Rusty gears

[rolesyboy]

I am on a bit of a gearbox rebuild mission at the moment. I have a gearbox with some hard to find components. They have been sat for a while so have some surface rust.
What is the best way to remove this? Vinegar? At what point does rust become a problem on gears? When it is visibly pitted? I would just replace them but they are not readily available.
Thanks. Mark

[smithyrc30]

I would not use vinegar on hardened steel. The pitting caused by the rust will cause micro cracks when the acid in the vinegar hits them.

I posted some pictures of rocker pads that I had tuck in vinegar as an experiment and two of six cracked. Not sure which thread it is. I'll have to see if I can find the pictures.

I would wet blast them and then assess the depth of the pits left by the rust.

[agricola]

If I remember rightly Nicholson Mclaren used to shot peen Hewland gears. So if the gears are worth it you could look at having them peened as there are firms that do it.

[Toby]

What ever you do, if you do chose to blast them make sure you don't strip the coating off the taper where the synchro ring seats

[Spider]

I've run them on the wire wheel.

If it's more that that can take off, then really, the gear is shot. If there's any rust on areas that bearings run, then the part is not usable. The Rust can be cleaned from them, but the surface that's left will make mince meat of the bearings.

Just keep in mind too, on the Gear Teeth, you can get away with a bit of pitting as it will only reduce contact surface and you don't generally tend to be in any one gear for long periods. In 4th gear, the shafts are locked together and all the gears as spinning unloaded, going along for the ride, so if there's any noise from them, it will only be for the short time that you are in that gear.

[Andrew1967]

I'd agree with Spider.

I've had lots of NOS gears (still have quite a lot in fact) and many had light surface rust and they come up well with a wire wheel on a bench grinder and are perfectly useable.

[agricola]

this is the process as i undestand it
https://gearsolutions.com/features/an-i ... igue-life/