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Discussion Starter #1
Hi everyone,
New to me '77 900SS, first real ride on it today and found that it will not stay in 4th gear. Shifts into 4th just fine (either up from 3rd or down from 5th), but pops out of gear shortly after, even at light load or engine braking. All other gears work fine, and it shifts easily and cleanly into every gear. Any ideas or advice?
 

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You didn’t ride it before you bought it. The PO was less than honest. Had you ridden it , and found the issue, you could have used it as a bargaining chip. Hopefully you are skilled enough to repair it yourself, and can find the parts. Finding a mechanic who knows old Ducatis will be a challenge, so will finding parts. I hope you got a deal on it.
 

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Hi everyone,
New to me '77 900SS, first real ride on it today and found that it will not stay in 4th gear. Shifts into 4th just fine (either up from 3rd or down from 5th), but pops out of gear shortly after, even at light load or engine braking. All other gears work fine, and it shifts easily and cleanly into every gear. Any ideas or advice?
Broken. Hope you didn't get shafted. Good luck!! :)
 

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One quick way is to drain the oil now and look for shrapnel - all clear, then it just might a misaligned shift fork or weak spring. Could be ugly, could just be messy, and I've read where these older bikes sometimes do stuff like this when they are low on oil, but I dunno,... in one case it was because the new owner switched to detergent oil from 30 years on non-detergent from the PO.
 

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... whole buncha ~I dunno~ out of us so far .... need more information. I think the OP was hoping to hear something to the effect of "oh yea, that year/model has a well earned reputation for having a fourth gear problem. Easy fix, just adjust the hangy dinger next to the metric hantoon rantoon and yer good ta get ... just whistle past the graveyard after ya do it ... "

.... or something along those lines.

Nawp ... not this time. At least it's not looking that way just yet.
 

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Bon Vivant
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These bikes and the gearbox are very simple, if the problem persisted in every gear I'd guess the gear selector box but only in 4th I'd have to say its probably rounded off dogs on the gear itself. Easy job to check the selector box but for the trans you're gonna have to split the cases which means a complete tear down. VERY expensive if you can find the right tech to do it. to drop the engine and split the cases I'd guess you'll be over $5K to fix it
 

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Get back to the seller and have a good rant and try to get some $$ out of him towards fixing the problem. As bulldog says it will be an engine strip. However, you will be able to get it all freshened up and end up with something very nice.You may even find a few other things not quite right. Good Luck.
Ian
 

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Archilla: Please share with us a little more about your bike and its condition. Pictures would be great. It would help in a great way to set the stage for more thorough advice. Also, where are you? There may be bevel buddy nearby who can help in person.

Are you a techie? Based on your description of the problem, I have to agree with flynbulldog; it's probably worn dogs on the 4th gear and if so, the original owner must have know this so you should discuss this with him. Has the motor every been split? If not, there should be a little lead seal and wire under the motor. If you paid a good price for a running bike then you should argue for at least a partial refund; it does not hurt to ask. If it has been split, why? ask the previous owner about what engine work was done.

I don't understand why so many owners are so reluctant to work on these motors. I've split a bevel twin before and as long as you are methodical and have the right tools, it's a pretty easy and basic (and fun) engine to work with. What scares people is shims, so if you split the motor, just ensure you check and save every shim inside the motor and when putting it back together, carefully measure and shim the cranks and gear shafts correctly. If the original shimming was done right at the factory/previous rebuild and a new gasket is used on clean crankcases then the shimming of the crank and gear box shafts should not change; this is why it's so important to keep track of all shims. There are a lot of people who have done the job on the Internet forums that can help. My old Haynes manual is not perfect but is a great resource for this type of work so you should consider finding one anyway, even if you don't play yourself.

The trickiest jobs when splitting the motor are removal of the pinion/flywheel (the right puller, a big hammer) and turning the kickstart shaft about 45 degrees to release the lock stop to allow the casings to split; I've done this bit alone but it's so much easier with a buddy. What I would do, if the rest of the motor is in good shape, is just split the casings with the right side down and all the left side shaft shims carefully put back on their shafts if they pulled away with the casing during the split. You can now carefully inspect the gears and see what is going on. Just look up "worn gear dogs" on Google to get familiarity on this subject. If the dogs are worn then you will need to use this and other forums (facebook has bevel specific parts groups) to source the replacement gear(s) (very expensive) and then disassemble and replace the worn parts; more shims and circlips. While the heads are off, it's a great time to check the valve shimming and correct if necessary; again a really easy job that so many seemed scared of. It is a horrible job to do with the heads in-situ.

You still have the Multistrada?

Rick
 

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Discussion Starter #9
Guys,

Thank you for all of the replies so far. There is a lot to unpack here, so let me start with the easy part, the bike and the transaction…

The bike was a non-running barn find years ago which was then restored. After the (quite extensive) restoration, the bike was started/run, but never actually ridden or shaken down. Between then and my purchase, it passed through two collectors, neither of whom ever ran the bike at all; it was a display piece for both of them. If there were pre-existing trans problems that were not resolved in the restoration, neither of them would have known, noticed, or probably even cared. It was a long distance purchase, and for various reasons (including COVID-19) I did not travel to personally ride the bike. If I had, I would certainly have noticed the 4th gear issue (and a few other things as well) and would have either negotiated a significantly different price, or passed on it altogether. I did have someone local ride and inspect the bike for me, but they did not notice the issue. Based on the location of the test ride, they may have never gotten it out of third gear. Anyway, for the moment I’m not beating myself up over things I should have done differently before the purchase, nor am I angry with or trying to assert blame on anyone involved. I just want to move forward and make the bike right so I can enjoy it.

So, back to the issue at hand. It will go into 4th gear, but soon after it slips out of gear into neutral, even at light load or engine braking. All other gears seem to work fine; no other gear has disengaged once, but 4th slips out every time, so the issue seems to be clearly isolated to 4th. It seems to me there are two possibilities:
  • the gear is not fully engaging, which could be something simple related to the gear selector (like the eccentric adjustment or a weak/broken return spring), or a problem with the 3-4 selector fork, or shimming adjustment of 4th gear
  • the dogs on 4th gear are completely shot
If there is another idea I’m missing, please let me know, but based on the above possibilities, I have a few questions for those more knowledgeable than myself:
  • Could a problem with the gear selector (return spring, eccentric adjustment, etc.) possibly affect only a specific gear (4th gear in this case), or would it more than likely prevent proper engagement of all gears (I’d find random false neutrals in various gears)?
  • Is it common that the dogs on 4th could be so worn and the rest of the gears would be OK? I personally would expect worn dogs on a lower gear (like 2nd) which sees more frequent and harder shifts than the upper gears.
  • If a bent or otherwise worn 3-4 selector fork were the issue, wouldn’t that cause problems for engagement of 3rd gear also?
The cases have never been open, and the original lockwire/seal is in place, so I’m clearly hoping it’s a problem with the gear selector, and I’m going to start there first. I don’t want to consider splitting the cases until/unless it’s clear that the problem is internal, not just due to cost but also because I’d like to keep the original seal intact.

Thanks in advance!

@rick81mhr900ss Yeah, I still have the Multistrada (and a few other bikes as well).
 

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Bon Vivant
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The gear selector box is built into the side cover on all of these old bevel drive ducs. the selector box is isolated from the transmission and does not share lubrication. A broken return spring or slight miss alignment of the fork (35) would keep the bike from going into or out of gear and would have no effect on the gear once its engaged and moving. Yes, having a worn or chipped dog in second gear would be more frequent but it could happen to any gear - sometimes the metals on these old parts have inconsistencies. But whether its a selector fork (13) or the gear if its not in the selector box (And I dont think it is) it will have to come apart.

990123
 

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Of note, it was the 4th gear of my 75 860GT that failed way back in 82. The gears worked OK but there was a new and odd sound in 4th so I broke open the motor to find the 4th gear had started losing it's surface on a few teeth. Fortunately no other damage was done. Different days; I found a whole gearbox for 50GBP.
 

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Discussion Starter #13
Yes, having a worn or chipped dog in second gear would be more frequent but it could happen to any gear - sometimes the metals on these old parts have inconsistencies. But whether its a selector fork (13) or the gear if its not in the selector box (And I dont think it is) it will have to come apart.
Certainly could be worn dogs on 4th, but if so, the dogs must be completely and utterly worn and rounded, not just a bit worn or chipped...it is slipping out of fourth at close to neutral throttle when there is very little torque being transferred through the gear, which could only happen if there was virtually no positive engagement of the dogs. What I'm having trouble imagining is that the dogs on 4th gear alone could be essentially destroyed, while the rest of the box is fine. Not impossible, but seems unlikely that there would be such massive wear or deterioration on just one part of the box. Also, I think the correct selector fork for 4th gear would be #16 on your diagram, no?
 

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(To the resident experts on the model) ... do the transmissions in these 1970s bevels shift into higher gears when the shifter is taken up and then back down ... or does the transmission go into higher gear when the shift lever is just moved up and doesn't "care" when it's let go of?

Reason I ask is if the transmission shifts into higher gear when the lever is just lifted (without anything happening when the shift lever is released by the rider's foot) then the OP could possibly gather more information by attempting to hold the shifter UP with the foot after it's shifted into 4th gear and see if it stays engaged while the foot is purposely holding the lever up. Whew .. long run-on sentence ... apologies. I'm unfamiliar with the way these bikes work, so I don't know if the buck standard ratcheting "drum" is used or some other gear selection method is used.

If possible, that test could be performed in all throttle conditions (accel, decel, trailing).

Just a thought.
 

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The first left-side shift Ducatis were notorious for gearbox problems, generally caused by the linkage crossing over from the right-side selector box to left-side lever. I'm sorry to be brutal, but it will require a complete gearbox rebuild, and it may be cheaper to buy a complete new gearbox from Vee Two or from Ducati Kamna which will be ready to fit. Vee Two does make replacement gears for the six dog box but they are not cheap. A Ducati restorer in the UK told me that he does not bother trying to fix gearbox problems as it takes so much time to go through the whole box, replacing what is necessary and re-shimming, he always fits a new box complete.

BTW, if you are doing that anyway, why not go for a new six speed gearbox from Nova Transmissions?
 

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I don’t know how similar your gearbox is to the ‘91-’97 carby gearbox, but I’ve noticed mine requires a more positive shift from 3rd to 4th than is required in the rest of the gears. I lowered my shift lever slightly so that I would get more lever movement when I shifted and I believe it helped . It’s free and worth a try before dumping a bunch of cash into it.
 

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I don’t know how similar your gearbox is to the ‘91-’97 carby gearbox, but I’ve noticed mine requires a more positive shift from 3rd to 4th than is required in the rest of the gears. I lowered my shift lever slightly so that I would get more lever movement when I shifted and I believe it helped . It’s free and worth a try before dumping a bunch of cash into it.
Hmmm ... I wonder if flipping over to GP shift might help with more positive upshift engagement of 4th (and other) ratios. I've got a '96 900CR that I've been getting road worthy, this is something I'll put on the mental checklist when I get the bike running/rolling. May be worth thinking about.
 

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Discussion Starter #19
Thanks for all of the comments so far. I'm hoping that through careful/complete observation of the symptoms, learning from those on here that know more than I do, and applying thorough deductive reasoning, I can clarify the most likely cause before opening the cases. Kind of like getting several second opinions and fully thinking things through before undergoing an invasive surgery.

I rode it again yesterday and tried a few different things...adjusted the eccentric screw on the selector box through its full range in small increments, and tried various shifting techniques. What I observed makes me think it is a selector issue (either the selector box or an internal selector fork) rather than rounded or worn dogs. I was able to get it fully into 4th on a few occasions where it would not pop into neutral, even at hard acceleration. Fiddling with the eccentric screw did allow 4th to work more reliably sometimes, but it would cause problems elsewhere. Also, I noticed that on some upshifts, the selector would not fully recenter and engage the next detent without a light push down on the shift lever, and without that light push it would not select the next gear. Finally, sometimes it seemed to shift past 4th and into a false neutral, meaning I would shift into 4th, it would slip into neutral shortly after engaging, but shifting down would result in it going back into 4th, rather than down into 3rd.

All of this makes me think pulling apart the selector box is the next step. There may be other issues with a selector fork in the transmission itself, but it seems certain that the function of the selector box itself is part of the problem. Between the selector box and the convoluted crossover arrangement from the shift lever, there is a lot of opportunity for tolerances to stack up and make things wonky between what the tip of your boot requests and what actually gets translated to the selector drum...

Updates if I find something interesting.
 

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Bon Vivant
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Keep the linkage arm bolted onto the output shaft when you open the selector box. That will keep the spring from becoming a surprise snake when you remove the cover. From there you can see if the spring is installed correctly or broken and you can also adjust the pawl fork without things coming apart. Adjust the fork with the eccentric so that the fork has equal space on each side of the fork face while in neutral.
good luck
 
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