Clunking on acceleration

[SkiFreak]

That is a lot of wear on the spline.
My assessment would be it was possibly caused by a lack of lubrication.
Did your mechanic give any opinions?

 

[Aussie Iron]

Okay, now I'm lost. Yes, that certainly is a lot of wear and possibly from lack of lubrication. It doesn't even look like an internal shaft by the crude on it. What year model is your truck. Do you have a model number for your gearbox because that is not the same as our gearbox output shafts.
On the right past the thread ( this is used to hold the gear on in the transfer case) is a plain piece of shaft that inserts into a bearing in the rear housing of the transfer case. There is no way that the gear in your transfer case can be held on - it just sits there.

Dan.

 

[Ultimark]

Fretting corrosion I would say. Looks like it is an external male female set of splines, which after use don't get used for a short while, oxidisation forms on the newly exposed (rubbed) metal, then the next time it is used the oxidisation (rust) is removed as the oxidised surface is ground into the base materials; hastening the process.

Wondering if what appears to be the remnants of lubrication showing, is residue from red lithium grease?

 

[westyss]

The mechanic seems to think it is wear, he had done many of the transmissions from the Other Fuso trucks that had bad transmissions some years back. I thought it was excessive wear myself from not enough grease but there was still some in there, particularly in the female end of the transfer case but it was not clean.
Dan the shaft slides into the transfer case, the year is 2007, not sure about the transmission number but I can see if I can find it. To me it seems like a bad design where there should be an avenue to grease the shaft but I don’t think it can be done without splitting the transfer case from the tranny.
Ultimate could have something as once we arrive at our location in Mexico the trucks sits for two to three months and is in a location that gets constant salt water mist all day.

This is the female of the transfer case.

 

[Aussie Iron]

Yes , that is totally had it as well. It is a different setup all right and only slides into that spline and is not really held in tight. In reality it looks like it should pick up oil seepage from transfer case oil. There is nothing to stop it from "working" on that spline. Bad design I'll agree with.
You would wonder how salt water mist could get in there unless the transfer case doesn't seal up to the gearbox. If that is the case than yes, that spline will run dry in the long run and be a problem again just like a normal tailshaft spline if you don't grease it and run it through water all the time.

If someone has an exploded view of the gearbox and transfer case of that year. I would be interested in having a look.

Dan.

 

[westyss]

Here are a couple of exploded views of the transfer case, not very much help I found and really the only ones I found.

 

[westyss]

 

[westyss]

 

[Aussie Iron]

Thanks. The drawings help me understand how it goes together. Totally different to the earlier setups. But as you say it doesn't give the finer understanding of the mating surfaces of transfer case to gearbox. By looking at the drawings, I still say that the spline should be oiled by seepage from I believe the transfer case.

Dan.

 

[westyss]

Dan I don’t think so, I am pretty sure but not 100% sure but there isn’t any seepage onto that spline. The mating surface looks sealed though.
Once the transmission was removed and looking at the spline it was relatively dry except for old grease mixed with metal bits as someone mentioned “crud”!

 

[westyss]

 

[Aussie Iron]

It is strange that it is an internal spline and not able to be lubricated. But if that is the way the engineers have designed it they know better than me.
That mating surface of transfer case to gearbox looks like it is sealable. The dark line on the join looks like it has had slight movement in the join. It may be tight - even temp changes can cause this with alloy cases.

Dan.

 

[SkiFreak]

But if that is the way the engineers have designed it they know better than me.

Yeah... I had originally thought that too, but I am no longer convinced that's true.
Probably a cardigan wearing accountant wanting to save money played a part in some of the design decisions.

 

[westyss]

Well I think I am part of that club too! The only lube is the grease on the initial install until you split the transfer case and transmission apart again! I am almost convinced that the chunking was that spline set up skipping while under load.

 

[SkiFreak]

If it is not too late already, it might be an idea to use a high quality, fully synthetic extreme pressure grease on the new shaft/spline when doing the assembly, as synthetic grease does not dry out like regular greases do.

Something like AeroShell 33MS or Inox MX6, which is what I use in my winches.