Anyone ever use scales to find your CG height? If yes, what was it? This is something I need to do on my car. The link below give good info on how to find your CG height.

http://www.jeepaholics.com/tech/cog/




Modified by 577HondaPrelude at 12:28 PM 11/15/2005

 

i've never done it myself. i use a cg height of 20" for my civic. it's a very rough number but gets things pretty close.

 

That's a great site. Thanks. Now I just have to hope Santa can get a set of Longacre scales down the chimney...

 

12 bathroom scales @ $5.99 each from Target, pieces of 2x12, and a coathanger rod cut up into a few pieces to use as rollers between the scales and the wood so that the suspension can relax after you set the car down with a floor jack. My car came in at 1880 lbs, I used 3 scales under each front, and 2 under each rear. I checked the car at 3 different positions on the scales, and came up within 3 lbs of total vehicle weight each time, so I think its accurate enough.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LBHgti &raquo;</TD></TR><TR><TD CLASS="quote">

My car came in at 1880 lbs, I used 3 scales under each front, and 2 under each rear. I checked the car at 3 different positions on the scales, and came up within 3 lbs of total vehicle weight each time, so I think its accurate enough.</TD></TR></TABLE>

I'm not quite understanding how putting multiple scales under the car would give you a good weight reading. Wouldn't they just max out the readings?

 

600 pounds on 1 board

3 scales under the same board (ideally equidistant from tire contact patch)

each scale receives ~1/3 or 200 pounds of load

same principle as 1 wheel holding up ~1/4 of total vehicle weight, just distributed between more points.

oh yeah, cool idea. how would you level something like that? shims and a laser level?



Modified by chjkingme at 12:22 PM 11/15/2005

 

wow. that's awesome! definetly gotta' put something like this together

I was also thinking of seeing if there are any scales at truck stops, anyone ever try this method?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chjkingme &raquo;</TD></TR><TR><TD CLASS="quote">
oh yeah, cool idea. how would you level something like that?
</TD></TR></TABLE>

Well, Everytime I hose the mess I made out of the garage, the water just kind of sits there, it doesn't pool up anywhere, and it doesn't all run out the garage, so judging by this, I'd say the garage floor is level enough. All the scales are the same height, and all the blocks are the same height, So its level.

BTW, its not really necessary to get the weight equally distributed over all three scales, so long as none of the scales are maxed out, just add up the numbers on all three and you've got the weight of that corner.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rollingCULTURE &raquo;</TD></TR><TR><TD CLASS="quote">wow. that's awesome! definetly gotta' put something like this together

I was also thinking of seeing if there are any scales at truck stops, anyone ever try this method?</TD></TR></TABLE>

That will give you a total reading, but not individual readings for each tire

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bosco500 &raquo;</TD></TR><TR><TD CLASS="quote">That will give you a total reading, but not individual readings for each tire</TD></TR></TABLE>

Sure it does, go back and look at his picture. There are three scales under each tire... add up the three readings, bingo, corner weight.

 

Anyhow, back to the thread, my mid-engine Mini CG height is 16".

 

Oh yeah....sorry about that

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">Sure it does, go back and look at his picture. There are three scales under each tire... add up the three readings, bingo, corner weight.</TD></TR></TABLE>

I was refering to rollingCulture's comment about using scales at a truck stop.

 

make something like these and you only need 4 scales

http://www.miatapower.com/race...n.htm

 

That was my first idea. The reason I went with the other setup is because of the sensitivity to proper positioning of the tire on the lever. If the car is not set EXACTLY at the same point on the lever on all four corners, you will not get accurate readings. Tires are not very acurate reference points, and I figured this would be more of a headache than it is worth. The scales were $6 each...with a lifetime warranty....total cost $72. Along with my ShopVac flow bench, I'm putting together a "build your own racecar" kit for under $1000 LOL


Sorry, you can have your thread back now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LBHgti &raquo;</TD></TR><TR><TD CLASS="quote">Along with my ShopVac flow bench, I'm putting together a "build your own racecar" kit for under $1000 LOL</TD></TR></TABLE>
C'mon Pat. You're not just gonna leave us hanging like that. Must see the Shop-Vac flow bench and the flow charts you've made with it...

 

http://print.google.com/print?...s6Jvs

saw this on google print (ironically while looking for something else). Looks like they have plans for a bathroom scale setup

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thawley &raquo;</TD></TR><TR><TD CLASS="quote">
C'mon Pat. You're not just gonna leave us hanging like that. Must see the Shop-Vac flow bench and the flow charts you've made with it...</TD></TR></TABLE>

oh, indeed.

 

The problem with shop-vac flow benches is that you need a LOT of shop vac's. Most of the ones I have seen use either 12 or 20 vaccum motors. That's a LOT of suck! Using only one or two will not produce acurrate readings.

 

I can't really get any actual numbers out of it....just figures to compare with other figures to see if I'm making progress or making it worse. I use it on the blow side, and measure the pressure in the runner. More flow = less pressure, less flow = more pressure. Its crude, but it works....and its cheap, like me

(still trying to figure out how to calculate compensation for temperature changes)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bosco500 &raquo;</TD></TR><TR><TD CLASS="quote">That will give you a total reading, but not individual readings for each tire</TD></TR></TABLE>

Truck scales work fine - they are pretty accurate, too (official interstate highway scales, not some cheap-o dump scale somewhere).

The ones I have used all have pavement around them so that you can drive just one wheel on to the scale pad at a time. I do a full weigh, then all fronts, then all rears, then all driver side, then all passenger side, then each wheel only, then each wheel only at a different place on the scale pad. The numbers aren't as close as a thousand plus dollar set of race scales, but they are pretty close.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MightyMouseTech &raquo;</TD></TR><TR><TD CLASS="quote">The problem with shop-vac flow benches is that you need a LOT of shop vac's. Most of the ones I have seen use either 12 or 20 vaccum motors. That's a LOT of suck! Using only one or two will not produce acurrate readings.</TD></TR></TABLE>

Are they connected in series or in parallel?

 

i read a portion of a book on google print called "how to make your car handle" the recommended the bathroom scale method as well.

how do you figure out what the center of gravity is?

 

Read through the link in the first post.

 

thanks i allways wondered how you calculated that.