Weigh your rig on Digital Scales

Yay!Gurrr

Yay!Gurrr

Better Faster Stronger
Moderator
Joined
Mar 17, 2005
Location
N. N. Raleigh, NC
I've got some digital scales on loan from Hi-Line Performance, so for the next 6 weeks. I will be scaling rigs at my house. These scales are accurate to 1/10th pound. Max weight is ~6000#

$30 – up to 1 hour of scale time for 1 rig.

I will email you a spreadsheet containing the following:

- corner weights
- total weight
- COG Height (* Z Axis)
- COG Left/Right (* Y Axis)

Again you have 1 hour so bring all your tools, gear, tires etc. with you and we can take readings as needed.

I will only have the scales for about 6 weeks, so PM me to set up an appointment. I will be available most evenings after 6pm and all day weekends. Email or PM with any other questions.

Edit: I've decided the COGh #s are not worth my time or effort, they are not very accurate with the method im using therefor probably not worth useing for anything other then general information... I do not have a lift or other safe method of rasing 1/2 a vehicle to obtain more accurate readings.. I will still be doing corner weights and will do that to $30
 
oohhhh... cool...

I'm down for that... with the CoG. Have to figure out when i can drag my pile up there. (Assuming it's still mobile after this weekend at DPG)
 
mine came out better than expected.... guess having 1500# of axles and tires is good for somthing...
 

Attachments

  • yager-cog.jpg
    yager-cog.jpg
    72.1 KB · Views: 350
Nice low Cg Mike... I'm estimating mine at 36" or so.. but we'll find out soon!
 
Yes to calc the COGH (height) you need a measured weight shift, and how high the new reading is. (really could tip any side you wanted) You can calc. the COG L/R and F/R with the flat % numbers, but you need the shift in weight to calc the cogh (height)...
 
Thanks for taking the time this AM Mike I am very glad I did this.. it has turned out to be very helpful info for me.

Here are my numbers with out me in the rig..
 

Attachments

  • COG.jpg
    COG.jpg
    61.8 KB · Views: 264
If you look at both number you can see the Center of Gravity changed A LOT when I was in vehicle compared to when I was out....

Very interesting numbers...
 
I'm having a hard time understanding that.. a 14" CoG change just from putting your butt in the seat? Let's compare your rig to Mike's for a second..

He's got heavier axles.. low CoG.
Hummer wheels.. low CoG
You've got a ton of sheet metal and glass up high - high CoG.

Yet your rig shows 8" lower CoG than his.

The 36" makes sense, but not the 22". It just doesn't add up...
 
yes but i have a lot of tube in the cage and front hoop etc.. gas tank in the bed... Some on the pbb had the same questions... Ken is ~180 if you've ever cut a unibody apart its stong be design not mass... glass ok.. few 100#s but it spread around...

Also its COG aka center of mass... scales don't see the belly clearance under the rig.. Its strickly the single point you'd hang it by on a string..

I'm gonna do mine again with me in it and see how much it shifts. Ill bet it's similer.. :)
 
OK, the tube, gas tank higher, etc..

but you could never design a suspension if it was going to change 12" every time a person gets in...

If I punched a 22" Vehicle CG height into C6 on the link calc, I get 120% AS on the suspension. Changing it to 36" takes me to 69%. That's a HUGE difference in how it's gonna work.

It may be right, but if that's the case, many experienced people have been throwing darts at numbers..

P.S. The Z-axis COGH number you come up with is what I'd be putting in that cell, right?
 
Rich your right any suspension will change. The second you tip/tilt or other wise do anythign different than your flat static calcs (like drive it off road) your numbers will be different... This is why some peoples rigs don't climb well or do wierd things off camber..

what numbers are you using in the 4link calc? with whos suspension ?

Im not sure what your point is about darts and numbers anyone doing any designing would be using real, as it will be driven data to do any desing. Not an empty chasis and hope to fudge the rest.

The thing with Ken's rig is that the driver seat is almost in front of the COG point that him hopping in caused a large shift... If he had a cage and high tire etc. him hopping in probably would have skewed things as much... He'd have had a higher 'empty' reading from the beginig..

anyway...
 
Hey yager maybe we should get about 4 rigs to either stop by and/or set a meeting place so we can get some more numbers to compare... I know Carl R.. said he would love to do his but he is in Fauqay and that is a long ride to your place...>?????
 
Ya im open to that... Not sure where a good central place would be ? If we can find a spot and line up ~4 people I won't worry about dragging all the stuff over... (with my tractor)
 
I've got a pretty level garage pad...
 
yager said:
what numbers are you using in the 4link calc? with whos suspension ?
Click to expand...

I'm using my numbers, with my proposed suspension, only altering the CG numbers, just as an example

Im not sure what your point is about darts and numbers anyone doing any designing would be using real, as it will be driven data to do any desing. Not an empty chasis and hope to fudge the rest.
Click to expand...

My point was: If adding one standard sized person can alter CG that much, then you cannot possibly begin to design something to a goal, since the performance will change SO drastically as you move a bottle of water from the cooler to the front.. :p

The thing with Ken's rig is that the driver seat is almost in front of the COG point that him hopping in caused a large shift... If he had a cage and high tire etc. him hopping in probably would have skewed things as much... He'd have had a higher 'empty' reading from the beginig..
Click to expand...

Basically, what I'm saying is I don't get the original, empty number. According to that, he's got as much weight below 22" as he does above. 22" is very low, and only includes the axles, and about 2/3 of the wheel/tire package. With the bottom of his door being 31" above ground, you can easily figure that a large majority of the engine weight (probably as much as the F&R axles weigh or close to it) is above this, and the trans & t-case are around that ~31" height. I just can't see how it all evens out..

In the most simplistic terms, the Vertical CG is just the "average" of all the weights of components, and their height above ground, ya?
 
last part yes....

on the mass distribution, with out going higher for the readings it not that acurate i guess if the scales were sensitive to a 1/10th pound you'd have enought resolution to say its precises. I redid mine COG tonight and other than a 15# differece in total weight from tools and computer crap the COGh empty moved down to 27.9 and with me in the jeep it went to 29.5 (original empty was 30) so as you can see its just a rough guide.

Honestly now i see why my brother said most don't even bother measuring for it... And to just use camshaft center line as a good estimate.. Which is with in 4-5" of all my #s... I think ill be skiping those COGh reading unless people truly want it..

sorry to get everyone all worked up :)
 
As posted above: I've decided the COGh #s are not worth my time or effort, they are not very accurate with the method im using therefor probably not worth using for anything other then general information. I do not have a lift or other method of safely rasing 1/2 a vehicle higher to obtain more accurate readings.. I will still be doing corner weights and will do that to $30... Thank You
 
engine hoist to the frame and a center limit strap to get the back up, then let it down onto the scales?

I've heard the cam centerline, or top bellhousing bolt, etc. too.. I'd hope mine is a little lower than that...

I'd still like to weigh it though...
 
Rich ill still do the COGh but im not going to say its anything other than informational. IE. you suspension doesnt work right so the numers but be suspect...

I've got an easy way to get it rasied 10" but anything over that you really need a ramp or a drive on lift..
 
Back
Top