Tag axle pondering

[mcapri92]

The learning curve has been steep since purchasing this 1993 Classis 360 last summer. However, I have hit on one issue that I don't have enough knowledge of how it was supposed to work to know if mine is right.

In the last month, I replaced the brakes and greased the bearings on the tag axle and learned about how it is made from unobtanium. Crossing my fingers and praying, I hoped for the best. While I was in there, I noticed the bushings on the air valve lift rod (that connects the trailing arm to the air control arm) were dry rotted one one side and missing on the other. The side where they were missing had bent the 90 degree rod which is welded to the trailing arm. Well, I replaced all the bushings and bent back the rod to match the passenger side. I also tested the axle by the means I found here (drive up on a block, tag axle should drop 3", at rest make sure trailing arms are pointing down or horizontal and not up).

I took it out for a drive tonight and it is definitely a harsher ride than it was before. I suspect it is pumping up the air springs more than before as the compressor ran a lot longer than usual for driving (I was trying to decide if it was the road or the changes I made, but determined it behaved different enough it was the changes). Since I didn't own this when it ran right, I don't know if the harsher ride is normal, or if I need to adjust the tag to not put as much air in the springs. I know the books all say this is adjusted at the factory to put the proper weight on the tag.

I know this is a rather ambiguous question, but I am not sure if there is a proper ride height I should be looking at (distance from rim to belt trim?) or some way to check to make sure this isn't taking too much weight off the tag.

Thanks,
Tim

[Smartstream]

Check out this video. https://www.airforums.com/forums/f31...ube-46363.html It shows how the axles work in the first minute or so.

I believe the 3" drop might be more appropriate for lighter weight trailer axles.

The ACE spec calls for a 10.625 ride height. This measures bottom cross beam to top cross member, or air bag height.



I believe the only way to check the tag is by weighing each axle. I built an air ride tag for my 345. https://www.airforums.com/forums/f31...-183003-4.html It starts about post #65. It's probably more than you wanted but it should answer your questions. When you get to the posts showing weighing the axles you can see where a small air pressure change in the bags which changes ride height, shows up in the scale weight on the tag and drive axle. It's an interesting system and all the components must function with each other to make it work.

By the way Miss Behaven is starting the conversion on his 345.

Any questions feel free to ask.

[mcapri92]

Holy Cow....I am saving that link on your build for the future. That is relieving to think their might be hope if this tag dies on me.

I had found the 10 1/2" dimension last night after posting, but wasn't sure where to measure on the air bag. The diagram helped, thank you. After pressurizing everything, I measured and am exactly where it is supposed to be.

I also checked the lever arms this morning on the tag axle for the air valves and they are set up to the same dimensions on each side at this point, which I am sure they were not when I bought it with the one being bent. The are rusted enough that I feel comfortable that this was how they came from airstream....and I would be scared to even try to adjust them for fear of breaking.

I wouldn't say my tag dropped 3" when we put the drive axle up on 6" blocks. It was probably closer to 2". I am gauging from pictures my wife took since I was in the drivers seat with my foot planted securely on the brakes

At this point, I will conclude that everything is working the way it is supposed to and the ride is just stiffer now that everything is correct. Thank you for all the help!

[Smartstream]

It is a problem all of us with tag axle will have to deal with at some time. My biggest concern is the hub/drum. If you lose one you are in serious trouble. I can see many running mismatched wheel size and type on the tag just to stay on the road.

Good luck with your coach.

[mcapri92]

Yeah, one of the many things that keep me up a night.