How much does it weigh?
I just bought my first Vette. It is a 75 L48 coupe with automatic, air, power steering and brakes. I was hoping to get a lighter car for recreational drag racing at the local dragstrip.
I know the specs, but I wonder if anyone actually put their Vette on a scale?
Please tell me it weighs less than the advertised 3529 lbs. This is only 32 lbs lighter than a stock 79 Trans Am.
If you have put yours on a scale (regardless of year) I would like to know what options it had and what it weighed - thanks.
Good question. With specs do they take into account a full tank of gas? How about 5 quarts of oil? An estimated driver's weight? Hmmm....
I'm Not Fat!!!
Oh...wait....you didn't really MENTION me...did you?
Originally Posted by Stallion
3500 is about right (mine's a '75 ragtop.) I used some private truck scales (they charged me $15 I think...) not long after I changed the front and rear suspensions and some other parts to see how they affected balance more than anything. I don't recall the spec now, but it was around 3500 - more importantly I was stunned to see I was within one percent! of 50/50! It was like they INTENDED my fatass to be in that car!
Sorry guy, vettes are strong, heavy cars with solid frames. They have good drag coefficients and nice low COGs. They are a nice solid frame and body design that don't bend apart like monocoque cars with higher power and hard banking, but they are not super light. Our '75's had some weight adders too, like much heavier doors. I've heard of skeletonized ones, even with decent roll cages, getting into the 2600-2800 range, and still (sort of) being drivable cars, but much more than that and it gets brutal.
The trade off is you can easily put in a nice, new monster displacement 700hp mill and everything except for the rear end takes it fine.
That comes to the really bad news - forget comparitively heavy weight, you're REAL problem for drag is the otherwise great IRS. The center is only a 10 bolt - I think all the '75's were at least Dana 44's but some were just Dana 36's. Because it is nonmoving and heavily bolted to the frame it really is stronger here than it would be on a normal dead axle car (like that TA,) but it still isn't that strong - and the halfshafts, especially the U-joints, are a common point of failure. I feel this was one key design shortcoming - going with a much heavier 12 bolt, Dana 70, 14 bolt or whatever GM had sitting on the shelves then, but the weight of those units was felt to be unjustified.
Still you will tend to grenade first the outter half shaft U-joints, then the inner, then the center section itself, then twist the halfshafts themselves, in that order of expected failure. There are upgrades available for all of that that will handle the power, but they are pricey. At least few ever damage even the lightest of the main driveshafts - unlike on other designs, they simply aren't normally known for failing, since they hardly move (angle wise) at all.
I have the Tom's Differentials 12 bolt conversion (a newer better one is now available from them) but have yet to get the "1480" 0.135" wall thickness halfshaft kit. Van Steel and Dragvettes also make nice lines of upgrade products, including some exotic material halfshafts and driveshafts. Even the best stock design big block setup help quite a bit but are still likely to grenade under hard standing launches.
Until you upgrade the 165hp L48 mill though, it won't be too much strain..
Oh, and none of this hits on the geometry changes under a launch with the IRS. The squatting down effect isn't that bad in itself - much better than wheel hop on dead axle designs, but untill all of this is controlled with better springs and shocks and the right rear sway bar (or none at all) the change in angle of the tread to the ground in that condition causes some problems in getting the best hookup.
Vettes are all around sportscars, capable of stunning handling and controllable at really high speed driving - yes, even C3's (especially with a limited number of key upgrades) - and with great acceleration rates with the REAL engines you can easily put in them - but they are not the ideal 1/4 mile all out, undrivable anywhere else, 10 runs before major rebuild drag car.
They can be modified to be good at that too, and many have, but it costs.
(Please don't hack out the IRS and put in a dead axle! Some HEATHENS do that too.... )
Thanks for the insight. Right now my Chevy powered Trans Am runs 12.60's in the cold air - 1.73 sixty foot times. It has a 700R4 and 4.56 gears in front of a stock bottom end 350 with some porting, a decent cam, intake and exhaust. It is not very pretty, but I enjoy driving it to the track and running 12's on 87 octane! Remarkably it has the same block and head castings as the 75 L48 engine.
Anyway I was thinking about drag racing the C3, but probably not to the level to which you are talking. I am thinking 12 flat is about as fast as I want to go. My TA has a stock 10 bolt with a posi and I have had no problems with it. Do you think the stock rearend is close to the 10 bolt in durability - or am I going to need an upgrade? Just how far into the breakage cycle will I go? I was aware of the issues with the IRS but not sure just how weak they really are.
I appreciate your insight about the frame, and the weight certainly explains why so few of them are at the drag strip. The TA just looks so much bigger I was having a hard time believing it would be the same weight. (In fact I am sure my TA is lighter since I have removed the AC, replaced the 403 with a 350 Chevy, tube headers, manual steering and brakes, etc.)
Do you think the convertible is lighter than the coupe?
If it doesn't work out as the race car I could make it into my summertime daily driver.
Thanks again - I am sure I'll be re-reading this thread closely when it comes time to make any improvements in the rear end.
Had my '76 weighed last summer. 3300# with almost full fuel. I do have aluminum heads and intake, headers, no CAT, factory aluminum wheels. Weight sheet said 3450# with me in it, but I weigh more than 150#, so 3300# is a little conservative.
Recreational drag racing - is that where you drive your street car to the track to try to win a trophy and hope you don't have to walk home? If you trailer the car you can remove the spare tire, air conditioning, heater, passenger seat, lights (everything electrical but the tach) and all the creature comforts they started putting in them in the '70's. Don't let the fiberglass shell fool you, the rest of the car is steel. And you know they weight convertibles down, right?
Originally Posted by L48
I don't mean to come off as sarcastic, but geez - don't ruin a Corvette for other people's amusement. You have the right idea with the Chevy powered T/A Just my opinion.
I can estimate the weight savings of the heads, headers, intake.
Originally Posted by glen242
Does your Vette have power steering and brakes? Does it still have A/C?
To me it's where you build a car to drive to the track eight or ten times a year - I win my share. I particularly enjoy beating the trailered cars btw. Though it doesn't pay for the habit I typically race the money brackets.
Originally Posted by craig32
Let me set the record straight about my C3. I got a great deal at an estate auction on a Corvette in a sorry state of mechanical disrepair. As I bought it the interior is black, most of the remaining parts were painted black over the original silver. The exterior is red, though it was originally silver. It has 100% rubber fuel lines from the tank. The choke blade is missing. The A/C compressor and brackets are missing, there are countless wires no longer attached, the original air cleaner is gone and most of the interior functions do not work. One seat belt is stuck and the other is missing. It had the wrong plugs, misadjusted timing and it barely started when I bought it.
Originally Posted by craig32
I can guarantee you that it will get better care from me than the prior owners - even if I choose to race it. If it does get to racing you can be sure that the # matching original engine will be on a stand in the garage.
You are certainly entitled to your opinion but please do not assume that drag racing it will be ruining it. I think the prior owners have already done a fine job of ruining.
PS & PB. No Air.
Originally Posted by L48
I'll TRY to put a few links....but I'm pretty stupid...
I tried cutting and pasting, but this silly thing is acting up - so those are written, and probably wrong.
Although I have yet to buy them or another product, the neatest thing from dragvettes is the half shaft loops, and they cite the racing specs requiring them (as does TD's.) Dragvettes offer is supposedly a quick drop in, unlike TD's which require a good sized alteration.
I couldn't find the links, but a guy by the moniker of ProSouth, another guy from Australia and I think Norval have 5 or 6 link conversions, which greatly increase the handling ability of these things. The additional upper arm from TD's is NOT a real control arm but a safety device that is not in usual actual control of anything (until a halfshaft blows up...)
Notice the high end of the TD's set up costs about 1.5x what a Currie Ent whole Ford 9" third member and axles will cost - just for the center section. The monster half shafts in the all out upgrade runs that much again. I don't even believe TD's assert their highest end products are really as tough as a reasonably tricked out Ford 9" design or GM Corporate 14", either.
Comparing to a 10 bolt in a T/A I would think the Vette 10 bolt, provided the heaviest standard half shaft ujoints and big block half shafts were used, would actually be stronger, and especially if one of the heavy rear covers was employed, if only because the center section on the IRS is firmly anchored to non-moving parts. I'm amazed you never grenaded your TA 10 bolt under the uses you mentioned.
One other concern, more for long duration high speed runs than drag racing, is that unlike traditional axle tubes, there is no active lubrication to the outter bearingsform the differential fluid through the tubes. I had one run dry of the sealed grease, seize up, and cut the wheel spindle off like it was hot butter on a lathe - with no grinding, whining, smoking or other warning.
It was the worst thing I've ever had happen in a car. A foot off a magnet wall on that side doing 80+ and my whole wheel decided it didn't like me no mo! The good thing about the IRS after all these weaknesses, is you STILL have power when you lose a wheel - I didn't hurt the POS any more than had already happened. Only once I got it shut down about 500 yards further on - on the other side of the highway, and after I moved it some more (after having come to a complete stop and starting it up again) did I even realize I did not have just a bad blowout, but had a BLOW-OFF and was resting on frame parts without benefit of any of that unnecessary overweighted wheel stuff.
Needless to say I have the rear wheel bearings inspected about every 10K miles (or less) by a good vette shop now - being paranoid on the matter more than a little bit. One of my weird-ass instrumentation and modification goals is to put together a bearing temperature warning panel, either mounted IR lasers or just welded on standard oil temp sensors - something to warn me something is going wrong next time!
My 1971 LS-6 coupe weighs 3340 lbs in pure stock form. Even the original 34 year old tires. Options are PS, PB, T/T, Rear defogger, AM/FM stereo. This is shipping weight, all fluids with 2 gals of fuel, curb weight would include 2 people at 300lbs.
..... I'm not exactly-sure " HOW " the pre-'80 C3 rear-ends are designated, but I believe that the '68-'79 rears are much stronger than the '80-up, and that those ('80-'82 ) were designated DANA-44 types:
I think that most C4s had the DANA-36, except a few stick-cars that received a different version of the DANA-44.
I used to race with a fellow that had an early-'70s C3 running 12-flats with his IRS (454, high-stall converter, slicks, etc.), and that he had several problems with it:
while I won't run much quicker than mid-12's when I build a C3 race-car, I'm still planning-on a full back-half (narrowed Ford 9", 4-link bars, wheel-tubs, big-by-wide slicks, etc.) to ensure consistency, reliability, AND safety.
Even-if your C3 DOES weigh more than you'd thought/planned, it's better weight-distribution wil help get it off the line better, as-long-as the rear-end doesn't crap-out on you.....
GlenG - I think you're essentially right.... I just
went on a short search to try to, sorry, basically, counter what you said about the Dana 36 and 44 types and, basically, CONFIRMED what you were saying....
One link I found went on about a conversion on a much later vehicle to a "bigger stronger Dana 44" (from a Dana 36), but all others were showing the Dana 36 as the improvement over the early Dana 44.... and all of these designations were on the lightened (and weakened) late C3's with the torque arm thing and all the aluminum or on the C4's.....and not able to find any info on the actual names used on the pre-lightened ass early C3's....
....now I am hopelessly confused on what is what....
At LEAST I know the thing mine came with was a "10 Bolt" and I'm STICKING WITH THAT NAME! (Now it's a hybrid - a strengthened 12 bolt in a modified 10 bolt housing....previously I would have called that stuffing Dana 60 innerds in a Dana 44 case....now I just won't say ANYTHING! )
I even went to the Dan Spicer site....yeah, *useful*....if I want to buy like 10,000 new electric slip 4 wheeler diffy's or "Protect the Earth" with new driveline technology or get stock reports!!! (I hate how so many of these tech suppliers cannot simply give straightforward information comparing their product designs, specs, ratings....)
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