Ron Gratz wrote:
RinconVTR wrote:
A tongue weight scale runs around $130. It will answer the question, with absolute accuracy, and no estimations.
Absolute accuracy??? I guess that depends on your definition of "accuracy".
There are several threads and many posts on ORF discussing the accuracy of one particular tongue weight scale.
This thread is just one of them.
I suggest anyone who thinks they can get "absolute accuracy" with a tongue weight scale should read the user comments.
Perhaps the simple formula offered by TundraTower in this post (as requested by the OP), reduced by 10% to account for the effect of axle spacing, will produce an estimate which is more accurate than the reading from an "absolutely accurate" tongue weight scale.
Ron
Ron,
With all due respect I would have to agree with RinconVTR on this.
I really do not think that the OP was looking for a way to calculate the exact change in tongue weight down to a fraction of an ounce..
While you are very welcome to show off your mathematical prowess it is not needed or as complicated as you are making it to be.. The OP (like I was at one time) is looking for any GREAT MASSIVE changes in the tongue weight for a given amount of weight added to the rear bumper..
Typically you do not need to know the exact weight to the ounce of what the tongue weighs, really a "ballpark" number can suffice..
Given you have tongue weights of 400-1,000 lbs or more you can have a acceptable error range of + (-) 10 or even 20 lbs..
It will never hurt a thing for trailer stability as long as you don't go under 10% AND provided long as your trailer tongue weight is not already on the tippy top brink of overload of your vehicle you have nothing to worry about.
What you are really missing is something called Center Of Gravity (AKA COG).. Your calculations are missing that and that will give you massive errors when driving down the road..
COG is a dynamic measurement and it messes with the tongue weight as you are towing..
Think of a trailer as a old fashion "teeter totter".. The tongue on one end , the rear of trailer on the other and your axles are placed in between..
The tongue weight IS fluctuating while your are driving down the road.. As the tongue goes up the COG shifts towards the rear and the tongue goes down the COG shifts towards the front. Your calculations are only good for a dead stop standstill..
Typically for bumper pull trailers the axles ARE placed using the "60/40 rule" or the "2/3 rule".. In other words the axles are placed at 60% from the front which will be 40% from the rear.. That IS the same as axles are 2/3 back from front and 1/3 from the rear.
This rule is pretty much across the board used for all bumper pull trailers in the North American part of the world.. It IS the recommended placement per Dexter and other axle manufacturers..
Using the info I posted you "dissed" earlier for ALL intents and purposes IS "accurate" enough for the OP to determine if the weight they plan to add to the rear will remove TOO much weight from the tongue..
Using 1/3 of the weight added to the rear as being the amount removed from the tongue I mentioned WILL be close enough.
As far as you "dissing" the Sherline scales, I don't have one, instead I use the bathroom scale method.. It works very well.
Sherline scales accuracy depends on PROPER placement of the scale, you MUST place it correctly under the ball part of the coupler.. Any other placement will introduce errors.
I also took multiple measurements then averaged them, this way I could rule out possible read errors or scale errors.
I also checked my bath scales against a shipping scale which is used for shipping freight via UPS/Fedex and even large bulk freight shipping companies (pallets).. I calibrated my scales so they would be as close to possible to known scales that have been verified as accurate.
The silliness of where this thread has gone is just unbelievable..
