Shifting into 3rd gear problem

I found after riding in traffic that after accelerating in 2nd, I could not shift into third gear until a pause with some reduction in RPM and pre-shift applied. Under slight acceleration, shifting is fine - a bit clunky into 3rd, but always shifts. This is a 1978 (08/1977) five speed transmission. I don't remember having this shift problem before now.

The problem happens after accelerating in 1st to ~4k RPM with mid throttle then similarly in second to ~ 4k mid throttle. The bike is stuck in 2nd gear and it takes accelerating in 2nd to ~ 5k RPM (to keep up with traffic) and then reducing acceleration to shift into third. After experiencing this, I instinctively changed the transmission oil but don't expect that will make any difference. This happens when accelerating with traffic on 45 mph roads. Is the flywheel the culprit - and lightening would help, is it my shifting technique (i.e. stop accelerating before trying to shift into 3rd), or a worn gearbox shifting mechanism, or some combination?

I had problems in which I'd hit false neutrals on my /7, mostly going from 4th to 5th. The suggestion from Oak was to continue to hold up pressure on the foot lever as I let out the hand lever. This has cured my false neutrals.

Another thing is to pre-load the shift lever before you pull in the hand lever. This helps take up some of the minor tolerances that might be in the system.

YMMV...

I had problems shifting from 3d to 2d, going down. I would make sure the clutch is adjusted properly, just to be safe. In my instance, a rebuild of the tranny was needed.

try your upshifts at 5K or above, see how/if that changes the equation.

It seems changing the oil helped. Also, shifting at a 5k RPM was a bit easier. Also, I wore my less cumbersome boots that allowed a better feel for shift pre-load.

gear shifting

years ago while returning from the finger lakes rally,on my 1977 R100S, I had problems shifting from second to third , I belive, then it stuck in second, for miles, third was blocked then when trying for third once again it went crack and all was well,and continued on home ,later while draining the gearbox oil I found a gear engagement dog broken off one of the gears in the cluster, apparently a common thing to happen on 1977 5 speed boxes rode it like that for a while, then stripped the gearbox Iwas told the cluster had to be purchased complete,got a used assembly and installed it with no problems since,touch wood!!,check your oil for debris, hope this assists Jimmy

How long has it been since you did a spline lube?

Barron

The clutch splines were recently lubed. The only false neutrals are when downshifting, and a blip of the throttle (generally) fixes those. Some metal was in the oil pan: not chunks, but some was found. The drain plug had more than just fuzz. I think the sticking in second gear may be an indication of shifting dog troubles in the not-to-distant future. Thanks for the input.


Edit: It seems switching oil solved that problem. I noticed the transmission oil last used back in 1996 was red. I think the previous oil was a synthetic (Redline ?) based on the kotex pad on the transmission shelf. The oil used during the shift problem was Mobil 1 75W/90 and switching to Valvoline 80W/90 seems to have solved the shifting problem. I may try some 85W/140 and see if that helps and probably try some of the Dow M Gear oil additive. Based on comments from Joerg's transmission site: http://jhau.maliwi.de/mot/gearbox.html a stuck gear is caused by the axial shaft play out of spec. The thicker dino oil may help with that - or it could just be my transmission does not like Mobil 1 75W/90 oil.