oil for rca mi-1040-e soundhead

[Carl Martin]

so i've been reading through this old thread to figure out what oil to stock up on for our rca soundheads. we have about a 1/4 bottle left of "soundhead gearbox oil"--as handwritten on the bottle from harrah's theatre equipment, which i believe to be out of business--but i want to take the opportunity to drain out the old and start afresh, since who knows when that was last done. i gather i need 30 or 40 wt non-detergent, non-wax oil, though the recommended brands seem no longer to be available.

i'm looking at amsoil as a likely candidate. does this seem like a reasonable choice? anything better out there?

[Sam Chavez]

I'm not sure I'd use synthetic oil on something that ancient. I wouldn't worry about the wax content either in this gearbox. It needs all the help it can get just to keep the oil on the inside. Harrah's is still around although he now resides in Lake Tahoe.

[Dave Macaulay]

I don't recall perfectly - years have passed - but we used low detergent straight grade motor oil, not multigrade, either SAE40 or SAE50 (can't remember which) in RCA and Simplex gearbox soundheads. Or their "official" gear oil.
But any fairly thick oil is going to be OK... I really doubt that you're running a grind house with these soundheads. For "home gamer" use a few hours a year... as long as there IS oil in there it's going to be OK. Thinner oil will leak out faster though.

[Gordon McLeod]

SAE 40 non detergent was the most common

[Mark Gulbrandsen]

If you want the gears to last... and there are no gears available then use Mobil-1 Synthetic gear lube. I had a gazillion SH-1000 and quite a number of RCA heads running and once I switched to the Mobil-1 stuff all gear failures permanently ceased. The best thing is you can get a quart at any Auto Pars store or even Wal-Mart.

[Sam Chavez]

I'm sure Mark is correct but some of these soundheads are even older than me and full of who knows what sludge. You certainly don't want to take the gearbox apart to find out. I'd keep using non detergent SAE 40 or so non detergent and hope for the best.

[Carl Martin]

thanks sam et al. harrah's in tahoe? sounds like a gamble.

guess i'm leaning towards the lubriplate sae 40 then. or the mobil rarus 427?

not a grindhouse but an actual theater where they in "normal" times see use once or twice a month. i'm putting some centurys together in my basement but that's another story and i'm sure i'll have questions about all that some other time...

[Mark Gulbrandsen]

Because of the results wioth the Mobil-1 stuff, we lubricated all the DP-70 with LaVezzi synthetic oil. None of those ever broke down in the gear train either. All these old sound heads have the same Wolk gears in the anyway. Few if any of the original gears are left. But had they had Mobil-1 gear lube back then,all those original gears would likely
still be around...

[Sam Chavez]

Mark,

The main problem with Simplex or RCA soundheads is not the quality of the oil but the absence of it. As in it leaks out and no one notices until it's too late.

[John Eickhof]

i always used a 50/50 mix of 40wt and 80-90 gear oil. on the simplex and rca heads, the operator was supposed to check oil daily as they inherently leak oil out of the sprocket shafts as there are no shaft seals, just oil slingers that would throw the oil back into the box while running, however when stopped oil residue would drip off the slingers and out of the gearbox thus requiring daily if not weekly top off of oil, and like sam said the actual oil is a moot point here except, i found the 80/90 would stick to the gears better, also the pipe from the gearbox to the sight glass should be cleaned out thoroughly at least once a year with a pipe cleaner while performing yearly oil change as dirt and residue can clog the pipe and give a false reading in the sight glass showing oil level is good when the box is actually empty! bronze gears dont last long when runing dry !

[Mark Gulbrandsen]

Mark,

The main problem with Simplex or RCA soundheads is not the quality of the oil but the absence of it. As in it leaks out and no one notices until it's too late.

That's another reason for using the Mobil-1 Gear Lube... As John E says above. It does not run out nearly as fast. And the PTFE that's in the Mobil-1 coats the gear teeth for those times when the booth monkey may have forgotten to check check the oil. Also, those gear boxes can be made fairly leak proof. Most of the issue is old gaskets, and oil oil sight gauges that should have been replaced decades earlier... I had many plex's running 6, 8 and 10 SH-1000 and never once had to change a bronze gear or pinion..

[Sam Chavez]

John makes an excellent point about the sight glass giving false readings. And there are no more gaskets to be found if anybody is foolhardy enough to open up an old gearbox just to have a look. Mark says gearboxes can be made pretty leak proof. Should be past tense as in could.

Pretty crude stuff we worked with but not very expensive compared to a $20,000 Barco light engine. We didn't know when we had it good.

[John Eickhof]

the other pitfall of these soundheads was the later replacement 'brass' gears made by wolk, the original gears used in both the simplex and rca soundheads were 'boston bronze'cast sintered nickle bronze and were a harder material and held up a lot longer even under the riggors of driving a brenkert head...for some reason, the simplex gears were tougher than the rcas even back then, but wolk simply used a 2" brass or lightly sintered bronze bar stock to cut the replacements...they were definitely softer and would also heat up faster...i had replaced many steel pinion shafts that were worn sharp and blued from heat in those days...oh well....still way better than gilmer belts and soft aluminum pulleys !! an era long gone now!

[Mark Gulbrandsen]

As people keep making pointless posts and ignoring the benefits of Synthetic lubes that all new cars today use. I would never return to using petroleum based lube in any piece of projection gear. I ran LaVezzi oil in my Century Vista Vision machine and never changed it for over 10 years. Regular petrol based oil would have long turned to tar by then, but the LaVezzi oil was still like I put it in yesterday. And there were almost no metal particles in the magnet I put inside it... I used to see the same lack of metal particles in the DP-70 oil filter magnets.

[Sam Chavez]

I would totally go with synthetic every time but I'd want to start with a clean gearbox and don't dare dismantle a 70 year old working gearbox full of who knows what, sludge, brass shavings, etc, and no parts or gaskets to rebuild it..