Transmission stuck in 4th

[aerojack7654]

Hey guys, it's been awhile!
Everything has been going pretty well with the Dream and the Hawk, but recently I was motoring along on the Dream in 4th and after awhile went to downshift and the shifter was not moving. Pulled the clutch in and coasted to a stop and got it home (on a trailer). Been jiggling the shifter and pulling the clutch in and trying to get it off 4th, but no luck so far. Any ideas as to what might of happened and what I can do to get it unstuck?

Thanks,
Jack

[aerojack7654]

Well,
some more info to report, although not something that I care to admit. It appears that the Dream was really low on oil (barely showing on the tip of the dip stick) and when drained, it was really thick and black. So it looks like I cooked the oil at least, maybe the trans too? I managed to get it to shift, albeit with great difficulty, after replacing the oil, so I was wondering if perhaps some of the cooked oil is fouling the movement of the forks and other internals, and if filling the transmission with some cleaner (like Sea Foam), pulling the plugs and cranking the motor as the gears are shifted might help clean it and get it to shift better. Obviously the fluid would be drained and rinsed with oil before running. The motor appears to be running fine, if nothing else a testimony to the robustness of the engine and their tolerance of idiots, but it hasn't been pressed since the shifting gummed up.
Any hints, observations, recommendations are welcome, and while chastisement is less welcome, it is expected.

regards,
Jack

[e3steve]

Jack, schidtt happens! Let he who is without sin... And all that! :-/

[48lesco]

aj - The likely culprit is the shift drum and forks since they reside high in the crankcase and rely on oil splash for lube. If it's moving a little, that's a step in the right direction. Don't put a lot of pressure on the shift lever, but if you can get it into first and ride a little to heat up the new oil, it may clear itself. That's what I'd try at least... Good luck!
-48

[aerojack7654]

Belated results to the transmission problem - I went ahead and ran some Sea Foam through the motor, cranked the bike with the plugs out while trying to manipulate the shifter, no joy in mudville there - the thing was still very difficult to impossible to shift. So bit the bullet and dropped the engine and started taking things apart. I finally split the cases and the good news was everything, including the cylinder bores, pistons, rings, gears, etc. all looked to be in very good condition, no signs of burning, galling or anything that would indicate how it was abused. The transmission gears themselves looked really good, the dogs, forks and drum all looked good. the thing that was impeding shifting was the fact that the third gear sliding gear was pretty firmly stuck on the splined shaft. I had to take it out of the case and pound it off the shaft with a piece of wood and a mallet. There was no evidence of damage or burnt oil on either part though, it was just really tight. I checked the shaft for any warp, ran out fine. So finally I just polished the splined shaft with 320 grit paper, enough to get the gear on (still tight), and then lapped the gear and spline with some rubbing compound til it slid nicely. After putting the parts together, I was able to smoothly operate the shifter through the shift pattern now.
I'm still finishing putting everything back together, so no final report, but it is definitely shifting better than it ever did. I'm not really sure what caused the issue, but I imagine things were getting hot and might have aggravated a situation where the clearance was tight to begin with - I don't know.
At least the internal parts were better than I expected. I had replaced the rings and gaskets a year ago, and had honed the cylinders, I could still see the light traces of the cross hatching, so any cylinder wear couldn't have too bad. It was actually kinda fun to go all the way and open up the transmission, something I had never done before on any of my bikes - at least not as intimidating as I feared. Hopefully once the weather gets a little warmer (it's 12 deg with a wind chill of -15 right now and supposed to get colder) I can see if it is back to normal.

Thanks for the encouragement!
Jack

[e3steve]

Jack, everything happens for a reason. The bike threw you a curveball and you hit a home run, gaining knowledge and experience at the same time; nice one!

You obviously have a good grasp on engineering & problem-solving, along with tenacity and a taste for adventure.... And you write with proper punctuation, correct spelling and perfect coherence!

You must be British....... :-D

Thanks for the update.

[aerojack7654]

Thanks for the compliments Steve. While not being British, but nevertheless being an Anglophile (many trips to England), I certainly take it as a compliment!
Still waiting for my garage to warm up a bit to finish reassembly, the great polar vortex is still hovering. Should be warm enough to not overwhelm my heater by Thursday!

Regards,
Jack