Gearbox gear whine

[GyroLandy]

I have had my Tdi 300 Def gearbox (R380) overhauled as the third syncro was noisy. Once it was back in the vehicle I noticed a whine in four and fifth when I took my foot off the accelerator. As soon as I step on the gas it disappears. It's only when the engine is running freely and there is no load on the gearbox. Does anyone know what it can be. i spoke to the guy that overhauled it and he says it's wear and tear on the gears and there is nothing one can to to fix it except replace all the gears. Does this sound right? Seeing as I am overhauling the engine I have removed teh gearbox agin so what is the best option to have it fixed?

Should I rather just buy a recon gearbox or try and repair the one I have? It's starting to become an expensive exercise.

While I had it out last time he also did the conversion to rectify the common problem with these gearboxes where the oil doesn't reach all the right places. I can't remember the details exactly but he had to drill a hole somewhere on a gear to ensure the gear receives enough lubrication. I take it a recon box would not have this conversion already done??

[rick130]

[snip]

While I had it out last time he also did the conversion to rectify the common problem with these gearboxes where the oil doesn't reach all the right places. I can't remember the details exactly but he had to drill a hole somewhere on a gear to ensure the gear receives enough lubrication. I take it a recon box would not have this conversion already done??

The only thing that tallies with is the t/case input gear where the later ones are cross drilled to lubricate the input spline. (gearbox output shaft)

Early versions often experienced excessive wear on both the male and female splines as adequate oil couldn't get up the shaft splines.

[GyroLandy]

So would I need to pull the t/case as well and have both gears replaced? Would that explain the whine?

Is it wierd that it only happens in 4th and 5th?

[rick130]

I was answering this

While I had it out last time he also did the conversion to rectify the common problem with these gearboxes where the oil doesn't reach all the right places. I can't remember the details exactly but he had to drill a hole somewhere on a gear to ensure the gear receives enough lubrication. I take it a recon box would not have this conversion already done??

Which is why I quoted it.

Regarding the whine in 4th and 5th I really don't know.

Were all the bearings changed ? At a guess, for whatever reason the mesh pattern has changed which is where the noise is coming from. A change in fluid may lessen it, maybe. What oil are you running in the box ATM ?

[GyroLandy]

All the bearings and seals were done and it runs on normal ATM.

What is the mesh pattern you are referring to?

[rick130]

All the bearings and seals were done and it runs on normal ATM.

What is the mesh pattern you are referring to?

All gears develop a 'mesh' or wear pattern when running against each other, change that ever so slightly and they'll whine, eg the difference from running together between a slightly worn set of bearings and a fresh set.

I'd dump the ATF and run a dedicated manual transmission fluid (MTF) Redline MTL, Castrol Syntrans 75W-85, Penrite SIN Manual Trans Fluid, Caltex MTF94 (I thought it had gone from the Oz market but someone last week claimed you could still buy it through a dealer) Valvoline Duragear 75W-85, etc.

Land Rover dropped ATF in the R380 around '97 and specced Texaco/Caltex MTF94 (75w-80) and made it a retrospective fill too. ;)

[GyroLandy]

So that whine should be coming from the gearbox and not the t/case?

[Scouse]

i spoke to the guy that overhauled it and he says it's wear and tear on the gears and there is nothing one can to to fix it except replace all the gears. Sounds good but doesn't quite add up.

When the gearbox is in 4th, there is no drive through any of the actual gears inside the gearbox.
4th gear simply locks the input **** & the mainshaft (output) shaft together which gives you a direct (1:1) drive. There is no load through any gears at all to give you a whine.

Most driveline whine is normally from the transfer case, unless you have a howling front or rear diff.

[GyroLandy]

The diffs have been redone. Is there any way to reproduce this noise without the box being in the vehicle?

[rick130]

Sounds good but doesn't quite add up.

When the gearbox is in 4th, there is no drive through any of the actual gears inside the gearbox.
4th gear simply locks the input **** & the mainshaft (output) shaft together which gives you a direct (1:1) drive. There is no load through any gears at all to give you a whine.

Most driveline whine is normally from the transfer case, unless you have a howling front or rear diff.

Good point Scott, and usually any noise in 5th is the rear support bearing going/gone, as per a recent thread.