Howdy !!
Ok you boondocking, wrought traveling, dune busting freaks – you’ve decided to buy the 5th wheel trailer of your dreams, the one that you can pull with your new 4X4 pickup truck. Thoughts of going up into the hills away from the crowds in the campgrounds flow through your mind until your brain hears the sales person saying something about having to flip your axles on the trailer before you can pull it with your truck. “What’s an Axle Flip?” you ask. The sales man explains that your truck is 51 inches high at the top of the bed side rails. The trailer neck is only 52 inches high to the bottom of the neck, which means that the trailer has to be raised by about 4 inches to keep the neck of the trailer from resting on the bed of the truck – an unhappy experience !
Axle flips are becoming more and more common as 4-wheel drive trucks are used to pull fifth wheel trailers. The axle normally rides on springs which are located below the axle and held by a mounting plate called a spring perch. Because trailer axles have a pre-stress curve built into them they can only be installed in one direction. This means that to raise the trailer a new spring perch must be welded to the top of the axle and the spring re-installed above the axle. This will raise the trailer body between 4 and 6 inches from the stock height.
The Job – Lots of safety stuff here ! Have a buddy stay with you while doing the work, use good jacks and jack stands and make sure the trailer can’t move while everything is disconnected from under it. It is crucial to think safe before you touch a single thing !! If there are ANY questions in your mind about how to do this job take it to a pro ! Now that I’ve scared the dickens outta ya let’s get started.
While the wheels are on the ground, loosen the lug nuts by a half turn. Now use a floor jack to raise the right rear of the trailer enough so that all the wheels clear the ground on that side. Place jack stands under the frame of the trailer to support the trailer and then repeat the process on the left rear of the trailer. Make sure that the jack stands are rated at or above the weight of the trailer !
Remove all the wheels from the axles. The brake wires are now exposed behind the brake hub. If they are connected with twist nuts simply unscrew them and separate the wires. If they are crimped together, cut the wires to separate them. Remember to mark the wires so that they can be reconnected the same way when we get to putting things back together.
The axles are then unbolted from the spring pad and the U-bolts are removed. Remove the spring pad from the opposite side of the trailer the same as the first. At this point the axle is being supported at both ends by the springs. Place the floor jack under the center of the axle to be removed and raise the axle slightly above the springs. Now remove the center shackle bolt from the springs on both sides and using the floor jack, slide the axle out from under the springs and lay the axle on the ground. At this point you can re-attach the shackle bolts to the springs. Now repeat the process with the other axles until all are on the ground.
Spring perches can be purchased from RV and trailer supply stores. You will need to tell the folks there the diameter of the axles and the height of the perch. If there is any doubt as to the size you need simply measure the old ones and order the same size.
Place the axles with the old spring perch pointed down and clamp the new ones to the top of the axle. Ensure that the new ones are directly over the old by using a straightedge or a square. Next measure the height of the ends to make sure that the perch is even on the axle. Use a hammer to lightly tap the perches into place. Now that the perches are clamped and aligned we can do the welding. Remember that this is where the entire load of the trailer on the axles is being carried as you go down the road so the welding must be first class. If there is any doubt, have the welding done by a pro after you have removed the axles from the trailer. Another thing is the alignment of the perches, they must be even to each other on the axle so when the springs and trailer are back on them the whole critter doesn’t go down the road sideways.
Now, using the floor jack, slide the axles under the springs. The new spring perch should be facing up. Adjust the axles so the new perch is centered under the spring in the same location as the original. Re-attach the spring pad and U-bolts to the axle. Repeat this process for each axle. Now reconnect the brake wires for each wheel. If wire nuts were used on the brake wires you may want to consider using crimp connectors. They produce a better water proof seal and provide a better mechanical connection.
This is also a good time to check the condition of the brake shoes and bearings before replacing the wheels on the brake hubs.
Use the jack to raise the right rear of the trailer and remove the jack stand on that side. Lower the trailer back onto the wheels and repeat the process on the left side of the trailer. Use a ruler to measure the height of the rear and front edges of the trailer to make sure that it is level. Now measure the height of the pin-box to see if it is high enough to clear the top of the truck’s bed. Ideally there should be between 4 and 6 inches of clearance between the bottom of the trailer neck and the bed of the truck.
There are a few things to check now. The umbilical cable for the trailer lights, brakes and power may be a bit too short. Your options are to relocate the receptacle or put on a longer cable. The trailer will tow a bit differently now that it has been raised and it will brake differently. Take it out to an empty parking lot, or open area, and practice making turns and stops with it until you feel confident enough to get out in traffic with it. After you have towed the trailer for about 50 miles check the u-bolts and spring shackle bolts to make sure that they haven’t loosened. Also check the wheel lug nuts. Repeat this process at 100, 200 and 500 miles just to be safe and sure.
Having a flipped-axle trailer will also provide you with extra benefits, like increased ground clearance so that you can try some of those back country roads that prevent others from being able to follow. Yee Hawww !!
Later – –
The Old Ranger