427V8

I borrowed a wheel scale from a friend, it measures the weight of the car one wheel at a time. You weigh each corner and try and ballance it.

I did my baseline tonight, but need to do it again with sandbags to simulate the driver weight, but I got VERY interesting results!

( almost empty gas tank )

____Front____
820______880

880______760
____Rear_____

Front total = 1700
Rear total = 1640

Total Car = 3340
Me 200
-----------------------
Total 3540

Note that a truck scale said my car with a half tank of gas weighed 3480 lbs...
so they agree within 80 lbs or 2.3%! Wow


Notice the difference between the two rear wheels! No wonder this car hops to the side over bumps, and it would be worse with my 200 lb butt in there!


[Modified by 427V8, 8:20 PM 11/21/2001]

Scott78

Why such a big difference left to right rear. Heavier on the driver side, right?
I imagine the battery makes a little difference , but what else?
Scott

norvalwilhelm

That is alot of weight difference on the back. All motors are offset to the right so that explains the front but a battery is the only think offsetting the back.
Can weight be jacked from side to side with either the springs ? in this case adjusting the spring bolt and in the front by jacking the weight with the sway bar by preloading one side?

MIKER

This is going to be a very interesting thread to watch!

Pete79L82

keith;

You are defenitly on the right track but let me go over the procedure for scaling a car. You may have already done all of these but i will list them anyway.

1. The car must be perfectly level. When I scale a car I use 4 scales of exactly the same height and then put shims under them (plywood cut in squares work good) to get them level front to rear and side to side. If you are using only 1 scale then make 3 platforms the same height as the scale so the car will still sit level. Most driveways and garage floors are pitched for drainage so if you don't level everything your readings will be inaccurate.

2. the car must be in nuetral. If the car is in park(auto), in gear (manual), or the parking brake is on then the suspension will bind up and your readings will be inaccurate.

3. The tires must have the correct amount of air in each one. One pound of air wrong in any tire can throw your numbers off as much as 20 pounds on the scale.

4. Put in the amount of gas you plan on running. Gas weight about 7# per gallon. You said your tank was about empty. If you added 10 gallons of gas that would have add 70# to the rear plus transfered some weight off the front which would give you 51% rear instead of the 49% rear you have now.

You will want the left rear wheel to be heavier than the right rear to compensate for inertia developed by the rotating mass. (the rotation of the engine and the driveshaft. 40 - 50# would be a starting point. The more torque you have the higher that number would have to be.

You will want the rear to be heavier than the front. 51 - 52% would be a starting point. Too much rear weight will cause the car not to want to turn (understeer) in a corner. Not enough rear weight will cause tire spin off the start and the car will be tail loose in a corner (oversteer).

If the spread between your left rear and right rear is that high after you check everything, measure your frame heights when the car is level and see if any corner is sagging caused by a weak spring.

Let us know!

Lohkay

Hey Pete...Everytime I see a post from you I get confused...thats not u in the pic right? Cause if thats the case you sure have a lot of experience for you age. :)

Pete79L82

no, thats not me in my sig. That is my son. He seems to have taken over ownership of the car (or so he thinks) :cool:

BSeery

Whoa -- you gotta put a stop to that right now !! Have him get his own Vette so the both of you can spend father/son time working on it togeather.
For him to get a good car without the work in my book is a bad thing. They don't learn to respect the cars, and the way they treat the cars on the street will prove that.
Time for a nice mid 70's project Vette. He gets a car and you get to help him work on it.

Lohkay

I totally agree with you BSeery....I ain't a father...I'm actually the son. ;) But that vette was mine to begin with...I know I didn't treat her good and it shows. To be fair with her, I'm giving her a complete facelift. :D I say buy him a '77-'80 in so-so condition so he learns to work on it and to spend his hard earn cash on it...then he'll understand...

redvetracr

427V8,
As stated above you need to scale your car on 4 electronic scales WITH you in the car. Anything else is unfortunately a waste of time. There is very little adjustment BUT you can get a slight change with your rear spring bolts. My car would be 50-50 side to side if not for the extra 60 lb ballast in front of the left rear wheel (my middle!). My car is also 200 lbs heavier in the rear and "turns in" perfectly. But then again it weights in the neighborhood of 600-700lbs lighter than the "average" Vette. ...redvetracr

Racer16k

Probably a weak spring in the left front. What measurements do you get with the shocks disconnected. A quarter of an inch difference in front spring height with stiff springs will jack around a good deal of weight in the rear.