In part 3, I want to discuss two area of weight reduction that were just slightly touched upon in Part 2, Reciprocating mass reductions and the more extreme weight reductions. We will step right into the reciprocating mass reductions 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 and affects it?s ability to accelerate, brake and corner. Reducing the total weight will enhance the vehicle's performance because less weight needs to be controlled and therefore, less energy is required. Unsprung weight is the weight under the springs which moves up and down as the vehicle rides over uneven roads and leans in the corners. Reducing unsprung weight allows the springs and shock absorbers to be more effective in controlling the suspension's movement. Additionally, a vehicle's rotational weight includes all parts that spin including everything in the vehicle's driveline from the engine's crankshaft to its wheels and tires. This affects the energy required to change speed as the vehicle accelerates and brakes. As you would guess, reducing the weight of any of these rotating components will enhance the vehicle's performance because less energy will be required to increase 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 half the weight of a stock one. Fidanza, a commonly used flywheel, comes in at 11.5lbs versus the stock flywheel which comes in at a massive 23lbs. Again, no calculating reciprocating mass just curb weights, we can save 11.5 pounds in the center area of the vehicle. 2) Lightweight Clutches ? Although these have been available for some time now, a lot of folks overlook the weight savings of lightweight clutches. Companies like Exedy have been making them for years. I have heard of folks shaving as much as 12lbs by choosing lighter clutch assemblies. So before you purchase your next clutch assembly, take the time to consider the weight of the units and other parts available to aid in saving a few pounds. I know that Exedy is currently offering a very nice clutch that has great clamping force and is probably the lightest assembly that I know of. There have been some great reviews on them as well. I also spoke with Coz who informed me that simply going to most any performance clutch assembly should shave between 3-5lbs on 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 from 5spd vs Na vs 2+2 vs 2 seater. My personal driveshaft rings the bell at 33.8lbs as a whole assembly including the two center carrier bolts and washers. Going to a single drive shaft saves a good amount of weight as it eliminates the center carrier bushing and the associated hardware. My Z1 aluminum drive shaft came in at 16.4lbs. So, I shaved off 17.4 lbs of curbweight as a total assembly. Aluminum, carbon and steel are all available in the market. Weight and torque capacity differ from various materials and versions. 4) Lightweight Crank Pulleys (Harmonic and Non-harmonic) ? There is a huge debate about pulleys that are simply machined as a one piece and not having a harmonic balancer versus those with harmonic balancers. Obviously the units with the harmonic balancer are the heavier of the two due to added materials. Some argue that eliminating the harmonic balance in a high output engine is unsafe while other argue that it is perfectly safe. I will leave that argument on the boards as this a dead horse that has seen better beatings and simply go over the two types and give their average weights. The stock unit comes in at 13.6lbs. The non harmonic units come in a 2.4-3.3lbs on the average (measured ASP/Unorthodox and cheap eBay unit). The Fischer unit, harmonic type, came in at 7.6lbs. Didn?t have any others to 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 ever take into consideration when picking rotors, especially your 2pc rotor designs. A 2pc design is one of the best designs for rotors allowing for the entire center section of the rotor to be eliminated for a lighter aluminum center section hat thus cutting down on weight as whole on the assembly. You can sometimes find a 1pc rotor out there that will 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 mine have been cut once but that is usually the average. Stock rotor size Brembro replacements came in at 17.25lbs. Lightweight 2pc rotors come in 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 equal and like many other things when it comes to automotive performance, you usually get what you pay for. Choosing lighter rims as opposed to some heavier type rims is a great way to loose a few more lbs as well. Most folks don?t op to buy them due to the usual high cost associated with a quality lightweight rim. There are many, many, many different types and I am not going to single any one vendor out. I remind you to consider not only the lightweight of the rim itself but also consider it?s manufactured materials and also consider it?s corrosion resistance as well. Again, consider all alternatives and also differences in size. 16-18?s are the usually average for most applications, 16?s being the same size as the stock wheels. 17?s and 18?s are the sizes where most folks usually stay.. I would only recommend 19?s for those folks that need them for huge brake kits and such. Now figure in your basic cheapie 18-19 inch wheel tips the scales between 27 to 33lbs per rim. Yeah, I know, but it?s true. Your typical 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 lug nuts that do a good job for cutting weight in place that most don?t every really think about. My Titek lug nuts came in at .08 of an ounce compared to 2.1 ounces to the stock units. That is more than half the weight cut from their original counterparts. I now this may seem minimal, but at this level you have to take it all in and consider it all. Also, consider lightweight valve stems as well. ****************** EXTREME WEIGHT REDUCTIONS***************** Each one of the weight reductions have been labeled as such because they each need to be taken with a grain of salt, meaning there are things to consider. What is there to consider, you ask? Safety, drive-ability, annoyance and not to mention legality for starters. Although some seem easy and cheap, you must consider the ramifications of each. Now that is on the table lets get down to it, starting with the mild and going on 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 cut weight. Removal of the interior is required of course. There are two methods of attack here; heat the patches and remove them and get messy as hell or utilize dry ice and simple chip them away. I set blocks of ice on sections of the deadening before I get to it. By the time I get to it to chisel 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 tranny tunnels and on the floor boards. I amassed a large bag and did my best of keeping them all together. I also just took off all foam/rubber piece behind each rear plastic panel and threw them in there as well. Obviously the downfall of eliminating sound deadening materials is the louder road noise. You can battle this with structure foam injection 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 another opportunity to shed a bit more weight. There are two systems that are avail for the 300zx. The earliest version is the system that only has the airbag in the steering wheel, the later version had both a steering wheel and passenger airbag unit as well. I don?t have an idea how much the passenger airbag weighs as I didn?t have one to put on a scale. Though I would figure it would be another 6lbs for the whole assembly or so considering how much the drivers unit weighs. When I pulled the system for the Project LOWFATZ the whole front end was off as well as the dash. This allowed me to pull the entire unit from the actuators mouned in the frame horns in the front of the vehicle, then all the wiring (yellow loomed wire normally), the airbag module box under the dash, another module that is mounted on the top of the tranny tunnel, then the airbag equipped steering wheel was swapped for a non-airbag Z32 steering wheel. Removing the steering wheel and other units require a special torque key that is not always available at the local auto store. I want to say that I used a T55 torque bit to remove the specialty bolts to these units, made life a lot easier. Put everthing in a bag and hit the scale, came out to 28.7lbs. But figured in the difference for 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 actual glass weight. For those that have T-tops and would like to cut the weight this is a small opportunity to cut weight but, like any mod, consider the downside of possible water leakage as I?ve heard that this is a common downside to T-top replacements. Also, there is also the rumor that you can loose a little bit of upper rigidity as well. This remains to be seen and/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 works for another carbon fiber version. Powertrix is also in the development for one that they 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 doors and panel replacement, for that matter, is an excellent method for shaving weight. BUT, always consider safety when doing this, especially with doors. A lesson in intrusion beam 101. Intrusion beams are just what they sound like. They keep the door from intruding on the driver and/or passengers. Basically they keep the other cars bumper off your lap. These intrusion beams are safety measures welded on the inside of the door for safety. When impacted the intrusion beam actually make contact via the shell the outer body 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 fiberglass doors DO NOT come with any internal protection. They are strictly a racing part and will leave that area open to any impact. Scary, huh? This is where a rollcage comes in and is mandatory in my opinion at this level. I?d rather build another car any day as opposed to, say, learning how to walk and speak again. Now that I have been your mother for second, we get down to numbers. There is another topic that we need to discuss with door replacement and that is, ?will this take away from chassis rigidity?? The answer is no. The door acts as a separate panel from the chassis until it is needed at time of a side impact (Ie, intrusion beam function). The doors is attached by three points (2 hinges and 1 catch/stricker assembly but these are hardly good sound points for rigidity in reference to chassis flex. So replacing this piece with a lightweight version will not cause a loss in rigidity but will cause a loss for side impact safety. A rollcage with side intrusion bars (Nascar or non Nascar style) would be sufficient for safety and will also further aid in chassis in rigidity. And the last piece of info to know on these doors is that stock glass will not work on these doors. Stock glass weighs too much and will start to cause cracking/wear in the door, so Speed Glass is required for these doors as well. I called Speed Glass and they gave me a round estimate of 7lbs per glass over the 12lbs the stock glass weighs and will require cutting again after you have the glass installed. Okay, here at the numbers. Stock doors are a massive 87lbs each. It would say much of that is intrusion beam internals. The fiberglass door versions come in at 8lbs and most of the carbon doors are around 9-10lbs. So a potential of 77+ lbs could be saved per door, add 5lbs per door. So around 82lbs per door, maybe 164lbs total. For those that want to do something different and are still going to run a cage, you could always consider ?the free?. Gutting the stock door. This is 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 a new skin on the door. This will cut all the intrusion beam weight out of the door and I can still run stock glass with power windows, also I can still have a bit of firmness in the door and not worry about cracks/runs in CF 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 have not covered anything on performance part replacement weights. Yes, it?s true. 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 some weight losses there. Stock mid pipes vs straight through pipes, is another example of a performance part being lighter than a stock piece. Going to a popcharger over the stock airbox actually saves you 2lbs. SPL sells a solid tranny mount that eliminates some extra pieces, thus shaving around 3lbs. Replacing your stock suspension with any replacement gives weight reduction as the stock shock and spring assembly are very heavy. I?ve heard folks saying they save up to 5lbs each assembly! I didn?t have time to go through every little piece and do a comparison to every one out there. Maybe one day I can do some type of master list of part weights or something but don?t hold your breath. Remember, always, that necessity is the mother of invention. Being innovative 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 owner that 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 questions folks have had. If anyone has any other items you would like me to do a comparison on, feel free to shoot me an email on it and I can always put together an addition to these three posts.
This was part 1. http://www.twinturbo.net/nissan/300zx/forums/technical/view/1065404/Weight-Reductions-101---Part-1-The-Basics.html
This was part 2. http://www.twinturbo.net/nissan/300zx/forums/technical/view/1065496/Weight-Reductions---Part-2---Bypasses-and-Basics-contd.html
33 pounds in sound deadening!!?? I better get cracking. here is a question. would the weight reduction in going fibreglass doors be cancelled out by the extra weight incurred going full roll cage? got any numbers? PS great post by the way.
Would it be more that you need to have a rollcage at that level of racing, so the lighter doors balance it out?
reply. Too hard to say. The door numbers are there but a rollcage has too many variables (materials used, how many points, materials removed from the car, etc) to give an accurate weight. It would have to fit into your individual equation for your own Z.
