Weight reduction: Running out of ideas.

Shipping weight for a 1976 Corvette was 3445, curb weight was 3541. Add 200 lbs for a/c, th400, telescoping steering wheel, power windows, power steering, am/fm radio (18lbs for the radio!)
I'm just under 3200 lbs (3160) with a full tank of fuel (I'm supposed to be 3200 for the class I run in) - with 3 gallons it'd be roughly 3060... which makes your weight even more impressive.
That said, my weight bias is almost exactly 50/50 (within 5 lbs)
One of my scales died, so weighing hasn't happened recently - but once resolved I'll see where I'm at now. I suspect I weigh more

*link https://corvettestory.com/specs/1976-Corvette-specs-options.php
 
Had a spa/mental-health day today, roaming my favorite junkyard. Looked around for parts for a few project cars. Was surprised to find another C4 (an '85) in the yard. Last time I was there I pulled some parts off an '89 C4. I checked dozens of GM intermediate size cars looking for 11.5" solid rear rotors, but kept striking out. Close to closing time I stumbled upon an '11 Buick Regal with 11.5" rotors. The quick measurements I made (and comparing them to the rear rotors on the '85 C4) indicate a good possibility of trying them on my car. The only measurement that looks to be a concern is the center hole. The Buick rotor "looks" like it's maybe .100-.150" smaller. Right now the plan is to stop in there again next week, pull the rear calipers off the Buick and the C4 , and see if the rotors are interchangeable on the spindle/hub or not. I'll also bring my portable scale to measure the weight difference between these two rotors to see if the swap is worth the expense of new rotors and a machining fee.
 
Well, scratch the rotor swap idea for reduced weight. Went to the junkyard today and pulled rear rotors off an '11 Buick Regal and an '85 Corvette. The Corvette had drilled aftermarket rotors, and some wear, but the Buick rotors had similar wear. I weighed them both with my HF hanging scale, and the Corvette rotors were about two ounces LIGHTER (.12#). Weighed them three times, and the results were repeatable. So, this economical option isn't going to work.

While wandering around looking at radiator sizes and shapes for my street rod truck project, I saw some small radiators that might package in the rear of my '69. In addition to trying to reduce mass in my car, I keep looking for ideas on how to move some of the remaining mass either to the right or to the rear. I keep entertaining ideas on how to reduce the radiator size and weight (and airflow) up front, and move some of the weight and work rearward. Would definitely take some duct work and plumbing to direct the fluids, pretty sure that's doable, but I have no experience on what it takes to pump the coolant in that long of a round trip. I suspect the overall weight of the cooling system would increase slightly, but possibly a better f/r weight balance (currently about 1400/1300 pounds) might net a better handling car. As I heard someone once say, you can only go around a corner as fast as the slowest axle/half of your car.

Just trying to figure out a next move.
 
Well, my parsimony paid off. Got my "pre-owned and generically priced" 26mm hollow front swaybar (off an '89 C4) finally installed. Went online to buy some poly bushings for it, and for some damn reason 26mm generic poly kits are noticeably more expensive than other kits of similar size range. Surfing the web I found some 26mm poly bushings for a Honda Accord for a pretty cheap price. Bought them, and last week scoured the junkyard for some brackets. No luck finding an Accord of the correct vintage, but did find a late model Jeep IIRC with the correct sized brackets. Got them (and a similar size pair off an Isuzu) for a very acceptable price. I welded short extensions on them to give additional fore and aft adjustment, and I was in business. Total cost for the bushings and brackets was about half compared to buying the generic kit (my labor is free, and the mental health benefit of wandering a junkyard on a nice sunny day is substantial).

Oh, and the weight of this mongrel kit turned out to be four ounces lighter than a generic kit of similar size. Win, Win.
 
A productive day at the junkyard is a good day. Especially when you are able to piece together exactly what you wanted.
 
Enjoyed a track day last week. The rear suspension geometry changes and the front sway bar reduction really helped the car rotate in the corners, and to be noticeably more steady during heavy braking. The car just seemed to go where I aimed the steering wheel. With a big block this car previously always seemed reluctant to flick the front end each way. This was a rare moment of owning this car when changes to it exceeded my hopes. Another item that made all the weight reduction work worth it was the braking into the corners. The car slowed down noticeably quicker than I was used to, and I found myself letting off the brakes into the corners, rather than trail braking. Not a big deal, it was a track day, not a race, so there's more opportunities ahead to adjust my braking points. One thing that did scare me was the brake booster seemed to have only one good application per corner. When I let off the brake, and then reapplied the brake a half or full second later, the pedal felt like I had no boost at all. Firm hard pedal, but seemingly no noticeable deceleration. I'm still trying to figure this out, and I'll be starting a thread in the Brake section shortly to discuss it in more detail.
 
69427 said:
Enjoyed a track day last week. The rear suspension geometry changes and the front sway bar reduction really helped the car rotate in the corners, and to be noticeably more steady during heavy braking. The car just seemed to go where I aimed the steering wheel. With a big block this car previously always seemed reluctant to flick the front end each way. This was a rare moment of owning this car when changes to it exceeded my hopes. Another item that made all the weight reduction work worth it was the braking into the corners. The car slowed down noticeably quicker than I was used to, and I found myself letting off the brakes into the corners, rather than trail braking. Not a big deal, it was a track day, not a race, so there's more opportunities ahead to adjust my braking points. One thing that did scare me was the brake booster seemed to have only one good application per corner. When I let off the brake, and then reapplied the brake a half or full second later, the pedal felt like I had no boost at all. Firm hard pedal, but seemingly no noticeable deceleration. I'm still trying to figure this out, and I'll be starting a thread in the Brake section shortly to discuss it in more detail.
Click to expand...
big camshafts don`t make vacuum, you might want to try the C-6 (maybe) aluminum master with no booster, you might just kill two birds with one stone, better brakes and a weight reduction, on my racer I ran a stock cast iron manual 1" master cylinder...
 
69427 said:
Enjoyed a track day last week. The rear suspension geometry changes and the front sway bar reduction really helped the car rotate in the corners, and to be noticeably more steady during heavy braking. The car just seemed to go where I aimed the steering wheel. With a big block this car previously always seemed reluctant to flick the front end each way. This was a rare moment of owning this car when changes to it exceeded my hopes. Another item that made all the weight reduction work worth it was the braking into the corners. The car slowed down noticeably quicker than I was used to, and I found myself letting off the brakes into the corners, rather than trail braking. Not a big deal, it was a track day, not a race, so there's more opportunities ahead to adjust my braking points. One thing that did scare me was the brake booster seemed to have only one good application per corner. When I let off the brake, and then reapplied the brake a half or full second later, the pedal felt like I had no boost at all. Firm hard pedal, but seemingly no noticeable deceleration. I'm still trying to figure this out, and I'll be starting a thread in the Brake section shortly to discuss it in more detail.
Click to expand...
you also might consider a triple disc clutch you can ditch your heavy scattershield, the triple disc has much less rotating mass allowing you to go into corners deeper (braking later) and come out quicker due to less rotating weight...
 
redvetracr said:
big camshafts don`t make vacuum, you might want to try the C-6 (maybe) aluminum master with no booster, you might just kill two birds with one stone, better brakes and a weight reduction, on my racer I ran a stock cast iron manual 1" master cylinder...
Click to expand...

My current setup is an '84 C4 booster (smallest OD of the C4 boosters, needed to clear my valve cover, and half the weight of a C3 booster), and a C5 aluminum m/c (about 1# with a 1" piston). My current engine combination idles at about 12" of vacuum, as it's also a licensed street car. This setup worked perfectly for the past ten years up 'til the other week.

I'll admit my possible ignorance on the next item. Regarding manual brake C3 Corvettes, I was/am under the impression that the 1" manual master cylinders have a deeper rear conical bore in the rear of the piston to better deal with the brake pedal pushrod, compared to the conical bore depth in the 1.125" PB master cylinders. Is this correct, or have I been fed incorrect information?
 
redvetracr said:
you also might consider a triple disc clutch you can ditch your heavy scattershield, the triple disc has much less rotating mass allowing you to go into corners deeper (braking later) and come out quicker due to less rotating weight...
Click to expand...
I've looked at those small diameter setups. They're fantastic in every way, except when taking off from a standstill. As I mentioned earlier, my car is still a licensed street car, and dealing with stop signs and traffic is still a concern. I presently have the 10.5" 14# L88 flywheel, a 13# pressure plate (the lightest I could find), and a pretty light 6.5" front damper. Given the M21 and 3.08 rear gear I have, my setup is already threatening to stall the engine whenever I take off from a stop.
 
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