Lippert Flex Air Installation

[BigGuy82]

I just oredered this unit and don't want to spend $100+/hr on labor for installaton. My guess is that the dealer will whack me at least 2 mechanics 2 hours each )and probably more like 3 x 2). After reading the installation instructions, it seems that a transmission jack, a socket set, open end wrenches, a torque wrench and one or two sturdy helpers will pretty much do the trick.

Has anyone installed (DIY) one of these 300 lb chunks of steel?

 

[Alan_B]

Try this: http://www.loveyourrv.com/installing-the-flex-air-pin-box-on-our-fifth-wheel-trailer/

And this: http://www.loveyourrv.com/lippert-air-ride-pin-box-review/

 

[BigGuy82]

Try this: http://www.loveyourrv.com/installing-the-flex-air-pin-box-on-our-fifth-wheel-trailer/

And this: http://www.loveyourrv.com/lippert-air-ride-pin-box-review/

Thanks! Very helpful.

 

[mlpeloquin]

I have and did it myself. Set forms up on the truck bed and parked under the king pin. Loosened up the old bolts and removed them. I had to pound the old original pin box out. It was in tight. The new one will have slop. I got some aluminum bar stock, 1/8" thick, and cut it to length. Marked the center of each hole and drilled them out oversized. Purchased new longer bolts same hardness. Trust me if yours is like mine you will need longer bolts. Put the new King pin on the blocking. Moved the truck under the fifth wheel and slowly lowered the front aligning the new king pin as I went. Once a set of holes align up, put a set of bolts in along with the shim between the king pin mount and the king pin to take up the slack, and start the nuts. Leave the nuts loose until all are in. (Now you do not have to shim it, but not doing so puts the welds under stress. The only problem with that is if you get hit in the rear, the welds could fail.) Lift the new king pin and align and install the other bolts. Tighten and torque 160 ft/lbs.

 

[JWalker]

Installed our FlexAir myself. Not to difficult.

 

[BigGuy82]

I have and did it myself. Set forms up on the truck bed and parked under the king pin. Loosened up the old bolts and removed them. I had to pound the old original pin box out. It was in tight. The new one will have slop. I got some aluminum bar stock, 1/8" thick, and cut it to length. Marked the center of each hole and drilled them out oversized. Purchased new longer bolts same hardness. Trust me if yours is like mine you will need longer bolts. Put the new King pin on the blocking. Moved the truck under the fifth wheel and slowly lowered the front aligning the new king pin as I went. Once a set of holes align up, put a set of bolts in along with the shim between the king pin mount and the king pin to take up the slack, and start the nuts. Leave the nuts loose until all are in. (Now you do not have to shim it, but not doing so puts the welds under stress. The only problem with that is if you get hit in the rear, the welds could fail.) Lift the new king pin and align and install the other bolts. Tighten and torque 160 ft/lbs.

Thanks. I'm not understanding what you did with the aluminum bar stock - can you elaborate? Also, curious why you didn't kick up to Grade 8 bolts instead of the Grade 5's that are on there. Shouldn't matter but you can get higher torque on higher grade hardware.

Thanks!

 

[JWalker]

Our stock box had 4- grade 5 bolts per side. Upgraded to 5- grade 8 per side. Cheap insurance. I had no problems aligning the FlexAir and installing it up into frame. Didn't seem to be any stress on anything. It is heavy!!! Used frontend loader on tractor. Worked well.

 

[BigGuy82]

Our stock box had 4- grade 5 bolts per side. Upgraded to 5- grade 8 per side. Cheap insurance. I had no problems aligning the FlexAir and installing it up into frame. Didn't seem to be any stress on anything. It is heavy!!! Used frontend loader on tractor. Worked well.

I'm with you on the hardware upgrade. The problem I have is that my son borrowed my front end loader and now he can't find it ...

I've got a transmission jack that will do the job, but I also think that using the truck's tailgate with the jacks on the coach is a slick way to go.

 

[JWalker]

I'm with you on the hardware upgrade. The problem I have is that my son borrowed my front end loader and now he can't find it ...

I've got a transmission jack that will do the job, but I also think that using the truck's tailgate with the jacks on the coach is a slick way to go.

After first install, I decided to raise the box up into the frame another set of bolt holes. I did use the tailgate trick.......very quick and easy.

 

[mlpeloquin]

The shim is for the difference in width. The new Trailair Flex Air is about 3/16 narrower than the original king pin. I did not want to add side stress to the welds holding the plates that the king pin mounts to. I used the same grade bolts because higher rated bolts are not required, added two bolts because I could, and torquing at 160 ft/lbs in the space that is there is not exactly easy. You have to get ether the box end wrench inside or the torque wrench. It doesn't matter which is which since both the head and nut ride on the washers. Do go back after your first trip and re-torque. I found two nuts and bolts that needed it. I used the torque wrench on the nuts on the inside, because it was easier to remove a socket than the box end wrench that jammed itself against the inside of the king pin.

- - - Updated - - -

Our stock box had 4- grade 5 bolts per side. Upgraded to 5- grade 8 per side. Cheap insurance. I had no problems aligning the FlexAir and installing it up into frame. Didn't seem to be any stress on anything. It is heavy!!! Used frontend loader on tractor. Worked well.

You may find it fit perfectly, mine did not. It was 3/16" narrower and when tightened it will put stress on the welds holding the kingpin mount that is attaching it to the frame. So I chose to make a shim to take up most of the difference. The grade 5 bolts are adiquit per OEM and I added two more one each side. Torquing to 160 ft/lbs is not fun having a box end on one side. Seen accidents with grade 5 bolts and a fifth wheel. The hitch will pull out of the truck frame before the kingpin bolts snap. So what will grade 8 buy?

 

[JWalker]

The shim is for the difference in width. The new Trailair Flex Air is about 3/16 narrower than the original king pin. I did not want to add side stress to the welds holding the plates that the king pin mounts to. I used the same grade bolts because higher rated bolts are not required, added two bolts because I could, and torquing at 160 ft/lbs in the space that is there is not exactly easy. You have to get ether the box end wrench inside or the torque wrench. It doesn't matter which is which since both the head and nut ride on the washers. Do go back after your first trip and re-torque. I found two nuts and bolts that needed it. I used the torque wrench on the nuts on the inside, because it was easier to remove a socket than the box end wrench that jammed itself against the inside of the king pin.

- - - Updated - - -



You may find it fit perfectly, mine did not. It was 3/16" narrower and when tightened it will put stress on the welds holding the kingpin mount the is attaching it to the frame. So I chose to make a shim to take up most of the difference. The grade 5 bolts are adiquit per OEM and I added two more one each side. Torquing to 160 ft/lbs is not fun having a box end on one side. Seen accidents with grade 5 bolts and a fifth wheel. The hitch will pull out of the truck frame before the kingpin bolts snap.

I understand what you are saying now. That is a lot of gap. And torquing down the bolts would pull the frame inward causing a great deal of stress. I did not have any gap. It's slid up in with very little tolerance.

I will say, I do love the FlexAir.

 

[mlpeloquin]

I understand what you are saying now. That is a lot of gap. And torquing down the bolts would pull the frame inward causing a great deal of stress. I did not have any gap. It's slid up in with very little tolerance.

I will say, I do love the FlexAir.

I do want to add that I watched a video of a FlexAir installation. They gunned the thing on and you could see the side pull in. And they did not torque. I cannot find that video again though. So the mounts attached to the frame apparently have a loose tolerance. With a loose tolerance almost everything will fit together.

I would not want to tow a fifth wheel again with out one. What a difference with the Trailair Flex Air pin box, Air Lift in the truck, and disk brakes.

 

[wdk450]

I repositioned my Flex Air pinbox by myself at my RV site using my multi ladder set up as a short stepladder, a 2X4, and my trailer bottle jack. I also had 2 13/16" end wrenches, a 13/16 impact socket, large tapered punch, breaker bar and torque wrench. I even did this in light rain underneath the pinbox overhang.

I wanted to move the pinbox down to the lowest set of bolt holes, and was able to do this by removing all but the top rear set of bolts, pivoting the pinbox down enough to expose the lower front set of holes, installing those bolts/nuts, moving the rear down, and installing all the rest bolts/nuts. The punch helped in holding things and getting the holes exactly aligned (along with leaving all bolts/nuts loose until all bolts/nuts were installed - there is some play in the bolt holes).

I modified the socket end of one of my end wrenches with 2 pieces of duct tape to make the nuts fit tightly for blind nut placement up inside the pinbox. I had to use a retrieval magnet tool one time for a dropped nut inside the pinbox.

In retrospect, the only thing I might have done differently is to install the bolts/nuts with the bolt heads INSIDE the pinbox. This is supposed to give you a more accurate torque wrench reading on the nuts rather than spinning the bolts. This DOES leave the exposed bolt shafts sticking out of the pinbox which is unsightly and may bind with the pinbox fiberglas trim. With the limited inside access, using a torque wrench on inside nuts is not an option.

I found that my pinbox air bladder had no air pressure, and now inflating this along with my truck airbags will be one of my last pre-departure steps. The air bladder stayed inflated for my short 1 hour trip from the Chula Vista area to Descanso, Ca.

BTW, does the group recommend inflating truck airbags under pinbox load, or is it ok to inflate them before hitching up?

 

[mlpeloquin]

I repositioned my Flex Air pinbox by myself at my RV site using my multi ladder set up as a short stepladder, a 2X4, and my trailer bottle jack. I also had 2 13/16" end wrenches, a 13/16 impact socket, large tapered punch, breaker bar and torque wrench. I even did this in light rain underneath the pinbox overhang.

I wanted to move the pinbox down to the lowest set of bolt holes, and was able to do this by removing all but the top rear set of bolts, pivoting the pinbox down enough to expose the lower front set of holes, installing those bolts/nuts, moving the rear down, and installing all the rest bolts/nuts. The punch helped in holding things and getting the holes exactly aligned (along with leaving all bolts/nuts loose until all bolts/nuts were installed - there is some play in the bolt holes).

I modified the socket end of one of my end wrenches with 2 pieces of duct tape to make the nuts fit tightly for blind nut placement up inside the pinbox. I had to use a retrieval magnet tool one time for a dropped nut inside the pinbox.

In retrospect, the only thing I might have done differently is to install the bolts/nuts with the bolt heads INSIDE the pinbox. This is supposed to give you a more accurate torque wrench reading on the nuts rather than spinning the bolts. This DOES leave the exposed bolt shafts sticking out of the pinbox which is unsightly and may bind with the pinbox fiberglas trim. With the limited inside access, using a torque wrench on inside nuts is not an option.

I found that my pinbox air bladder had no air pressure, and now inflating this along with my truck airbags will be one of my last pre-departure steps. The air bladder stayed inflated for my short 1 hour trip from the Chula Vista area to Descanso, Ca.

BTW, does the group recommend inflating truck airbags under pinbox load, or is it ok to inflate them before hitching up?

Bill, if the surface area on the bolt head and nut are the same and both have the same washers under them, then it does not matter weather the bolt head or nut is torqued. Surface tension is the determining factor for torquing. Most of the pressure when torquing is used to overcome the surface tension and the rest is to put the threads of the bolt into spring tension.

 

[BigGuy82]

Intreresting thought. To your point:

"Most mechanics will opt for grade 5 unless the manufacturer specifically requires grade 8 for warranty or safety issues. Often using a bolt or nut that is overly hardened can be more harmful than beneficial. So it is important to understand the stress factors placed upon the fastener as they relate to the base materials that they are being applied to.


"Sometimes, like in life itself, being a little more pliable than stiffly rigid can get you through the inevitable bumps in the road. "

This is from the folks at MRO Industrial Supply. Don't know if they know what they're talking about but it sounds logical to me.

On the other side of that coin, a technical guru at Lippert told me that #8's were cheap insurance. So the solution to me is quite obvious ... I'll use #5's on the right side and #8's on the left. Problem Solved !!!