View Full Version : GT6 1969 GT6 MkII weight reduction techniques

04-12-2005, 07:33 PM
I'm building an electric car of my GT6, and reducing weight will leave more room for batteries without going far over GVWR. TR6 transmission and drive axel installed.

The car has a dry weight of 1,793 pounds. The gas engine, which will be removed, is 402 pounds, and its ancillary components, like carbeurators, fuel lines, gas tank ect. weight about 90 pounds. I do believe dry weight is with an empty tank and no spare tire.

This gives a 'glider' weight of around 1,300 pounds or so.

So far I plan the following in order to cut down weight:

a) Replace the stock seats with lighter seats from a Miata or some such(-50 pounds
after replacement seats are put back in)
b) Remove all carpets(-15 lbs)
c) Remove all sound deadener(-25 pounds)
d) Remove wood panel dash, replace with custom leather
dash(-5 pounds)
e) Shave down or perhaps even remove bumpers(-15 to -40

So minus 110 to 135 pounds to the car for a glider weight of around 1,200 pounds or so.

BUT, I figured out how to fit 25 Optima Yellowtop batteries into this car, at 45 pounds each. That's a 1,125 pound battery pack. The Netgain WarP 9'' electric motor going in it will weigh 160 pounds, the controller 23 pounds, charger 16 pounds, and about 100 pounds of miscallaneous parts like battery racks, rubber motor mount, battery cable, contactors, EMeter, shunts, ect.

That brings the car to a very porky 2,620 or so pounds. Plus I weigh 130 or so, meaning the car will be about 400 pounds over its 2,350 pound gross vehicle weight rating.

I'd like to get car weight as low as possible, preferably below GVWR while still fitting such a large battery pack(For 80-100 miles range per charge at highway speeds and over 300 battery horsepower on tap). It's obvious the easiest way to reduce weight would be to use less batteries, but I'd prefer not to do that if at all possible as that means less cruising range and after enough are removed, les performance.

Weight reduction will thus be needed, if not for keeping the car under GVWR, but for the fact that I'm not sure if the unibody would be strong enough to handle that kind of weight placed upon it!

What other recommendations are there to lower weight?

How much can be saved by using fiberglass doors, bonnet, hatch, fenders, rocker panels, ect? Or are better components readily available for saving weight? Any techniques I have not mentioned that will shave down weight?

I'd love nothing more than to get car weight, including driver, to a scant 2,200 pounds WITH that weight of batteries in it, but I'd like to do what is possible for a reasonable amount of cash.

For those interested, here is a simulation of my electric motor's power and torque curve at 216 max motor volts and 1,000 max motor amp, just to let you know what will be going to the installed TR6 transmission and differential. 8,000 RPM redline.


Can the TR6 transmission and differential handle this kind of torque and horsepower?

04-12-2005, 07:44 PM
For many years racers "swiss cheesed" cars by drilling out non essential frame and body material. This would take expert help. I mean really good car engineers.

04-14-2005, 12:40 AM
Interesting, but probably out of my price range as that sounds as if it would be over $5k. Any other common techniques?

04-14-2005, 11:48 AM
Beavis, really an interesting project, and lots of hard work I'm sure.

Your peak power and torque figures are a lot higher than the stock GT6 had. If you require the power, fine, but 50% less HP and torque might suffice for the purposes of your experiment. Fewer batteries would dramatically reduce weight.

I'd definitely remove the bumpers, they're heavy and the car looks pretty good without them. Also wheels and tires can be heavy, there are lightweight alternatives out there for reasonable pricing.

Windows and glass are heavy, remove all the door and window glass and replace with plastic or a similar material. You may wish to leave the windscreen glass for safety purposes.

Best of luck with your experiment. Drive safely!