Tacho drive oil leak

Beachy · Post by **Beachy** » Sun Sep 28, 2008 5:28 pm

The oil leak appears to come from the tacho cable knurled nut, where it joins the drive. Being a bit lazy here and not dismantled to investigate. Has anyone got any ideas?

EMS · Post by **EMS** » Sun Sep 28, 2008 6:03 pm

There is an O-ring under the drive cover p/n 91302-704-000 and more important, a small shaft seal on the tach drive p/n 91208-551-013 or -015.
This is probably still available from Honda. I bought one not that long ago.

Rick Pope · Post by **Rick Pope** » Mon Sep 29, 2008 6:26 am

A leak at the knurled nut is often and indication that the cable is about to fail.......

Beachy · Post by **Beachy** » Mon Sep 29, 2008 4:01 pm

Thanks EMS. Seals are ordered and in stock.

SteveG · Post by **SteveG** » Mon Sep 29, 2008 4:12 pm

The more information I get, the more paranoid I become. My tach drive is not wet, but damp.

More concerning to me is after reading the other thread (couldn't find the link real quick) about RPM vs MPH, I started watching the tach more. At about 5K it would hesitate / hang up before swinging quickly up to the "correct"

RPM.

The quicker the acceleration, the worse it would be. Accelerate slowly (boring) and the needle hesitation was nonexistent. Accelerate briskly (usual) and it hangs up noticeably before continuing. Accelerate quickly (shouldn't be looking at the tach now anyway) and the needle would almost seem to stop before resuming its search for the red zone.

I took the tach cable off, pulled the cable out of the sleeve and cleaned both. The cable showed no signs of wear, and was not overly dirty. I used WD40 to clean, and then lightly coated the cable with 10-40 dino oil before putting it back together. Made no difference in the needle hesitation.

Does this sound like the cable going bad or (worse) something possibly wrong in the tach itself?

alimey4u2 · Post by **alimey4u2** » Tue Sep 30, 2008 6:04 am

If your cable still has nice square drive ends & is in one piece, it does sound like your tach may be on the way out...

You could do a test with a variable speed electric drill...

SteveG · Post by **SteveG** » Tue Sep 30, 2008 8:39 pm

I can't say I looked very closely at the ends to see if they were still square. I was looking for wear / loose / worn areas on the cable along the length of it. I will have to take a look at the ends. Thanks.

alimey4u2 · Post by **alimey4u2** » Wed Oct 01, 2008 3:49 am

In the tacho the square drive socket is pot metal & quite soft. This can round off the socket & also the cable. It was a common trick on British instruments to jam a matchstick in between to get a few more miles.

You may have some debris inside the tacho making it erratic or it has been stored on it's front face & damping fluid has been lost. The support bearing may be goin out. A few "drops" of WD40 in the bearing has been known to help. Please keep us updated....

SteveG · Post by **SteveG** » Wed Oct 22, 2008 9:23 pm

SUCCESS!!!

While at the Fall Foliage Rally and discussing assorted CBX maladies with people in the know, I was made aware that the rubber / foam cushions that the tach and speedo sit in tend to deteriorate. The gauges then sit loose in the housing.

I paid attention to mine, and found the tach was sitting somewhat cockeyed in its space. More attention paid, and found the bezel ring of the tach was in contact with the housing.

Even more attention paid, and noticed that at 5K rpm, where the tach started to hesitate, there was / is a slight increase in the vibration / power throbs

coming from the engine.

2+2= the vibration coming from the engine through the housing, bypassing the cushion, into the bezel and tach was causing the tach to do its dirty deed and not continue up the scale.

I went to my local friendly Honda dealer and ordered the cushions (part #37115-422-008)(they are the same for both the speedo and tach)(about $10.00 each). Two days later the parts are in.

I then delicately, carefully, hesitantly take the gauge pod off, figure out how to remove the trip meter reset knob (very small phillips head screw buried deep in the center of the knob) and take it all apart.

The cushions looked like this. The tach cushion is on the right, the speedo on the left. The speedo cushion looked ok, but was almost worn through in the center of the ring. The tach cushion is obviously compressed / worn, which was not plainly visible from the outside.

After putting it back together, I went for a short ride. Ohhhhhh Yeeaahhhhhh! One sweet, smooth moving tach. All hesitation / hanging up was gone. Gotta stop looking at it now and pay attention to riding again.

I do have to cover up the spot where the tach bezel was vibrating against the housing. I think a simple black magic marker will do the trick

Steve

EMS · Post by **EMS** » Wed Oct 22, 2008 9:46 pm

Good form, Steve, good form!

alimey4u2 · Post by **alimey4u2** » Thu Oct 23, 2008 5:23 am

Thanks for the feedback Steve, glad you have a happy ending....