Gearbox oil

Question What gearbox oil do you use ?

I used to be able to make good gear changes but the oil I used is no longer available.
I changed the oil to a new gearbox oil Penrite 75W - 145
I now have trouble trying to get a good gear change especially into second and third. It always grates and crashes either changing up or down.

So please advise.

All the best Andrew

Hi Andrew

I have been lucky enough to ride two ABCs recently with different gearbox oils. The first had an SAE 80 weight oil and the gears did indeed tend to crunch. The second had a much thicker and more "treacle like" oil in it. The gear selection on the second machine was indeed a lot smoother. I should also add that the gearbox on the second Machine appeared to be in better condition (lower miles?) and 4th gear was a lot less worn.

The gearbox for the first machine is currently on the bench partly to rectify 4th and also do something about gearbox oil leaks. I was surprised to see that both gearboxes leak in similar place despite the viscosity of the oil. I am, however, tempted to find a thicker gearbox oil for the first machine to see if it reduces the crunch.

Phil

Bonjour Phil
J'utilise de la graisse verte du fabricant Restom
https://www.restom.net/fr/310-geloil-5095.html
C'est parfait

Further to my previous post the recommended lubricant was Penrose Semi-fluid grease now still available Dell

OK the saga continues.
I started with 90 grade limited slip diff. oil and "Morrys" oil additive. Result crunching gears.
Next Penrite 75W - 140 gearbox oil. Result crunching gears.
Next Harley Davidson 145W gear oil. Result crunching gears.
Next Penrite semi fluid grease. This is some old oil I have had for 30 years and more so I presume you can still buy it. Result less crunching gears. I went for a longer ride and the gear changes seemed to improve as the engine got hotter.
Each time I changed the oil I only drained it from the bottom drain plug so there would be dregs of the previous oil left in the gear box.

Conclusion. I think we need to do a lot more testing of each oil to find a recommendation.
The Penrite 75W - 140 and the Harley oils may improve with more heat.
But at this point I shall leave the semi fluid grease in and see how we go, it would also be very difficult to get all the grease out without totally stripping the gearbox.

So what do you use ?

Dear All

I have now completed the rebuild on the "leaking and crunching" that I mentioned in my earlier post. The next step was selecting the oil for the box and so I phoned Penrite and spoke to their technical chap about the problem. Firstly, I was very happy that the Penrite man knew what an ABC was and secondly, he suggested a semi-fluid and steering box grease.

I have decided not to go down this route and have decided to use Penrite Transoil T250 (SAE250) oil. The main reason for this is that I was concerned that the semi-fluid grease would not flow easily between the main gearbox chamber and the transfer box as there are only 3x 1" holes in the gearbox end plate.

Having now filled the gearbox I can report that the Transoil T250 fluid does look very much like the "treacle" in the other non-crunching box. I hope to re-install the rebuilt gearbox over the next week and then run the bike once I have done this I will report back on the progress.