blackmount

Hi guys, I've had my RX-8 for awhile now - I've put about 20,000+ very fun, and rewarding miles on it over the last 18 months or so since I bought it ( It is not my only fun car, or my daily) Originally I was keeping it respectively stock and nice incase I decided to turn around and sell - which a few days ago was something I was about to do.



I started searching for used RX-8's across the internet (mainly on Autotrader) to try to get a good idea what to ask for my car - After looking around, I saw values are at a all time low, and with the mileage and 7/10 overall condition that my car has, it wasn't worth the time and effort to sell it for how little money I would get in return, especially since I know I would miss it. So I decided to start making moves on changing a few things here, and there that would not completely ruin the car, or make the car become "Over-modified"

I really enjoy the car, It's alot of fun - but there has been this just one thing making me feel like it is holding the car back, and believe it or not, it is NOT the power, Since the day I got it I've always felt the car was far too soft, which to me made it feel heavier then it really was, and since as the car aged, bushings have worn out, things loosen up, etc. it has not helped much at all. I replaced the original, and well worn out shocks with a set of Tein Street Flex Coilovers, I learned that those are not the best choice in a "Street" Coilover for the RX-8, but they I guess they work, I might try Koni's and a good spring here soon, Mazda also replaced both lower control arms, some sway bar end links, and gave it a fresh alignment over the summer per the LCA Recall, but this car still has this slightly soft feeling to me that bugs me, So I'm wanting to truly improve the cars handling.

I would like to:
Eliminate more Body Roll
Tighten up the Chassis
Reduce Weight

I do not want to racecar it out, or make it tiring to drive, I already have a car like that haha. The big thing is good ways to eliminate weight that can retain the following.

Car must keep AC, Heat, Radio, and Room for 4 Passengers, 100% full Interior
It must still function, run, and drive like a factory car. I don't want to go ripping things out of the engine bay in effort to shave weight, if they will make it cold start weird, or sometimes idle funny, have light throttle modulation hicups, etc...

I'd prefer it to still look like a factory car on the outside too with maybe the exception of the wheels (if I can ever find a lightweight set of wheels, I like)

I have no interest in chasing power, I enjoy the RX-8s power, it's not the fastest thing on the road sure, but It's really fun just to row the gears, and listen to that wonderful induction noise the Renesis makes when you go Wide Open, I did briefly install a exhaust on the car, but decided it was too loud, and put a stock one back on. I'm keeping stock airbox as well.

So Shoot Me some Recommendations and Ideas, and I'll update this thread occasionally with things I do.

Here is my Idea's/To-do List currently: Let me know what you guys recommend for these.
*Replace/Lightly Upgrade Motor Mounts, Diff Bushings, etc (I have alot of Trans, engine, and Drivetrain slop that I feel like should not be there, no clunks, just slop, most noticeable with upshifts, and on/off Throttle)
*Lightweight Flywheel + New Stock Clutch or One Step above stock Clutch. I'm addicted to ultra quick revs when blipping the throttle during those extra spirited heel-toe down shifts.
*Header Upgrade for the weight Savings
*Smaller/lightweight Battery
*Racing Beat (Or better based on suggestions?) Sway Bars
*New Stock/Upgraded Rear Control Arms
*Lightweight Front Seats (Good Recommendations? I don't mind some FIA Buckets as long as they aren't too racecar, and can sorta match the interior, as well as work with stock seatbelts)


A good thing I like to do when Considering modding a car these days is "How Would the Factory improve these things?"

UnknownJinX

I personally am looking for a set of R3 Bilstein suspension(which bolts right up to my S2 GT), and possibly some two-piece brake rotors.

When I need a new clutch/engine(whichever comes first), I will throw a lightweight flywheel in there.

As for the header, you can get a Racing Beat one, but I am not sure how significant the weight saving is, and you might want to add some heat shielding above it, so the end result might not be that worth it.

If you are serious about the battery weight reduction, then buy a lithium battery and relocate it to the trunk. The heat under the hood will kill a lithium battery quickly. I am not that serious, so I just use an AGM battery. People have informed me to stay away from Optima ones, though.

For seats, you could probably rip out some Recaro seats from a junkyard R3 if you want something OEM+. People have said it's not the greatest on long highway trips, though.

Loki

iTrader: (1)

The list sounds about right. Motor mounts make a huge difference in driveline movement, which also keeps the shifter in the same place under turns. You don't need crazy aluminum ones, BHR Red is just fine even at the track. Be aware though that you will have more noise in the cabin.

The thing you talk about the most is body roll, so sway bars for sure, if you're not willing to increase the spring rate. I would go stock R3 Bilsteins waaay before I would go Koni. Just make sure you use Series 2 rear springs if you do that. I kept my Konis for less than a year. I would encourage you to go Bilsteins B12 coilovers or even better quality coilovers from Ohlins, FortuneAuto, and the like, or keep it stock and add sway bar. Depends how much front to back weight transfer matters to you. Coilovers will control it, sway bars won't.

Nothing to be gained by upgrading rear control links.

I'd skip the header entirely. There is nothing to be gained there. A few pounds isn't super good ROI on the cost and effort.

See how far that gets you..

As far as weight savings... get lighter wheels, and see about the rest after. A few pounds of sprung weight here or there don't make that much difference, especially on the street. Seat comfort goes a long way.

​​

blackmount

I'll have to see on the header, I'm not looking for massive weight savings, but a few lbs here and there would be more then awesome!

I'd like to keep the battery in the front of the car - again no race car stuff. also I don't want to lose trunk space, the RX-8s trunk is small enough haha, that is why I was more just aiming for a slightly more compact, but equally powerful battery. Yeah Optimas were good like 15 years ago, battery tech has come such a long way.

I thought about the R3 seats, but for the cost I wasn't too sure, and task of finding some, plus they are most likely still pretty heavy in terms of seats, I am sure they still have side air bags in them, and not sure if they have seat heaters or not...

I'll keep my eyes open, maybe I'll stumble upon a good deal.

I thought about finding a full Front and Rear set of NICE Cloth RX-8 seats on the cheap with no power adjustments, or heaters.. I am sure on the driver side that would save alot of weight, and cloth tends to be lighter than leather/vinyl most days.

I was thinking maybe something like these too, I love good bucket, I've never found them uncomfortable on long drives either. https://www.recaro-automotive.com/us...tion-2018.html

NotAPreppie

Quality basic coilovers (Bilstein, Ohlins, KW).
Motor mounts.
Diff mount bushings (the entire driveline is bonded together by the PPF, if you're doing the motor mounts, you should check the diff mount bushings)
Adjustable swaybar so you can tweak for best comfort/performance compromise.
R3 Recaro front seats so you keep the airbags.

Sydo

Loki

iTrader: (1)

The R3 ones were valved to Mazda's specs. No idea how they compare in performance to B8s but I thoroughly enjoyed the R3 suspension when I had it.

I don't super understand this thread. You say "no racecar stuff" and then start looking for minor weight savings that make no difference unless it's a race car. I would definitely not use seats that don't have airbags if all you do is drive on the street. The SRS system was built to work as one, if you remove components, your head becomes the crumple zone if anything were to happen.

UnknownJinX

To add to Loki's point, some of the stuff have better value than others.

A new header has a pretty low value. The stock header isn't that restrictive and it comes with a heat shield. RB helps smooth out the flow a bit, but it's not a huge gain and you might need to add some heat shielding now, so the weight gain isn't that much.

If shaving weight off the exhaust is a concern, start with replacing the stock cat with a mid-pipe. Your car will stink upon removing the cat, though, and the only aftermarket ones proven to survive the Renesis exhaust heat are the HJS units, and those aren't cheap.

And as mentioned, unless you go full racecar, keep the stock airbags. You never know when some idiot might T-bone you. The R3 seats don't come with seat heaters, but should be a bit lighter than the leather powered seats due to not having any powered parts.

Otherwise, if you truly want to go faster by shaving off weight, start with smaller wheels(17" is the smallest you can go to clear the stock brakes) and possibly 2-piece rotors. Removing unsprung weight is quite a bit more effective than sprung weight. Helps with handling, all while you reduce the rotational inertia.

blackmount

Thanks! Yeah I want to avoid any type of Metal on Metal/Hard/Solid Bushing/mount/etc. If there is a firm/higher quality rubber available, That would be ideal - at most some type of poly is as far as I would go, I would imagine mine are just really worn out, so at this point even new stock ones would be an upgrade.

It is purely side to side, Pitching is not bad at all in comparison, there is about 4 times left/right roll as there is forward/rear word. I understand Mazda dials in alot of body roll into their cars, but man, its a bit much sometimes, haha.

Two things I want to avoid is the loss of the rubber isolated top hats, and a really high spring rate, The Roads up here in Wisconsin, especially around me are very rough so I am accounting for that...I am confident sway bars will be enough at this point, hopefully.

I wasn't sure. Sometimes there is a nice lightweight aftermarket control arm with "soft" bushings. I'm worried about the cost, and I'm not looking for power, It was more just for weight, isn't the stock RX-8 manifold a big cast boat anchor?


Hmm, Weight Savings are weight Savings - If I can do it without making the car less pleasant to drive, 1lb or 100lbs,

I mean, might as well. haha I'm a big fan of Colin Chapman... I'll see on the seats, I find most stock seats to be less comfortable then most non-reclinable buckets.

I've never really noticed a loss of comfort from stiffer sway bars, but then again I've never upgraded them in a car as soft as the RX-8 before, haha.

When I say no racecar stuff, I mean no Metal on Metal Bushings/Suspension/etc that typically has rubber between it and the car, no Roll Bar,s Loud exhausts, Ditching AC, and heat, removing large pieces of interior or sound deadening (except the big mats in the engine bay probably) Gutting unused wires and plugs from harnesses, using lexan, or large carbon panels (unless they look like stock once painted) etc etc.

It's not power I am looking for, but shaving a couple pounds off the nose is always a rewarding time.

My stock Cat is deleted, I was thinking about building a nice midpipe - the problem that is holding me back is actually building one that is A: Lighter than Stock, and B: Equally Quiet/Similar sound to stock, with mufflers/resonators that will not burn up their packing after a track day or really long spirited drive.

Problem is I doubt my Airbags will work anyways, I have had the recall done, but my airbag light randomly started coming on lately for no reason - I can take it to the dealership and have it fixed sure, but chances are the cost to do so will total out the car in a hurry.. At this point I have already assumed the risk.

I am having a hard time finding wheels that suit the car as good as stock and don't look aftermarket, having them fit equally well is important too.
2 Piece Rotors is a good idea though.



Think of a sleeper style build, that instead of a unnecessary amount of horsepower, it was a handling focused, all while retaining a comfort level measurable to stock.

Brettus

iTrader: (2)

I consider what i have as ideal for back road driving and I've not really done much to the handling .
Mazdaspeed shocks/springs plus redrilled the sway bars for a little extra roll resistance.
Two pot calipers on the front are nice but stock brakes were good too.
What really makes it nice for me is more than double the low down torque (via turbo )...... so driving fast is really quite relaxing .

Drives like stock otherwise and quite comfortable carrying 4 adults on trips.

UnknownJinX

IDK, $500+ on negligible weight loss on the header isn't what I consider value. That's valuable to a race team, but not poor old me. Again, whatever weight you shave off, you will add back on with an aftermarket heat shield. If money is no object then go for it.

If you had the recall done and now you have issues, have a nice talk to your dealer and ask what they can do for you. Goes without saying, but dying sucks.

I am in the same boat with you on the wheels. I don't want to change the stock style too much, and that's why I am skipping out on the wheels myself and going straight for the 2-piece rotors.

blackmount

Sadly the Airbag Recall was done long before I bought it, and the dealership that performed the work is no longer a Mazda Dealer, or Services Mazdas, ontop of being several hours away.

thebubbadog

If you are planning on building a road car. I probably won't worry to much about the weight of the car and more about getting it on a good set of coil overs, sway bars and a good set of 9.5in wide wheels (or bigger) and some nice gripy tires. It will help tighten up the car a lot.

blackmount

I had it on 18x9.5s with 275 wide 200 Treadwares on all 4 corners earlier last year



It was way more tire then I could reasonably use on the street/backroads for the big penalty I took in unsprung weight, and the higher cost of tires. It also really killed the cars acceleration, and even took a notable toll on MPG...Granted neither the Tires or the wheels are the lightest examples of those sizes in the world...

I think a square 245 setup with some really good 300TW summer tires is ideal for me here personally... which fits nicely on a 8-8.5" wheel, saving me from a unsprung weight penalty.

I've got another car that is my beyond-reason car, haha, this is supposed to be the more mature and refined car....

TomD_Cincy

iTrader: (2)

Given any thought to something like this: https://www.rx8club.com/rotary-swaps...3/#post4877124

Reddozen reported 15 lbs weight savings, so would expect you to net a few more pounds (assuming you can live without a sunroof). I have no clue what it would look like painted.

NotAPreppie

15 lbs of sprung weight is meaningless if you aren't competitively racing the car.

TomD_Cincy

iTrader: (2)

I don't disagree. I was just throwing it out there for the OP based on his statement below.

UnknownJinX

Again, poor value if you are not racing.

Let's assume it's about $1300 painted. For the same amount of money, you can buy a set of 2-piece rotors from Racing Brakes, which reduces a similar amount of weight, but that's unsprung weight you are reducing with brakes, which is more effective.

blackmount

Yeah, I talked to him about it, Bryan he has actually been a friend of mine for several years from another life, long before I got a RX-8.

The only downside is, I do enjoy the sunroof in the summer time, that thing is practically glued open from may to october if I am driving it.

I guess I'll just be off wasting my money then I guess huh?

I feel a pretty dramatic difference in the RX-8 just from going from a 1/4-1/2 tank of gas to a full tank of gas... If you think can't feel a 30-50lb weight gain (or loss) you should spend more time driving, and less time posting. because trust me, you can especially on a sub 3,000lb car. Even just casual back roads driving you can feel that... Will the car actually be faster? Probably not, but will it feel better to the driver? Absolutely and that is essentially the whole idea of this thread, I don't care about being faster.

Weight Adds up, I don't really have a preference if I find one place to remove 30 lbs, or 30 places to remove 1lb. Being able to do it without making the car less pleasant to drive is a bonus.

NotAPreppie

Oooh, condescension... I LOVE THAT!

UnknownJinX

I like the sunroof as well. Have it open when it's sunny out.

As for the effect from the weight difference from the amount of gas... I actually have a G-meter installed in my car, and the number I see on it has been fairly consistent despite the amount of gas I have when I floor it in 2nd gear. There might be a small difference but it's not really much.

Placebo can do a lot of things...

Loki

iTrader: (1)

The amount of gas in my tank hasn't demonstrated any difference in my lap times. We can only advise on facts, not feelings.

​​​​​​Getting back on topic, the point has been made here repeatedly: if you want to make a real difference, your list is good, but start with rotating mass and unsprung weight. These things have no impact on comfort. So wheels, tires, brake rotors.

blackmount

again, not out here for lap times, I have a shitty Mitsubishi for that, just trying to make the RX-8 feel better to me.
So far I am at.

Header, that doesn't do anything, but looks cool
The Lightest Flywheel I can find
Sway Bars
Unsafe Airbagless Seats
Engine Mounts
Diff Mounts
Lightweight Battery

Unsure what the battery tray is like on the RX-8, but I built this one for my 3000,



It is two thin sheets of Carbon with an aluminum honeycomb core in the center, It saved about 2lbs over the steel one combined with the tie down, and the battery I went with saved another 20lbs, I won't use near as small of a battery though since the RX-8 has so many more electronics, and demands alot more power.

I may make another one and relocate the battery somewhere closer to the firewall RX-8. I saw RE Amemiya do something similar in a old Best Motoring video with a RX-8 they were messing around with.