Background
We bought our 1972 boler American knowing it needed a lot of work to restore it. Our trailer tracked fine during the initial 10 hour drive to its new home even though we thought it sat a little low. We had a big trip planned two months down the road and had a lot of work to do. We did what we could, when we could, where we could. New tires were installed while at Bolerama 2006 and they scrubbed the wheel wells on the way home.
Link to tire change post.
With less than 10 days to go before our big trip, we knew we had to do something before we left. We got a local welding shop to cut off the old axle, weld 2x2 square tubing to the underside of the frame and weld the axle back on. It was a cheap quick fix that worked not only for the trip, but also for the next year or so while I researched axles here and elsewhere on the web. There was a lot to learn about axles and a lot of varying opinions to filter through.
On the way home from our 1st big trip we came within inches of T boning a police cruiser as it came flying through an intersection against the lights. I distinctly remember the wide open eyes of the officer in the passenger side of the cruiser as he watched the front of my truck bearing down on him. The sound of squealing tires competing with the siren. Carol Ann remembers the faint single thank you wave as I finally stopped as the officers window passed her side of the truck. Once the adrenaline rush was over and the heart rate came down to normal my mind switched from uttering a flow of expletives to proclaiming the trailer was getting electric brakes if at all possible.
Once home we started to learn more about torsion axles. We compared our trailer to lots of pictures on the web, then read many posts on what others have done. Our 34 year old trailer showed all of the following:
1. Low riding appearance
2. Less than 3 clearance from top of tire to wheel well
3. Tire marks on wheel well
4. Minimal torsion movement in axle with bumper bounce test
5. Things bouncing around in the trailer, jumping out of cupboards etc.
6. Uneven tire wear
All this led us to believe we still had the original axle that needed replacing.
Comparing the specs for both Dexter and Flexride (2200 Lb axles) at the recommended down angles (10 and 24 degrees respectively) both provide for about 3.25 (+/- 0.1) of movement of the spindle between no load and shock load. Dexter has a little more movement between no load and loaded, that is trailer off the ground and trailer setting on the ground. Dexter is at 2.34 and Flexride at 1.69.
The spindle should drop about 2 when you jack up the trailer. When setting down on the wheels the trailer should have about 1.25 of movement between the body of the trailer and the top of the rim if somebody is jumping up and down on the bumper. If these numbers are out of whack, chances are your axle needs replacing.
Another way to check to see if your trailer is riding low is to level the trailer on level ground using the tongue crank and no jacks. Then measure the height from the ground to the floor at the door and compare that to the specs for your trailer. For the boler American, total height is specified at 6 11, inside height 6 1 giving a difference of 10. That should equal the height of the floor at the door.
There are a great number of discussions on leading arm vs. trailing arm configurations for these trailers. Many of our trailers came with the leading arms which have worked well over the years. Today the axle manufacturers recommend the trailing arm configuration. There are some reports of manufacturers saying that a leading arm is still OK. Consensus for leading arms seems to indicate that a low down start angle to up angle is what is recommended and that a high down angle be avoided.
Some have reported using brakes on a leading arm arrangement. This usually requires switching the brakes to the opposite side since brakes are left and right handed and all axles are currently manufactured on assembly lines to be trailing arms. For our trailer I chose to install a new trailing arm axle with electric brakes. I felt this would be the safest and that it could be done without major modifications to the frame.
Changing to a trailing arm, requires raising the trailer about 3.5 to allow the main bar of the axle to be located under the dropped kitchen floor rather than behind it. Raising the trailer can alter the center of gravity of the trailer making it more unstable side to side. I tried to keep the amount of rise to a minimum for stability, appearance, function and towing considerations. By using the smaller diameter tire and zero degree angle the net change was more in the line of 2.5 higher than stock. Considering the trailer had probably settled 2.5 over the last 36 years, the net change was approximately 5. Raising the trailer also reduced the air dam effect experienced in towing with my 4x4 Ranger.
In all honesty, it was a complex decision to make. I had to put all the specs for the various axle manufacturers into a spread sheet to compare the final ride heights and space under the wheel wells to accommodate the movement of the tire and axle. I then added various tire and rim dimensions into the spreadsheet to find the best match for my wants and needs. Keep in mind the original 6.00 13 tires are no longer available.
Many of the Bolers and its descendants have the body offset from the center of the frame by an inch towards the street. Some have stated that this is to balance the weight from side to side. I do not think that is the case because the side with the greatest weight is furthest from the frame. I feel this was done to maximize floor space by keeping the frame as close to the curbside closet as possible. The wider kitchen counter allows for the frame to be set further in without affecting floor space.
This in turn keeps the curbside of the trailer more in line with the passenger side of the tow vehicle, while the streetside extends further out from the TV. The end result is the wheel and tire end up closer to the outer body on the curbside than on street side.
How I did this will follow in the next few posts.
Replacing an Axle - leading arm to trailing arm, plus adding brakes (long post)
Apr 5 2009, 12:49 PM
