S1 Gearbox 4 speed problem - Third gear jump

[Huib]

Of course the selector parts on the outside have to be checked and fixed. Don't give up on the slider too soon!!! Everything overlooked on the inside is heavily punished as the thing has to be taken apart again.

The story is that the job of the navigator of Sandro Munari was to hold the gear in 3rd (in the days of the 1.2HF and 1.3HF). On the 1.6HF Lancia put a short stick which was mounted upright.

In the parts book I have I see that the slider for 3 and 4 comes from the 815.000 which is the first Flavia. That one has column shift. The problem does not occur on the cars with column shift. There is no long stick hanging from the mechanism under an angle. It is very well possible that early sliders did not have the back cut on the teeth inside the slider for the 3rd. I recommend to actually check the teeth for the 3rd for the back cut on all the teeth. To the untrained eye it looks like wear. If in doubt, buy a new slider. Same for the springs and balls inside the sliders and the fork mechanisms. They are available at acceptable cost.

Did you replace the bronze bushes for the yoke at the top? Don't forget those. Are the forks straight? Are all the clearances indicated in the book correct?

On the outside, do everything. If you really really want a perfectly shifting gearbox also put bronze bushes in the aluminium piece holding the small shaft with the hammer at the yoke end. The yoke has two wings at the top which function as anvils for the hammer at the end of the shaft. They often have one or two dents. Fill them by welding steel on them and grind them for minimal clearance with the hammer.

[lancia7550]

Thanks for all the advice Huib and fellow forum users. I am glad to report all my gearbox issues seem to be resolved:

After a few hundred kms no oil leaks visible: I replaced the two front seals and the sideshaft seals, as well as all the gaskets. I put some sealer on the surface inside the half shafts where the nut seats. Also replaced the small oil seal inside the speedo drive - see attached - that has clearly never been replaced!

3d gear stays in place now when the clutch is pushed in:
The 3-4 slider was on inspection installed correctly. So I put a small shim in with the ball and spring in the inner selector mechanism and tightened everything on the outside mechanism up to the point just before it restricts movement. Clicks in and out of third with a nice "click" now.

Best of all, my second gear downsift issue is fixed! Have been nursing that for 10 years... The syncro was basically brand new, but has clearly not been lapped when installed by a gearbox shop previously. From the shiny and dull marks in attached picture you can see the inside of the syncro ring did not fully make contact with the cone. After lapping with grinding paste for about 30 second the "grip" on the cone drastically increased. There is now no delay or grinding when shifting (down or up) into second, even when cold!

[Huib]

Thanks for the feed back.

[khrell]

I'm very glad that this thread is helping more people. Today I finished turning the 3rd gear selector pinion and installed new synchronizers.




Now I have another doubt when assembling, I have seen that I am missing some cotter pins on one side of the gearbox output (I put a photo from a magazine where you can see the assembly)



I don't remember that they were in the first disassembly and I don't know if it is possible to get them

[Huib]

Oops. You absolutely need 3 in each flange. Loosing one is normal when you dismantle a Lancia gearbox for the first few times. What you can do is follow the system of the series 2. Use circlips:

circlip.jpg (8.03 KiB) Viewed 125 times

Nice book. Which book is that?

[khrell]

Thank you for your answers Huib. I finally got the original keys and they are now in place.

Now I'm a bit desperate, I've assembled the box (without putting the transmissions together yet) , I've tried to put the gears in when stationary and all of them go in except 1st and 2nd. This shifter has new first gear pinion and the two synchronisers.

Neutral, 3rd, 4th and reverse are all perfect. I don't know if it's because we haven't fitted something right on the 1st and 2nd gear shifter or if it could be something simpler: like the synchronisers haven't been aligned properly... I don't know, I'm worried that I'll have to open the box again . We tried shifting everything before assembly and it was fine.

P.S: What you can see in the photo are French Gazoline magazines, where in several issues you can see how they repaired a box identical to mine and I used it as a reference. I scanned everything and made a manual, I'll look for it and share it.

Thank you!

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