135 weight reduction thread


Oct 28, 2017
wha if we do a official weight reduction thread here to 135.
i have a us spec 135 e82 6at so there is sunroof on it and i want to keep it daily drived
so no such as totally gutted race car, rather a sleeper on street.
i drive those GC`s to some 27 psi boost levels with E85 with all support mods
so performance should be quite decent.

weight reduction have similair effect on suspension than stiffening it, lighter
10% weight reduction equal 10% stiffer spring rate too

i had now it down to 3060lbs with empty fuel tank with race seats, didn`t like those
leather slippery electric adjusted fronts and throw away rear seat just to get more
space foe cargo, yes, i use it for dd at work and transport stuff with it.
i kept all sound isolation, stereos, ac, sun roof, etc but as exhaust, berk street,
battery is lifepo4, front seats weight combined total 40lbs, rear safety belts gutted,
front bumper steel support is aluminium, apex arc8 wheels. and it`s still with
decent sound levels.
for truth, most mods will add weight to the car so reductin is not so easy, hevier turbos, hevier
fmic, hevier cold and hot side, double barrel shotgun, double ldpf, more electronics on engine management, heavier coils ( not arrived yet, precision raceworks )

and at the end, why not similair to 335, body style and weights


Mar 21, 2018
Bay Area, CA
I think you can drop some weight by switching over some m3 suspension parts (control arms, etc). I think you can drop weight by changing out the brakes too.


Oct 28, 2017
i forgot to mention about control arms, have swapped those M3 arms too..
and about brakes, it`s still DD so i don`t want to reduce braking power and scarifice
something on that area.

michelin pilot sport cup2 was lightest tyres i could find for this build but it was suprice
to me that they don`t offer any significant traction so i swapped them to DR2`s
but we got even more snow here so real testings on traction will be moved forward some weeks now.

i think i can manage to gow sub 3000lbs with it on race conditioning on empty fuel tank
if i really want with gut out sparco passenger seat with
sparcos aluminium brackets, 21 lbs, handrest, mats, etc.

it`s still fat pig but compared to engine size, it start to sound reasonable.


Oct 28, 2017
Not yet carbon hood or trunk, cause they don't sell them here in some reasonable prices ans if orded from us, price is skyrocketing
Caused od freight cost... 1000eur /pc and taxes so hood and trunk is in cost of 4000 eur total
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Reactions: doublespaces


New Member
Apr 7, 2019
Lexan window replacement saves significant weight (about 50%) when compared to the glass that it replaces, all at a relatively low price. Depending on the setup you go with and where you live I’d estimate replacing both door windows, side windows, and the rear windscreen to cost $600-1000.

Another major weight saver I haven’t seen in this thread is the Evolution Racewerks FE widebody kit. This kit allows you to run a square tire setup on your 1er eliminating potential understeer. The kit replaces your bumper, fenders, and side skirts with either fiberglass, wet carbon, or dry carbon each weighing less but costing more. Stock these parts weigh about 49 lbs combined, these kits save 17, 25, and 32lbs respectively; costing 2k, 2.5k, and 3.5k respectively.

Carbon kidney grilles will also save a few ounces of you’re really trying to get every bit off.

Personally I want to do a carbon roof panel but haven’t found anyone to copy off/ produce the panel.
Getting rid of the sunroof, headliner, and heavy steel paneling should save in the realm of 100-150lbs off the top of the car which is massive in comparison to other mods (gutting the interior being one mod comprable. I hope I covered any missed bases


Aug 7, 2018
If he wants to keep it daily drive-able lexan would be the last thing I'd do. There are easier and better items to attack first IMO.

Sounds like you've done a decent amount already but I'd ditch the sunroof and replace with a carbon plug as stated above. It's a lot of weight on the top of your car. But I despise sunroofs because every single BMW I've owned has had a leaky sunroof.

You have a lightweight front crash bar, what about the rear?

You're only going to get so far if you're trying to keep some luxuries and call it a daily driver unfortunately.


Jan 24, 2018
Charleston, SC
Where did you get the lightweight front crash bar and how much weight did it save?

Bimmerworld makes a CF sunroof delete plug specific for the E82. I'm ordering it soon. Can also get a full CF roof panel from Revozport but that's almost 4x the price.
Weight reduction costs big dollars, you can do a full titanium exhaust which will save you heaps also a tube and fin ic can net significant weight reduction.

The cowl mod is worth quite a bit and helps with cooling.

remove the back seat as that thing weighs a ton.

rear bumper support is worth a lot.

Full cf roof, bonnet, trunk, cobra master wheels, brakes, all these mods will cost you more than the car but can save you easily 3 to 4 hundred lbs.
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