Gearbox locked

[Bjorn Nilson]

This is how to test shift the 5 speed without using the gear linkage. You can do this with the transmission in the car. You only need to disconnect the linkage.

Thanks Steve. This was the method I used to test the gearbox when I first got it. The test was successful and that's why I decided to use it instead of my old gearbox. As I wrote, it worked fine also after mounting it in the car. I also performed the same test with gearbox in the car when the problem started to eliminate problems with the linkage.
I am not sure I used the correct length on the mounting plate bolts, so I will start there as that would be easy to fix. Do you know the correct length of these bolts? I will then continue troubleshooting as per your advice.

 

[Bjorn Nilson]

Hmmm.....couple of long shots here....but are easy to check

If...your X was... a 1300 model....I think you have to use the complete 1500 5 speed shifter and all linkage. And there is something in the tranny tunnel on the 1300 models that interferes with part of the 5 speed shifter.

Or......if...when you bolted on the lower engine mount.....you used a bolt that was just a bit too long.....the end of the bolt then jams against the shifter rod inside the tranny and locks it up. Someone here was dumb enough to do that.......

It's a 1984 1500 5 Speed, now with a UT Mk1 engine and another X1/9 5 Speed tranny. The mounting bolts are 25mm long (probably a little bit too short?) and they don't hit the bottom of the threads on the gearbox.

 

[Dr.Jeff]

The "too long of mounting bolt" issue has to do with one of the lower bolts being a stud rather than a bolt. There have been a couple threads describing it in detail, but I'm sure others can elaborate here as well.

Is it possible the UT flywheel/clutch in a X1/9 trans has anything to do with it? Maybe it isn't the shifting per se, but a hung-up clutch not disengaging? Others can say for sure, I'm just throwing out thoughts.

And another thought - even more remote. I had a gearbox that was stuck in one gear. Turned out to be a rather rare situation where the selector mechanism inside the box (pic below) actually broke. But your situation does not sound at all the same. However there might be some odd thing like that happening? Sure hope not.

 

[Bjorn Nilson]

The "too long of mounting bolt" issue has to do with one of the lower bolts being a stud rather than a bolt. There have been a couple threads describing it in detail, but I'm sure others can elaborate here as well.

Is it possible the UT flywheel/clutch in a X1/9 trans has anything to do with it? Maybe it isn't the shifting per se, but a hung-up clutch not disengaging? Others can say for sure, I'm just throwing out thoughts.

And another thought - even more remote. I had a gearbox that was stuck in one gear. Turned out to be a rather rare situation where the selector mechanism inside the box (pic below) actually broke. But your situation does not sound at all the same. However there might be some odd thing like that happening? Sure hope not.

Today I had look at 5th and R mechanism and it is working as it should. The problem is in 1-2 or 3-4 but a lot of work would be required to reach further inside the gearbox and possibly fix them. SO repairing this gearbox will become a winter project and a good opportunity for me to learn more. For next summer I would probably like to have a taller final drive and LSD anyway. Tomorrow I will clean up my old gearbox and have it fitted and then prepare for dyno/mapping.
BTW, I am still using the X1/9 flywheel as required to fit the X1/9 starter. I also have a 4 paddle clutch made by Helix UK to handle the extra torque delivered from the UT engine. The clutch for X1/9 and UT Mk1 are the same I think. At least they share same article number at Helix.

 

[Steve Hoelscher]

Bjorn, which mounting plate bolts are you referring to? Jeff mentioned the transmission support mount bolts, which are located right beside the main shift rod. Key to know that the forward most position should have a stud and not a bolt. Its common to see someone replace the stud with a bolt that bottoms out in the case and locks the shift rod into place.

If there is in fact an internal problem it likely existed before you installed the transmission. I am curious as to the failure.

Installing a used transmission of unknown condition is very much a gamble. Given the age and known issues they have there are two very likely possibilities: 1. That the unit was previously replaced because it was very tired or had a significant failure. 2. Someone tried to repair or rebuild it and failed to do the work correctly. Both are common. Of the units I get approximately half have come to be because a previous rebuild was of either poor quality or failed entirely.

 

[Bjorn Nilson]

Yes there is one stud and two or even three bolts I think. I did not replace the stud (why should I ). I used 25mm bolts but I assume they can be little bit longer.
Unfortunately the shipping cost would be too high to send you the transmission for repair, and as far as I know there's no expert in this type of Fiat trannies in Sweden so I must trust my own mechanics skills. I will read your tips and tricks carefully and do my best.

I noticed that the 5th synchro was very worn so maybe this gearbox need a full rebuild. I will revert with more information.

 

[rizthewiz]

I rebuilt my 5 speed several weeks ago and had the same issue you describe. When I reassembled it, I checked that I had all the gears whilst it was on the bench using multi grips. I then installed it in the car and connected the gear stick linkage and made sure that I had all the gears again.
After I installed everything back on and tried to drive it, I could only go right in the neutral position. I could get 5th and reverse but not go left to get 1-4 gears.

I pulled the gearbox back out and found that the interlock pin had fallen out and the gear sleeve and shift rod was stuck in 3rd gear internally. As this gear was selected I couldn't get across to select any other gears.

If you have the end cover off and in neutral, you should be able to see if the ends of the shift rods line up or if not then you have a gear already selected. If they don't line up, then you can try and take off the detent ball cover and check to see if the balls are in there. If a gear is selected you can push the shift rod back into place with a screwdriver.

I reassembled mine again and everything works fine now. I think the interlock pin fell out when I installed the shift fork on 5th gear. I think I pulled the shift rod up too much to attach the bolt and it must have dislodged then.

 

[Dr.Jeff]

I rebuilt my 5 speed several weeks ago and had the same issue you describe. When I reassembled it, I checked that I had all the gears whilst it was on the bench using multi grips. I then installed it in the car and connected the gear stick linkage and made sure that I had all the gears again.
After I installed everything back on and tried to drive it, I could only go right in the neutral position. I could get 5th and reverse but not go left to get 1-4 gears.

I pulled the gearbox back out and found that the interlock pin had fallen out and the gear sleeve and shift rod was stuck in 3rd gear internally. As this gear was selected I couldn't get across to select any other gears.

If you have the end cover off and in neutral, you should be able to see if the ends of the shift rods line up or if not then you have a gear already selected. If they don't line up, then you can try and take off the detent ball cover and check to see if the balls are in there. If a gear is selected you can push the shift rod back into place with a screwdriver.

I reassembled mine again and everything works fine now. I think the interlock pin fell out when I installed the shift fork on 5th gear. I think I pulled the shift rod up too much to attach the bolt and it must have dislodged then.

This sounds similar to what might have happened with one of my trans. It's the one I mentioned earlier with the broken selector fork. I tore it down just to find out what the problem was. Once I realized the issue I decided to reassemble it temporarily until I could gather all the needed parts, and the time, to go completely through it. However I welded the broken fork back together just so I could find out how everything else was working (I'll replace the fork when I actually rebuild the trans). I must not have got all the shift rods aligned correctly or something came loose as I was assembling it because it won't shift into gear on the bench (or the welded fork still isn't right). I recall someone (Steve?) saying it is sort of easy to get things incorrectly aligned during assembly, leading to this problem. I haven't bothered to get back into it yet to see.

 

[Bjorn Nilson]

Got my old working gearbox in today.The swap took me almost 3 hours, but I hope to shave a couple of minutes next time. I am curious about what happened so I will start digging deeper into the failing gearbox as soon as the UT engine is alive. I hope I can dyno and map the car next week.

 

[Niklas Andersson]

I'm no expert but I've been through my tranny a couple of times. I have a 4 -speed converted to 5-speed and I have changed a couple of synchro rings and gears over the years. I'm in Sweden, Eskilstuna. Let me know if I can assist you in some way.
PM me in that case, svenska går alldeles utmärkt

 

[Janis]

 

[Dr.Jeff]

View attachment 35384

The perfect solution to a destroyed gear :

 

[Bjorn Nilson]

Finally got the time (and guts ) to dismantle two of my gearboxes. I started with the Regata/Strada tranny, the donator for a taller final drive. It seemed to be untouched and in good condition except for synchronizers that were completely worn out.
Then I continued with the "locked" gearbox were only fifth and reverse could be in position. And when in position, the gearbox got blocked. This gearbox had obviously been opened before as there were no signs of paper gaskets, only silicone. The gear selectors were jammed, most likely because the tiniest interlock plunger was missing. This in turn resulted in that the gearbox locked in two gears and a malfunctioning selector rod. This is my theory at least, but maybe one of our gearbox experts have another idea. Also this gearbox seems to be in a good condition AND someone already put the tall 17:61 diff in it. So now I have an extra Regatta final drive that I didn't know about .
I've got big help from @Rupunzell and @Steve Hoelscher write-ups during the operation, so a big Thanks to both of You. I never dismantled a gearbox before and your articles was a big help in the process.

It is soon time to put everything together again with new seals and gaskets and I am looking for advice.
Should I go for a paper gasket (it hadn't before)? And if I do, would it be necessary to adjust the bearing preload? Should I glue the gasket?

Two synchronizers seem to be a little bit worn. There are 1.4mm resp. 1.3mm gaps between ring and bottom of cone as you see in pics below. Should I replace them? Even replace the driven gears/cones?

 

[Dr.Jeff]

Nice work. I find the more difficult task is reassembling them.

I'm certainly not one of the gearbox experts but I'll throw out my opinions on your questions.

I'd use a sealant like Hylomar on the cases rather than a gasket. Old alloy cases like these tend to develop mating surface issues that will leak over time. So sealing them with something other than a thin paper gasket seems appropriate. The blue stuff works incredibly well. There is another one that is even more aggressive that all of the vintage Porsche guys use on their engine cases. I use it on vintage motorcycle cases that are always warped. It is made by ThreeBond and has a strong adhesion property. That makes it seal better but also very difficult to separate and clean up if you ever need to open the box again. Another popular one is Loctite (Henkel) 574. I've used it but not on a gearbox or similar case so can't comment on it. Elring makes one that's also highly recommended called Curli-T. I haven't tried it. One thing I would NOT use is any type of silicone sealant...I hate that goop.

Regardless of what you use between the cases the preload will need to be checked and adjusted accordingly.

Typically I'd want to replace any/all worn (or even non-worn) synchros in any gearbox as a preventative measure. However we seem to be finding the replacement synchros for these boxes do not last very long at all. The original OEM ones are difficult to find (and very costly), so if the existing ones are not worn, or just marginally worn, I'd be tempted to keep them. That's a tough call.

 

[Bjorn Nilson]

so if the existing ones are not worn, or just marginally worn, I'd be tempted to keep them. That's a tough call.

Thanks for your reply Doc. But what do you think about my synchronizers (OEM or not, how should I know)? A little bit worn, or badly worn? Should I replace them?
To me, the other type, with the friction ring design, seems to be a lot better. But unfortunately, that can't be changed .
EDIT: This will be a temporary solution for next season until I have the C510 with cables ready.

 

[Dan Sarandrea (Phila)]

Finally got the time (and guts ) to dismantle two of my gearboxes. I started with the Regata/Strada tranny, the donator for a taller final drive. It seemed to be untouched and in good condition except for synchronizers that were completely worn out.
Then I continued with the "locked" gearbox were only fifth and reverse could be in position. And when in position, the gearbox got blocked. This gearbox had obviously been opened before as there were no signs of paper gaskets, only silicone. The gear selectors were jammed, most likely because the tiniest interlock plunger was missing. This in turn resulted in that the gearbox locked in two gears and a malfunctioning selector rod. This is my theory at least, but maybe one of our gearbox experts have another idea. Also this gearbox seems to be in a good condition AND someone already put the tall 17:61 diff in it. So now I have an extra Regatta final drive that I didn't know about .
I've got big help from @Rupunzell and @Steve Hoelscher write-ups during the operation, so a big Thanks to both of You. I never dismantled a gearbox before and your articles was a big help in the process.

It is soon time to put everything together again with new seals and gaskets and I am looking for advice.
Should I go for a paper gasket (it hadn't before)? And if I do, would it be necessary to adjust the bearing preload? Should I glue the gasket?

Two synchronizers seem to be a little bit worn. There are 1.4mm resp. 1.3mm gaps between ring and bottom of cone as you see in pics below. Should I replace them? Even replace the driven gears/cones?
View attachment 54683

View attachment 54684

View attachment 54685

View attachment 54686

According to Steve H.'s 5-speed 101, a gap of 1.3mm (approx .050") or bigger indicates good service life left in the synchro rings and gear hub (the "ribbed" part of the gear that contacts the inner surface of the synchro ring).

 

[Dr.Jeff]

Should I replace them?

That's where my lack of expertise falls short of helping, sorry. I like the answer from @Dan Sarandrea (Phila). I recall something about that in Steve's threads. To be completely honest I don't recall exactly where that measurement is taken. Could you post a pic to show it? Thanks.

Especially considering this is only temporary I'd certainly reuse the old ones so long as they have some life left (i.e. they weren't already grinding). No only has there been issues with the current supply of new replacements, but they are quite expensive (at least compared to the same type used in other cars).

 

[Bjorn Nilson]

Continued my work today and found another issue that maybe had an impact when the gearbox got locked.This broken pad seems to have jammed the synchronizer and hub in gear which in turn blocked the 3rd/4th gear fork from going neutral. After spending several hours on the gearbox I am feeling quite comfortable working with it now. Replaced the broken pad with a good one from the donator gearbox.

 

[Dr.Jeff]

Continued my work today and found another issue that maybe had an impact when the gearbox got locked.This broken pad seems to have jammed the synchronizer and hub in gear which in turn blocked the 3rd/4th gear fork from going neutral. After spending several hours on the gearbox I am feeling quite comfortable working with it now. Replaced the broken pad with a good one from the donator gearbox.
View attachment 54753

Interesting how such a small simple piece can lock up a complete unit and render it useless. Fortunate that broken bit stayed in place rather than migrate around the gearbox and get ground up by the gears.

 

[Steve Hoelscher]

Finally got the time (and guts ) to dismantle two of my gearboxes. I started with the Regata/Strada tranny, the donator for a taller final drive. It seemed to be untouched and in good condition except for synchronizers that were completely worn out.
Then I continued with the "locked" gearbox were only fifth and reverse could be in position. And when in position, the gearbox got blocked. This gearbox had obviously been opened before as there were no signs of paper gaskets, only silicone. The gear selectors were jammed, most likely because the tiniest interlock plunger was missing. This in turn resulted in that the gearbox locked in two gears and a malfunctioning selector rod. This is my theory at least, but maybe one of our gearbox experts have another idea. Also this gearbox seems to be in a good condition AND someone already put the tall 17:61 diff in it. So now I have an extra Regatta final drive that I didn't know about .
I've got big help from @Rupunzell and @Steve Hoelscher write-ups during the operation, so a big Thanks to both of You. I never dismantled a gearbox before and your articles was a big help in the process.

It is soon time to put everything together again with new seals and gaskets and I am looking for advice.
Should I go for a paper gasket (it hadn't before)? And if I do, would it be necessary to adjust the bearing preload? Should I glue the gasket?

Two synchronizers seem to be a little bit worn. There are 1.4mm resp. 1.3mm gaps between ring and bottom of cone as you see in pics below. Should I replace them? Even replace the driven gears/cones?
View attachment 54683

View attachment 54684

View attachment 54685

View attachment 54686

Bjorn,

The synchro clearance looks quite serviceable on these. If you can source FIAT OEM synchros, replacing them will give you piece of mind. I would not replace a serviceable OEM FIAT synchro with an aftermarket of any type.

Just as important as the synnchro is the friction ribs on the gear's synchro cone and the engagement teeth below the cone. Both should be inspected for wear and the gear replaced if worn. Its hard to see detail in the photos but they look to have normal wear and be in serviceable condition.

As for the choice on gaskets. I would suggest re-assembling the case as it was, without the gasket and checking the diff's preload. If its within spec, then pull the case half and do a final assembly with your preferred sealant. If the preload is too tight then you can fit a (thin) OEM Fiat paper gasket to remove about 10/1000's of preload. Be sure to use sealant on both sides of the gasket.

People seem to have the same stubborn opinions on sealant as they do motor oil or Bar-B-Que sauce. I use Permatex Ultra Black because it is OE quality sealant formulated specifically for manual transmissions. I have used it for many years with excellent results. I used it in my commercial transmission shop on hundreds of manual transmissions in everything from Toyota Corollas to Superduty pickups. I know people swear by the Hondabond but the Toyota sealant is every bit as good. People certainly love Hylomar and seem to have an unusual loyalty to it. Me, I have seen all of this stuff in operation and still use Ultrablack. Your mileage may vary.