MFU Coupler Switch: Required?

[Rick.K]

I purchased the complete motorized support leg kit. it included a 5th wheel so I used it. it includes Part B3 which slides under the passenger side of the 5th wheel and acts as the actuator for the support legs. Step 35 of the Knight Hauler manual does include the coupler switch, but the directions for the 5th wheel in the MSL kit does not.

I connected the coupler switch to the MFU and tried 1st gear with and without engaging the coupler switch. With switch closed the transmission begins forward with slight throttle. There is a noticeable lag in transmission engagement with the coupler switch open. Switch closed the truck appears to accelerate more quickly as well.

I'm going to find a way to mount the coupler switch just in front of the leading edge of the coupler, and on the frame, so that when the 5th wheel tips forward as the trailer slides on to the 5th wheel the coupler switch will be engaged. This way I retain the sliding bar under the 5th wheel the actuates the trailer landing gear.

As a first build buying the truck kit plus motorized support legs and the MFU has been a real challenge. Three sets of instructions open at once, parts and hardware everywhere. in addition, trying to figure out where to install the electronics so that the front seats can be installed and the MFU and wires hidden behind a partition between cab and sleeper. This is a blast and a brain bender at the same time!

Don't like the vibration unit. A shudder at start-up, and frame twist when starting under a load. no truck shakes like the vibration unit makes it. Unless the truck is built by Harley.

[Supermario]

Originally Posted by Rick.K

As a first build buying the truck kit plus motorized support legs and the MFU has been a real challenge. Three sets of instructions open at once, parts and hardware everywhere. in addition, trying to figure out where to install the electronics so that the front seats can be installed and the MFU and wires hidden behind a partition between cab and sleeper. This is a blast and a brain bender at the same time!

Ahhh, the good old days. Reminds me of my first build.. Nothing like being frustrated and yet loving every minute!

Great idea to relocate the switch and act on the plate pivot! I'd love to see what you come up with! Take pics and keep us posted

Mario

[ricm]

Originally Posted by Rick.K

I'm going to find a way to mount the coupler switch just in front of the leading edge of the coupler, and on the frame, so that when the 5th wheel tips forward as the trailer slides on to the 5th wheel the coupler switch will be engaged. This way I retain the sliding bar under the 5th wheel the actuates the trailer landing gear.

I would suggest you stick with the original Tamiya design - it works fine - if you mount the switch as you suggest you'll get constant coupling/ uncoupling sounds if you drive over an uneven road surface, as the 5th wheel moves relative to the tractor truck chassis...