flubyux2

is this right?!

i let my cousin drive my rx7 to school today, but the stipulation was he had to get it weighed at the rock quarry.

he came back and said the front weight was about 680 lb, and the whole vehicle weight was 2070 lbs. i flipped out. im expecting to hear 2700 lbs...but not 2070.

its an 1988 SE (Base) 2+2 seating, no power ANYthing (except brakes) and the seats dont evne have adjustable head rests. heres whats gone:

PS pump
AC comp.
AC lines
AC dryer
AC condenser
AC/PS bracket
Engine fan, shroud
Intake airbox and duct
stock exhaust, 2 whole cats, and guts from precat 1
spare tire out, jack out, tools out
subzero assist
stereo
FTP lenses
normal seat belts (not the power sliding junkers)
doesnt have rear window wiper or washer either.

is this even physically possible?

i did use the horsepower calculator. and using my trap speed and ET's w/ the 2070 Lb weight, it said 150HP at the flywheel.

if it is only 150 HP at the flywheel, im sorta disappointed. that means i only gained 10 hp from my K&N intake and race-only exhaust (basically 2.25" straight pipe w/ an Unpacked canister muffler)

thanks guys
chris

Scott 89t2

not right

silverrotor

iTrader: (1)

He was wrong. http://2ndgenrx7.freeservers.com/specsmaster.html

jarrod

dude sorry but he is wrong no way ...

man my car is gutted to the max and there is no way...


unless,...

he has no doors, hood,rear hatch,fenders,glass
1/16 tank of gas,5quarts low on oil.no H20
in radiator

CanadianRX7

Go on the highway at night and find a truck scale and pull up on it. It weighs the whole car at once and its free too use once its closed.

flubyux2

i just double checked w/ my cousin, apparantly his brain doesnt function normally till he gets a few beers in him.

it was Twenty seven-twenty! not Twenty-seventy...

anywho, i also had him weigh the Front. and its 680 lbs, meaning my front-to-back weight ratio is SHOT. it understeers SOOO bad now.

but, still, isnt 2720 WITH a 200lb driver pretty good?

chris

Cheers!

Canadian rx7... are you serious? i have never thought of that....

don't they turn off the scales at night?

telus.net

When I first saw the weight and the list of ***** removed, I was like, damn...those are stuff I am gonna remove...Exact same *****.

After reading the responses, my bubble is bursted!

flubyux2

do it anyhow man, it still helps. any dead weight you can remove makes a difference, even if its a couple pounds... itll all add up in the long run.

NZConvertible

Your mate seems to have trouble with numbers...
680lb on the front of a 2720lb car is a 25/75 weight distribution. Again, not possible!
Do you mean 680lb on each front wheel? That makes it 50/50. Much better! This is not the cause of your understeering problem...

CanadianRX7

Cheers they dont turn the scales off at night. Or atleast the ones i have been to havent. Go give it a try and i bet those scales are very accurate.

flubyux2

well, the scale at the quarry is on when they are open.

but, when you drive onto it, the front wheels go on first. so itll show the weight of the front wheels on the scale. and then when the rear rwheels come on, then it measures the whole car.

if thats nto why my car understeers so much, then what is the reason? cuz it sits like 2" higher than it used to.

chris

NZConvertible

Why?

flubyux2

didnt you see this?

most of the **** i took out, came out of the front, maybe 100 lbs. what did you think was gonna happen when i took all that weight out? is it supposed to Lower my car?

if so, i think the laws of physics cease to exist in my driveway.

my front suspension is probably really stiff now since the weight isnt in the front, compressing the springs, and planting the tires like it used to. so there is less traction.

like i said, it understeers like a ****. id like to return its tendency to oversteer, cuz its not easy to drift anymore. i have to use my throttle quite a bit now. and theres 2 ways to do it:

1. reduce traction in the rear
2. increase traction in the front.

i go for option 2, but im not sure where to start as far as improving front traction.

chris

telus.net

Most of the weight you removed are from the front. Therefore, your front will be lighter.

I think you should be tail happy now because your front is lighter than before. Also, you won't lose traction because your rear didn't lose any weight at all, thus, it would not reduce traction on RWD.

If you want to oversteer, try put the spare tire and jack back in. Drive it and see if it still understeer too much.

From my understanding, a lighter front should help oversteer.

NZConvertible

Removing only 100lb from the front of the car won’t cause the front to come up 2”. I can’t remember exactly, but the stock spring rate is around 200lb/in, meaning if you put 200lb on one on them, it’ll compress one inch. This implies if you have to remove 200lb to make the spring extend one inch. Now do you see why I asked? Your springs are just as stiff as they were before...
Yes the reduced weight will reduce the grip of the front tires, but I don’t think you’ve removed enough weight to transform your car from you say you can drift to an understeering pig. There are lots of other things that can make a car start to understeer. Incorrect tire pressures, worn suspension bushings, work shocks, incorrect alignment, etc. Check them all out.

flubyux2

you might have a point. cuz thought about my sit-e-ation a little more.

i took the weight out of the front, so since these springs are linenar, they are just as stiff as before, just a little more extended. but since the weight is gone, its not pressing down as hard as it used to. so the contact patch is smaller, and so it doesnt grip as well.

it might not have been 2" exactly, that was jsut an estimate. but the car DOES sit higher in the front than it did before, and that will raise my COG too, which wont help.

i think overall, my car wont stick to the road like it did before since theres less weight pressing the tires to the road, so itll push into the corners alot more than before.

i dont think putting MORE weight in the back will help, thatll make the rear tires grab more than before.

how can i lower the front end back down again? do i need softer springs?

would struts help my handling any?

im sure that stickier, wider tires will help in the front.

what do you guys think?

chris

maxpesce

You need to get SHORTER springs (Not Softer)
Moving the weight bias rearward should add Oversteer when BRAKING and add Understeer w/ POWER on - think Porsche 911
to alter Oversteer/Understeer the rule of thumb is to make the end w/ TOO MUCH traction Stiffer - Stiffer springs and/or roll bars. - to force weight transfer to the end with LESS traction. - in your case you would add stiffer roll bar and/or springs to the rear.

Ichiban

wouldnt you be happy it it weighted 2070

casue it would be much faster

thats why i ike old skool cars that weigh 900 rx2+ stock 13bt and whallah you have a 12.5 sec car

bloody good aight it

flubyux2

yea, i can get the rear end to drift out if i trail brake and then get back on the gas. Or, if i jerk the wheel to the outside if the turn and then back to the inside while hitting the gas, but it only works some of the time. the other times, ill just push REALLY Hard. it basically handles the way you describe the Porsche. when i get on gas into the turn, itll understeer and the tires will let me know.

well i can get my Center of gravity back down if i just use Shorter springs. but how can i get my grip back despite the lack of weight?

Barwick

Ok, listen.. Even if your whole car only weighed 2070 lbs, there is NO WAY that your front end only weighs 680 alltogether, I don't CARE what you pulled out of the front of it. It is just about impossible. Trust me, there is no way that is the case.

flubyux2

hey bud, i dont know if you read the whole thing, but i established that it was 2720 w/ the driver...

maybe it was 620 as a corner weight, im not sure cuz i wasnt there. so ill have to go weigh it myself.

but, i still need to get my handling back...i hate understeer.

chris

Barwick

yeah I read the whole thing, I was saying even if it was that light (which we already established it wasn't) that it couldn't be possible.

Just put a stiffer swaybar on the rear if it's really that bad, or put a strut tower on the rear and take off the strut tower on the front (if you have one on it)

flubyux2

yea, but, im not sure if puttin a stiffer sway bar on the back would Reduce my traction in order to induce the oversteer.

cuz if thats so, thats the wrong way to do it. the right way to do it is to Increase the traction in the front, and leave the rear traction the same. and im not sure how i would have to go about that...maybe some wider tires w/ stiffer side walls, and different geometry (caster/camber) Settings. i dont know if the struts and springs would affect anything. or what kind of benefit i would have from changing them. infact, i dont even know what kind of spec's i should look for when spring shoping for the car, since its not its stock weight anymore.

thanks
chris

btw, i dont have any Strut tower bars

wozzoom

Even if you removed 100 lbs from the front, your not going to disrupt the weight distribution of the car. Second gens don't have perfect 50/50 distribution. From the factory it was 51/49 front/rear. If anything, you're closer now to 50/50

If you've got handling problems, I'd look at your shocks and springs...worn sway bar bushings.

What are you using for shocks/struts/springs? Stock equipment?

FYI: My 86 Base weighed 2660 lbs without me in it. I have A/C, Sunroof, and a spare tire in the car... It sounds like the scale you went to was accurate since you had a 200 lb driver in the car.