Coupler assembly aka 5th wheel

[NickelPlate]

Hi All,

I just spent nearly the entire evening assembling the 5th wheel coupler with the MFC switch on my new Grand Hauler. What a gigantic PITA . Anyway I'm not even sure I got it right. I have a trailer with the motorized support legs and all three kits came with their own 5th wheel. I was reading on janderson's build article that he built the "motorized support" leg version? Is that somehow different from the MFC version?

Also which way does the hold spring go (shown below)? Is the 5th wheel supposed to be normally sprung back or forward? And how do you guys route the coupler switch wire? Out the front or back? I had to bend the leads just to get it to fit which didn't seem right.

Anyway I'm thoroughly confused on this. Any help is appreciated.

[mavrick0]

The motorized leg kit has extra pieces that attach to the fifth wheel to be able to push the switch mechanism on the trailer to make the landing gear go up and down.

The spring on the side should sit so the fifth wheel is tilted towards the rear of the truck. As for the coupler switch you do have to move the wires a bit to get it to fit in but I've never had an issue with that. What I do is I usually take the connector off and side down a piece of shrinks tubing to cover that wires and then route it through the fifth wheel plate and through the frame.

[ricm]

yes, it is confusing....you need to simultaneously cross reference between the MFU installation manual and the support legs instructions...

there are basically 3 types of 5th wheel:

1) there is a basic oval type version, similar to the one in your pic. I think this is a 'Euro style' design, it comes with Scania R620 and probably the other cab over trucks although I'm not certain on that last point.

2) a basic round version, 'US style', comes with the king hauler, globeliner and possibly the other bonnet style trucks

3) the oval one that comes with the MFU kit - ie. the one in your pic.

All 3 types are compatible with the support legs. You just need to fit the right parts for the sliding tongue on the 5th wheel, as shown in the motorised legs manual, which operate the leg switches on the trailer. FYI, the motorised legs kits comes with a spare 'basic' round type 5th wheel.

However only the 3rd type, the one which comes with the MFU (ie. the one in your picture), is compatible with the coupler switch. Therefore, to use the MFU and the motorised support legs, you can only use this type. In your pic, you have assembled correctly for the MFU coupler switch if you didn't want to run the motorised support legs.

At this point, you need to refer to the bottom of page 13 in the MFU installation instructions to add the support legs linkage. It shows you which parts you need to dis-assemble from what you have built (shown in white), and which parts you need to add from the motorised support legs kit (shown in grey).