Oil for worm-gear drive - Stearns-Knight, Stutz

[Stearns-Knight]

I'm restoring a 1929 Stearns-Knight eight.  It has a worm-drive differential with bronze gears.  Stutz used the same type of rear end, as well as some others.  Does anyone know the proper lubricant to use for non-ferrous gears?

[Spinneyhill]

The Peugeot 404 club suggest Castor Oil.

https://www.peugeot404na.com/single-post/2017/03/01/Bulk-Import-of-Bronze-Safe-404-Differential-Castor-Oil

 

Here is a bit more general as well as specific information:

https://www.machinerylubrication.com/Read/30388/lubricate-worm-gears

https://www.machinerylubrication.com/Read/169/worm-gear-lubrication

 

Others recommend Mobil "600W", for which Mobil say

 "Mobil 600W Super Cylinder Oil is recommended for the following applications:

•    Splash-lubricated enclosed worm gear sets operating at moderate to high speeds and temperatures.
•    Steam cylinders, couplings, bearings, and the break-in of compressor cylinders."

 

They also say it has a copper strip corrosion test result of 1B. A 1A result would be best so I would keep looking!

 

Here is another one. They say this SAE 250 gear oil is non-corrosive to copper and bronze gears, but the pdf download is broken.

https://www.lsc-online.com/worm-gear-oil-250/

Edited March 16, 2019 by Spinneyhill (see edit history)

[AHa]

The Ford TT Truck uses a brass worm gear. You could check with the T suppliers as to what is recommended but I suspect it is the 600W steam cylinder oil.

[Otahuhu]

As a Stutz owner do not use any oil that contains Sulphur as it will eat the bronze wheel Oil used originally was  camphor I use Penrite Transoil 140 that is designed for use in non ferrous bronze worm wheels In the past have stripped a number of Timken worm diffs to find wrong oil used with bronze wheel eaten away 

[oldcar]

Hello 

You can use an Automotive Castor Oil but not a medicinal one. Any modern straight grade (SAE 30) engine oil will do but not a Multi grade. Penrite Oil do make a suitable oil if you look at their web-site. Peugeots up until the mid 50s used a worm drive rear axle. Look and see what their recommendation is and you will not be far off. A lot of competition two stroke motorcycles use "Castor oil" in their "petrol mix" They like the distinctive smell of the exhaust smoke!  Oil companies as a rule do a lot of "label engineering" but if it sells more oil, why not?

 

Bj.

Edited March 18, 2019 by oldcar (see edit history)

[Stearns-Knight]

I've had several people recommend using Penrite Transoil 140.  Apparently that is safe with non-ferrous metals (from a corrosion standpoint), but the Penrite website says "DO NOT use with any type of hypoid gears".  It doesn't say why.  Hypoid gears are defined as those for which the axes of the input and output shafts do not intersect.  So a worm drive is, by definition a hypoid gearset.  I have found other sources that say any oil used for hypoid gears must contain EP (extreme pressure) additives.  That makes sense to me, but Penrite Transoil 140 is a non-EP oil, so it seems like that wouldn't be appropriate.  My guess is that is why Penrite says it should not be used.  So I'm back to square one.  Any petroleum engineers out there?

[Spinneyhill]

As I said, the Copper Strip Corrosion test result must be 1A to be sure of it not attacking the copper-bearing metals. The oil touting itself as suitable has a 1B result. ALWAYS check that result for your oil. If not given, look elsewhere.

 

A worm gear has only sliding friction, whereas a hypoid gear is a hybrid of bevel and worm technologies. In hypoid gears there are friction losses due to the meshing of the gear teeth, with minimal sliding involved. Meshing proceeds along each tooth as it turns. Worm gears run quite a bit hotter than hypoid because of this friction. Hypoid gears require EP additives to handle the tooth meshing friction. Worms do not.

 

Note the first bullet point in my post about Mobil "600W".

[Stearns-Knight]

OK, I'm slowly getting educated, but I'm not quite there yet.  Here is my plain-English description of the problem as I now understand it.  Please tell me if I'm essentially correct or if I'm still missing something.

 

1. A hypoid gearset has spiral-cut teeth on the driving gear that sort of "walk" partly forward and partly sideways along the teeth of the driven gear, whereas in a worm drive the worm is essentially a screw, the "threads" of which slide along the teeth of the driven gear.  The hypoid has higher contact forces and meshing friction, hence the need for EP additives.  The worm has more sliding friction, which results in higher operating temperatures, hence the need for a higher viscosity oil.

 

2. The corrosion problem comes from sulphur, which most EP additives contain (although some newer ones may not?).  I'm being led to the conclusion that I don't need or want an EP oil.

 

3. What viscosity?  Are SAE and ISO viscosity scales the same?  I've seen recommendations from SAE 140 to ISO 1500.

 

[edinmass]

Go to the Stutz forum and ask.......they ran Worm drive from 1928 to 1934.

[Bloo]

I suspect the worm needs the EP protection even worse than the hypoid does, it just can't have any because of the brass. I don't know what the best answer is but this thread has some good ideas. It has been an interesting read.

 

Plain bevel gears or spiral bevel gears are the ones that do not typically need EP oil. The driveshaft comes in at the axle centerline on these. They can have EP oil as long as there are no brass parts inside.

 

The viscosity scales are not the same. SAE numbers are ranges. SAE gear oil ranges are completely different than SAE motor oil ranges. ISO is more specific about viscosity. 600w is neither. It is a brand of steam oil, and is available in a couple of different viscosities.

 

Edited March 19, 2019 by Bloo (see edit history)

[C Carl]

EP protection for worm gears depends on load. A number of factors determine load. The speed, torque, and ratio for automotive worm gears makes for relatively high load. PARTICULARLY when the gears are backdriven. Nature of the beast. Also, to point out again, there is another variant of spiral bevel gears. That is SKEW spiral bevel gears. These are cut to operate in applications where the axis of the input shaft, and that of the driven shaft (s), do not intersect. Still not hypoid, no sliding component. Hypoid allows extreme offset by a quantum leap in the annals of gear hobbing. Hint : The "Hyp" in "Hypoid" refers to "Hyperbolic". I believe this was done in 1923 by a real genius of a mathematician/engineer at Gleason. I am so unsophisticated that I find it astonishing that this could have been figured out before computers and CNC. You can do more with hypoid than just extreme offset. Perhaps a real engineer, or real crackerjack old machinist could join in and shed more insight on this subject. My amazement is that of a very ill educated tinkerer.

 

This has been a build up to an intentional segue. Just as there are sophisticated specialists in all realms of everything, you can safely bet your ears and/or arse that highly educated lubrication specialists exist who  can give a definitive answer for this subject. Why not give tech support at, say Mobil 1, or Amsoil a call.? The phenomenal range of specialized synthetic lubricants from these companies (and others) should include a most suitable product. Please report back.         Gearloose old     -   Cadillac Carl 

Edited March 20, 2019 by C Carl
Add a sentence & spell check correction (see edit history)

[Spinneyhill]

6 hours ago, Stearns-Knight said:

hence the need for a higher viscosity oil.

I am not sure this is the case. The important thing is the viscosity is correct and doesn't change from cold to hot so much that it is too thin when hot.

 

6 hours ago, Stearns-Knight said:

2. The corrosion problem comes from sulphur, which most EP additives contain (although some newer ones may not?).

There are more than one type of sulphur in EP additives. More recent additives use a less reactive form of sulphur. Other elements are used to, some of which are active with sulphur. The copper strip corrosion test ASTM D130 tells you the corrosivity of the oil (additives) on copper, which is what is corroded in brass or bronze parts by some EP additives. The rub, though, is that the corrosion rate is increased at higher temperature (chemical reactions speed up with increasing temperature). On this basis, it would be best if you did not have EP additives - remember worm gears run hot because of the type of friction.

 

6 hours ago, Stearns-Knight said:

3. What viscosity?  Are SAE and ISO viscosity scales the same?  I've seen recommendations from SAE 140 to ISO 1500.

What does the owner's manual say? I have old texts that may have enough information to cross over.

 

If you ask the www, you will find that oil changes are more frequent for worm gears than for hypoid.

[Spinneyhill]

This one looks to be the bee's knees:

http://www.royalpurple.com/product/thermyl-glyde-worm-gear-oil/

 

The Copper Strip Corrosion test result is 1A at 100 ^oC. This is a good one. Unfortunately you need to find someone with a drum that will sell you a small number of litres for your application.

 

To help educate yourself, speak to the tech, rep. of the company. Write down a list of questions.

[C Carl]

Oh, that reminds me Spinney'. Speaking of reporting back. I was to have looked in to gear oils on a parts run to O'Reillys a few weeks ago. The only product they stocked which ostensibly would work was the Royal. Pricey, though. However in checking analysis by independent labs, Royal purple was the only gear oil to totally fail, and thus be unacceptable ! Failed ! Amsoil, Mobil, and another I can't remember, all were at or near the top in all categories. Be careful, my friends. The good old standards have the most experience, and the greatest product lines for an extremely wide spectrum of applications. You have their number, give them a call.   -   Carl 

 

 

[Stearns-Knight]

Thanks, everyone for your input.  I figured the SAE and ISO viscosity scales were different but didn't have a correspondence chart until now.  The stuff that Restoration Supply sells is Chevron Meropa ISO 1500, which according to the chart has a viscosity roughly equivalent to SAE 250.  That makes sense.  But I don't have any info on how much the viscosity changes with temperature.

 

What does the owners manual say?  Nothing!  Stearns was in the habit of building cars first and then printing manuals at a later date.  The company went out of business a couple of months after this car was built, so any info in the owners manual was only preliminary, and was never finalized. 

 

Haven't found the silver bullet yet.  Still looking.

[Spinneyhill]

20 hours ago, C Carl said:

analysis by independent labs,

Where did you find these Carl?

[C Carl]

The smart young guys at O'Reillys found the analysis for me. I should have had them link me up. It was extremely compmprehensive. Some oils had good qualities in some areas, for example Lucas, and were lacking in others. It was quite revealing. Yes, I think this is so important that I should go back soon and get this. I am impressed with the way the guys there found info for me. I think these days one does not have to embody vast knowledge, but must know how to quickly access most anything. I think I will call Amsoil and Mobil myself in the next couple days if I can. As I mentioned, I do recall these two companies did well.   -   Carl 

[Guest]

48 minutes ago, C Carl said:

I think these days one does not have to embody vast knowledge, but must know how to quickly access most anything.

Just like a Lawyer, you don't pay him big bucks for what he knows.  You pay him big bucks for knowing where to find the information.

[Spinneyhill]

I wonder if it was this one, by AMSOIL:

https://www.lastgreatroadtrip.com/wp-content/uploads/2010/11/gear-oil-comparison.pdf

 

Is it linked on many web sites. Here is another: http://goodsenseoil.com/G2457-GearOilWhitePaper.pdf

 

It is not independent though, so add your own pinch or two of salt.

 

 

Edited March 21, 2019 by Spinneyhill (see edit history)

[C Carl]

What I saw certainly came from this study. I don't recall as long a document. But my recall these days is poor. Time was limited, and since I have Amsoil sensitivity,  my not picking this up is indicative of distraction and very cursory review while at O'Reillys.There was considerable interest in my old car pictures, and explanations were owed to all in turn. I only looked at the comparative ranking, and the supporting graphs. And even at that, did not have time for the attention that data deserves. 

 

Thank you, Spinney'. Having now spent more time reading this, I feel it is extremely valuable. I had best read up before making the calls regarding worm lubrication.     -    Carl 

Edited March 22, 2019 by C Carl (see edit history)

[Stearns-Knight]

Thanks to everyone who contributed advice, technical articles, etc.  I still can't claim to be the world's expert, but I now feel like I'm a fairly well-informed buyer and have made my decision.  I bought Phillips 66 ISO 460 Compounded Gear Oil.  It's a non-EP compounded worm gear and steam cylinder lubricant.  It was one of only a few with an ASTM D130 copper corrosion test rating of 1A.  That appears to be the most important factor, to protect the gear from corrosion.  Even though they all claim to be safe for non-ferrous alloys, nearly all of the other lubes, including Chevron Meropa, are rated 1B.  Phillips also specifically states that this product is recommended for differentials on antique and classic cars.  It's hard to find any of them in quantities less than a 400-lb barrel, but I was able to buy a 35-lb bucket online from Petroleum Service Company.  And you don't have to be a distributor or company to order from them.

[John_Mereness]

The last Royal Purple i was asked to buy was not what was commonly on the shelves and I ordered via NAPA and two days later received the call from local store manager to pick-it-up.

 

I tend to just buy product though from www.restorationstuff.com 

[Otahuhu]

Good you found an oil you like. Suggest you drop the diff out and have a look at the condition of the Worm Wheel you maybe in for a surprised as to what you find. Hope it does not have deep scuffed out marks across the matting face of the of the worm. GOOD LUCK Len   

[Stearns-Knight]

I've already opened up the diff.  The gears are is great shape.  I just want to keep them that way. 

[alsancle]

On 3/29/2019 at 4:19 AM, Stearns-Knight said:

I've already opened up the diff.  The gears are is great shape.  I just want to keep them that way. 

 

What is the ratio?    I believe that George Holman's 3.8 high speed setup for the Stutz will work in the later Stearns Timken setup.  Might be worthwhile if you are going to drive the car.

[alsancle]

Also,  George says to run Mobil SCH 634 for gear oil. 

[Stearns-Knight]

I appreciate all the help I have gotten on this subject, but unfortunately it's all moot now.  The car was totally destroyed when my shop burned to the ground last August.