G'box issue - locked in gear

rjplenter

rjplenter

True Classic
Hi all,

My gearbox is locked in 1st gear. After a day of competition (more on that later) the gearbox was fine until we were putting the car on the trailer. I tried to select reverse and the car moved forward. I moved the gear stick out of the reverse position and found I could not select any forward gear, i.e. the gear stick was pretty much solid. Tried reverse again, the gear stick would go there, but the car still wanted to go forward. I've been under it and disconnected the banjo and the gearstick is now free, so it is an internal g'box problem. Before I rip into it and take the gearbox out and apart, does anyone have any suggestion on what might be happening?

Cheers,

Rob
 
I had the same thing happen after I rebuilt my gearbox for the first time. In my case it was because the reverse gear was upside down on the shift selector, and was engaging both 1st and reverse at the same time. While we know this is not the same case, the result sure seems to be the same. Locked up. I would pull it apart and see what is going on. It's only time and a couple of gaskets. And as Jim pointed out, there is another similar thread.
 
rjplenter said:
Hi all,

My gearbox is locked in 1st gear. After a day of competition (more on that later) the gearbox was fine until we were putting the car on the trailer. I tried to select reverse and the car moved forward. I moved the gear stick out of the reverse position and found I could not select any forward gear, i.e. the gear stick was pretty much solid. Tried reverse again, the gear stick would go there, but the car still wanted to go forward. I've been under it and disconnected the banjo and the gearstick is now free, so it is an internal g'box problem. Before I rip into it and take the gearbox out and apart, does anyone have any suggestion on what might be happening?

Cheers,

Rob
Click to expand...
Rob: It is most likely a misalignment problem due to a loose (and hanging down) trans crossmember. With a jack try raising the crossmember and snugging up the 4 bolts that connect the crossmember to the unit body. The holes in the body can be stripped out by improper assembly techniques.
Also check the condition of the rubber trans mount and the stud/nut and two bolts that attach the mount to the trans.
 
Thanks for the responses so far.
Jim, thanks for the other thread.
Eric, reverse gear is in the correct way, lot's of driving on the road and two rallysprints since the last strip down.
John, absolutely no issues with the crossmember mounting and I checked where the shifter rod comes out of the body and there are no binding issues.

Okay, update. I've drained the oil, taken off the detent plate (still can't get any movement at the gear stick) and the g'box end plate and this is what I can see:

IMG_9151.JPG


1st gear is definitely engaged, my only question is; is that selector shaft protruding too far? Not willing to put any force on it yet.
As you can see, it's a 4 speed (sorry, didn't mention that earlier), so not looking forward to the job of pulling it out.

Cheers,

Rob
 
Further update.
Turns out it was stuck in 2nd gear, not 1st.
I tapped the selector shaft lightly with a wooden drift and it popped right back in.
I can now select all the gears again.
End plate back on, detent springs and cover plate back on, still good. Can refill with oil.

Seems to be fixed, but I'm not a fan of fixes with no identifiable causation. Makes me nervous it could happen again.

Thanks for the help!

Rob
 
The first time I took my 86 HD Sportster to my FILs camp in Northern NH I trailered it up. After the 2 hour drive I went to unload it & the motor was knocking and running rough. Luckily my FIL was a mechanic and my BIL owned his own bike shop. We determined a lifter had collapsed. We called my BIL & he said these lifters never fail. He had seen 1 collapse if left under load. I had let the clutch out before the motor stopped fully & so happened the the motor stopped right where the lifter didn't like it. Took almost 2 miles of easy riding to get the pressure back up & never happened again.
Maybe you ran into a similar set of circumstances?
 
rjplenter said:
Further update.
Turns out it was stuck in 2nd gear, not 1st.
I tapped the selector shaft lightly with a wooden drift and it popped right back in.
I can now select all the gears again.
End plate back on, detent springs and cover plate back on, still good. Can refill with oil.

Seems to be fixed, but I'm not a fan of fixes with no identifiable causation. Makes me nervous it could happen again.

Thanks for the help!

Rob
Click to expand...
Might not stay "fixed"...

~Problem could be rooted in a bent shift 1st / 2nd rod or a cracked shift rod boss in the housing.
~Bent shift fork.
~Gear select lock out "bean" has an issue.
~Or_?_
Recommend taking apart the G'box followed by a careful check over of these parts to discover the root of this stuck gear problem.

Will likely happen again.. Stuck gears while running is no fun at all,
Bernice
 
2nd on checking the detent balls and the list from Bernice. When I was doing racing, I had a gearbox change down to less than 30 minutes. You can do it!
 
fastx19 said:
2nd on checking the detent balls and the list from Bernice. When I was doing racing, I had a gearbox change down to less than 30 minutes. You can do it!
Click to expand...
I assume that’s for a 5 speed? Taking out the 4 speed is not a quick job.
If you were able to do a 4 speed swap in 30 minutes I want to know your secrets!
 
It was the 4 speed, in the 128. Not much to it, the big secret is removing strut, and lower mount as a single unit along with the axle. Then you have a nice space to get to the transmission. Everything comes right out through the wheel well. Just need to support the engine when removing it.
 
fastx19 said:
It was the 4 speed, in the 128. Not much to it, the big secret is removing strut, and lower mount as a single unit along with the axle. Then you have a nice space to get to the transmission. Everything comes right out through the wheel well. Just need to support the engine when removing it.
Click to expand...
Same works on the X, and if I haven’t done 30 minutes I’ve come very close. There is one complication on (at least) the ‘74: the rear a-arm bolt will foul the muffler if inserted from the wrong side and then the muffler has to come off as well.
 
Gear box removal from the exxe is not that difficult, removing the LH lower A-arm is one of the key items. Once the axles are off, shifter disconnected, clutch slave, speedo, reverse and maybe other switches disconnected, remove flywheel cover and four M12 fasteners, it's mostly good to remove.

4 speed, should be drained before removal or there will be an oily mess once the tripod axle joints come off. 5 speed can come out filled, not as messy.

More difficult is install. Make two long as reasonable (no less than 100mm) M12x1.125 studs with a slot or similar ability to drive studs to be installed on the top two threaded holes on the engine block to help support and line up the gear box for install. If the clutch disc does not need to come out, leave it be or if the clutch disc comes out, line it up with the proper tool.


Bernice
 
Bernice, that is no fun on the reinstall. Instead, worm your way under the car and proceed to spend 1/2 an hour to a bench press of the transmission the engine swearing at the person who designed this system. Then, and the 999th try, and when your arms are completely dead, it will magically slide into place and life will be filled with visions of glory from this one, simple, task.... ;)

Eric H, on my 128 racer at the time, I had the transmission in and out quite a few times as I was learning about it and messing around with an LSD at the time. So lots of practice.
 
That was indeed 2nd gear. Somehow the internal linkage got put in the nutral position while 1st was still engaged. If you were driving in a competitive event it is very likely that something got bent. The internal translator linkage or the fork itself. Or the plunger got damaged.

Has the transmission been rebuild previously? Its also possible the plungers got miss-installed.
 
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