International Lancia Forums

I'm rebuilding a 4-fourspeedbox for my Fulvia 1200 HF series 1 to replace the 5 speed currently fitted
I wonder if any improvements could be made in the bearing arangement of the driveshaft located in the bellhouse.
Acc the Q&A database the bearing and seal numbers are quote:
"Gearbox

As far as I know the sizes are the same for all Fulvia gearboxes unless noted otherwise.

Gearbox input drive shaft seal is 20x30x7. You have to take the front off the gearbox to get to it. It is inside the front of the gearbox.

Needle bearing for drive shaft HK2016. Also in the front of the gearbox housing.

Secondary drive shaft seal: DH 20x26x4. This seal is shown in S2/3 part books. I could not find it in S1 part books. I have never found it on a car, neither S1 nor S2/3. unquote"

I can imagine if the needle bearing is 19mm (HK2019?) instead of 16mm for the height it carries the driveshaft better, or am I wrong?
It will still fit the bush it is pressed in only it sticks out 3mm. I think the secondary drive shaft seal: DH 20x26x4 is located inside the bush. There are two seals and there is an oil hole present I believe to keep the seals lubricated but I might be wrong.

Please let me know if above installation needs improvement or not.
Cheers,
William

I just learned that a HK2020 needle bearing exsists. This bearing is 4mm longer than the original HK2016 and can carry about 25% more load.
Would this be a good idea?

The section in the Q&A is about 10 years old.

There are bearings of the same size with full compliment of needles and half compliment of needles. In the later a cage seperates the needles. The full compliment carries more load of course. I don't remember if the HK2016 is the full compliment one or the half compliment one.

I doubt if a needle bearing of even double size would be able to handle the engine power. The needle bearing is however not at all important. It is there to sort of keep the shaft in position when mating the gearbox to the engine and to keep the clutch disc centered when the clutch is released together with the very small ball bearing in the crankshaft. The clutch is not transmitting any engine power when released.

I have never seen a bad one except once as a result of a bent drive shaft. In this case the seal was also destroyed causing massive oil loss.

The seal has apparently been a problem from the beginning till the end of production. On the S2 gearbox the extra seal was added to provide a lubrication bath for the front seal. I don't think it really helped. All gearboxes from the first Flavia till the last Fulvia I have seen had leaked through the front seal.

Two weeks ago I did one of my own gearboxes and stacked two 20x30x4 seals instead of the single 20x30x7 seal with silicone grease between them. I doubt it will help. We will know in 10 years or so.

The roller bearing and oil seal system is really not much good; I have replaced quite a few of these, very often because the owner had clutch slip owing to gearbox oil escaping.

The very first gearboxes had shorter roller bearings and just one oil seal which shows that the gearbox designer (Luigi Bosco) got it seriously wrong, since the improved version is still not as it should be in my view.

If replacing these parts then the quill shaft portion that runs in the bearing and seals must be checked carefully for wear otherwise the new parts will not last long. I have no idea what you would do to find a good replacement; I suppose that the shaft could be metal-sprayed or plated and then ground to the correct size.

I have not given any thought to an improvment for this area; I imagine it would be complicated and expensive!

Paul