In August I noticed I had the beginnings of a leak around my pulley. I probably could’ve left it alone a while longer but having never been into my primary I wanted to see how tight the chain was and how the bearings were doing after 20k miles. I started researching seal replacement, tools, etc and decided to go in to replace all of the oil seals. What started out as a seal replacement has turned into a much bigger project than I had planned for. I took some pictures along the way which I figured people might like to see.
Beginning of the leak


Bike on jack


Disconnect and remove battery


Drain the primary


Remove outer primary cover. Ring gear marks on inner primary. Not a good sign.


View of exposed drive system


Compensator, clutch, tensioner, chain removed


This nut is the worst. Careful and time consuming grinding with a dremel got it off. My 6 foot fence post breaker bar over a 24” pipe wrench on the socket wouldn’t budge it. Also removed mainshaft race to get at inner main drive gear seal.


Pulley nut off after a few days of messing with it.


Bare mainshaft


Large seal removed exposing MDG bearing. The inner MDG seal seals between mainshaft and inside of MDG. It’s a royal pain to remove. Set me back another day or so.


Seal finally off


At this point I thought I was in the clear until I went after the shifter jackshaft seal. .very small clearance in there to get at it, while trying with a pick I nicked the jackshaft. At that point I had to decide whether or not to chance installing a new seal on a nicked shaft. Sanding didn’t prove too helpful so figured why not see what a transmission looks like. Removed exhaust, exhaust bracket, clutch cover, trans top cover, bolts, rested shifter shaft pawl on top of transmission, and pried the gearset out of the transmission case from the right side of the motorcycle. This is all spelled out in the SM and was surprisingly easy to do.

Shifter needs to rest on this gasket prior to removal of gearset


Trapdoor and gearset ready to come out as a unit. Tape the mainshaft splines up so they don’t rough up your MDG needle bearings.


Gearset out. Never worked on a transmission before. This is a constant mesh design. Mainshaft on left, countershaft on right. Constant mesh means each gear is rotating with its counter gear at all times (meshed), with one of the two being a ‘freewheeling’ gear (ie its on a bearing). First gear is at bottom, closest to trapdoor, going up in order to 6th, or main drive gear at the top as shown. 1st-4th gears are fixed on the mainshaft with their countershaft gears riding on bearings. The shifter cam and shifter forks actuate shift dogs which engage the selected gear and fix it to the shaft which it was previously spinning on. This locks the two shafts together at the chosen gear. 5th-6th gear mainshaft are freewheeling while the countershaft gears are fixed. This is all shown in the SM. Having it on the bench and running through the gears made it easy for me to understand.



Needle bearing in MDG had some worn needle rollers


Clutch hub teeth chipped off


I called around to get quotes and shops either didn’t know what I was talking about or wanted an hour labor to just replace the clutch hub. I did some more research and decided I could do the hub myself as well as the MDG bearings. Ordered a press from Harbor Freight for $95 w/ coupons. Got that put together this week and borrowed some specialty tools from forum member Hullhorr (thanks again) to R&R the Main Drive Gear, the MDG bearing, and the MDG needle bearings. That’s where its at now, waiting on parts.

Going back together using all new seals, retaining rings, gaskets, 2014 Big Twin Compensator, new clutch hub, Andrews 30T Pulley, and Hayden M6 chain tensioner. Already replaced the countershaft bearing in transmission case. Have yet to replace clutch hub bearing, MDG bearing(s), and inner primary bearing. Leaving trapdoor bearings alone as they feel okay to me.

 

I've done the seals a couple of times, not an easy job. You are braver than I am going into the trans. Great shots, great write up, keep us posted.

 

Subscribed. Any chance to see the innerworks is appreciated. Best of luck!