Calculate tongue load from wheelarch height?

jumpy · 08-09-2005, 07:13 PM

Got into a discussion with a friend based on the low rear ride height of my 04 CC 4wd with tow pkg while towing a load of hardwood flooring. I have been thinking about creating a gauge that will tell me my tongue weight for a given load based on my rear wheelarch height. This is just a curiousity...I have scales and such that can measure directly but I thought the basic engineering exercise would be interesting. I am having trouble finding any info on spring constants for the rear leaf springs. Can you offer help?

92TripleBlack · 08-09-2005, 08:29 PM

Probably could. Wouldn't work for mine. I have the air bag leveling rear.

rjspitz · 08-09-2005, 08:41 PM

Gonna be kinda hard. Since different loads are spread out differently within the bed, the actual weight on the springs will differ. These numbers are not right, I'm just guessing at numbers, but the logic is right. If you load 500 lbs. in the front of the bed, the rear springs might see about 70% of the weight and the front 30%. If you move that same load into the rear of the bed, the rear springs will see 110% of the load and the front will lose weight due to the seesaw effect. If the 500 lbs. is directly over the rear axle, the rear will see 98% and the front 2%.
This will work if you're only talking tonge weight, since the load center of gravity is constant, but move that weight around, and your math will be way off.

Good luck if you figure this out. I'd like to use if it works.

jumpy · 08-10-2005, 07:08 PM

Thanks! I am going to conduct an experiment where I record the stock height and each change after the addition of 25 pounds to the hitch up to 600 pounds. Also going to look for a tongue load limit buzzer.

Thanks