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Default Weight Reduction

Introduction to Weight Reduction
Weight reduction works double time for an EV conversion, on one hand you are improving the handling, efficiency and speed of your conversion and on the other hand it is useful in making room under the GVWR for batteries and passengers. A lighter car takes less force to accelerate, has lower Rolling Resistance, is easier to stop in emergencies, handles better, has more potential for batteries and reduces the need for suspension and brake upgrades. Luckily the performance and racing driving sector provides plenty of tips and mods for ways to reduce weight in your conversion. Each converter will need to decide on whether or not each mod is suitable for their situation; A specialised one seater commuter will have different priorities from a family car. Some of these mods would be very expensive and/or difficult, it aims to be an inclusive list not a recommended list.

Possible Ways to Reduce Vehicle Mass:
  • Removing any unnecessary items from the car; rubbish, drink bottles, even floor mats or car seat covers, anything that is not essential for driving.
  • Remove all unnecessary remnants of the ICE system e.g. wiring, sensors etc.
  • Removing the spare tyre and using run-flat tyres or Roadside Assistance in case of a puncture.
  • Remove sound deadening material.
  • Installing light weight racing seats/removing seats which aren't used (and their seatbelts and seatbelt mounts).
  • Removal of the glass windows and replacement with Perspex
  • Using lightweight alloy (magnesium or aluminium) wheels.
  • Removing of non driving/safety components such as head-liners, Air conditioning, Radio etc.
  • Replacement of body panels with aluminium, fibreglass or Carbon Fibre
  • Switching from Lead Acid to Lithium Batteries.
  • Drilling out holes from structures/components when it will not compromise its integrity (see Autospeed Article).
Sources:
torquecars.com
hondaclub.com


Contributors: EVEngineeer, mattW
Created by mattW, 12-23-2007 at 08:28 AM
Last edited by EVEngineeer, 10-09-2012 at 06:32 AM
13 Comments , 15369 Views
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  #2  
Old 12-25-2007, 01:14 PM
Brendonbosy Brendonbosy is offline
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Default Re: Weight Reduction

Some of these tips seem a little outlandish:

Removing seats? The passenger seat weighs maybe 25 lbs at most, unless you got power seats

Carbon fiber? That sh*t isn't cheap at all. If you want panelling with decent quality, you'll be looking at about $600+ per panel. CF also has many drawbacks. You often need to add backings with extra mounts and pins to support them at highway speeds. If not, you're hood will fly open into your windshield. Also, CF performs VERY poorly and dangerously in accidents. It has a tendency to shatter like glass in an accident rather than crumple.

Magnesium wheels? There's a reason why the UK banned these. Nevermind the extrodinary cost, mag wheels are very dangerous and highly flammable if they overheat. The most common problem is a tire blowout. They are also notoriously difficult to put out once they do catch fire.


Weight reduction is a good idea, but it has its limits when you're talking about a practical, daily driven car, not an Indy 500 or a Carrera GT supercar.
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Old 12-25-2007, 08:23 PM
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Default Re: Weight Reduction

Yeah they were supposed to go from reasonable and easy to ridiculous and expensive, i was sort of joking about the crazy stuff but i thought i would let other people decide what was reasonable...

Quote:
Each converter will need to decide on whether or not each mod is suitable for their situation; A specialised one seater commuter will have different priorities from a family car. Some of these mods would be very expensive and/or difficult, it aims to be an inclusive list not a recommended list.
Who knows, we might get some rich environmentalist on the site who wants to build a carbon fibre specialist commuter. Who are we to say its not reasonable . You can change it if you like, that's what the wiki is for
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Old 03-11-2010, 10:52 AM
JRoque JRoque is offline
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Default Re: Weight Reduction

Hi. This is a very old, and probably tried and true, post but I'd say you get the most bang for your buck if you change to thinner and low friction tires with the right air PSI in them. Unless you're driving a sail boat, tires will likely contribute most of your drag. A thinner tire also helps steer easier requiring less power steering assistance.

Cheers,
JR
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Old 09-11-2010, 03:29 AM
Greasemonkey84 Greasemonkey84 is offline
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Default Re: Weight Reduction

Quote:
Originally Posted by Brendonbosy View Post
Magnesium wheels? mag wheels are very dangerous and highly flammable if they overheat. The most common problem is a tire blowout. They are also notoriously difficult to put out once they do catch fire.
Lamborgini uses forged aluminium/magnesium alloy wheels on the murcielago SV.
The fastest Lamborgini to date.
I think if a high performance car like that can use these wheels the way they do, an elctric bug or miata won't be able to give the required performace to overtheat such wheels. Unless you go drag racing with, it instead of using it for your daily commute i don't see any reason why it would be dangerous.
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Old 09-16-2010, 06:49 AM
Pirape Pirape is offline
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Wink Re: Weight Reduction

Quote:
Originally Posted by Brendonbosy View Post
Magnesium wheels? There's a reason why the UK banned these. Nevermind the extrodinary cost, mag wheels are very dangerous and highly flammable if they overheat. The most common problem is a tire blowout. They are also notoriously difficult to put out once they do catch fire.

HUH?? I am in sales for Husqvarna global leader in outdoor products

the professional chainsaws uses a magnesium cylinder and crank case

can't get hotter than that
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Old 10-06-2010, 11:43 AM
jeremyjs jeremyjs is offline
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Default Re: Weight Reduction

There's no way Mag Wheels or engine parts are pure magnesium. It's some sort of alloy that's not prone to burning. Hell half or more of an F1 car's engine including the cylinders are a magnesium alloy. Maybe if you're talking about magnesium wheels from the 50's and 60's it was true that they would burn; because they were made from pure magnesium. They were also junk. They broke easily and leaked air like a sieve.
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Old 02-09-2011, 09:36 PM
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ElectriCar ElectriCar is offline
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Default 1940's Ford truck goal to weigh <1500lbs with batteries!

I met a guy tonight who turned me on to some things. He has to me a lofty goal stated above. He's running the Advanced FB1-4001A with Curtis 1231 controller. Here's what he's doing or has done with the truck currently stripped to the frame.

  • Cut holes in the framing where he says it won't affect the structural integrity.
  • Will use ALL TITANIUM bolts and nuts to put it together.
  • Front hubs remade from aircraft aluminum.
  • Aluminum Motor mount
  • Composite leaf springs
  • Carbon Fiber inner fenders
  • Carbon Fiber bed
  • Light weight brake parts, maybe ceramic rotors.
  • Light weight no vacuum assist master cylinder - Says it will be easy to brake too.
  • Delete vacuum pump due to master cylinder selection
There may be more stuff but I can't think of any now. I did turn him on to this site though so maybe he'll chime in. He's worked with race cars for years so he knows a lot of stuff because of that.
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Old 02-16-2011, 08:29 AM
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Default Re: 1940's Ford truck goal to weigh <1500lbs with batteries!

Quote:
Originally Posted by ElectriCar View Post
I met a guy tonight who turned me on to some things. He has to me a lofty goal stated above. He's running the Advanced FB1-4001A with Curtis 1231 controller. Here's what he's doing or has done with the truck currently stripped to the frame.

  • Cut holes in the framing where he says it won't affect the structural integrity.
  • Will use ALL TITANIUM bolts and nuts to put it together.
  • Front hubs remade from aircraft aluminum.
  • Aluminum Motor mount
  • Composite leaf springs
  • Carbon Fiber inner fenders
  • Carbon Fiber bed
  • Light weight brake parts, maybe ceramic rotors.
  • Light weight no vacuum assist master cylinder - Says it will be easy to brake too.
  • Delete vacuum pump due to master cylinder selection
There may be more stuff but I can't think of any now. I did turn him on to this site though so maybe he'll chime in. He's worked with race cars for years so he knows a lot of stuff because of that.
I am very interested in how to swap out power brake master for purely mechanical... to avoid the whole vacuum pump and switch thing would save weight, complexity, time and space under the hood!

The rest of this is sounding like the (many) 'weight weenies' in the bike racing world where grams matter when you are looking for an extra .5% of acceleration. The thing is that exotic materials drive cost up rapidly, and 'lightening' structural members is rarely a good idea. Machining cool AL parts from billet gets super expensive unless you happen to own/work in a machine shop with access to 'scrap' for free.

most of us can probably drop 50 pounds out of the car by lightening the OCCUPANTS and carrying less crap around in the vehicle. I have made a decision to not lug around spare tire and jack in my EV; I'll never be very far from home!

I am still interested in the high 'bang for the buck' items though. For instance:
- using AL instead of steel for battery rack edges
- swapping OEM seats for light racing seats
- carbon-fiber/fiberglass hood, fenders if available
- swapping flat glass with Lexan if possible


and then doing the same for the 'major' aero mods like:
- blocking grill
- smooth belly-pan
- consider backup cameras instead of mirrors... legal?
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Old 02-16-2011, 09:46 AM
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Default Re: Weight Reduction

Here's some data re weights & strength of metals.

Titanium is 1/2 the weight and strength of steel.
Aluminum is 1/3 the weight and strength of steel.

Another thing is wire weight. Aluminum is 1/4th the weight of copper and is practically the same capacity as copper but slightly less for small sizes like 2/0 it's nothing. I was running two parallel cables of 1/0 copper but recently removed the second set saving about 20 pounds.

Because the voltage drop is so small in my truck, much less than I estimated because of wire length, I may go to #1 aluminum next week when I switch to lithium, saving even more. Because of the loss of 700 pounds in batteries, an increase in pack voltage, less sag and the much less internal resistance, my current is going to decrease a lot for a given speed.

The smaller cables will try to warm on hill climbs but that only lasts 30 seconds at the most and wire isn't going to get HOT in 30 seconds due to being overloaded a little bit, even a lot.
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