JantzenRX-8

iTrader: (9)

My Rx8 has been my daily driver and weekend track car for almost 4 years now and along the way i've made light modifications here and there along with some weight reduction. I've recently bought a BMW as a daily driver so technically now my RX8 is a dedicated weekend and track car which is parked in the garage for the winter. I've been working on a few projects over the winter which caused me to start pulling off bits and pieces i didn;t think were necessary to try to make this thing as light as possible. I will say that i do want the car to appear to be a street car at a glance but is actually a street car with a very trim waistline. I also love the way it sounds so exhaust changes are off limits... And i have the Mazdaspeed sides and rear to cover damages from a small accident so those are off limits too.

I'll list off my mods that i think matter and what weight reduction i've done so far. Let me know if you have any ideas for shedding a few more pounds.. i'm running out of ideas.

Mods:

• Street wheels: Advan RS 18x9
• Track wheels: Enkei NT03 17x9.5 with very light 255 BFG R1 tires
• Racing Brake two piece slotted rotors on all corners
• Racing Beat Dual Resonated mid-pipe
• Exoticspeed R1-T cat-back exhaust
• Status Ring GT Carbon Fiber Racing Seats (leather)
• Delrin shift ****
• Tein Basic Coilovers
• AEM intake
• AP sluminum underdrive pulley

Weight Reduction:

• Odyssey PC-680 battery relocated to trunk
• Battery tray and everything that is attached to it removed
• intake tray removed
• air pump delete
• front engine hoist removal
• Exhaust heat shield removed (below trunk area)
• rear floor mats gone
• Front brake dust shield removal (still need to do the rears)

Random:

• The trunk panels are out for the time being but aren't usually
• Rear seat bottoms are out on track days
• Front floor mats are out on track days

Thoughts:

• I've seen people remove the hood liner but i'm not sure if that is a good idea
• Does the sound deadener in the trunk weigh much?

The last time i weighed my car was pre racing seats and pre most of the weight reduction with a half tank of gas and it was 2950 lbs on a truck scale. I'm hoping i'm in the 28xx's but i think i have a bit to go.

Thanks all!

WTBRotary!

iTrader: (6)

Do you have a sunroof? Just wondering if you are a GT or not

JantzenRX-8

iTrader: (9)

Yes, sorry, Its a 2004 GT MT with sunroof.

WTBRotary!

iTrader: (6)

Oh and you can remove the upper seats, theres only 2 bolts (12mm) that hold them on.

Try a good racing seat and bracket also.

JantzenRX-8

iTrader: (9)

How much do the upper seats weigh? I was thinking about removing those for track days but never looked into how to remove them.

14 lb carbon fiber racing seats not good enough for you?

Highway8

iTrader: (11)

Unless you remove daily driver comfort items, there is not much left besides CF body panels (doors and the trunk) and lexan glass.

WTBRotary!

iTrader: (6)

^^^ Yup Thats what I was thinking as well

GeorgeH

iTrader: (2)

Light flywheel
RB aluminum front calipers
Remove engine cover
Remove OEM shock tower brace
Remove rear deck speakers (fronts should be good enough for the trip to the track)
Aftermarket steering wheel (Use a harness when driving to & from track)
Remove fog lights
Aluminum shock tops
Remove interior panels (keep 'em nice for when you sell the car)
Swap out Bose head unit for cheaper (and lighter?) stock head unit

Some of these may be more extreme than you want to do. I'm sure there are other ideas that I missed.

alnielsen

iTrader: (4)

TeamRX8 did some work on this and had a thread about it about 2 yrs ago. Search back through his posts and see what you can dig up.

JantzenRX-8

iTrader: (9)

...

Highway8

iTrader: (11)

The RB Front calipers would be about 15lbs of unsprung weight which is like 50lbs of weight elsewhere. Not bad for $500.

Correction: $500 per side and 5lbs per side = 10lbs total.

bse50

Remove the center dash\shifter cover from the front to the rear.
Remove the rear seats and the lid that leads to the trunk
Remove the glovebox
Replace the rear compass windows with lexan ones or carbon fibre panels
same for the sunroof
Replace the rear view mirrors with lighter, non electric ones

Most of this stuff is free too!

StuttgartRX8

Also to add to bse50's list

Remove the stereo and all the speakers.

I'm doing pretty much everything right now.

L337fpc

iTrader: (4)

when you change your flywheel, go for the BHR one...i believe it is the lightest flywheel we can buy.

i don't think i saw a midpipe in your list unless its the exotic speed one that came with your cat back. You might want to add the Racing Beat header to your list as well. Marginal weight savings, but you get more mid range wtq.

GeorgeH

iTrader: (2)

Calipers alone do not eliminate 15 lbs - the OP already has two-piece rotors.

Aluminum shock tops at this point are, I do believe a custom endeavor. TeamRX8 made a post in the last few days about how he did it in the STX thread.

However, the thing about following us STX guys in terms of weight savings is that we are playing by a very specific set of rules. For a track car with no rules, there are cheaper ways to save weight, like removing stuff.

I recall years ago a Miata guy went through this same exercise, but he took it to an extreme, even trimming off the ends of bolts, etc. He saved buckets of weight. But it was a total transformation - he had no desire to keep any aspect of "streetness" to the car.

As for the downside of removing the OEM shock tower brace, I have not seen any. I recently put it back on just to see, and didn't notice any difference to the car.

Highway8

iTrader: (11)

Your right, its only about 10lbs, 5lbs per side.

bse50

I forgot...
Remove the front and rear crash bar, or replace them with something lighter and still somehow functional.

JantzenRX-8

iTrader: (9)

I'm pretty sure its $1026 for the RB calipers. They're listed on their website for $513 (minimum order 2). GeorgeH just made my other point.

RB header is definitely on the list but i dont see it happening any time soon. Maybe before Pettit SC which is planned for 2012.

JantzenRX-8

iTrader: (9)

I like this idea because those are really heavy but i would not want to sacrifice safety whatsoever. Is there any example out there you know of where people who have done this and maintained equal or better safety?

bse50

here's an example of what other cars adopt

dmitrik4

iTrader: (5)

you need to decide how serious you are about losing weight off the car. i don't think you can get it seriously light unless you are willing to commit to it.

and roof:

http://www.mazdatrix.com/getprice.as...um=CF-ROOF-RX8

front doors (rear doors and hood are already aluminum; i don't think the CF pieces are lighter):

http://www.mazdatrix.com/getprice.as...=CF-DOORS-RX8F

trunk lid (ditch the lifts):

http://www.mazdatrix.com/getprice.as...m=CF-TRUNK-RX8


also front fenders; i'm sure there is a source somewhere.

all the interior stuff can go.

are the Tein dampers aluminum or steel?

use stiff enough springs that you can ditch the swaybars. use the shortest springs you can get away with. Swift springs use fewer coils, IIRC, and are therefore lighter than most.

a header should save some decent weight.

bse50

Highway8

iTrader: (11)

My concern with door the doors and roof is safety. They would need to be dry carbon to save weight and still be strong and there still needs to be some sort of bracing inside the doors and roof. On a car with a full race cage it would not be an issue.

bse50

I agree on the doors completely. The roof, intended as the foil that keeps the sunroof in place, doesn't look that important though.
That's probably because our chassis still has a spider as a starting base:

JantzenRX-8

iTrader: (9)

Dont you have to break the rear glass to remove the roof panel and the replace the extremely expensive rear glass when you install the new roof?

I agree with the CF doors. Wouldn't do it without a full cage.