CMS-Japanese Motorcycle Supply Parts

How to change the gear shift shaft oil seal on a CX500, GL500, CX650, GL650

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The shift shaft seal on the CX500/CX650/GL500/GL650 is known to leak; fortunately it's a quick and easy fix.

For this, you will need a replacement part;


Genuine Honda seals aren't particularly expensive in this instance. Part number 91251-ZW5-003 (click here to grab one from eBay):


It should have a circular spring visible from one side:


...and the other side it should look like so:


We used to have a link to a site with an explanation about the spring here, but it's now dead. We'll do a separate article. Now, you will need an 8mm spanner or socket:


A 19mm socket (or thereabouts) for pressing in the new seal:


A screwdriver or pry tool to pry out the old seal:


...and a little bit of fresh oil to coat the new seal with before you put it in. It doesn't seem that you need to drop the oil to do this procedure - and we certainly didn't in this instance - but the bike was low on oil when we did it, so YMMV.

First, locate your gear shift lever.


If you look closely, you'll notice a screw with an 8mm head. The view from underneath:


This screw prevents the shift lever from sliding off the shaft. Before you remove it, make note of the alignment of the lever on the shaft; there is an alignment marking on the lever:


See the little markings at around 10 o'clock? There's a marking on the shaft to match:


The small round dot at around 11 o'clock. This may or may not help you if you have a shift that has been bent by a previous owner, like the one we have - either take a photo of the alignment, scribe it or otherwise mark it so you know how it goes back on. If you forget this step it's not a big deal to experiment afterwards to find the right alignment, but it's quicker and easier to get it right the first time...

Undo the screw:


The screw itself:


This allows the lever to slide free - it may require a slight amount of wiggling:


The shaft, lever-less:


You can see the oil seal surrounding it:


The old seal is likely to be brittle; press your screwdriver against the shaft against the inside of the seal and carefully dig your flathead screwdriver into the seal a couple of millimeters, making sure not to mark the shaft. It should lever out:


At this point we had a couple of oil drops, and no more:


Old and crusty next to new:


Closeup of the crud in the old seal:


Apply a small amount of fresh oil to the new seal:


Clean out any gunk from where the seal is going into, and grab your 19mm socket. We tried an 18mm - while it's a better fit for the seal (it doesn't hit the surrounding metal at all) it wasn't wide enough in the neck to reach it over the shaft, so 19mm was the smallest available option from our set.

Press in the seal by hand - spring side goes inward:


Now apply the socket:


We were able to smoothly press it in using only hand strength, no significant leverage required. YMMV.


One new seal, successfully installed. Now put your lever back:


Double check that it doesn't foul the exhaust pipe on downshift:


...or the engine on upshift:


It also helps to double check that it is in the same position ergonomically as when you started, as there may be several fittings which don't foul but aren't where you started. Once you're satisfied, reinstall the screw:


Make sure the screw is tight enough not to fall out, go for a short ride, check your results - hopefully no more leaks, and you're done!

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