S1 Gearbox 4 speed problem - Third gear jump

[khrell]

Hi, I'm Guillermo from Spain. I have a Fulvia S1 Rallye 1.3 S with 4 gears. We have done engine and gearbox.

We did the gearbox because the second gear was not working properly and had oil leakage problems. We opened the gearbox and changed the first gear pinion for a new one, a third gear pinion for another one in better condition and two synchronizers.

The problem is that now the third gear goes out on its own in neutral when braking or slowing down. I have been told that it could be a spring that goes inside the selector fork, but it didn't do it before. Now I can't open the box again either can you think of anything I can do to minimise the effect from the outside?

Thank you very much, best regards!

[Huib]

90% chance that the slider for 3 and 4 is reversed. The splines for the 3rd have a torque lock design. A small back cut prevents dropping out of 3rd.

There are marks on the outside of the slider which should point in the direction of the pinion (or 3rd if you like). I am posting from home. Can't check it. If I remember correctly there are 3 rings machined on the outside. It is in the work shop manual.

[khrell]

Thanks for the explanation, I have some spare parts from another box that I used to swap with mine. I think you are referring to this outer spline, right?



What would be the correct position?

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Thank you very much for your help, it's bad luck that I have a 50% chance of getting it right, but I've mounted it wrong.

I just found a picture of the state of the box just before closing:

[Huib]

Exactly.
Yes. It is the wrong way around. The 3 rings should be on the side of the 3rd gear.

[khrell]

Enigma solved. Thank you very much, I'm sure someone can use it.

What bad luck!

[Huib]

It is the way homo sapiens learns. Join the club.

[khrell]

I was looking for the photos of the gearbox you made at Fulvia, and I see that the spline is also in the same position as mine

[Huib]

Oops. Thanks. I had not noticed myself. I think it is for a car which is not yet on the road.

[khrell]

I'm glad, one less worry for the future, it was to be confirmed.

Those photos were very useful when making my box


Since I have to open the box again. I changed the first gear and its synchro. The second speed one comes in very hard with the car cold, anything to check?

[Huib]

About the 2nd gear. There is a trick to make it shift faster even when cold. I keep it secret because if you shift quicker all the time the wear goes up.

I use the Millers CRX75W90 Synth oil for the gearbox. This already should make it shift a lot faster when cold.