Weight Reduction - Putting the C5 Corvette on a diet!

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Shred Jesse's white C5 Corvette with full aero making it's way around a corner at Thunderhill West

Lately, I've been wanting more from my corvette. After a weekend with a mustang group where they'd all corner so slow but gap me on the straights, I was frustrated. Then I went and competed in an SCCA time trial weekend where I yet again was frustrated by my inability to keep up with some of the more powerful cars in the straight. It just annoys me when inferior drivers can put down faster lap times than me just because they've got more powerful engines on more modern cars!

The solution for this will be two-fold, and all based around staying with the confines of the SCCA Max 2 class.

First, there's the obvious choice of adding power. I'll be doing that and blogging about it when I get around to it.

The second part, which I'm writing about here, will be weight reduction. No sense dragging around a bunch of extra weight I don't need to, it's just slowing me down! Besides, this car has long since departed form being a street car.


Initial Weigh In & Weight Reduction Game Plan

C5 Corvette being corner weighed on Proform scales. Showing 888lbs front left, 864lbs front right, 749lbs back left, 801lbs back right. Total weight is 3302lbs.

So I obviously can't go back in time to tally the various modifications I've made to the car, but as it sits, it currently weighs in at 3302lbs. That's with a lead acid battery, nearly all of the interior carpet, a working tape deck, air bags, aftermarket seats, a roll bar setup, C6 seat belts and harnesses to boot... it's more than nescessary and likely adding a bunch of weight. The current weight distribution is 53/47, which isn't half bad, but I think I can improve a bit as well. I'll also work on corner balancing the car as I can.

The rough gameplan as it stands:


Swapping the Battery for Lithium

An Antigravity ATX30HD battery partially mounted in a C5 Corvette.

So I reached out to the folks over at https://antigravitybatteries.com/ about swapping out my old boat anchor of a lead acid battery for one of their new awesome lithium batteries. Per their recommendations, I went with an Antigravity ATX30-HD Lithium Battery, which they descirbe as a heavy duty Motorcycle / Powersports battery. The reccomendation was largely based on the minimal needs of the car, which is simply reliable starting throughout the corse of a weekend at a track event.

Shred Jesse's C5 Corvette on corner scales after battery. Shows a 29lb reduction!

Weighing the car after swapping in the Lithium battery demonstrated a 29lb weight reduction! Pretty significant loss of weight, and on the front of the car where it so desperately needs weight reduction. Some folks like to relocate their battery to the back left portion of the car, which as you can see would help corner balance the car, however that still doesn't reduce the total weight, and infact increases it as it's a rather long run of heavy duty wiring.

Antigravy battery mounted in Jesse's c5 Corvette, fully mounted in place with DIY bent aluminum over the battery.

Install was simple enough. I removed the OEM battery, took some simple measurements of the new battery, centered the new battery on the old battery tray and bent up some aluminum bits to hold the battery in place. Rivnuts ensure reasonable install and removal of the aluminum straps, and honestly it wasn't that big of a deal. The biggest headache I would say is cutting the OEM sidemount terminals, finding new terminals in the large gauge that you need but with the smaller diameter opening for the small powersport sized bolts you would need , and then navigating crimping the new terminals on in the rather limited space of the OEM battery location. Was it really all that difficult? Not terribly. Would I just get a properly sized battery with sidemounts for the next time? Yes, I probably would recommend that for the average person who isn't scrimping for every single pound of weight retention that they can.

I'll report back on how this works over the first few track days where I take it out, but overall I'm pretty happy with it and it yields some notable weight reduction up on the front of the car!


Weight Reduction on the rear of the car

C5 Corvette Targa top rear compartment with the carpet and padding underneath partially pulled out to demonstrate the process Jesse is understaking of removing weight from the rear of the car.

So the simplest place to start on the C5 was the rear of the car. Per SCCA Max class rules, if you've got a rollbar you can remove everything from the seat back. So away I went pulling up all the carpet, padding, and anything else I could find. Speakers went out, trim went out, assorted brackets were removed (5 disc changer bracket, targa top holder, etc etc). I even went so far as to cut anything off that couldn't be removed!

The rear area of a C5 corvette targa top, with all of the carpet and unnecessary brackets removed. An autopower roll bar is in place.

As you can see above, I was able to strip the rear pretty easily! I left the carpet over the gas tank part behind the seat, but that will eventually go along with any carpet under the seats. Should yield some notable weight loss. Unfortunately... this isn't exactly where the car needs the most weight loss, but eh whatever weight I can avoid having to drag around the track is a gain!

Shred Jesse's C5 Corvette with a pile of carpet, carpet padding and other bits and bobs from stripping the rear compartment of the Corvette down.

As you can see, the pile of stuff removed from the back is fairly significant!

C5 Corvette being weighed after removing rear carpet and speakers, bringing weight to 3242 lbs.

...and here is the weight savings from stripping the rear of the car down. The car now weighs 21lbs less. I honestly was hoping for a bit more of a weight savings, but I'll take that as a start to the weight savings on the car!  Incidentally... the corner weights moved around a bit, probably mostly relating to not settling the suspension before taking the weight values. For now, I'd mostly focus on the total, later I'll corner balance the car properly.


Optimize Cabin / Dash

Click here for the full in depth article here!

So the weight loss journey on the front of the car was so involved with so much information... I figured it is worthy of it's own article, so go check it out if you want to get way into the weeds of what was involved and what individual parts weigh! The short version for here I'll post though is: I was able to ditch 100lbs of weight off the front of the car*! I also managed to upgrade the steering wheel which was long overdue for both driver control improvements along with safety as I can now egress the car notably easier with the wheel removed.

Some Larger Notable Items removed and approximate weight:

  • Driver airbag - 3.5lbs
  • Passenger Airbag - 8.5lbs
  • Glove Box - 3.75lbs
  • Front Speakers - 8lbs
  • OEM Tape Deck Stereo - 4.5lbs (RIP tape deck, you worked until the very end!)

Now of course there were a lot of other little savings that added up, but those are all the big ticket items people often guestimate at the weight of. Feel free to pop over to the indepth article for actual scale weigh ins on those items.

It's also likely worth mentioning there are some additional weight savings to be had up front. What I did was just the basics, and you may find yourself in a less restrictive class or just not care about rules in general. There's additional carpet up front to be removed, you can remove HVAC, and the entire dash itself weighed in at 19lbs so ditching that would yield some notable saving as well. In my case though... I ditched a bunch but the car largely remains a street legal car with a lot of it's factory functionality in place.

It's worth noting the asterisk I put there in the my weighing in of the car. That is weight loss with the passenger amazon seat removed as well (someday I'll also upgrade this to a bucket seat). Turns out, that seat and mounting bracket weigh 18lbs. So the actual weight savings was closer to 80lbs up front, at least for me in SCCA Max 2as I don't believe I can remove the passenger seat. Your class may allow you to remove the seat, or if you're just tracking the car and aren't taking passengers out it's 4 minutes and 4 bolts to remove the seat. Why wouldn't you ditch it?

Final weight of my C5 with the glass on the top and the passenger seat installed... 3160. Down 142lbs from my initial weigh in of 3302lbs. Not too shabby!


Optimize & Skeletonize splitter

An example picture Jesse found of a splitter with the parts behind the air dam skeletonized (material cut out) to reduce weight.

So while cruising the internet one day, I noticed a picture of a splitter off of a car where the part of the splitter behind the airdam was skeletonized. This was a "well duh!" kind of moment for me, because that area is just extra weight. This got me thinking, could I skeletonize my splitter to reduce weight? It would be weight off the front of the car for sure as well which is the main area I would benefit from removing weight. Plus, the splitter I designed was done in a hurry outdoors with less than ideal tools. With a shop space all my own I could probably do a way better job!

So I began the process of removing and optimizing my splitter. All of my notes are in a child article on the topic here. The article is pretty in depth and I didn't want this article to blow up with all the nuanced details. This will just be about how much weight can be saved by skeletonizing a splitter!

The splitter weight in right at 27.5lbs, so not svelt by any means! We'll see just what kind of weight savings I can get out of this puppy! Definitely lends some credibility to the claim that alumalite is a smart material to work with!

I estimated the following weight savings:

Original 3/4" plywood weighed 27.5lbs.
5/8" is a reduction of approximately 17%, or 4.59lbs of savings (22lbs)
The 3/8 sheet consists of approximately of 60% of the total weight (13.2lbs) and I removed about 40% of it (5.28lbs).

This should reduce the splitter weight to a hopeful 17.63lbs.Or, a 36% weight savings! Factor in some random bits not included (splitter ramps, paint, etc) I'd be happy with a 15lb weight savings!

What were the actual weight savings in the end?

No weight savings. Infact, I gained .25lbs. I believe this is because I went with a different wood than I had originally used. While the new wood is much more robust and water resistant... it weighs more. So in the end, it's a wash weight wise, but I've got a strong wood setup and adequeate thickness where it matters!


Other C5 Corvette Weight Reduction Topics are Coming soon!

Look forward to posts on reducing the weight up front through emissions and A/C removal, along with exhaust upgrades and more!

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