WEIGHT REDUCTIONS 101 - Part III

[Milo (San Antonio)]

In part 3, I want to discuss two area of weight reduction that were justslightly touched upon in Part 2, Reciprocating mass reductions and the moreextreme weight reductions. We will step right into the reciprocating massreductions and save the extreme reductions for the end.

* Reciprocating (aka, rotational) mass and unsprung weight.

A vehicle's total weight is the sum of all of its parts andaffects it’s ability to accelerate, brake and corner. Reducing the totalweight will enhance the vehicle's performance because less weight needs tobe controlled and therefore, less energy is required. Unsprung weight is theweight under the springs which moves up and down as the vehicle rides overuneven roads and leans in the corners. Reducing unsprung weight allows thesprings and shock absorbers to be more effective in controlling thesuspension's movement. Additionally, a vehicle's rotational weight includesall parts that spin including everything in the vehicle's driveline fromthe engine's crankshaft to its wheels and tires. This affects the energyrequired to change speed as the vehicle accelerates and brakes. As youwould guess, reducing the weight of any of these rotating components willenhance the vehicle's performance because less energy will be required toincrease or decrease their speed. As a side benefit, better MPG can also be gained as well. So let’s cut some rotational mass.

*****************ROTATIONAL MASS REDUCTIONS********************

1) Lightened Flywheels –

Across the board, you can roughly expect a lightened flywheel to be halfthe weight of a stock one. Fidanza, a commonly used flywheel, comes in at11.5lbs versus the stock flywheel which comes in at a massive 23lbs. Again,no calculating reciprocating mass just curb weights, we can save 11.5pounds in the center area of the vehicle.



2) Lightweight Clutches –

Although these have been available for some time now, a lot of folksoverlook the weight savings of lightweight clutches. Companies like Exedyhave been making them for years. I have heard of folks shaving as much as12lbs by choosing lighter clutch assemblies. So before you purchase yournext clutch assembly, take the time to consider the weight of the units andother parts available to aid in saving a few pounds. I know that Exedy iscurrently offering a very nice clutch that has great clamping force and isprobably the lightest assembly that I know of. There have been some greatreviews on them as well. I also spoke with Coz who informed me that simplygoing to most any performance clutch assembly should shave between 3-5lbson the average but again. DO YOUR RESEARCH and purchase the best application for your Z’s needs.

3) Lightweight Driveshafts -

The stock driveshaft varies in weight from5spd vs Na vs 2+2 vs 2 seater. My personal driveshaft rings the bell at33.8lbs as a whole assembly including the two center carrier bolts andwashers. Going to a single drive shaft saves a good amount of weight as iteliminates the center carrier bushing and the associated hardware. MyZ1 aluminum drive shaft came in at 16.4lbs. So, I shaved off 17.4 lbs ofcurbweight as a total assembly. Aluminum, carbon and steel are allavailable in the market. Weight and torque capacity differ fromvarious materials and versions.



4) Lightweight Crank Pulleys (Harmonic and Non-harmonic) –

There is a huge debate about pulleys that are simply machinedas a one piece and not having a harmonic balancer versus those withharmonic balancers. Obviously the units with the harmonic balancer are theheavier of the two due to added materials. Some argue that eliminating theharmonic balance in a high output engine is unsafe while other argue thatit is perfectly safe. I will leave that argument on the boards as this adead horse that has seen better beatings and simply go over the two typesand give their average weights.

The stock unit comes in at 13.6lbs. The non harmonic units come in a2.4-3.3lbs on the average (measured ASP/Unorthodox and cheap eBay unit).The Fischer unit, harmonic type, came in at 7.6lbs. Didn’t have any othersto compare but I imagine they are in the same area.

5) Lightweight Brake Rotors –

There is a dual advantage to lighter rotors that most don't evertake into consideration when picking rotors, especially your2pc rotor designs. A 2pc design is one of the best designs forrotors allowing for the entire center section of the rotor to be eliminatedfor a lighter aluminum center section hat thus cutting down on weight aswhole on the assembly. You can sometimes find a 1pc rotor out there thatwill save you some weight by just a difference in materials it was made out of, but so far the 2pc rotors are some the lightest rotors available due their design.

My stock front rotors weight in at 17.6lbs, note that minehave been cut once but that is usually the average. Stock rotor sizeBrembro replacements came in at 17.25lbs. Lightweight 2pc rotors comein between a ultra light 9.95lbs (Coleman and Willwood) - 12.8lbs (Baer. Most folks save in the neighborhood of 5lbs per rotor.



6) Lightweight Rims –

Believe me when I say, “Not all rims are created equaland like many other things when it comes to automotive performance,you usually get what you pay for. Choosing lighter rims as opposedto some heavier type rims is a great way to loose a few more lbs aswell. Most folks don’t op to buy them due to the usual high costassociated with a quality lightweight rim. There are many,many, many different types and I am not going to single any onevendor out. I remind you to consider not only the lightweightof the rim itself but also consider it’s manufactured materialsand also consider it’s corrosion resistance as well. Again,consider all alternatives and also differences in size. 16-18’s are theusually average for most applications, 16’s being the same size as thestock wheels. 17’s and 18’s are the sizes where most folks usually stay.. Iwould only recommend 19’s for those folks that need them for huge brakekits and such.

Now figure in your basic cheapie 18-19 inch wheel tips thescales between 27 to 33lbs per rim. Yeah, I know, but it’s true. Yourtypical 1 piece forged racing 17” comes in at 13-15lbs. Enkei RPF1’s,15.5lbs. SSP Type C’s, 14.7lbs. Hell….stock Ray’s 350z 18” track wheels, 18.19 in front and 18.62 in rear. Not bad for a huge 18” wheel in stock form. This is just one more thing to consider when being weight conscious.



7) Lightweight Lug Nuts –

Companies like Titek, Kyokugen and others make excellent lightweight lugnuts that do a good job for cutting weight in place that most don’t everyreally think about. My Titek lug nuts came in at .08 of an ounce comparedto 2.1 ounces to the stock units. That is more than half the weight cutfrom their original counterparts. I now this may seem minimal, but at thislevel you have to take it all in and consider it all. Also, considerlightweight valve stems as well.



****************** EXTREME WEIGHT REDUCTIONS*****************

Each one of the weight reductions have been labeled as suchbecause they each need to be taken with a grain of salt, meaning there arethings to consider. What is there to consider, you ask? Safety,drive-ability, annoyance and not to mention legality for starters.Althoughsome seem easy and cheap, you must consider the ramifications of each. Nowthat is on the table lets get down to it, starting with the mild and goingon into the more aggressive ones at the end.

1) Lightweight Racing Seats –

This may seem like a not so “extreme” of a lightweight reduction but often a logical one. The only real downside of going to these seats, is comfort and range of motion. If you have never been in a vehicle equipped with 1pc seats or even 2pc reclinables with extra lumbar support and have been in the vehicle for long non-track periods it can be annoying. You give up some vision blind spots depending on the seats and depending on both the seat and instillation, your range of arm/body/head motion is limited. It’s not the seats fault, it’s the seats job to keep you locked into place the best it can for safety. The side benefit to these seats is their huge opportunity to shed some poundage.

The stock drivers power seat may seem like it weighs in at 200lbs but in reality it comes in at 63.7lbs. This is due to the heavy under the seat motor that control the seats power functions. The passenger on my NA totaled 47.1lbs. When I first did mine, I was expecting much more but that is what the scale says. A trick that you can do on a budget is to simply swap out the drivers power seat for a non-powered drivers seat, the weight is identical to the passenger seat.

Now the range of seats and styles is vast and constantly changing. Your 1pc aluminum racing seats can come in as low as 11lbs for seat and seat overlay. Recaro Speed seats (2pc reclinables) come in at 30.9lbs each. So you get the idea that most of your 1pc designs are lighter as they don’t need the hinges and assembly to make the seat reclinable, thus eliminating more weight out of the seat design. Also, don’t be fooled that all 1pc carbon fiber seats are the end all be all. Some of the cheaper fiberglass 1pc versions beat them by a few pounds. Again, do your research. Consider also your seat rail assemblies into your equations.



2) Sound Deadening Removal –

Sound deadening is one of the simplest things to do to cutweight. Removal of the interior is required of course. There are twomethods of attack here; heat the patches and remove them and get messy ashell or utilize dry ice and simple chip them away. I set blocks of ice onsections of the deadening before I get to it. By the time I get to it tochisel it away it comes off in huge sectioned layers. Works like a charm. You will have sound deadening mattes in the whole of the rear, behind the seats,under the seats, on the transmission tunnels and on the floor boards. I amassed a large bag and did my best of keeping them all together. I also justtook off all foam/rubber piece behind each rear plastic panel and threw themin there as well. Obviously the downfall of eliminating sound deadeningmaterials is the louder road noise. You can battle this with structure foaminjection which I will post up about in another VTF.

Total weight saving – 33.8 lbs total weight for my project (may vary a bit)



3) AC System and Heater Kill (optional) –

Pulling the AC system and heater core is commitment. For us in Texas, it’s a big commitment. So really make sure that this is something that you want to do, as going back and installing this all is a royal pain. Now that you’ve been warned that you will have no blowers at all after this mod. Let’s get on to what is involved.

Killing out the AC system and Heater system is pulling entire system from under the dash all way to the draw fan in front of AC condenser. AC compressor, AC engine bracket, AC condenser, AC lines, blower motor, heater core, AC vents, Nuts/bolts, sensors and wiring, etc. I pulled out and weighed everything and came out with 103.7lbs. Keep in mind this is not accounting for the additional radiator fluid that runs through the condenser. Eliminating the condenser does require looping the rear heater hose hard pipes on the rear of the engine.

4) Radio Kill –

To pull the radio unit isn’t very involved but more spread out throughout the car. Rear speaker enclosures (1 or 2 depending on the model, TT’s have 2/NA’s have 1), door speaker enclosures, cage, wiring and radio. I was expecting much more to be eliminated, but only ended up with 22.4lbs. I would have assumed it would have been closer to 30lbs over but nope. I am sure there is variances depending on the units you are pulling out but this was all the stock Bose stuff.

5) Airbag (SRS) System Kill –

For those that have this in their vehicles, this is yet anotheropportunity to shed a bit more weight. There are two systems that are availfor the 300zx. The earliest version is the system that only has the airbagin the steering wheel, the later version had both a steering wheel andpassenger airbag unit as well. I don’t have an idea how much the passengerairbag weighs as I didn’t have one to put on a scale. Though I would figureit would be another 6lbs for the whole assembly or so considering how muchthe drivers unit weighs. When I pulled the system for the Project LOWFATZthe whole front end was off as well as the dash. This allowed me to pullthe entire unit from the actuators mouned in the frame horns in the frontof the vehicle, then all the wiring (yellow loomed wire normally), theairbag module box under the dash, another module that is mounted on the topof the transmission tunnel, then the airbag equipped steering wheel was swappedfor a non-airbag Z32 steering wheel. Removing the steering wheel and otherunits require a special torque key that is not always available at thelocal auto store. I want to say that I used a T55 torque bit to remove thespecialty bolts to these units, made life a lot easier. Put everthing in abag and hit the scale, came out to 28.7lbs. But figured in the differencefor the steering wheel swap and that put me 22.3lbs total savings.

6) Carbon Fiber and Fiberglass T-Tops Replacements –

14.6lbs each is what each T-top comes in at. Maybe 4-5lbs of that is actualglass weight. For those that have T-tops and would like to cut the weightthis is a small opportunity to cut weight but, like any mod, consider thedownside of possible water leakage as I’ve heard that this is a commondownside to T-top replacements. Also, there is also the rumor that you canloose a little bit of upper rigidity as well. This remains to be seenand/or tested for that matter. AMZ Performance made some but I am not sure they are still for sale or available to the public. Ionic Dynamics is currently in the worksfor another carbon fiber version. Powertrix is also in the development for one thatthey will most likely do in a material other than CF to allow for maximum durability. After speaking with Charles at Powertrix, they believe they can deliver a T-top that should come in at 6lbs per t-top. So by rough guestimate you would be looking at 17lbs of total weight savings.

Pics courtesy of TT.net archive.

7) Speed Glass and Lexan Replacements –

After calling and speaking to a tech at Speed Glass, they claim that they can shave as much 125lbs out of the vehicle from glass replacements as a whole. The stock windshield comes in at 26lbs and the rear glass comes in at 19lbs. Again per Speed glass, they said I should be able to get away at 12lbs each for front and back. So a total saving of 21lbs total at a cost of $375 per piece and it still requires fabrication and custom fixing to panel. There is also flex in the glass while on the highway. Last piece of bad news, is that lexan scratches very easy. No to mention the barely legal fairy flying above my head telling me this is not a good idea, kept me from doing this mod. I may consider the rear glass after weighing Project LOWFATZ, if I still need to balance out the vehicle. But no plans for it now. Tried to get a hold of Escort Racing who are said to have a direct replacement for the 300zx at around 5mm thick, but they have yet to reply with figures and amounts at the time I am finishing this article up.

8) Fiberglass/Carbon Fiber Doors –

There is a reason I saved this for the extreme section. Fiberglass doorsand panel replacement, for that matter, is an excellent method for shavingweight. BUT, always consider safety when doing this, especially with doors.

A lesson in intrusion beam 101. Intrusion beams are just what they soundlike. They keep the door from intruding on the driver and/or passengers.Basically they keep the other cars bumper off your lap. These intrusionbeams are safety measures welded on the inside of the door for safety. Whenimpacted the intrusion beam actually make contact via the shell the outerbody hinge pillar (aka, A pillar) and B pillar to offer further protection.Removing this beam leaves you open for a very nasty end. CF and fiberglassdoors DO NOT come with any internal protection. They are strictly a racingpart and will leave that area open to any impact. Scary, huh? This is wherea rollcage comes in and is mandatory in my opinion at this level. I’drather build another car any day as opposed to, say, learning how to walkand speak again. Now that I have been your mother for second, we get downto numbers.

There is another topic that we need to discuss with door replacement andthat is, “will this take away from chassis rigidity?” The answer is no. Thedoor acts as a separate panel from the chassis until it is needed at timeof a side impact (Ie, intrusion beam function). The doors is attached bythree points (2 hinges and 1 catch/stricker assembly but these are hardlygood sound points for rigidity in reference to chassis flex. So replacingthis piece with a lightweight version will not cause a loss in rigidity butwill cause a loss for side impact safety. A rollcage with side intrusionbars (Nascar or non Nascar style) would be sufficient for safety and willalso further aid in chassis in rigidity.

And the last piece of info to know on these doors is that stock glass willnot work on these doors. Stock glass weighs too much and will start tocause cracking/wear in the door, so Speed Glass is required for these doorsas well. I called Speed Glass and they gave me a round estimate of 7lbs perglass over the 12lbs the stock glass weighs and will require cutting againafter you have the glass installed.

Okay, here at the numbers. Stock doors are a massive 87lbs each. It wouldsay much of that is intrusion beam internals. The fiberglass door versionscome in at 8lbs and most of the carbon doors are around 9-10lbs. So apotential of 77+ lbs could be saved per door, add 5lbs per door. So around82lbs per door, maybe 164lbs total.



For those that want to do something different and are still going to run acage, you could always consider “the free”. Gutting the stock door. Thisis my actual plan. I will actually cut the front repair panel (aka, skin)and cut the intrusion beam out with a plasma torch and then simply put anew skin on the door. This will cut all the intrusion beam weight out ofthe door and I can still run stock glass with power windows, also I canstill have a bit of firmness in the door and not worry about cracks/runs inCF or fiberglass doors. This is my plan and opinion and to each his own.

9) Swiss Cheesing Panels –

Personally, I have yet to see it done on a 300zx but whoever is the first has a set that clank. To take it to this level is the ultimate. I included some pics of cars that have had this done. I plan on doing this in just a few panels after I get a general idea of where I sit with weight in the front when everything is said and done.

A 280Z in the section behind the seats. * Pic courtesy of HybridZ

The left front strut for the same car.

An full out track S2000 professionally done.

And a last note for everyone. Keep in mind in these three parts that I havenot covered anything on performance part replacement weights. Yes, it’strue. Swapping out for performance parts does often save you some poundage.Say going from stock cast pre-cats on a TT to a downipes, there is someweight losses there. Stock mid pipes vs straight through pipes, is anotherexample of a performance part being lighter than a stock piece. Going to apopcharger over the stock airbox actually saves you 2lbs. SPL sells a solidtranny mount that eliminates some extra pieces, thus shaving around 3lbs.Replacing your stock suspension with any replacement gives weight reductionas the stock shock and spring assembly are very heavy. I’ve heard folkssaying they save up to 5lbs each assembly! I didn’t have time to go throughevery little piece and do a comparison to every one out there. Maybe oneday I can do some type of master list of part weights or something butdon’t hold your breath.

Remember, always, that necessity is the mother of invention. Beinginnovative will always help you towards your goal. Kuah at SPL parts eliminated the stock harness for simplified unit to simplify a lot of the electronic workings, a side benefit was the loss of a few additional pounds. I know of an Australian Z ownerthat actually went so far as to replace all of his engine bolts with titanium and SS bolts to save weight. Consequently this same member is crazy enough to take the stock alternator bracket and PS brackets and swap them for a set custom CAD cut pieces that he made himself. These are just some examples of being innovative that impress me.

I hoped these three posts helped some of you and answered a few questionsfolks have had. If anyone has any other items you would like me to do acomparison on, feel free to shoot me an email on it and I can always puttogether an addition to these three posts.

[sampsonJ]

man you should post the first two parts to this.... Great job, this is one project i cant wait to see the outcome for.
Modified by sampsonJ at 11:45 PM 11/13/2008

[evan_aggie]

That is a really good article.

I wanted to follow up on how the weight reductions for the rotational parts affect the horsepower produced at the ground.

I have a NA, so let's use a stock NA as an example.

It is said that your typical NA will produce somewhere around 165 rwhp +/- 5 rwhp.

I read somewhere that every lb you remove from the rotating masses connected to the driveshaft/crankshaft will result in a 2.5 rwhp gain. Personally, I think this is total BS, and for the sake of being conservative, let's go with 1lb saved = 1 hp.

Say you put a aluminum UD pulley and a 1 pc aluminum driveshaft.That should save 9 lb + 17 lb = 26 lb of weight, and give you about 25-26 rwhp. Combined this with a JWT POP and maybe 30-31 rwhp.

That would mean I should be getting somewhere close to 195-200 rwhp.

From what I've seen/read, I don't think many people get that sort of result, or am I wrong? If you were to add the ECU, and exhaust, and headers, that would be close to 230 rwhp, right? I am fairly certain that somewhere the math is wrong, because I don't come across many dynos showing a NA producing anywhere close to 230 rwhp.

How would reducing 5 lbs from each stock rotor help? That would light the wheel rotational mass by 5 lbs each.

[Milo (San Antonio)]

Really I didn't touch on any equations for the post as I honestly couldn't get a straight answer either. But you want to realize that rotational mass isn't really about horsepower so much as it's freeing up weight on moving parts to allow them to work in their natural function easier.

Lighter wheel and rotors help a vehicle stop quicker. Lighter drive train parts will help quicken the acceleration to the rear wheels. It's not really about HP's so much as response. But it will eventually translate into some type of usable HP but so much of that is circumstantial and case by case.

[SuperHatch]

It's also important to note that the effects of reduced drivetrain weight vary from gear to gear.

[evan_aggie]

Can you elaborate about the gear to gear comment? Do you mean because there is less inertia on the crank, the engine will likely rev down more quickly?

[Tsukiko]

I've actually seen demonstrations showing that dimple-die'd or "swiss cheesed" sheet metal is actually stronger than untreated panels. lightening for strength!!!

[NissanFairladyZ32]

great write up, this should be saved

[Milo (San Antonio)]

Thought it was already. There is a part 1 and 2 as well.

[SBC300]

Does anyone have a source for fiberglass doors?

[i_love_my_300zx]

Z1 sells these. Hope it helps.

http://www.z1motorsports.com/p...=2931

[SBC300]

Z1 sells these. Hope it helps.

http://www.z1motorsports.com/p...=2931

Ouch! I guess I will be making my own. $1500 is too spendy for me.Thanks!

[VigorousZX]

WEIGHT REDUCTIONS 101 - Part I And intro?zerothread?id=348806http://www.twinturb ... sa....html

WEIGHT REDUCTIONS 101 - Part IIhttp://www.twinturbo.net/nissa....html

Love your dedication to the Z Milo

Does anyone know how much the hood and side panels weight?look at SBC300's custom hatch at 6lbs. What if one rivets very thin fiberglass for the front end? the stock aluminum isn't much of a crumple zone, so no safety concerns there. Maybe one can make fiberglass just strong enough for a human to sit on and could end up saving 100+lbs

ps, I wouldn't mind if my panels warped and paint cracked, if I can save a whole lot of weight by replacing it with fiberglass, it would many folds better then taking out Z luxuries

edit- one would probably need a stock bumper or something as strong because it will get impacted by street parking

Modified by VigorousZX at 3:50 AM 9/1/2009
Modified by VigorousZX at 4:12 AM 9/1/2009

[ztommyx]

... and the only thing thats a bit heavy is your pocket change

[franklin93zx]

Charles of powertrix had the carbon t-tops on his track z at z nats and they felt like feathers

[SBC300]

My rear hatch w/o lexan and top combined weight < 10lbs. Cost = $65Labor..... well thats another story.



The hatch is hanging off the back when I took the pic, they follow the top bar line. Pic just to show top contour.

Keep in mind that this was a vert and I fabbed the whole deal. That carbon stuff is nice, I wish I started with a t-top car.

[Re037]

I've actually seen demonstrations showing that dimple-die'd or "swiss cheesed" sheet metal is actually stronger than untreated panels. lightening for strength!!!

yep, this is true. i learned the same thing in a structure engineering class. only downside is it takes a lot of man hours so not too common if anything at all on street cars but you see it everywhere in race prepped cars.

the hood is not structural, its purpose is to cover the engine.

[AAAnomalyyy]

Pictures arent Showing up on the other parts...

Im Still Deleting alot and can see why the Z's are Heavy.

Old Thread...

[raremotive]

It's expected from a 1989 car.. however even the NA 300zx is slightly lighter than the 370z. The TT is slightly heavier, but has a bit more torque at stock boost.

[AAAnomalyyy]

It's expected from a 1989 car.. however even the NA 300zx is slightly lighter than the 370z. The TT is slightly heavier, but has a bit more torque at stock boost.

Kool!

I prolly have one of the lightest Z's at the moment.

"Racing with Hopes and Dreams."




Never bothered to ask what happened when I bought her engine went bad and all I see is alot of black GRIME...

Got alot of cleaning to do along with AC delete etc.. etc..