Why does the shaft drive gear oil smell so bad?

Klubis · Nov 10, 2013

Been groovin' on my new-to-me 2007! Changed the oil and filter. The PO told me it was fresh and it looked fresh too. Changed coolant. I like Suzuki blue for that. The coolant looked old and kind of dark amber. I couldn't bring myself to do the BJ , I'm just wierd that way. Couldn't y'all have named the technique something else? Oh yeah, the punk in lube. Changed the fin drive fluid. Man, that stuff smelled sulfury and bad! It didn't look good either, kind of both shades of caramel (light and dark). Put some Mobil 1 Synthetic 75-90 gear oil in and will change again in 6 months and compare olfactory repugnance!

Does y'all's gear oil smell bad too?

Bounce · Nov 10, 2013

Sulfur compounds are part of the extreme pressure lubrication additive pack needed by hypoid gears. Hypoid gears are found the FJR and in rear-drive differential ring-and-pinion sets where the centerline of the pinion is offset below the centerline of the ring gear in cars.

The gears are sort of halfway between normal straight-cut bevel gears and a worm gear. That means that as the teeth engage and release, they brush across each other while under high pressure. Special additives are needed to keep the specially hardened surfaces from degrading under that kind of contact.

Or at least that's my understanding.

Klubis · Nov 10, 2013

Ah, now it all makes scents! Haha. Is my choice of Mobil 1 synthetic a good one? It didn't smell sulfury?

Pterodactyl · Nov 10, 2013

Klubis said:
Ah, now it all makes scents! Haha. Is my choice of Mobil 1 synthetic a good one? It didn't smell sulfury?

Yes.

rPGoatBoy · Nov 10, 2013

You should smell it when it burns. Quite possibly the most permeating worst smell ever.

TomInPA · Nov 11, 2013

As far as the coolant BJ, that is what compressors are for. How close are you to doing a valve check? You will need to drain down the cooling system a bit and install new O-rings when you do.

Gear oil smells a lot like ATF does after a bit.

Klubis · Nov 11, 2013

26,000 minus 1,700 equals "a whole bunch" before I need to check the valves, I think.

wfooshee · Nov 12, 2013

Coolant BJ is completely unnecessary. When that was first posted, note that he was switching from the green stuff to Dex-Cool, and the two CANNOT be mixed, thus the need for a complete flush of all the old green stuff.

That level of completely flushing is not even remotely needed for a normal coolant change.

TomInPA · Nov 12, 2013

wfooshee said:
Coolant BJ is completely unnecessary. When that was first posted, note that he was switching from the green stuff to Dex-Cool, and the two CANNOT be mixed, thus the need for a complete flush of all the old green stuff.
That level of completely flushing is not even remotely needed for a normal coolant change.

That damn coolant change tutorial has probably ended up putting more crappy Dex-Cool into bikes than you'd care to believe. I recall threads of members who followed that procedure and then made getting the Dex out their highest priority.

HotRodZilla · Nov 12, 2013

TomInCA said:
wfooshee said:

Coolant BJ is completely unnecessary. When that was first posted, note that he was switching from the green stuff to Dex-Cool, and the two CANNOT be mixed, thus the need for a complete flush of all the old green stuff.
That level of completely flushing is not even remotely needed for a normal coolant change.

Click to expand...

That damn coolant change tutorial has probably ended up putting more crappy Dex-Cool into bikes than you'd care to believe. I recall threads of members who followed that procedure and then made getting the Dex out their highest priority.

Because Dex-Cool sucks sweaty donkey nuts in systems not designed for it. Almost as bad as putting diesel in a car designed for unleaded. Well, maybe not that bad, but not good!!

SoCalFJR1300 · Nov 15, 2013

rPGoatBoy said:
You should smell it when it burns. Quite possibly the most permeating worst smell ever.

NOTHING smells as bad as a dead body.........nothing!

Klubis · Nov 15, 2013

I'm afraid to ask?

SoCalFJR1300 · Nov 15, 2013

Klubis said:
I'm afraid to ask?

Bounce · Nov 15, 2013

Let's keep it on track since it's in the tech section.

Thanks in advance.

Queensland Ken · Nov 16, 2013

Obviously you haven't changed out you fork oils, phew !

Constant Mesh · Nov 16, 2013

Don't believe the FJR's rear drive is a hypoid gear system. It's just a spiral bevel gear system. Both gears have the same centerline.

https://en.wikipedia.org/wiki/Spiral_bevel_gear

Klubis · Nov 16, 2013

Interestinger and Interestinger! I didn't realize that's what hypoid meant. What would be the reason to have different shaft center lines? So is there a term for non-hypoid?

Bustanut joker · Nov 16, 2013

Yer fukin kidding right? Unbeleiveable how far this joint has decayed.

Pterodactyl · Nov 17, 2013

Klubis said:
Interestinger and Interestinger! I didn't realize that's what hypoid meant. What would be the reason to have different shaft center lines? So is there a term for non-hypoid?

Spiral bevel gear.

Why does the shaft drive gear oil smell so bad?

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