Speedometer Cable Question

[bmwr80k]

I own an '85 R80RT with about 29k miles on it. I just received my repaired speedometer back from Palo Alto Speedometer with a note that I should replace my speedometer cable and housing. Does anyone have any experience with this? With only 29k miles is it likely this cable is bad? Any tips for the replacement proceedure?
Thanks.

[manicmechanic]

When I had my instrument cluster done 2 years ago, the note was saying that they would not honor their warranty unless the cables were replaced. It's not a hard job, just pull the tank, loosen or cut any cable ties, remove the old cable, put the new cable in the same location, then put it all back the same as you found it. Take a ride and make sure it all works. Might take you a half-hour, if you take your time.

[pmdave]

The speedo cable drives off the rear of the transmission. Removing the ground bolt also releases the plastic fitting that holds the cable housing in the hole. When reinserting, note that the round cutaway in the plastic gizmo needs to be aligned so the bolt will go in.

The upper end is attached with a large round nut. Use a pair of adjustable pliars to grip the nut, and remove in the counterclockwise direction. That allows the cable to detach from the speedo.

Take a close look at the rubber cover that snaps over the cable at the lower end. If it's loose or cracked, replace it--there should be a new one on the cable sheath. You don't want water dribbling down into the transmission. Before you remove the old cable, make some notes about where it routes, and put the new cable back in the same locations. You don't want a hot wire or the fuel tank to rub against the cable, and you don't want any tight kinks or sharp bends.

When I install a new speedo cable, I carefully extract the inner cable and check that it's lubed. If not lubed well, I add some grease and reinsert.

The square ends must mate with the square holes as you insert the cable. If there seems to be a problem, rotate the inner cable slightly. It should go together without a struggle.

pmdave

[AntonLargiader]

With only 29k miles is it likely this cable is bad?
It's not an issue of the cable being bad, just of the cable not being perfect. If the old speedo was killed by being shaken to death by the old cable, or your old cable was damaged by excessive drag from the dead speedo, why risk your new $150~ $250 repair to save the $20 or so? Use a new cable and know that you have a 100% new speedometer system.

[RandyB]

While you've got the bolt out, be sure and clean the vent hole that runs through the center of it. Pressure build up in the transmission makes for some weird leaks on occasion. Also, some people cut the ground wire into a u shape so they can remove it without removing the bolt.

[Boxerkuh]

I would replace the cable and make sure that you replace the cables about every 4 years. Time, moisture, wear and tear, does have an effect on cables. Most people only replace speedocables when they break. I think it is a good practice to replace all cables every 4 years. That should also slow down with the needed repairs of the speedometer. Follow the advise already given... I also suggest lubing the cable on the top and applying some grease to the rubber boot on the bottom. It assist keeping the rubber fresh and plyable and keeps water out of the transmission. Take your time and you can do it. Good luck. My food for thought anyway.... :eat :drink

[bmwr80k]

While I have the tank off, is there anything else I should replace at the same time?

[pmdave]

Removing the tank is a 5-minute job, but as long as you're under there, take a look at the coil wires, the starter relay (front left) and the ground wire (brown) to the frame. If any wires or cables are rubbing the paint off the tank, see if you can reposition them with cable ties, or add some abrasion resistance to keep metal away from metal. Perhaps a short section of rubber tubing, or a piece of foam rubber.

Unplug, clean and replug any connectors, especially the starter relay--whose socket contacts are pointing upwards saying "please feed me dirt and water".

I have added plastic spacers between the rear tank support and the flex couplings, to raise the rear of the tank a smidgen and provide more clearance. Those tough black or blue videotape boxes make nice material for such things.

When the tank is removed, it's common to pull off the gas lines from the spigots on the valves, which leaves the spigots ready to ingest debris. Especially if your valves have the spigots sticking straight down, support the tank on a plastic bucket or cardboard box so that the spigots are not resting on a dirty floor.

While you're looking around under the tank, take a close look at the "frame" side of the gas valves. It's not uncommon for a choke or throttle cable to rub on the valve, wearing a hole in the aluminum. Best to prevent this, gas being flammable etc.

pmdave