69427

Couple more items while I'm having some luck with photobucket.

Several years ago while trying to figure out how to pull weight off the front I happened to notice the limit brackets on the front headlight assemblies. I noticed that the stock parts are way overkill (but were probably damn inexpensive). These parts aren't incredibly heavy, but they're way up front ahead of the axle centerline, kind of upsetting my engineering sensibilities. Made some duplicates in aluminum. (I drilled the holes a bit bigger after this photo was taken, so I got about 12 ounces off each part.)



A year ago I ended up beating the crap out of the exhaust system due to a combination of low ride height and a hard bump at a corner apex on a track I go to on occasion. Darn near scraped through the exhaust pipe, and eventually one of the bumps broke the hanger bracket and I ended up dragging the left side muffler a distance down the track. While holding the muffler and trying to figure out how to fix all the cosmetic damage to the muffler and the stainless tip, I was reminded that these mufflers have a bit of bulk/mass to them. Rather than spend a lot of time welding and painting a heavy muffler I decided to spend that energy on making a visual copy in aluminum to pull out some weight. I've had good luck with the home-made aluminum muffler on my turbo C4 so I made a jig to capture the external dimensions of the damaged muffler and then welded up a replacement. The steel muffler (with SS tip and entry elbow) was 16#. The aluminum replacement is 10#. (Picture prior to polishing the aluminum tip and painting the housing flat black to match the right side muffler.)




A couple items below. The exhaust system after some repairs from the track damage, and a sacrificial wear patch on the bottom. The system is aluminum (dual 3"-single 4"-dual 3") from the transmission tailhousing area back, except for the RH muffler, which will hopefully be swapped out this winter for a lighter substitute. Also, I run a bellypan on the car during track days so I needed a shallow transmission crossmember to keep the pan flat all the way back. I ended up welding an aluminum crossmember to fit the bellypan and take some weight out. The crossmember is shorter in height but wider in width to gain back some of the strength. The pipe pass throughs are IIRC 5" pipe that I ovalled for ground clearance and clearance for the 3" pipes. (The lighter engine/flywheel and M21 eased some of the weight on the crossmember). Pulled 10# off with this piece.



The odd looking stuff up by the oil pan are supports to hold the front section of the bellypan. Here's just an old picture while trying to figure out how to attach everything. (Yes, the bellypan adds weight. )

Shark Racer

The digital wires used for CANBus are very cute(small gauge). I am working on a side project right now related to CANBus and RaspberryPi...

69427

Yes I did.

I agree with your assessment that it might be possible to pull some weight out of the car by going to a bus setup, but my car is short on remotely located electrical devices (other than the headlights and tail lights). I don't believe the tradeoff point works for my antique. And I'm kinda thankful for that. While technically I'm reasonably sure I could do a bus system, there is just something about the rat's nest appearance of car wiring that just makes me nauseous. I enjoy circuit board and IC design, but messing with a taped up and partially hidden wiring harness just depresses me. I think most everybody has one part of a car's construction that they absolutely would like to avoid having to deal with if at all possible, and wiring harnesses are it for me.

What can I say?

jim2527

I've replaced all the harnesses in my car and can say 'not much'. If I remember I'll weigh the dash harness later....

ignatz

And with your resume too. I'm shocked, just shocked. Oh well I wouldn't touch it either!

7T1vette

Can a Corvette have anorexia (by owner)? How "lean" is lean enough?

69427

I suspect it will be when my stock '69 bodywork with 275mm width track tires can reliably corner equally with a widebody Z06 on 335mm width tires.

The laws of physics don't play favorites.

ignatz

From the point of view of having enough rubber to control the weight, I did some math. I find the weight of a 2015 Z06 online to be 3524 #'s. That gives me 335 mm / 3524 #'s, or 0.095. You have 275 mm / 2783 #'s, for a ratio of 0.099, i.e. a bit more rubber / pound. The older C6 Z06's are 325 mm / 3150 #'s, for 0.103. That works out to 120#'s less for you to find. Good luck on that!

Metalhead140

The more I look, read, and see, the more I love the work you've done on your car, it's my version of perfect... Huge improvements, but mostly kept subtle and relatively hidden. Dibs when one day you sell?! I also own a ~650kg (~1430lb) British sports car, lighter weight is always better...

69427

Yeah, the C6Z tire/weight specs are pretty impressive. Also helping the C6Z cornering ability is the 5-8% wider track width compared to a C3. The only "equalizer" I currently have is 400# less weight (750# vs a C7) which helps with acceleration and braking.

One option I've kicked around for the last two years is swapping the tires around. I'm running C5Z wheels (17"F/18"R), with 275front/285rear tire size. Front end grip is generally what limits cornering speed, so if the rear wheels (18x10.5") and tires will fit up front I'd like to try them some time. Doing the math (285/2780#) gives us .1025. An improvement, if the tires will fit.

69427

I appreciate the kind words.

I suspect there's a noticeable difference in low speed cornering response between your Corvette and your much lighter British car. Less mass to change direction. Pure physics in action.

Metalhead140

HUGE difference... Difficult to put into words. Even with mostly stock suspension and on skinny 13" wheels/tyres, (just some lower stiffer springs, shocks, and swaybars) the British car feels like a go kart, the Vette feels positively lumbering in comparison (despite 17" wheels with high performance rubber, borgeson steering, poly bushes, tubular upper arms, bilstein sports etc). It doesn't have a V8 though... Totally different car to drive. I still haven't run the Vette on a track yet, but now that I have my new engine and box in I hope to soon.

69427

Twenty damn minutes fighting with Photobucket, and this is all I've got to show for it. Gotta go look for another sight this week.

Here's my front brake package (the rears are pretty similar). It took me quite a while to find a setup that would simultaneously fit under 15" wheels (for my street tires) and also fit with the particular shape of the '96 C4 front suspension knuckle. Wilwood had some pieces that would do the job (these parts also work damn well on the track too). The rotors (stock 11.75" diameter) are 5# lighter, and the calipers are 7# lighter, for 12# of unsprung weight off each tire.



Lately I've been kicking around trying to see if a set of C5 calipers would fit up front. I don't know the weight yet of the C5 parts, but I do like the looks with the Corvette lettering on those calipers. I need to track down a used/wornout C5 caliper somewhere to do some mock-up work over the winter.

Kubs

I wouldn't mess with any C5 stuff. You already have a more solid caliper. The slide rail stuff is garbage on track. Too much flexing and pad taper.

ignatz

I've seen the same sentiments expressed elsewhere.

69427: Curious as to what other trades you're going through than just sheer avoirdupois? i.e. piston area front/rear. You might recall my post as to diminished rear brake authority. I put front Wilwoods all around my car with a proportioning valve on the rear. Am happy with the results.

I don't track my car but it is my understanding that thermal mass is pretty important. You've lost some of that. For my autoX'ing I could go with lighter rotors. Hard to tell but it looks like it says Wilwood in the picture on the rotors. Is that their replacement for stock?

69427

I've added more rear brake "authority" with these calipers (1.75"F/1.375"R vs 1.875"F/1.375"R stock piston sizes). My experience with the original calipers (when doing track days) was a ton of wear and taper in the front pads, and very modest wear in the rear (which makes sense for a production setup as that's a lot safer for the typical driver in a car that can have varying option or cargo weights). The stock rear brakes weren't 100% ballast, but sure seemed damn near that. With these brakes (calipers) the rear half is actually doing some productive work now. With the car's present weight and brake setup I can damn near brake with anyone else on the track. Seriously.

Regarding thermal mass, IMO, that's only "necessary" if there's a shortage of cooling air to pull out the BTUs, and a helluva long cooldown time available between applications (low speed autocross, or perhaps an airliner during landing where the energy input into the rotor keeps increasing while simultaneously the wind speed is decreasing). Thermal mass is just kind of a Band-Aid IMO. (And, it's hard to get thermal mass without just plain mass, and then you have to deal with F=mA, blah, blah, blah...)
These rotors are light weight because of the thin wear surfaces, providing a short thermal path to the cooling air (versus into already warm/hot cast iron for another eighth inch) being pumped through the internal vanes. I've got some air diverters under the front of the car to do two things: Get a lot of air to the rotors, and keep a lot of air from tumbling around under the back half of the car creating lift and drag.

These rotors are just generic Wilwood 11.75 x 1.25" pieces, which I believe is just a common size for many vehicles equipped with 15" wheels. It's the aluminum hat that then customizes the application usage (and ramps up the initial cost ).

69427

I appreciate the information. I hadn't run into much brake feedback info from C5 guys over the years, and had assumed that they were comfortable with the performance of those calipers.

Thanks again.

Kubs

No problem. I put C5 brakes on my C4 track car and the only thing it gave me was a higher pad bill. Same terrible taper and lots of flexing. I also have issues with my dad's '02 because he insists on keeping it stock. For any decent track use you want to use a fixed caliper with differentiating piston bores. I now use 4 piston Brembos robbed from a Gen III Viper with 40mm and 44mm leading/trailing bores and pad wear is perfectly even. Also, all that flexing gives you an inconsistent pedal feel. I used to have to tap the brake pedal on straights to make sure it was there before I hammered it into the next corner. The Brembos give a nice solid pedal feel.

ignatz

The six piston Wilwoods have a preferred orientation and, so far, no taper.

69427

An addition to post #21. I finally finished up the right side muffler replacement (in aluminum). It's as much a mirror image of the left side aluminum muffler as I could make it. This got another 6# off the car outside the wheelbase, for a slight reduction in the moment of inertia too. I haven't had an opportunity so far this summer to get the car on a scale again, but it should be at about 2770# at an eighth tank of fuel.

Here's a picture with the new mufflers (I'm still polishing the aluminum tips).



Also, you can kinda see the C4 batwing that takes an additional 5# off compared to a C3 batwing, which is 15# lighter than the cast iron cover and steel crossmember.