OK, I read through this thread 3 times trying to ascertain what force shock thingies (they are actually air springs not shocks) to use on the front of my Grandby. Seems the majority is 40 lbf, but some use higher (up to 100 lbf?) force springs.
Today, I went out and cobbled together a test of how much I am lifting at the front. With the rear raised and locked, lifting 22" from the front (as close to the front as I can get with the lift panels), I am seeing ~100 lbf to lift the front
Does this seem right? Has anyone else actually measured the force needed to raise the roof?
My camper:
1977 Grandby with 24" overhang, ceiling is 1/8" wood paneling, 200W solar on front of roof = ~35 lbf, Maxxfan in back.
I currently use a speaker stand jack to raise the roof, front and rear.
My setup:
Bathroom scale, scissors jack, wood blocks = 14.2 lbf.
The test:
With the rear raised, raised the front ~1/2 way so I could fit the jack on the overhang. Located the jack as close to the lift panels without touching and proceded to finish the lift with the scissors jack, while monitoring the scale. Took 5 readings on the way up (about every 3") and 4 going down. Readings varied from 95 lbf just before lock to 103 lbf at 1/2 way. Numbers were repeatable X2.
I am going to try to borrow a better system and re-do the measurements, as I was expecting 60 - 70 lbf, not 100. Maybe this explains why my roof bows so much when I raise the front (which is why I am considering adding the springs).
jim