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-   -   Another shifting problem (I know, I know...) (https://www.vn750.com/forum/26-transmission-rear-end/103349-another-shifting-problem-i-know-i-know.html)

BarryOregon 11-07-2018 11:46 PM

Another shifting problem (I know, I know...)
 
Hi everyone! My name is Barry, long time rider and first time Vulcan 750 owner. I just got a 1998 with 25K miles. Pretty good condition but had been dropped low speed on her left side on dirt and grass, breaking the left headlight bracket, bending the headlight assembly and bending the shifter. Nothing major EXCEPT now after doing all the repairs and service to get her up and running again (she had sat for 2 months until I found her) everything is peachey but she will only do 1st and neutral. Now I have read everything pertaining to shifting problems on this forum going back to 2006 (geez, you guys are as old as me!) and I don't see my particular malady. So, she will shift 1st and neutral but whether on center stand or riding her I get full travel into 1st, back to neutral and almost full travel for second but she won't engage. It feels like there is something stopping the pawl from engaging the drum enough to turn it for a shift. Spring seems fine but after reading everything i'm beginning to think it might be the spring is just weak enough to not let 2nd engage. I don't think there is internal damage, the shift shaft has no lateral play, maybe 1/16 inch at most so I think the clips are still in place.

Could the PNF be a source of this? The three ball bearings I read could stick due to dirty oil, I have done an oil change but had thought maybe another one with added Sea Foam just to make sure everything is really clean. Would that process clean the balls (no offense) and possibly solve the problem?

And what about the clutch? Cable adjustment seems important, is there adjustments to make that also may help solve the problem? I don't have a Clymer yet so looking at service diagrams isn't an option yet.

I have had old GS Suzukis so I am very familiar with the quirks of our older bikes and have found forums like this are the best place for help and guidance. Any suggestions, advice, comments, bills of lading or dirty money is appreciated. Thanks in advance.

Thorn 11-08-2018 02:46 AM

I think the positive neutral finder is an unlikely culprit (though it could certainly cause the problem). The three ball-bearings would ALL need to fail to get a complete disengagement of second gear. The location of the balls is not likely to get gunked up, being sandwiched between the transmission output shaft and the ID of a gear, so a triple failure would be a rare occurance, and probably unrelated to a lay-down.

A couple non-PNF ideas:
1. The shift lever might be bent. Is the frame limiting it's travel?
2. If it's hitting the frame, the shift lever might be rotated on the shaft one spline.
3. The internal linkage rod might be bent, causing the pawl to not be pushed far enough when shifting (but I think a bent rod would make it harder to downshift, not harder to upshift)
4. The one arm of the shifter pawl might be bent, preventing it from pushing on the drum cam. This can be accessed behind the left engine cover where the oil level sight glass is. I think this requires tilting the engine out of the frame to unscrew and remove?

BarryOregon 11-08-2018 10:55 AM

Okay, good to know the balls won't be the problem.
The frame does not limit travel, plenty of clearance for both up and down shifts.
Doesn't seem to be internal, although being unfamiliar with a vulcan 750 might mean i'm not aware of what the little idiosyncrasies are.
I have been thinking it might be the pawl but have yet to remove the clutch cover. I understand that cover can be rotated out of the way enough to get at the pawl and spring without loosening engine mounts. I just want to try and narrowe down where I need to look.
At least going into winter I have the time to explore. Thanks for the insights.

Spockster 11-09-2018 08:59 AM

#3 or #4.

I lean toward it being a bent pawl, on the left side. If the shifter was pushed upwards, that could bend the upshift side of the pawl. It could still reach 1st, but the throw is shortened enough to not reach for upshift.

A bent rod on the right side would make the shift throw shorter, but it seems that should affect all shifts.

The pawl (left side)

https://www.vn750.com/photopost/data...ium/SHIFTB.JPG

BarryOregon 11-09-2018 10:44 AM

I'm going to try and remove the left side cover this weekend. I'll see what the pawl looks like and post pictures. If the pawl is bent should I try to bend it back or replace with known good one? Also am I correct in thinking I can pivot the left side cover out of the way enough to get to the pawl?

Spockster 11-09-2018 12:07 PM

I've never been in there, but one forum member was able to work through the holes in the inner case, he said it was like microsurgery.

If you could find that old post in the search, he gave quite a bit of detail. Shift pawl, should be a good search term.

Think you'll have to at least tilt the engine to clear the stator cover and shifter shaft. But you can leave a lot of items connected if just tilting.

Thorn 11-09-2018 06:15 PM

I think the 'microsurgery' post was about a bend shift linkage. The pawl should be much easier to access, though the frame blocks some of the bolts. spinning it out of the way may be possible.

BarryOregon 11-10-2018 03:53 PM

Thanks for the picture and help. I'll not be able to remove the left cover for a few more days but it seems I can get to the pawl without too much extra effort. If I have to replace the pawl is it a good idea to also change the spring? Also, should I adjust the clutch and cable at the same time?

Spockster 11-10-2018 06:48 PM

Quote:

Originally Posted by BarryOregon (Post 1269857)
Thanks for the picture and help. I'll not be able to remove the left cover for a few more days but it seems I can get to the pawl without too much extra effort. If I have to replace the pawl is it a good idea to also change the spring? Also, should I adjust the clutch and cable at the same time?

The spring is probably ok, but if a new one comes with the pawl, use it.

I wouldn't adjust the clutch yet. But, if you remove the clutch arm, take note of where the clutch arm is located on the splined clutch shaft (bottom of left side cover). The stock setup has the split on the arm aligned with a dot on the splined shaft. Sometimes people will slip the arm ahead one spline to get more pull on the cable. Just put yours back the way it sits now.

DaParvize 04-13-2019 09:20 PM

Anything ever come of this??? Did you figure it out?


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