Transmission Falling Out of First Gear

[JC85]

I've been having a problem for a little while with the transmission Falling out of first gear and into neutral. It only happens in first, and only when I've taken off, after first starting the bike; never from another gear, and never when the bike has already been running for a while, for instance, taking off from a stoplight. In the past, it's usually happened when I come to a stop, such as when I go to leave my shop for a ride, and pull out to the end of my driveway, then stop to check, before pulling onto the street. This morning, when I was on my way to work, however, it happened while under power, as I was pulling onto the street. Which was, needless to say, fairly alarming. The fluids in the transmission and rear hub are good and full. Any ideas as to what's causing this? I have trouble believing it's just from an incomplete shift, given that it only happens in such a specific way.

[yogidozer]

The dogs are worn. You're going to need to have it disassembled and replace all worn parts. Sorry.

[Vagrant]

What bike? Floorboards?

[JC85]

What bike? Floorboards?

74 Eldorado Police Model with floorboards.

[Vagrant]

74 Eldorado Police Model with floorboards.

Might just be sloppy bushings on the heel toe. Check and lower the arm for less throw. It might be bottoming out.

[Tom H]

As mentioned, the shift lever could be hitting the floorboard when you shift to first. If you can push it down by hand and it hits the board, adjust the linkage so that it just clears the board.

Again as mentioned, your bushings or the holes where the linkages attach could be worn as well.

Take a few minutes and check these things, let us know what you find.
Tom

[JC85]

So, after checking everything over, there is, indeed, a lot of slop in the shifter, due to the bushing on the heel toe and the pins in the linkages been worn. It's doesn't even come close to bottoming out on the floor board, though.

[JC85]

The dogs are worn. You're going to need to have it disassembled and replace all worn parts. Sorry.

I'm not trying to disregard your knowledge or opinion, but I find that hard to believe, given that the transmission was totally rebuilt, back around 2000, and the bike has only had a total of about 1200 miles put on it, since.

[yogidozer]

I'm not trying to disregard your knowledge or opinion, but I find that hard to believe, given that the transmission was totally rebuilt, back around 2000, and the bike has only had a total of about 1200 miles put on it, since.

Guess you forgot to mention that. Doesn't mean it was rebuilt correctly though.

[JC85]

Guess you forgot to mention that. Doesn't mean it was rebuilt correctly though.

Valid point. Sorry I didn't mention that, before. I'm going to look at some simpler fixes like tightening up the shifting action with new bushings and pins, but if that doesn't solve it, I'll be taking the trans to the work bench to see if it's something like what you suggested. I'm sincerely hoping I don't have to go that far.

[Rich A]

Isn't there an adjustment on the back of the gearbox that affects shifting? As I recall, it is a pita to get to, and you should make very small adjustments with it.

Rich A

[Ryan]

When you are checking to see if it hits the floor board, are you pushing by hand or using your foot? The  play in the linkage could be exacerbated by the extra pressure you would apply in  a normal shift. It may be moving forward or backwards, and could be binding up above the floorboard but before the gear is fully engaged. Shift with your boot, then check to see if you can move the shift lever at the gearbox. If it moves further, your sloppy linkage is binding up short of a completed shift.

[Tom H]

One more thing to check if you didn't already. Is the shift lever on the trans hitting the battery tray when you shift to first?

From what you describe, it only happens when the bike is cold. As in you get up in the morning and take it for a ride. Once warmed up the problem does not happen again.

You also mentioned that the trans was rebuilt and has low miles. When did this issue start happening? If it was fine after the rebuild, what changed?

A loop can shift fine with a very sloppy linkage as long as the bits don't hit anything during the shift IMHO, been there.

If all the bits move fine, then Yogidozer may have the answer with bad dogs on the gear??

Tom