Ciao Giovanni, sharp as ever. Good to see you .... uh read you. Good to remind everybody. Grazie. I have always wondered what the difference is. I have never seen nor felt a difference. Spaghetti?
Perhaps someone else on the forum knows. I will ask around again. In any case I continue swapping and remain alert that any mishap may be due to a possible difference.
S1 Gearbox 4 speed problem - Third gear jump
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lancia7550
- Posts: 74
- Joined: 10 Nov 2012, 22:26
Re: S1 Gearbox 4 speed problem - Third gear jump
When buying synchros they don't appear to list different parts for different gears:
https://www.pieces-fulvia.com/gearbox-s ... models.htm
https://www.pieces-fulvia.com/gearbox-s ... models.htm
Re: S1 Gearbox 4 speed problem - Third gear jump
Hello,
I have no doubt that the cones are compatible each others, also because on S2 the spare parts book list only 2284496 for all gears.
My "problem" is the curiosity to understand the differences between the various listed part numbers...
I'm sorry for that ;-)
I have no doubt that the cones are compatible each others, also because on S2 the spare parts book list only 2284496 for all gears.
My "problem" is the curiosity to understand the differences between the various listed part numbers...
I'm sorry for that ;-)
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lancia7550
- Posts: 74
- Joined: 10 Nov 2012, 22:26
Re: S1 Gearbox 4 speed problem - Third gear jump
I'm about to open my gearbox to replace the oil seals, but also because it drops out of 3d too easily when I depress the clutch. Great tips in this thread regarding the 3-4 slider that may be installed incorrectly.
The other issue I want to check is 3d to 2nd down shift that crunches, even when not really rushing it. 1st to 2nd shifts perfectly, even when cold. It has bothered me for a long time, as I had a new 2nd gear synchro and sleave installed years ago (minimal km's since then though) by a gearbox workshop (who I suspect also reversed the 3-4 slider). I wonder if the reversal of the slider on 3d may affect the downshift to 2nd? Sounds unlikely, but you never know.
I will measure the clearance on the synchros to check for wear. I will see if lapping the 2nd gear synchro might help if it is not worn.
Any tips for installing new synchros, or anything else to check that might affect the 3d to 2nd downshift?
The other issue I want to check is 3d to 2nd down shift that crunches, even when not really rushing it. 1st to 2nd shifts perfectly, even when cold. It has bothered me for a long time, as I had a new 2nd gear synchro and sleave installed years ago (minimal km's since then though) by a gearbox workshop (who I suspect also reversed the 3-4 slider). I wonder if the reversal of the slider on 3d may affect the downshift to 2nd? Sounds unlikely, but you never know.
I will measure the clearance on the synchros to check for wear. I will see if lapping the 2nd gear synchro might help if it is not worn.
Any tips for installing new synchros, or anything else to check that might affect the 3d to 2nd downshift?
Re: S1 Gearbox 4 speed problem - Third gear jump
When shifting gears a lot of gear wheels (and also the clutch disc!) have to change speed. That is a lot of mass. Making that faster requires holes to be drilled in the gear wheels etc. How much is the change in speed? Maybe someone likes to do the calculations. For me school is too long ago. It may explain the difference between changing from 1 to 2 and changing from 3 to 2.
Pushing a synchro to a cone is the braking principle. When pushing a pad against a disc, air has to be displaced. That is easy. When pushing a synchro against a cone, oil has to be displaced.That is a whole lot more difficult. The Millers oil which is commercially known as CRX75W90NT+ is technically more a 60W90. When cold it has the viscosity of a 90W when hot. So if your gearbox shifts ok when warmed up, changing to the CRX 75W90NT+ solves the problem. When you like to shift as a gentleman with a Borsalino, you may try the CRX75W140NT+ It has a magic of its own. Certainly not for the jockey with a cap. Changing the type of oil is the smart solution.
One can also use force by lapping the synchros. It is like mounting brake pads with a higher friction coefficient but one's hand has to apply a higher force on the stick as thick oil has to be pushed away. Wear is much higher. I check the braking action by hand by pushing the synchro against the cone while rotating. If slippery, just lap a bit. When lapping make triple sure there is no contamination of parts by the lapping paste.
As Marnix pointed out also get rid of any play between parts of the mechanism between yoke and stick.
Always keep all senses open for any other parts which may need repair or replacement.
Pushing a synchro to a cone is the braking principle. When pushing a pad against a disc, air has to be displaced. That is easy. When pushing a synchro against a cone, oil has to be displaced.That is a whole lot more difficult. The Millers oil which is commercially known as CRX75W90NT+ is technically more a 60W90. When cold it has the viscosity of a 90W when hot. So if your gearbox shifts ok when warmed up, changing to the CRX 75W90NT+ solves the problem. When you like to shift as a gentleman with a Borsalino, you may try the CRX75W140NT+ It has a magic of its own. Certainly not for the jockey with a cap. Changing the type of oil is the smart solution.
One can also use force by lapping the synchros. It is like mounting brake pads with a higher friction coefficient but one's hand has to apply a higher force on the stick as thick oil has to be pushed away. Wear is much higher. I check the braking action by hand by pushing the synchro against the cone while rotating. If slippery, just lap a bit. When lapping make triple sure there is no contamination of parts by the lapping paste.
As Marnix pointed out also get rid of any play between parts of the mechanism between yoke and stick.
Always keep all senses open for any other parts which may need repair or replacement.
Re: S1 Gearbox 4 speed problem - Third gear jump
Thank you all for the contributions. It is a very interesting post. For my part, I have everything ready to start the party,
when I find time and it starts I will post photos. Greetings!!
when I find time and it starts I will post photos. Greetings!!
Re: S1 Gearbox 4 speed problem - Third gear jump
Hello everyone, first of all I wish you a Merry Christmas.
I haven't started on the box yet, but I'm gathering pieces in the meantime. I'm having my head spin with the hard second gear shift.
Do you think it could also be due to the wear of the shifting sprocket between first and second? Is it worth looking for one?
Best regards!
I haven't started on the box yet, but I'm gathering pieces in the meantime. I'm having my head spin with the hard second gear shift.
Do you think it could also be due to the wear of the shifting sprocket between first and second? Is it worth looking for one?
Best regards!
Re: S1 Gearbox 4 speed problem - Third gear jump
There is hardly anything wrong with the sliders. Keep your eyes open though, yours could be the first one.
The gear wheels on the main shaft have cones onto which the synchro's lock. Note that those cones and their teeth are seperate parts pressed into the gear wheels (or heath shrunk). AFter all those years I have seen only once that the cone had separated from the gear wheel.
Just go ahead, disassemble the gearbox. Wash very well. Do the measurements of the synchro's. Usually they are like new. Testing the ball bearings is more difficult. Make sure you have all the special tools.
Is the gearbox still under the car? If so you can already change the oil to the CRX75W90NT+ and test what that is doing. It works magic.
The gear wheels on the main shaft have cones onto which the synchro's lock. Note that those cones and their teeth are seperate parts pressed into the gear wheels (or heath shrunk). AFter all those years I have seen only once that the cone had separated from the gear wheel.
Just go ahead, disassemble the gearbox. Wash very well. Do the measurements of the synchro's. Usually they are like new. Testing the ball bearings is more difficult. Make sure you have all the special tools.
Is the gearbox still under the car? If so you can already change the oil to the CRX75W90NT+ and test what that is doing. It works magic.
Re: S1 Gearbox 4 speed problem - Third gear jump
I don't want to tempt fate, remember that there was a 50% chance of putting the sliding sprocket wrong... And I did it hahaha.
I'm afraid of opening the box and not leaving it properly. I changed the first gear pinion (the original one literally had the synchro teeth undone), I exchanged some synchronizers... But I have the feeling that it is worse than at the beginning, all the gears engage very smoothly when stopped, but when moving I think which should go better than at the beginning.
For now I have bought the oil that you told me about, but I don't know if I should look at something else since I have to open... I don't know, maybe it's just in my head.
Thanks for your help
I'm afraid of opening the box and not leaving it properly. I changed the first gear pinion (the original one literally had the synchro teeth undone), I exchanged some synchronizers... But I have the feeling that it is worse than at the beginning, all the gears engage very smoothly when stopped, but when moving I think which should go better than at the beginning.
For now I have bought the oil that you told me about, but I don't know if I should look at something else since I have to open... I don't know, maybe it's just in my head.
Thanks for your help
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lancia7550
- Posts: 74
- Joined: 10 Nov 2012, 22:26
Re: S1 Gearbox 4 speed problem - Third gear jump
Following this topic with interest - I was convinced that my car dropping out of 3d gear must be due to the 3d-4th slider being reversed previously only to find it installed correctly.
I am currently focussing on the selector mechanism. I will follow Marnix's advice and tighten things on the outer selector mechanismas much as possible without restricting movement. I have also added a small shim to the 3d gear spring on the inner selector and it feels like it clicks into third a bit more solidly now. I guess there is no way of really knowing if these springs still have their original tension and what to replace them with?
Also, what role do the springs in the synchro hub play, and are these known to need to be replaced?
While inspecting the inner selector mechanism, I noticed there is a machined shim floating freely at the rear of the shaft. This looks correct from what I can see in the workshop manual (not very clear). I noticed in the original poster's pictures that this shim is not present. Can that be part of your shifting issues?
I am currently focussing on the selector mechanism. I will follow Marnix's advice and tighten things on the outer selector mechanismas much as possible without restricting movement. I have also added a small shim to the 3d gear spring on the inner selector and it feels like it clicks into third a bit more solidly now. I guess there is no way of really knowing if these springs still have their original tension and what to replace them with?
Also, what role do the springs in the synchro hub play, and are these known to need to be replaced?
While inspecting the inner selector mechanism, I noticed there is a machined shim floating freely at the rear of the shaft. This looks correct from what I can see in the workshop manual (not very clear). I noticed in the original poster's pictures that this shim is not present. Can that be part of your shifting issues?
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