Nevada transmission filler?

[SED]

Installing a 750 Nevada transmission (about 2005) in the Monza and there is a screw plug into the clutch housing, but I can't find it's purpose.  Is it a way to vent the clutch housing while filling the transmission?   Or is it to add additional gear oil to the reduction gears? 

Photos suggest it is a passage directly to the reduction gears - which suggests oil should be added there, but I can't find a reference for it in the shop or owner's manuals.

Thanks for your help!
Shawn

[pehayes]

Might cross post your question over at small_block_guzzi on yahoo groups.  Might be more people with direct experience.

Patrick Hayes
Fremont CA

[guzzisteve]

Don't mess w/it and you'll be fine. That screw started showing up w/the last of the 650's, who knows why. If it ain't broke don't fix it.   The breather is on top, same old place.

[Chuck in Indiana]

FWIW.. I installed a baby Beaver transmission on the Lario. (Maybe 04, but I've forgotten) Breather looks the same, but isn't. Doesn't puke oil, even when filled to a liter.

[guzzisteve]

Well then you should know what that drilling screw plug is for?? Hey, I just know it's there.

[SED]

Well, it took a liter plus a little down the plug hole...   

[Chuck in Indiana]

Well, it took a liter plus a little down the plug hole...   

If you ever figure out what it's for, let me know.. 

[sib]

The clutch housing even on my '13 Stone had a drain plug, complete with aluminum crush washer.  I'll speculate that way back in misty history, engine rear seals were less reliable and could leak oil into the clutch housing, where it would collect instead of dripping out onto your garage floor.  When the bike was serviced, the clutch housing drain plug could be removed and, if no oil was present, everything could be considered to be fine until the next service.

My '13 Stone's clutch housing also had a timing mark inspection hole, complete with a rubber plug, even though this model didn't have timing marks on the clutch ring.

These things can be described as vestigial, like our appendix and dewclaws on dogs.  Eventually, evolutionary drift results in their disappearance.  I can report that the clutch housing on my '16 Stone has evolved to the point where neither the drain plug nor the inspection hole exist.

[SED]

Also asked on one of the yaphoo forums and there is no info yet.

Collected some pictures.
Location of plug on 2005 Nevada transmission:




It apparently connects to the bulge for the front bearing of the output shaft through the raised rib that runs diagonally from the outside of the housing (from Nevada shop manual):




Compare to the 1984 V65 housing that has no diagonal rib:




Perhaps it is to pre-lube the bearing and reduction gears at the factory?

[pete roper]

Interesting. My guess is that it is a cross drilling that will intersect with one that runs longitudinally in the case to allow more oil to be carried to the front bearing and possibly its adjacent gear. I can't remember which way the gears go. That wouldn't be fifth at the front there would it?

Pete

[sib]

Oh, THAT hole.  Forget what I wrote about the drain plug and inspection hole, this is indeed a different hole.  Yes, I'd be interested to know why it's there.  It does seem to be a port that leads to the front bearing of the primary gear shaft.  The parts manuals show the hole in the drawings, but there's no mention of it or its plug in the parts and service manuals.  I'll stay tuned along with the rest of you until we get an authoritative explanation.  I'll also check my copy of Guzziology.

Update:  No help from Guzziology.

[sign216]

I posted on the Yahoo 750 group https://groups.yahoo.com/neo/groups/MG_750/info but I'll repeat it here too:

Check of Guzziology ch. 10, shows an update to later 650 and 750 models to better lubricate the layshaft i.e. the driven shaft.  A "gutter" or lube tube was added to disperse oil to the shaft.  But the gutter is parallel to the shaft, so it shouldn't be in the channel Shawn showed in his pic.   I bet the channel was added at the same time, maybe to collect oil to feed the gutter?  This makes sense, as the boss shown in Shawn's pic is where the layshaft should sit.

Joe

[SED]

Interesting. My guess is that it is a cross drilling that will intersect with one that runs longitudinally in the case to allow more oil to be carried to the front bearing and possibly its adjacent gear. I can't remember which way the gears go. That wouldn't be fifth at the front there would it?

Pete

Looking at the the parts book again the drilling seems to intersect the forward end of the mainshaft (#1 in picture).  Order of parts on mainshaft is idler gear #9, bearing #13, 5th #2.  It's looking like the drilling goes into the cavity for the nut #12 on the end of the shaft and lubes the idler gear.




From Greg Bebder's site:
www.thisoldtractor. com/mg_manuals/spare_parts_catalog_breva_750_2003.pdf

This book also shows that clutch housing #8:

[sib]

If we could see what's on the other side of this casting we'd have a better idea about this.  For example, maybe there's a slot or one or more holes that would allow oil to splash into the diagonal tube and then dribble down to the bearing.  Who knows?

FWIW, the new 6-sp gearbox has 2 plugged holes on the outside, looking like they're capping internal passages to bearings.  These boxes have an oil pump and don't rely on splashed oil to lubricate the bearings.

[sib]

I posted on the Yahoo 750 group https://groups.yahoo.com/neo/groups/MG_750/info but I'll repeat it here too:

Check of Guzziology ch. 10, shows an update to later 650 and 750 models to better lubricate the layshaft i.e. the driven shaft.  A "gutter" or lube tube was added to disperse oil to the shaft.  But the gutter is parallel to the shaft, so it shouldn't be in the channel Shawn showed in his pic.   I bet the channel was added at the same time, maybe to collect oil to feed the gutter?  This makes sense, as the boss shown in Shawn's pic is where the layshaft should sit.

Joe

As I understand it, the layshaft is the one that's driven by the input shaft from the clutch, and the layshaft in turn drives the output shaft, which is also referred to as the driven shaft.  Confusing?  The layshaft is the one that turns in the opposite direction from the input shaft and the driven (output) shaft.  That said, the diagonal channel shown in the pic seems to go to the layshaft (not the driven shaft).

Also, the gutter that's written about in Guzziology is part 28 in the diagram.  It's hard to see how it would connect to the diagonal port, but, what do I know?  I've never had one of these boxes apart, so I'm just an armchair mechanic about this issue.

[sign216]

As I understand it, the layshaft is the one that's driven by the input shaft from the clutch, and the layshaft in turn drives the output shaft, which is also referred to as the driven shaft.  Confusing?  The layshaft is the one that turns in the opposite direction from the input shaft and the driven (output) shaft.  That said, the diagonal channel shown in the pic seems to go to the layshaft (not the driven shaft).

Also, the gutter that's written about in Guzziology is part 28 in the diagram.  It's hard to see how it would connect to the diagonal port, but, what do I know?  I've never had one of these boxes apart, so I'm just an armchair mechanic about this issue.

Sib, we are in agreement, just using different words.  I.e. the "drive shaft" is not the same the "driven shaft"
As my English teacher would say, "to drive" vs "to be driven."