: Forward/Backward COG


Way
08-19-2002, 01:26 PM
Anyone weigh and calculate their COG from front to back. I weighed my heavy ass rig a few months back and got this data:

5740 Full Weight (2603.62 KG)
2680 Front Weight (1215.62 KG)
3060 Rear Weight (1387.99 KG)

This works out that 46.69% is up front and 53.31% is in back. How do I figure out at what point this is at exactly? Stock SWB Range Rovers are 175" long and have a 100" wheelbase. Mine has a rear bumper and a front bumper that add about 12-15" on both sides. Making it 205" long overall ish. Can I just take 53.31% x 205" and get 109.29". It makes sense to me that my roll center front to back would be 109" from the ass end of my vehicle. Is this right? I went to a feed scale place and they zeroed their scale and that is how I got the LBS on my vehicle. It sounds heavy over stock, but then again I have a lot of shiat on my vehicle.

In case you are wondering, I am trying to calculate antisquat % and see where I am at currently, and what effect would happen If I lengthen my rear arms by a few inches to move the rear axle back. Also curious about mounting points on the axle end. If one goes with a Rovertym style heim joint set-up and moves the frame mounting location up, what effect does this have on rear suspension geometry in relation to antisquat. Assuming that your mind is set on frame mounting location as it is the one that always gets hung up, what would be the best was to to counter the movement of the frame mount up, on the axle mounts? Curious about axle wrap as well? Seems to me that making the rear links and the A-arm mount furhter apart would help things out??? However, on the general 4x4 section I always hear that they think one should make the rear links fairly horizontal??? Ideas??? Anyone toy with the idea of making the rear arms angle horizontally in or out? With a wider rear axle like Doug Ms D70, for instance, he would have the option of doing this.

Way

road1will
08-19-2002, 02:00 PM
jesus adam... i think you are overthinking this a ton. just do it and see what the hell happens!

JSBriggs
08-19-2002, 02:09 PM
I do recal an old saying about the color of kettles and pots...or somthing like that...Lets face it we are all tech junkies.

-Jeff

RockRover
08-19-2002, 03:25 PM
Dude...Use this:
http://www.jeepaholics.com/tech/cog/#_Toc535118730

I plan on doing this someday soon to find were my CG really is...Not so much for the X axis, but for the Y axis CG...I've had enough jack stands under my rig to know exactly where my horizontal CG is...However I really want to know were my vertical CG is.


It's gonna' be tough to run a rover chassis and have little anti-squat, and still have enough separation between your lower and upper links....Especially if you want to run with your fuel tank in the stock location.

Now that my rig is on all four's (at last!) my only real words of advise is to pick a design that's been proven before, make sure it will work within the limitations of your vehicles dimensions, build it stout and then execute.

If you get too hung up on roll centers, axis, CG and anti-squat, you will quickly find out that the only way to maximize all of the above is to build a custom chassis...And that my friend is a chore to do right the first time!

--D

JSBriggs
08-19-2002, 03:27 PM
Now that my rig is on all four's (at last!)


PICS!!!

-Jeff

RockRover
08-19-2002, 03:58 PM
Coming! Didn't have the gerd-dern digi-cam with me last night...

I have to say...In my humble opinion, that it F'IN ROCKS!!

She looks sorta' Fat City Bronco'ish (without all the killer fab work!)...Big and fat and low.

--D

Way
08-19-2002, 04:19 PM
jesus adam... i think you are overthinking this a ton. just do it and see what the hell happens!

I know some people on the board like to evaluate and make educated decisions and others like to make tin foil underwear and post pictures. To each his own I guess. I personally feel more comfortable making educated decesions and discussing popular topics in the general 4x4 section but on the Land Rover section where it is more Land Rover specific. :flipoff2:

In retrospect, I wish I would have asked more questions when doing my Dana 44 swap. Since I didn't know of anyone that had made custom brackets for theirs, I figured people didn't have anything to contribute. Boy was I wrong. It turned out great, but lets face it. What could have been a weekend job took me several months to get everything figured out and executed. LUCKILY I ended up only needing to do everything once, with the exception of the panhard rod mount on the axle, which I am still contemplating doing over.

Doug,

Thanks for a link. GREAT SITE.

WBCOG (Wheelbase Center of Gravity) formula:
(1 - (WF / Wt)) * LWB = WBCG location, in inches, behind the front axle.

Where WF=Weight on front axle
LWB= length of wheelbase
WT=Total Weight

So I get (1-(2680/5740)) * 100" =WBCG
(1-(.466898954704)) * 100"
.533101 * 100"
=53.31 inches behind from axle (measured from hub center I think).


I haven't measured the passenger side of my vehicle before so I can't do “Y” The Wheel Track Center of Gravity (WTCG). But very cool site! Makes me all warm and fuzzy inside...oh shiat did I type that out loud..I should be locked in a round room.

Way

redrangie
08-20-2002, 10:13 AM
Originally posted by Way


I haven't measured the passenger side of my vehicle before so I can't do “Y” The Wheel Track Center of Gravity (WTCG). But very cool site! Makes me all warm and fuzzy inside...oh shiat did I type that out loud..I should be locked in a round room.

Way

Geek alert!!!!!!


:flipoff2:

Way
08-20-2002, 11:24 AM
Why!?!, in one of my 4x4 pictures can you see me with tin foil antennas and matching underwear watching star trek or something in the background??? Damn, I will have to be more careful where I take my pictures.

Way
Oh yeah...













:flipoff2:

redrangie
08-20-2002, 11:31 AM
Originally posted by Way
Why!?!, in one of my 4x4 pictures can you see me with tin foil antennas and matching underwear watching star trek or something in the background??? Damn, I will have to be more careful where I take my pictures.

Way
Oh yeah...













:flipoff2: ROTFLMAO !

lwg
08-20-2002, 10:05 PM
And we thought Physics was just for High School!


I do more thinkin' reading these post then I do setting up and testing Million Dollar computers. That's some crazy shit!

Way
08-20-2002, 10:12 PM
More like scarry shiat for the people paying for the computers......:flipoff2: LOL

Way