Weight reduction: Running out of ideas.

IIRC the stock fuel tank in my car is 16 gallon capacity (and twenty something pounds empty IIRC). I've been kicking around for a while the possibility of fitting an 8 to 10 gallon tank from a junk car somewhere and adapting it to mine. The smaller tank should be lighter and smaller in size, which would hopefully allow mounting it on the passenger side of the frame centerline. This would improve L/R weight ratio (but obviously "worsening" F/R weight ratio, but I'll gladly take the hit when reducing total vehicle weight), and reduce lateral weight transfer due to fuel slosh in the corners.
I made a "spa day" at the local Pik-N-Pull today to see what I could find, and pretty much struck out. All the compact cars I could crawl under had pancake shaped tanks, while the Corvette tank is shaped like a big stick of butter. Ideally I was hoping to find a tank that was about 12" by 12" by 15-18" long. I'm not terribly encouraged at the moment, but I'll keep looking.
Another item that may not work out is replacing my aluminum coolant expansion tank with a newer plastic piece. On a slow day sometime I might pull the tank and see what the empty weight of that thing is, and than take my small scale with me on the next trip to the junkyard to compare weights. Until somewhat recently I had a damaged spare aluminum expansion tank, and I had planned on cutting the tank vertically in half at the middle, and then welding a new vertical wall there, reducing the weight and coolant volume. But, it has disappeared during one of my moves the past decade, so scratch that plan.

This probably doesn’t have any cert, but I’m thinking about using it as a passenger seat. Looks like a copy of a Kirkey pro street.

6 lbs, under $450

EDIT. Looks like it sold out.

I've been working the floors - drooping them about 2" for seating height. Reg says; a minimum of 2 inches from top of the helmet to top for roll bar/cage. But my "skull bucket" would still "tap" the cage - so I am dropping the floors. [Don't raise the bridge - Lower the Water -obscure movie reference}.



The regs don't specifically spec Aluminum seats, so those CF would be a nice addition. Or take lessons from Pappy and DIY!
The regs do spec :

• One-piece bucket seat: For most events, the driver's seat must be a one-piece, bucket-style race seat that provides strong fore/aft and lateral support.
• Secure mounting: The seat must be securely mounted to the floor, cage, or transmission tunnel. Bolting through aluminum floor panels is prohibited unless a backing plate of equal or greater thickness is used to distribute the load.
• Headrest: A system to prevent whiplash and keep the driver's head from striking the roll hoop is required. Racing seats with an integral headrest meet this rule.
• Harness routing: Aftermarket seats must be installed according to the manufacturer's guidelines and provide appropriate routing for a 5-point (or more) harness.
• Mounting hardware: All bolts and nuts used for seat mounting must be a minimum of SAE Grade 5 or Metric 8.8.

Rules by racing program
Regulations can differ between SCCA's racing programs (e.g., Solo vs. Time Trials). You should always check the most current rule set for your specific event.

• For Time Trials and Club Racing: Aftermarket seats are permitted and must meet the general specifications for safety and mounting.
• For Solo (Autocross): Depending on the specific class, factory original seats may be required. In some cases, a driver's seat may be replaced with a one-piece bucket seat, but stock seats often cannot be modified for harness installation.
• For Club Spec: In programs like Club Spec, different safety levels dictate what interior modifications are permitted. Upgrading to aftermarket seats and restraints is typically allowed at higher safety levels.

Take that for "what it's worth" its an AI ref, but pretty close to facts. I'll be in Special Production - so some open options - but the safety section [Chapter/Section/Appendix 9] is not a waver-able item.

BTW, all the form cars tend to use the floor pan and rear firewall with a foam insert as the seat. I've considered that too.

Cheers - Jim

rtj said:

This probably doesn’t have any cert, but I’m thinking about using it as a passenger seat. Looks like a copy of a Kirkey pro street.

6 lbs, under $450

EDIT. Looks like it sold out.

Amazon.com

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$450 is a bit out of my budget, but I certainly would love to take more weight out of the left side of the car. I'm presently using seats out of a '79 Corvette (Thank you again Karsten!). IIRC they are 12# lighter each compared to the original '69 seats, and heaven knows, have significantly more side bolster than the stock seats. I need to reweigh one of these seats to refresh my memory of the actual weight.
I never think about seat weight while I'm wandering the junkyards. I should start bringing my portable scale with me on future trips. While I concede that racing seats will be lighter, I'm trying to keep my car looking somewhat stock if I can.

Edit: I weighed the '79 seat, and it's 19#. That gives me a baseline for comparison with any junkyard candidates.

Just a thought - and across town:


On FB. listed as John Chase for $200. Looks like could use some work - but lightweight?
Disregard - weight more than the "79 seat - maybe.
Cheers - and happy hunting!
Jim

The '79 seats are very light for a factory seat, I'm not sure that my fibreglass buckets are much lighter at all. I normally leave the bucket in the drivers side and the factory seat in the passenger side so that I can still access the rear, I only bolt both buckets in when running and event that allows passengers or requires a codriver.

Running out of better and easier weight reduction ideas, so I'm looking at two items this winter.
1) Going to try to locate a used C3 fuel tank for modification. I believe I mentioned this before, but I'm thinking of cutting off the left half of the tank, and welding in a new sidewall just to the left of the fill port. This should take half a dozen pounds off the tank weight, bias the tank and fuel weight to the right side of the vehicle centerline, and if my thinking is correct, the force vector of the fuel weight and the fuel slosh in a right hand corner might still remain within the rear axle trackwidth. (That vector will be way outside the axle trackwidth in a left turn, but there's enough driver ballast to offset that. ) I have to still confirm my understanding of the tank empty weight (I believe a helpful member here gave me a weight for the tank previously in this thread), and I also have to confirm that the gas gauge float will still package in there.
2) Just ounces here, but I'm going to drill a few big holes in the P/S pulley. The original composite serpentine pulley on the pump weighed 8 ounces, but the steel vee pulley I'm currently using is 15.5 ounces. It's rotating weight up front, so I'm willing to put in the effort for those few ounces.

Tanks are pretty heavy. You car is probably old enough not to have the steel crash protection cover. That thing is heavy. You can mount a small fuel cell pretty easy on the oem brackets. And, the fuel cell can’t be seen from the rear.

There used to be an extensive list of part weights in the "Tech Section" but it seems to have disappeared. That's a shame, lots of good information there.

I didn't know modern vehicles with ~10 gallon tanks existed until I filled our CR-V with a little less than 12 gallons. I found this list of newish cars with small tanks:

Smart ForTwo Passion 8.7
Chevrolet Volt 9.3
Fiat 500 Sport 10.5
Fiat 500c Pop 10.5
Honda CR-Z EX 10.6
Honda Fit (base) 10.6
Honda Fit Sport (manual) 10.6
Honda Insight 10.6
Scion xD (base) 11.1
Scion xD (base manual) 11.1
Toyota Yaris LE 11.1
Kia Rio EX hatchback 11.3
Kia Rio EX sedan 11.3
Mazda2 Sport (manual) 11.3
Mazda2 Touring 11.3
Nissan Versa sedan SV 11.3
Hyundai Accent GLS 11.4
Hyundai Accent SE (manual) 11.4
Lexus CT 200h Premium 11.9
Suzuki SX4 Tech hatchback 11.9
Toyota Prius IV 11.9
Toyota Prius V Three 11.9
Chevrolet Sonic LT 12.2
Chevrolet Sonic LTZ (manual) 12.2
Ford Fiesta SES hatchback (manual) 12.4
Ford Fiesta SE sedan 12.4
Ford Focus SEL hatchback 12.4
Ford Focus SE sedan 12.4
Nissan Juke 11.9

C5 had two tanks, maybe use one.

Caught my interest.
Best I could find (short search) was for C6 Corvette. Had to zip. Just about 100 items. Might be vaguely interesting/useful.
Maybe more out there. I used to have an uprights list from the Locost Build sites, etc.

Cheers - Jim

rtj said:

C5 had two tanks, maybe use one.

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We're on a similar wavelength. I looked at several C5 tanks on ebay yesterday to see if that would be a workable option. Lots of availability, but I need to still get some packaging info. The shape is certainly odd, so I still would need to get some dimensions and internal capacity, and the tank weight. Do I assume correctly that it's plastic, as the C3 obviously packages the fuel tank behind the rear axle, versus ahead of the axle in a C5. (I don't know, steel versus plastic may be academic in the event of a rear impact to a C3.)