Wiring harness replacement R75/5

[achermside]

I am replacing the wiring harness on my '71 R75/5 and have a couple of questions.

I would not like to remove the luggage rack (BMW set case holder for hard bags) if I don't have to since it is mounted to the top shock eyes. Does anyone know if the wiring can be run through the frame and the taillight rewired with the rack still on? If not, will I need a shock compressor to remove the frame?

I was given the advice to work from the front to the back with the wiring harness, starting with the connections in the headlight bucket since this is the most complex part. I was also told that this was easiest with the bucket removed so it can be turned upside down for access to the connection board. It looks like I will need to remove the speedometer cables and instrument wires to do this. Is there anything else to be aware of or careful for in removing the bucket?

Thanks for any advice you can share.

[sblaylock]

Hi Alex,

I just finished the same process on a '71 R60/5. The trick I use to get the wire through the rear subframe is to run a piece for shrink tube through first. You can attach it to the old wires when removing them or run some lock wire through and attach the shrink tube to that. Once it's through push the new wiring harness about and inch into the shrink tube - just to where the wire cover of the new harness starts. Tape it with one wrap of tape as you don't want it to get too thick. I put Vaseline on the tape to help prevent it catching on the frame, then slowly and gently pull the shrink tube out from the taillight side while feeding the new harness in. This method always works for me and I've done a bunch of harness replacements.

I usually lay the harness on with loose tie wraps to be sure I have the length for the rear brake light switch correct. From there I secure the rest of the harness moving forward towards the front. I've found the routing on the rear brake light switch to be a factor with where the rest of the harness lays.

The bucket is a pain for sure, but EME has large colour laminated wiring diagrams that really help with getting the wires connected correctly. Be aware, there are two different wiring diagrams for the /5 series. The one with the fuses and the one without. Your '71 should be the one without the fuses, but several '71s I've worked on, including the R60 I just did, were converted to the fused version. I do the bucket wiring with the bucket disconnected, but not completely removed. I hang it with large tie wraps through the ears and through the bucket. It gives me the ability to move it up and down when I need to see the board, but is supported so I can use both hands to fish wires.

Hopefully this info helps. I'm sure others will provide their methods as well as to what works for them.

Scott.

[achermside]

Thank you Scott. I like the shrink wrap trick for the wires, I was going to try a piece of stiff wire to fish through, but that sounds much smoother. I'll try hanging the bucket in place also - I wasn't looking forward to disconnecting the speedo and everything else.

[sblaylock]

Just watch the front signal light harness, as it's usually short with only two wires and should not be helping to support the load of the bucket.

Scott.

[cbclemmens]

Just passing on a tip from John Watts; While you have the headlight bucket off, paint the inside of it white. It will greatly improve the visibility inside the bucket.

Craig