Speedo drive gear questions

[Bainford]

I pulled the speedometer drive gear assembly from my 365 trans to sort an oil leak, and I have a couple of questions;
- Is there supposed to be some sort of spacer/shim between the gear and the green bushing? Referring to the photo, what appears to be a bit of melted plastic came out with the gear, and the outboard face of the gear almost seems to have some plastic melted to it. It all seems odd, but aside from the appearance of melted plastic, nothing seems/feels amiss.
- Should there be some type of supporting bushing for the inboard end of the drive gear? A spigot on the nose of the gear and a bore in the transmission housing suggests that some type of bushing is supposed to be present, but nothing was there.

Everything seems to be OK, and the speedometer operates well. Just wondering if there may be a problem here.

[jbcollier]

No outer bushing, the speedo gear is well supported in the housing.  365 transaxles especially tend to leak oil.  This may result in the 5th gear area running dry which leads to the plastic gear heating up and melting.  Sounds bad but what is worse is that your irreplaceable, Hewland manufactured, 5th gear is also running dry and wearing out!

This is a common failure mode for many 5 speed trannies as often the 5 th gear set is located high and at the back, the first place to run dry as oil levels fall.

[Bainford]

Interesting comments, John.  I did have a significant leak here but it seems to be sorted now. Though the oil leak has been significant, the oil level is regularly checked and topped up.

Regarding 5th gear, there is always a light whine whenever under power in 5th gear. All other gears are quiet. I guess the up shot is that my car is almost never in 5th gear. Whole summers go by where I never select 5th.

[4129R]

I have just bought a new plastic drive gear from Renault 16 in Holland.

The end of the plastic drive is a taper from 5mm down to 4mm.

The hole in the casing is 7.5mm.

This question seems to have been asked and answered above, but can somebody please confirm that the plastic taper on the end does not fit into the same sized hole in the gearbox housing?

[4129R]

I am not having much luck with the speedo drive replacing the gear and the plastic surround which fits down the hole in the gearbox casing.

I bought a new gear, plastic surround, oil seal and O ring all from Renault 16 in Holland. Not cheap.

I am now assuming that the taper on the end of the gear does not need to be an exact fit in the 7.5mm hole in the casing.

Next problem, the plastic surround does not fit in the hole in the gearbox housing. It is about 0.5mm too big.

Time to work out how to make it fit.

Put a long 1/4" bolt through the hole in the plastic surround, tighten a nut on the thread to hold the tube in place on the bolt, put the bit of thread left over into an electric drill, and carefully remove the plastic on emery paper until it fits in the hole.
Check often with accurate callipers until it is the correct diameter down the whole length of the plastic tube.

After about 2 mins, enough of the plastic had been sanded off evenly until it fitted snugly down the hole in the gearbox. Result !

[HoraceM22]

4129R, I'm in the process of trying to eliminate (or reduce) the minor oil leaks from my 5 speed box and have just replaced the O ring and small internal oil seal on the speedo drive but if this doesn't work I will try and change the speedo drive gear as I could see the shaft on mine was worn. Is Renault16 the place to go please? Can you remember the part number please?

Also, even after carefully replacing the gearchange oil seal (again), I  can see that this is still dripping. I'm thinking of trying to fit a 14mm bore O ring to sort this as I feel sure the 26mm OD of the current 15mm standard seal must be doing its job due to the light interferance fit in the casing. Any experience of this approach?
ATB
Horace Marks