rear seats was partly to assist in being able to transport a spare set of wheels to/from the track days although I still value the comfort of A/C & a radio as I’m the one who normally drives it to /from the circuits.. We’ve also added coil-overs & changed all the fluids & the header tank (a known weak point).

The considered advice (if you haven’t found this already) is to get matching width front/rear alloys to allow you to swap them front-rear as well as giving you more choice of tyres as well.

As ever, a pic to show our car being used....

[E-bmw]

Having done 3/4 hog & 1/2 hog before if you drive it to track do not remove either stereo or AC.

My first 325 had the ventilation output of an asthmatic spider at 5 paces so when I went to 328 I kept the Ac & it was an absolute boon on hat TDs.

If you REALLY want to lose the 15kg of the AC go on a diet.

Same for the stereo.

I would say lose everything you can at the back & keep everything you want at the front.

Obvs there are things like door cards as you say, carpets, even dash, but keep the other stuff.

Edited by E-bmw on Sunday 21st March 16:29

[Muzzman]

motorhole said:

Good fixed seats will be fine. Can remove head unit, speakers etc if you're happy doing that. Would be tempted to keep the air con!

Lightweight battery is super easy.

Back seat removal is a cheap win too. The other thing that might be worth doing is lifting all the carpets and removing the insulation underneath and the bitumen sound deadening stuff (heat gun and scraper). You'd be surprised how much weight is there. Then put the carpet back in to keep things civilised.

The other easy wins will be carbon/fibreglass bonnet (metal bonnets weigh a sh*tonne) and perspex rear 3/4 windows.

Depending how comfortable you are with doing it, can also remove the front/rear bumper crash structures and reattach the bumper skins with custom mounts. Bear in mind though you will lose a lot of damage mitigation from low speed bumps.

I'll have a look at removing the insulation but keeping the carpet. Is that just a Stanley knife job? In regards to the bitumen stuff, I take it the heat gun won't distort any of the metal will it? Is it an easy enough job or a bit of a sod?

Good call on the bonnet, I'll take a look!

Edited by Muzzman on Sunday 21st March 17:59

[Muzzman]

MrC986 said:

Hi, I’ve a half share in a 325ti Sport which we’ve owned for about 2.5 yrs. I’ve done the work to make it more useable as a track car....removing the rear seats/seats belts, parcel shelf & the spare wheel /carrier is the the main work as well as fitting Cobra Suzuka seats. The removal of the rear seats was partly to assist in being able to transport a spare set of wheels to/from the track days although I still value the comfort of A/C & a radio as I’m the one who normally drives it to /from the circuits.. We’ve also added coil-overs & changed all the fluids & the header tank (a known weak point).

The considered advice (if you haven’t found this already) is to get matching width front/rear alloys to allow you to swap them front-rear as well as giving you more choice of tyres as well.

As ever, a pic to show our car being used....

I'll have a re think about the aircon and stereo, might see if I can find a light unit.

I've got hold of a set of old M3 Style 22 alloys, 7.5" all round, will see if that's a bit narrow, hopefully be okay, the car isn't that powerful. I'll look for a light set of aftermarket at some point but these will do for the time being.

This is the spec so far, might put in a half cage

M54b30 engine

Gaz Gold suspension with adjustable top mounts

S50b30 exhaust manifold + adapter plate

330 brakes calipers

Brembo discs

Mintex 1144 pads

Braided hoses 

BMW Style 22 square setup wheels 

Nankang NS2R tyres

MSport bodykit

Bimarco Expert seats

I want a Gripper LSD but that will have to wait.

Edited by Muzzman on Sunday 21st March 18:00

Edited by Muzzman on Sunday 21st March 18:03

[Muzzman]

E-bmw said:

Having done 3/4 hog & 1/2 hog before if you drive it to track do not remove either stereo or AC.

My first 325 had the ventilation output of an asthmatic spider at 5 paces so when I went to 328 I kept the Ac & it was an absolute boon on hat TDs.

If you REALLY want to lose the 15kg of the AC go on a diet.

Same for the stereo.

I would say lose everything you can at the back & keep everything you want at the front.

Obvs there are things like door cards as you say, carpets, even dash, but keep the other stuff.

Edited by E-bmw on Sunday 21st March 16:29

I'm 5ft10 and 67kg, I think that losing 15kg could be an issue :-)

I better get intouch with the guy building the car and hope he didn't remove the aircon last week

[motorhole]

Muzzman said:

I'll have a look at removing the insulation but keeping the carpet. Is that just a Stanley knife job? In regards to the bitumen stuff, I take it the heat gun won't distort any of the metal will it? Is it an easy enough job or a bit of a sod?

Good call on the bonnet, I'll take a look!

Edited by Muzzman on Sunday 21st March 17:59

Haha the heat gun and scraper approach is a nasty job! But that bitumen stuff is heavy. I think I removed about 8 kg of it in my E30 and there will be more in the E46 I would expect. Doesn't need a lot of heat to soften the stuff so I don't think distorting anything will be a prob.

Carpet insulation - depends, you may just be able to tear it off or you might need to cut it off. Or you could even use the carpet as a template to make something similar out of something thinner, like acoustic/camper van carpet. Not something I've done before but a possibility.

[Muzzman]

motorhole said:

Muzzman said:

I'll have a look at removing the insulation but keeping the carpet. Is that just a Stanley knife job? In regards to the bitumen stuff, I take it the heat gun won't distort any of the metal will it? Is it an easy enough job or a bit of a sod?

Good call on the bonnet, I'll take a look!

Edited by Muzzman on Sunday 21st March 17:59

Haha the heat gun and scraper approach is a nasty job! But that bitumen stuff is heavy. I think I removed about 8 kg of it in my E30 and there will be more in the E46 I would expect. Doesn't need a lot of heat to soften the stuff so I don't think distorting anything will be a prob.

Carpet insulation - depends, you may just be able to tear it off or you might need to cut it off. Or you could even use the carpet as a template to make something similar out of something thinner, like acoustic/camper van carpet. Not something I've done before but a possibility.

Cheap!!!

https://www.screwfix.com/p/titan-ttb773htg-2000w-e...

According to Harry's Garage the Carbon roof on the M2 CS only saves 10kg!!!!!

I'll check out the acoustic carpet, could be a plan!

Edited by Muzzman on Sunday 21st March 18:43

[CedricN]

Stereo is easy to live without, my car never came with one. On long trips a decent portable Bluetooth speaker does the job. The only thing from beyond the 70s i would want i my car on track is AC, keep it if it works. Sweating to the track, on the track, and home from the track on hot days isn't always great sure its worth the hassle with the bitumen stuff, lots of work for a couple of kgs, freezing it with dry ice seems the quickest and cleanest method (Google it). The upside of keeping it is that it doesn't rattle and feel like a tin can with the smallest little gravel stone. Maybe take it in steps so you can find a nice level without going to far?

[Krikkit]

Yeah I wouldn't bother removing the bonded insulation.

Keep the AC, get a cheap mechless BT stereo for cheap.

I'd hollow out the boot lid as well to a single skin, bond in the rear windows and throw the motors etc. Rear wiper, wash tank etc all easy.

[Muzzman]

I managed to stop the removal of A/C.....phewwww

[E-bmw]

Muzzman said:

I managed to stop the removal of A/C.....phewwww

You definitely won't regret that move.

[brillomaster]

When i tracked an old e46, i kept the radio, ac and cruise control. Everything else went.

Id bin the carpet, but not the bonded stuff. Even with no backbox on the exhaust, it was still fine for long distances.

I kept the standard front seats and seatbelt, but added a cheap 4point harness. Nice to just use the intertia reel seatbelt when just cruising.

[FNG]

These days I'd keep the headliner, door cards and carpet. But definitely remove the foam under the carpet (it also holds moisture around the lowest points of the floorpan and can cause rust to take hold). There's also a fair bit of sound deadening behind the rear quarter trims.

And if you're binning that lot, yes I would probably say get a pair of rear quarter windows in polycarb. The rear window will save a lot more weight but you can find you need to add half of that back in with reinforcing strips if it drums or flexes.

Replace the seats with fixed backs if you find them comfortable enough. Do you need two? I've never been mad on having passengers in my track cars so usually only have the one fixed seat.

I'd rather remove some surplus metal in the door shells and the tailgate shell, and take the speakers out, than replace the door cards with sheet. On a long run you welcome the armrest. I don't personally miss a stereo.

Battery is an obvious one, and you'd save a fair few kg relocating it from the right rear quarter to somewhere just behind your seats, too - there's a lot of heavy duty cable running to the rear, and to the jump start location under the bonnet.

When I had a 330ci for track use I cut out the spare wheel well and panelled over with aluminium - but get it profiled with a bead roller or it'll drum and drive you mad.

I also cut out the battery tray, removed the lower part of the rear bumper, replaced the bumper beams with carbon ones from an M3, and deleted the aircon (it stuffs my sinuses, so no loss). Oh and the exhaust is heavy, you can save quite a bit by deleting the pre-cats and the rear silencer box if you don't mind the extra noise.

I also downgraded to halogen lamps and fitted aftermarket, non motorised door mirrors - if it's only you driving it, once they're set, they're set. Window motors are barely ever used if you're the only driver.

Rear part of the centre console can be binned. I also took the airbags out and put a sticker over the SRS logo on the passenger cover.

The only other thing I wanted to do, but didn't, was to replace the heater tray in the engine bay, it's fixed to the bulkhead and sits below the air inlet vents at the rear of the bonnet. It weighed fair bit and would seriously warrant replacing with a glassfibre one, but no-one sells one as far as I can tell, and I never got round to making one.

Other things, if you haven't done them already - remove the clutch delay valve, get it remapped largely to improve on the very slewed throttle map, get the front brakes ducted (there's a guy who makes GRP duct adapters to fit in place of the front fogs) and fit a solid steering column bush. These things really improve the feel of the car, taking out the sluggishness and damped responses to your inputs.

[Muzzman]

FNG said:

These days I'd keep the headliner, door cards and carpet. But definitely remove the foam under the carpet (it also holds moisture around the lowest points of the floorpan and can cause rust to take hold). There's also a fair bit of sound deadening behind the rear quarter trims.

And if you're binning that lot, yes I would probably say get a pair of rear quarter windows in polycarb. The rear window will save a lot more weight but you can find you need to add half of that back in with reinforcing strips if it drums or flexes.

Replace the seats with fixed backs if you find them comfortable enough. Do you need two? I've never been mad on having passengers in my track cars so usually only have the one fixed seat.

I'd rather remove some surplus metal in the door shells and the tailgate shell, and take the speakers out, than replace the door cards with sheet. On a long run you welcome the armrest. I don't personally miss a stereo.

Battery is an obvious one, and you'd save a fair few kg relocating it from the right rear quarter to somewhere just behind your seats, too - there's a lot of heavy duty cable running to the rear, and to the jump start location under the bonnet.

When I had a 330ci for track use I cut out the spare wheel well and panelled over with aluminium - but get it profiled with a bead roller or it'll drum and drive you mad.

I also cut out the battery tray, removed the lower part of the rear bumper, replaced the bumper beams with carbon ones from an M3, and deleted the aircon (it stuffs my sinuses, so no loss). Oh and the exhaust is heavy, you can save quite a bit by deleting the pre-cats and the rear silencer box if you don't mind the extra noise.

I also downgraded to halogen lamps and fitted aftermarket, non motorised door mirrors - if it's only you driving it, once they're set, they're set. Window motors are barely ever used if you're the only driver.

Rear part of the centre console can be binned. I also took the airbags out and put a sticker over the SRS logo on the passenger cover.

The only other thing I wanted to do, but didn't, was to replace the heater tray in the engine bay, it's fixed to the bulkhead and sits below the air inlet vents at the rear of the bonnet. It weighed fair bit and would seriously warrant replacing with a glassfibre one, but no-one sells one as far as I can tell, and I never got round to making one.

Other things, if you haven't done them already - remove the clutch delay valve, get it remapped largely to improve on the very slewed throttle map, get the front brakes ducted (there's a guy who makes GRP duct adapters to fit in place of the front fogs) and fit a solid steering column bush. These things really improve the feel of the car, taking out the sluggishness and damped responses to your inputs.

Thinking about it, i probably don't need two seats, over the years i find that i prefer being on my own, i tend to get in the 'zone' a bit more. Other times i don't mind taking mates and family to have a go, i could just whack a seat in on those occassions.

I don't mind having a tinker with things but not sure i'm confident enough to start cutting bits and pieces out of the car. I like the lexan 3/4 window idea and removing unnecessary motors.

In regards to the clutch delay valve and solid steering bush is that something that i could potentially have a crack at myself?

As said earlier i think i'll start removing pieces bit by bit and see what my tollerance level is.

[FNG]

The steering bush is tight to get at, best time to do it is if you were removing the pre-cats.

Clutch delay valve is in the clutch hydraulic line in the tunnel, basically you undo the valve and reconnect the line without it - don't need any unions etc. You do then need to re-bleed the clutch, but a good old chance that the fluid is old so it's not a bad thing to do anyway.

I'd think if you didn't fancy bleeding the clutch yourself, a garage ought to be ok with removing the valve while they're replacing the fluid. As with many things it's ten times easier on a ramp than on your driveway.

[Wh00sher]

E-bmw said:

Obvs there are things like door cards as you say, carpets, even dash, but keep the other stuff.

Please tell me that`s just a photo you found on google and not your car.

I'm all for saving weight, but that looks awful. The lack of any sort of door covering just leaves loads of sharp edges exposed, regardless of it looking so bad.