Wednesday, August 31, 2011

Transition: Custom Rear Rack to Factory Rear Rack

I while back I mentioned that I had managed to win (on that giant on-line auction site) an original equipment (Honda) rear rack from an '89 NX125. I contacted the seller to ask if he happened to have the rare (and expensive), but still available, turn signal supports. He did not. The factory rack bolts through the same hole, in the rear of the frame, that the turn signals use. So, I needed to figure out how to use the existing turn signals or acquire (and modify) some other turn signals. I ended up finding a set of Suzuki DRZ400 front turn signals that did not require any modification. This allows me to use the NX's rear turn signals on my Transalp.

So, I got started by removing the custom rear rack:

  1. remove the side panels
  2. remove the seat
  3. remove the turn signals
  4. remove the custom rack (most likely permanently)

The first thing that needed modification were the rubber grommets from the rear fender. The turn signals go through these grommets. However, they're too thick to fit inside the factory rack. So, I trimmed them down.

The left side has been trimmed. The right side is the original thickness. So, the grommet is about 3/4 of the total thickness that is used to be. The groove in the middle is where the fender rests when the grommet is installed (the grommet fits in a hole in the rear fender).

These are the two steel spacers that will fit inside the grommet (shown above). They will mimic the steel shaft that protrudes from the original turn signals. They needed to have about 1/8" (.125") removed from their length to properly fit.

This the right side grommet installed in the rear fender with the steel spacer in place. The left side looks exactly the same way (except the picture I took was blurry).

Here the factory rack is in place. Through the mounting hole in the rack you can see the steel spacer. I had to use two thin bladed putty knives to get the rack to slide over the rubber grommets. The putty knives help compress the grommets instead of having the rack push them down (which will eventually cause them to pop out of the rear fender).

Here the rack is in place with the DRZ400 turn signals in place. If you look closely at the horizontal rack surface, you can clearly see that it's been assembled improperly. The right side is higher than the left. I fully expect that the Honda worker responsible for this to have committed hara kiri (seppuku). Kidding. I first thought the rack was twisted (from a fall or something). But no, every bolt hole lined up without force. And, closer inspection revealed the error in assembly (welding). My partially disassembled Transalp can be seen in the background. It's now running and will be re-assembled shortly.

Here's a close up of the right rear turn signal. You can see that the DRZ400 turn signals come with a nice bracket that makes mounting easy. I will swap that Allen head cap screw for a stainless steel version when the rack is sent out for powder coating (this winter). I'll use the lower hole, in the mounting bracket, as a wiring harness guide.

Here's the left side. Just above the tool kit holder you can see that the rack support nicely clears the fender. I can revert to the factory bolts to hold the seat and rack (eliminating the longer Allen head caps screws and spacers made from steel tube).

A view of the left turn signal from above. Again, it's almost as if the DRZ400 turn signal mounting bracket was meant for this application. There is plenty of clearance for the wiring to exit the base and the bracket is tight to the rack. Nice and neat.

Here's the right turn signal from above. With the bracket in this position, there's plenty of muffler clearance and no need to fret about (possibly) melted plastic.

I soldered the wires so that I don't have to worry about mechanical connectors failing.

The joints were sealed with shrink tube. I also used some Honda wiring harness sleeve to protect the wires from dirt/debris/water/etc. There are not three wires there, the "middle" one is a refection in the muffler.

Here the rack is completely installed with the wiring in place.

Another angle of the installed rack. To complete the process, I needed to put the seat back on and install the side panels.

Here's the Honda rack plate that I was using on my custom rack. I used a couple of pieces of 1/2" square tube to bolt the plate to the rack. If you look closely, above the leading edge of the tail light, you'll see that the plate has two clips that snap over the horizontal rack tubing. In conjunction with the forward square tube, the plate won't be able to slide off of the rack. Later I decided to add a spacer between the plate and the square tubing. The spacers are 1/2" diameter nylon with a 1/4" hole. I had to cut them down from 0.5" in length to 0.4". The thickness of the horizontal rack tubing is 0.4". Now the plate doesn't bend/flex under the pressure from the attaching bolts.

Another view of the plate on the rack. It's a little easier to see how the forward square tube is captured in the rack support. This will prevent the plate from sliding off of the rack. I will most likely end up bolting the Givi base plate to the Honda plate so I can use the Givi top case (again). I also plan to have the square tubing powder coated as well.

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