I'll post this here but maybe it should be in the suspension section. I'm not sure.
My Chevelle had the following weights on each wheel (no driver, spare or jack):
LF = 1064 lbs
RF = 1069 lbs
LR = 778 lbs
RR = 643 lbs
SO 59.7% front and 40.3% rear. But right (51.8%) to left (48.2)? I thought it would be the same..
Does anyone else have weights on their Chevelles?
Does anyone have info on weight changes by moving the battery to the trunk?
What about moving the engine back toward the rear? How much would that change the weight distribution?
I searched the forum using the search engine and did not come up with anything from the past.

I'll post this here but maybe it should be in the suspension section. I'm not sure.
My Chevelle had the following weights on each wheel (no driver, spare or jack):
LF = 1064 lbs
RF = 1069 lbs
LR = 778 lbs
RR = 643 lbs
SO 59.7% front and 40.3% rear. But right (51.8%) to left (48.2)? I thought it would be the same..
Does anyone else have weights on their Chevelles?
Does anyone have info on weight changes by moving the battery to the trunk?
What about moving the engine back toward the rear? How much would that change the weight distribution?
I searched the forum using the search engine and did not come up with anything from the past.

What motor and trans combination are you running?

Lower the rear!

This was with a 350, 4L60 and 10 bolt rear.

I didn't know a 4L60 bolted up to a small block chevy.

Like you I am curious how the RR is almost 150 lbs less than the left rear.

The drivers side should weigh slightly more due to steering column, guages, steering gear box, and master cylinder/booster where as the passeneger side usuall only has a the heater assembly.

I think moving the engine back would be way too much work and I doubt it will make a huge difference. If you want to be closer to a 50/50 weight distribuation I would look into light weight and removing parts. (intake manifold, heads, pullies, hollow sway bar, plastic inner fenders, delete power steering or A/C.) This would help overall performance but it is also easy to get carried away.

I am going to through out the idea out there that you car was in an accident some time during its life. Maybe the frame is slightly tweaked, and one quarter panel has a good amount of filler on it?

I was able to place the engine with less than a half inch of clearance on the passenger side head on my LS1 swap. I feel like the lighter weight of the LS1 and setting it back and down low as well should help my weight transfer quite a bit.

I didn't know a 4L60 bolted up to a small block chevy.


They come from the factory with that combination!

I'll post this here but maybe it should be in the suspension section. I'm not sure.
My Chevelle had the following weights on each wheel (no driver, spare or jack):
LF = 1064 lbs
RF = 1069 lbs
LR = 778 lbs
RR = 643 lbs
SO 59.7% front and 40.3% rear. But right (51.8%) to left (48.2)? I thought it would be the same..
Does anyone else have weights on their Chevelles?
Does anyone have info on weight changes by moving the battery to the trunk?
What about moving the engine back toward the rear? How much would that change the weight distribution?
Elementary my dear Watson...

They teach this stuff in basic aviation ground school and call it "weight and balance". The location of the CG is rather critical on an airplane and you have to make sure you don't screw it up too far. If you do it can quite easily be a life ending lesson. Now it has been a few years since ground school, but let me see if I remember how to do this...

The first thing you have to do is calculate just where your CG is now. If we assume 100" wheelbase, then the CG is 40.3" back from the front wheels.

Now we pick a semi-arbitrary reference point in front of the car to reference "moments" around. These moments are really rotational torques caused by the weight of an item multiplied by it's distance from the reference point. Let's use 40" ahead of the front wheel center for fun.

Your Chevelle has a total weight of 3554 lbs and since the CG is 80.3" back from our reference point for a total moment of 285,386. That is your base moment.

Now let's move the battery. First we need it's weight and distance from the reference point. I am going to guess 50 lbs and 6" for a moment of 300. We remove the battery so we can subtract 300 from our total moment which becomes 285,086. We move the battery back 24" behind the back wheels so it's 164" behind the reference point and it's moment is now 8,200. This we need to add to our total which becomes 293,286.

That is nice but what happened to the CG? Well if we take that moment and divide by the weight, which did not change (used those new weightless battery cables :yes:), we get a CG at 82.5" behind the reference point. Which works out to a 2.2" rearward movement of the CG.

So there you go. Now you too can figure out what difference it will make when you move parts around :beers:

BTW the new weight distribution would be 57.5% front and 42.5% rear.

Makes sense, a rotating vector around the CG! Why didn't I see that?:confused:
That means a 500 lb engine moved back an inch won't make a large difference (500).

I owe you a cold one. If you leave me your phone through a private message I will buy next time I'm in Loomis. I have a house there.

Ron

Oh geeze... cannot resist...

500 lb engine probably 6" behind wheel center == 23,000 moment.
500 lb engine 7" behind wheel center == 23,500 moment.

285,386 - 23,000 == 262,386.
262,386 + 23,500 == 285,886.
285,886/3554 == 80.44
80.44 - 40 == 40.44

So from 59.7%/40.3% you change to 59.26%/40.74%. Have not even busted a single percentage point with that engine shift :beers:

Steve...

I know what you wrote was an example. As a general point to all who are interested, placing weight close to the ends of a car increases the car's polar moment of inertia. Doing so increases the amount of torque necessary to alter the rotation of the car (more torque necessary to turn the vehicle, more torque necessary to stop a rotation). What this comes down to is: the higher the polar moment of inertia, the more force the tires need to apply to the road to turn the car, limiting turning response or 'handling'. It may be better to place a battery directly behind the rear seat above the rear axle rather than at the rear most extreme of the trunk. You'll end up with a more responsive car if you pull the mass toward the center. Of course, you may notice nothing at all between the two battery locations I mentioned. :D

Good point. And to clarify just a bit more...

Think of polar moment like a set of dumbell weights on the end of a bar. The longer the bar or heavier the weights, the harder it is to change the rotation speed. This is an important point here that polar moment affects the transitional characteristics of the car. In some cases you could make a point that high polar moment is a good thing as it stabilizes the car although this is probably not a problem on our cars with fairly high polar moments to start with. It could be a very good thing on a drag car though.

It may still be a worthwhile tradeoff to increase polar moment beyond optimal because while polar moment is a transitional affect, weight distribution is a static affect. Thus we spend more cornering time being affected by weight distribution than we do polar moment.

The reason we get so excited about weight distribution is that a tire gets the most grip with the least weight. Thus the proverbial optimal 50/50 distribution to equally minimize weight on all four tires to maximize total tire grip. Getting closer to this balance will increase cornering capability once you have gotten through the transition period and established the turning rotation.

Using our battery relocation example, if we move the battery the same distance behind the CG as it was in front of the CG then the polar moment will remain unchanged. It is when we get aggressive and move the battery further back and further away from the CG that we increase polar moment.

This is fun stuff to play with. We`ve done quite a lot with it on various projects over the years. One an aluminum bodies "Jeep Wrangler" off road racer (yeah,we done some off road too) with perfect 25%/25%/25%/25% weight distribution. Center seater,engine set back 12",wheelbase stretched, battery in the rear (naturally). We used wheel scales and mocked the whole thing up before we even welded a bracket. That includes gallon jugs of antifreeze,fuel,seat belts etc. all just set in their basic locations. It was a lot of work but it`s one of the winningest machines in it`s sanctioning body (EC4WDA). Another one that comes to mind is a street legal unlimited class open course road race car we built. That had 4" of engine setback (don`t forget you`re also moving the weight of the transmission rearward BTW),dual rear mounted Optimas,set back seats (moving the weight of 2 seats,driver and navigator back). Many race cars have a big fuel tank hanging way out back. That increases the polar moment as well as changing the handling characteristics of the car as fuel burns off. We ended up having two custom ATL fuel cells made (total capacity 48 gallons) that fit in and around the extensive cage,one behind the seats on edge inside the main hoop and a second horizontally under the package tray just above the center section (IRS). We put an aircraft fuel filler in each B pillar to fill them. They could be run as one big tank or individually via 2 valved transfer tubes. It was neat but a huge pain in the rump to do! On a street car it`s hard to beat the gains of just moving the battery to the trunk. Mark SC&C

I've been toying with the idea of moving the battery to the rear on my wagon project. Unfortunately, unless I want a battery riding around in the passenger compartment itself, the only logical place I can come up with to put it is in the spare tire hole on the right rear. That would place the weight quite a ways behind the rear axle and depending on how it could best be mounted, it might be fairly high in the chassis (at least as high as the cargo floor in back).

That leads to a number of issues. The wagons are already longer and heavier from the axle to the rear bumper than a coupe so I'll already be battling more polar moment issues than a coupe and adding more weight to behind the axle may not outweigh the benefits of getting it off the already overloaded front with an all iron big block. And if I would have to mount the battery high in the chassis, it would begin to contribute to body roll. I must be nuts trying to make a wagon that will handle in the first place!

BUT, I am installing an aluminum radiator, aluminum water pump and an aluminum intake so I will be lessening the front weight bias to some extent, I just don't know if the battery location ideas would be beneficial or detrimental. Once the body goes back on the frame later this summer I might be able to investigate better locations for the battery. I might be able to fabricate a battery box directly below or behind the rear seat similar to how it's done on C1/C2 Corvettes.

you are considering weight transfer for tire traction in a static state, what about during acceleration and at speed with downforces (or lift forces) applied, this is when you want equal traction, no?

a

The station wagon as well as the El Camino and Sedan all have the same wheel base at 116". The convertible and Coupe are 112" but both the El Camino and Station Wagon are are 207.1" overall length.
I would think that the guys who make the El Camino handle well have what is needed to make the station wagon handle too.
As for polar moment, it seems to me the bumpers are the biggest culprit. They are heavy and out at the end of the chassis!

I have checked out the body of the Chevelle fo excess bondo etc. Can't really find anything that explains the weight offset from side to side.
I am looking for a set of scales to do more measurements. I'll post more when I get some more numbers.
Anybody got any leads on a good set of scales?

My '71 is 51/49. Wierd.

Jim

The station wagon as well as the El Camino and Sedan all have the same wheel base at 116". The convertible and Coupe are 112" but both the El Camino and Station Wagon are are 207.1" overall length.
I would think that the guys who make the El Camino handle well have what is needed to make the station wagon handle too.
As for polar moment, it seems to me the bumpers are the biggest culprit. They are heavy and out at the end of the chassis!

My wagon is a '65. For the years 1964-1967 the wheelbases were all 115 with the wagons and El Caminos having an additional five inches of body between the rear axle and the rear bumper that the coupes/sedans/convertibles do not have. Overall length of a coupe/sedan/convertible is 196.6 and the wagons and ECs are 201.4 long.

The 112/116 inch wheelbases were for the 1968-1972 models.

Additionally, a lot of weight is held in the wagon tailgate. A fully dressed tailgate with glass, latch mechanisms, etc. is a VERY heavy piece. The weight of the bumper pales in comparison. The El Caminos have a tailgate but it does not contain a window or window mechanism. The wagons are the heaviest by far, and carry more weight behind the rear axle than any other body style. For example, the 65 2-door wagon curb weight is 3480 while the El Camino is listed as only 3280 (actual weights will likely be more, these are just documented AMA spec values). The only body style listed as heavier than the 2-door wagon is the 4-door wagon. And even more, the wagons carry the spare tire between the rear wheel and the tailgate while the El Caminos carry it behind the driver's seat.

This is an important point here that polar moment affects the transitional characteristics of the car. In some cases you could make a point that high polar moment is a good thing as it stabilizes the car although this is probably not a problem on our cars with fairly high polar moments to start with. It could be a very good thing on a drag car though.I've gotta disagree with this... true it may make the car more stable, but once things go bad, it makes it much harder to straighten back out as well... for example, I used to drive a '93 Caprice sedan, which was a blast in winter weather and I always felt "in control" when "drifting" with it... When I got my '95 Caprice wagon (same chassis, but 400lbs heavier in the rear) I immediately noticed it was much harder to control in a skid. First, it was harder to put into a skid, but once it started to go, it was WAY harder to correct.

you are considering weight transfer for tire traction in a static state, what about during acceleration and at speed with downforces (or lift forces) applied, this is when you want equal traction, no?Interesting observation... these cars generate a LOT of front-end lift at speed, so a nose-heavy car will get closer to 50/50 the faster you go, however the CG would still be in the same place. Lateral forces would still be pushing against the tires the same 57% and 43% although the theoretical lateral grip would then be 50/50.

I must be nuts trying to make a wagon that will handle in the first place!

BUT, I am installing an aluminum radiator, aluminum water pump and an aluminum intake so I will be lessening the front weight bias to some extent, I just don't know if the battery location ideas would be beneficial or detrimental.On a wagon, I don't think I'd bother moving the battery. You're already going to have a lot of weight in the rear with all that glass, I just don't think it will be worth the hassle. Your balance is already going to be much closer to 50/50 than any coupe/sedan, I'd focus on losing weight more than moving it.

On a wagon, I don't think I'd bother moving the battery. You're already going to have a lot of weight in the rear with all that glass, I just don't think it will be worth the hassle. Your balance is already going to be much closer to 50/50 than any coupe/sedan, I'd focus on losing weight more than moving it.

Thus the desire for some aluminum parts under the hood. But, I've already gone in the opposite directly by putting a boxed El Camino frame under the thing, but at least that extra weight is about as low in the structure as you can get. Of course the all-iron big block is a killer, but I ain't changing that out!

I'd love to put it on a diet, but I don't know where I'd remove weight. It's intended to be a comfortable cruiser as well so it's going to be fully dressed. I have shaved a little weight here and there with aluminum up front including the SPC upper control arms which have to help but aside from gutting the interior or installing plexiglass side windows, I'm not sure how else I can seriously cut the weight. Ideas are welcome though! Aluminum wheels should help all around and I could run without a spare at all, but those are pretty minor changes. Aluminum heads on the engine would certainly be a huge step in the right direction, but again I haven't even had it on the road yet and I've already got too much in the heads I have.

Gearhead, I notice you have a roll cage installed, that would shift weight a lot toward the rear but add weight too.
What were your actual weights?
Very nice car too! Major wheel lift on the front!

Thus the desire for some aluminum parts under the hood. But, I've already gone in the opposite directly by putting a boxed El Camino frame under the thing, but at least that extra weight is about as low in the structure as you can get. Of course the all-iron big block is a killer, but I ain't changing that out!

I'd love to put it on a diet, but I don't know where I'd remove weight. It's intended to be a comfortable cruiser as well so it's going to be fully dressed. I have shaved a little weight here and there with aluminum up front including the SPC upper control arms which have to help but aside from gutting the interior or installing plexiglass side windows, I'm not sure how else I can seriously cut the weight. Ideas are welcome though! Aluminum wheels should help all around and I could run without a spare at all, but those are pretty minor changes. Aluminum heads on the engine would certainly be a huge step in the right direction, but again I haven't even had it on the road yet and I've already got too much in the heads I have.
I hear what you are saying, there is a point where reducing weight starts reducing the fun factor. That is part of why todays cars weigh what they do inspite of extensive use of plastics and aluminum: they have electric windows, electric seats, big stereos (and maybe a DVD), and power everything. Of course part of the weight on todays cars is the extra safety stuff built in too. As a prime example removing AC reduces weight but is not much fun in the summer in many places.

You already have the right idea with respect to aluminum parts up front. But here are some concepts to ponder:

A full tank of gas is a pretty good ballast and it is hanging way back there. Would it be possible to swap fuel tank and muffler locations for a reduction in polar moment? Isn't there a fair amount of space under the seats that could be used more productively? On an Elky that smugglers box kinda screams out as a great fuel tank location.

The battery is hanging way out front of course. Rather than relocate the battery to the rear could it be relocated to the firewall? Note that the passenger does not have pedals taking up space and thus has more foot room than the driver. Could some of their "excess" be redirected to house the battery?

I may be mistaken, but I believe there are aluminum housing versions of the Saginaw steering gear available?

Wagons usually have automatic transmissions... Aren't automatic transmissions heavier than manuals? I think you already have this covered though ;)

Failing all that though just put the widest tires you can fit under there.

A lot of this depends on how radical you want to get and most of it requires hacking up the car. And that is something, quite understandably, you may not really want to do.

If the car is never going to be on a track, it really doesn't matter... sure it could handle better if you lighten it up, but are you going to use the car in a way that you'll ever need that handling benefit?

First, unsprung and rotating weight is the best place to cut it if you can... lightweight wheels, AFX spindles, aluminum driveshaft, etc.

Then you want to cut weight at the front and rear, and also as high-slung weight as you can... fiberglass bumpers, fiberglass hood, lexan windows, etc. would all be a HUGE improvement, but not worth it if the car is only going to be used on the street.

How hard is it to remove the rear windows on a 2dr wagon? Would it be too time-consuming to have a set of side glass for the street, and replace them with Lexan for track events?

The rear-most side windows are glued in like a windshield. The front half of the side windows are a slider and can only be taken out by removing trim and whatnot. The tailgate window is a load in itself and removing it would be even a bigger hassle and likely risk damaging bodywork, trim and the glass itself.

I do hope to get the thing to the track just to see what it can do with what it is and some bolt-on equipment. It will also see the drag strip at some point so I already have some divergent tasks planned for it, but in the end it will be a street car.

I think I'll only plan to move the battery if I can find a way to move it to a location that is low and between the axles. Behind the back seat is the only possibility I can think of but may be impossible, I'll just have to wait until the body goes back onto the frame later this year to measure things up. There also seems to be some wasted space under the cargo floor in the back, but again, that's behind the axle. It's that darn heavy tailgate hanging out at the end of the vehicle that's going to be my biggest built-in issue with which I will have to cope.

I also feel the spare tire well is kind of wasted space so I might choose to run without a spare and install some stereo equipment in that space. There is also a lot of wasted space inside the quarter panel on the driver's side and gaining access to it isn't that hard even when the car is assembled. Since there are no window mechanisms below the rear side windows, there are also some hidden spaces behind the rear seat side panels, but I'm not sure what good those spaces may do for me (yet).

One good thing about having driven an MR2 for past 22 years, I am familiar with driving a rear heavy but yet well handling car. I know the car can be made to handle and I feel I'm somewhat prepared for working with what quirks are inherent to a car with some weight hanging out the rear. The MR2 is actually a really great chassis and easy to drift, hopefully I can set up the wagon to work in a similar manner with the proper tuning of springs and sway bars.

Acid Dip the tailgate. :yes:

One thing I'd like to do on my car is use fiberglass bumpers, but have them "chrome" plated by one of the companies that can do that on fiberglass so it will still look stock.

One thing I'd like to do on my car is use fiberglass bumpers, but have them "chrome" plated by one of the companies that can do that on fiberglass so it will still look stock.

DO you know of someone who makes a set or can custom make them?

Glasstek lists both front and rear for a '69 on their website... ( www.glasstek.com ) I don't know about the quality, but I have one of their hoods on my Caprice which I would consider "driver" quality... wouldn't look good on a show-car without putting a lot of effort into it.

These guys can put a "chrome" finish on anything, including fiberglass. www.xxxplating.com

My $.02

I hear what you are saying, there is a point where reducing weight starts reducing the fun factor

As far as autocross relates to this, weight is not s much of an issue as balance. If you combine decent suspension with good power to weight and good balance the car will not F.E.E.L. like it is heavy at all. It will also perform.

My impala is 4300 pounds. It is very balanced from side to side like less than .5%. Front to back is 4% difference. At autocross events I'm tagging behind whatever the fastest lap time is by a couple of tenths. I'm usually doing it with a passenger screaming there brains outs to bring the total weight well past 4300 by a large margin. The Miata guys with no A.C., fuel cell, no radio, one race seat Ect.. really hate that. Cars like Cadillac Atack are good examples that weight is not a full detroment that will ruin a cars handling.

Don't let the weight of your ride or the parts that you may or may not have stop you from autocrossing! As long as the car is safe and a wont hurt you or it's self....Go play. Autocross is one of the most fun things I have done on this earth. And is way up on the list for fun with your pants on.

On a street car it`s hard to beat the gains of just moving the battery to the trunk.

I have had nothing but trouble with rear mounted batteries on late model LS1 LT1 type EFI cars. It really effects the programming and general happiness of the car if it's not done with a good amount of overkill.

I have checked out the body of the Chevelle fo excess bondo etc. Can't really find anything that explains the weight offset from side to side.
I am looking for a set of scales to do more measurements. I'll post more when I get some more numbers.
Anybody got any leads on a good set of scales?

Try unbolting your front sway bar. When I was running a "pure stock" dirt car we played with the link spacer length to put more weight on the left rear. Also check your tire pressure.

artmalibu, I think you may be on to something here. An inspection of the front suspension shows that there are two bump stops on the drivers side front!
I need to look into this. Good idea about the sway bar too.

Thanks

Let us know what you find. I do not have access to scales anymore so any info you provide about our Chevelles would be great.

Ok guys it took a while but I got my scales (Longacre) with a ramp system (which is too short for Chevelles). Getting it all set up is more work than I thought...
The car is:
4 door Mailibu, ZZ430 Clone (FAST Burn Alum Heads, Alum intake), 5spd Tremec, Currie 9" F*#d rear end, Mag Wheels.
Total weight (no driver) full tank, 3804 lbs. (heavier than I thought)
LF 1060 lbs, RF 1056lbs, LR 871 lbs, RR 817 lbs
Cross weight ratio: 50.6%
Left Weight based ratio: 50.6%
Front based ratio: 55.5%

So the distribution is better than I thought but the total weight is more.

The Norcal Chevelle Club will have a Weigh-In in May and I will get the weights and distributions from some of the members cars and post them with their permission afterwards.

Ron

Hmmm... the way I see it you picked up about 200 lbs in the back only (rough math).

Did you change the amount of gas in the tank? Got a mother-in-law in the trunk? ;)

Fun toys.

I thought the original readings from a quick weight check at the track was goofy. I was told by the Longacre people that the scales are NIST traceable so as they are new and in calibration I believe them.

The mother in law is in your neck of the woods; or is she?

Ron

Thanks for the great info. My 4 door scales in right at 4100 without the driver so I guess I need to go on the "aluminum heads" diet...

FYI, my corner weights last time I checked them:

LF 1028
RF 1042
LR 832
RR 850

Weights were taken last year with a Longacre corner scale setup. Now that I've changed to ATS spindles and SPC Pro-Lite uppers it shaved 11 lbs of unsprung weight off each side of the front suspension. I've also recently changed back to a smaller front sway bar which took off probably another 5 lbs or so.

FYI, my corner weights last time I checked them:

LF 1028
RF 1042
LR 832
RR 850

Weights were taken last year with a Longacre corner scale setup. Now that I've changed to ATS spindles and SPC Pro-Lite uppers it shaved 11 lbs of unsprung weight off each side of the front suspension. I've also recently changed back to a smaller front sway bar which took off probably another 5 lbs or so.

Is yours a coupe (2 door)?

Ron

Is yours a coupe (2 door)?

Ron

Yep.

Those weights were taken with 1/2 tank of fuel so with a full tank I'd expect an additional 40 lbs or so on each back wheel.