So I put new torsion axles on my 5th wheel. I am the first to admit my boo-boos. it had a slight dog track before with the spring axles that I attributed to them being buggered up. Why I did not think they were put on crooked? Why oh why? :Facepalm: So I took it for the first drive. It rode great, is lighter on the truck, and turns more crisply in tight maneuvers because I put the axles closer together. All good. The bad? about a 2" dog track by my eye in the mirrors. Brakes are weak probably due to rust on the surfaces. These are new surplus but have been sitting in the yard for a while. I will pull them and clean up and refresh the grease. I will egg the mounting bracket holes on the one side and move the axle(s) a bit. I was going to start with 0.25" What do you think? Enough to start with or go more like 3/8"?
A tape measure can be used.
We use the tape measure. My big mistake was trusting the original axle tabs from the manufacturer. So my next move would be tape measuring the front of the frame or the back of the frame, trusting that they were built on square. The next maneuver is trying to get a clean shot through there to do an x measure.
the easiest way is if you can flip the trailed upside down. use a string line down the center and locate all your measurements off the string. Just guessing is a shot in the dark.
LOL that would really be handy! I don't think that piece of crap fiberglass fifth wheel would survive though
I use a plumb bob and a level floor. Mark the floor under the center of the king pin, mark the floor where brackets are and pull measurements on the floor. Make your adjustments on the floor and then plumb bob back up to mark the frame for the brackets or in your case how much the bolt holes need to be adjusted. No guess work that way.
I'll try that.
What JPV said, especially on something you can't flip like a RV. We also check that the whole trailer isn't tweaked too before we do axles.
Maybe you could just put smaller tires on the side that is the outside of the curve and straighten it back up, or scootch you 5th wheel mount to one side.
The frame is not what you are aligning. The king pin to the axle on each side must be the same. I often put a piece of pipe under the center of the king pin. Put blocks under the bottom to get close and lower the landing gear until it is snug.Then bump the bottom around until the pipe is true with a level. Then let it down a bit to be tight. Do not want it to move when you pull on the tape tie strapped to the bottom. Then align the rear to the front axle. Just a different way to accomplish the same thing. Measuring to tires or rims can get you in trouble.
My chicken eye and tape measure agreed, 1/4" will be the fix. I will get the front moved, inspect the brakes and bearings and put tires back on the front and then move the back and replace the back tires when I have them off. The bent spring/axle/dogtrack took them down well ahead of the fronts.
run a string parallel with the tire going forward to the the king pin distance. Measure from the string to the king pin on both sides. Make that measurement the same by moving your axle mounts. Do this for both axles. At 25'+ forward of the axles (where the king pin line is) you will be close enough to be aligned well. I have a laser alignment system, but the string does the same thing. String must touch the front and rear of tire sidewall without bending.
I went a little more than 1/4", more like 5/16". I drove it a couple of hundred miles and as far as I can tell, it is very close and looks great in the mirrors. I bedded in the new brakes and watched the hub temperatures, then backed off the controller once they started performing. I tried getting a good weight on each wheel at the Buckley scales, but they are an old balance beam set with the scale pad recessed down a bit. That won't work with torsion axles so I will do it at the scales on the way to the beach.
I'll agree, except for the plumb bob. I find a plumb bob only works well indoors. I guess I'd use a spirit level.
The brakes had surface rust all around, so I cleaned it all up with 120 and my air 90 sander, freshened up the grease, and I still had one that did not work. Oh well I figured I had a wiring error. Tracked it all down to an open magnet coil. luckily the axles I took off had the same dexter brakes and I robbed one. Being new, they were not all that grabby till I got them properly bedded in. I turned up the controller and got them pretty warm. I go out and feel the lugs and hubs and tires regularly on a new setup, and at each rest stop. Coming home over Chinook Pass, I made the section from the top to Cayuse Pass with one ~2 second long brake application on the lower hairpin. The rest was all exhaust brake I like having new brakes, and they are going to last a long time.