The original spec was for 90 wt gear oil, but Chevy changed that to a semi-fluid grease by service bulletin, retroactive to the earlier models in the mid-50's, due to customer complaints of gearbox leakage. Today, many people use John Deere "Corn Head" grease, which is an NLGI "0" semi-fluid grease. I prefer Chevron's Delo EP 00 for two reasons - full specs are published showing very good wear test data (J-D hasn't published full data), and the EP 00 is closer to the original update spec. It also flows a bit better than the EP 0 grease, being a consistency grade lighter. Nothing wrong with the J-D product, I just prefer Chevron's.
Downside with the Chevron product (and similar industrial gearbox greases by Shell, Mobil and others) is that it comes in a minimum container size of 35 pounds - 5 gallon pail. So, I have excess. If you are interested in seeing the specs or obtaining some Delo EP 00, please take a look at my posting in the "Services Offered by Other Members Forum:" Semi-Fluid Grease for Steering Gearbox.
[img]/images/groups/vccamember.gif[img] Member #56408
I use Penrite steering gear lube which is NGLI 00. I agree the NGLI 0 is too thick and does not flow adequately to keep grease between the worm and sector.
I used to think that the the John Deere Corn Head grease was a good choice until I took the steering gearbox on my ”˜37 apart. There was a large cavity where the sector moved back and forth. The limitation is that the steering gear box does not get warm enough for that grease to become semi-liquid so it will flow.
I also agree that regular gear box grease like 85W-140 or what ever would work great except for the leakage problem. I know there are a few members who have adapted a lip seal to the gear box to stop that leakage.
Rusty, I know a lot of vintage-car guys use the Penrite fluid, but did you know by their own published specs, they don't make the minimum wear test results to meet EP standards? Specifically, the minimum requirement in the "Timken OK Load" test, ASTM D 2509, is 40 pounds. Penrite cites 18 pounds in that test. Anyway, I was very surprised by that when I was researching appropriate "00" greases, since Penrite is at the high end of pricing. Same thing goes for some of the other "00" fluids that are meant for agriculture/lawn/garden equipment (Smitty's, Champion, etc).
The only EP 00 greases that I found that have decent specs across the board are industrial gearbox greases by Mobil, Shell, Chevron. For example, all of these test >50 pounds in the "Timken OK Load" test that Penrite doesn't pass. Among the industrial greases, I chose Chevron simply because I could source it easily here in the Dallas area.
Hope this all entertains, if not helps. Cheers!
[img]/images/groups/vccamember.gif[img] Member #56408
I appreciate your inputs. My thinking is that if I drive this car enough to wear out a rebuilt gearbox that will be a miracle. The reality is that I will probably never live long enough to know if I made the wrong choice. At one point when I was doing my search I was getting pretty confused. i was ready to stuff it full of a mixture of bananas and coconut oil and call it good. At least that would not leak out!
My career work with standards for materials also taught me that testing to a spec simply means that the product meets the spec.
The trick is for an engineer to determine if the requirements of that spec are relevant to the actual requirements of the component.
One of the other products I considered was a gear lube that is sold as “cotton picker spindle” grease. It claims to be an NGLI 00 grease with excellent flow and cling properties.
Like you, I chose what was easy to source for me and what I feel is better than the corn head grease.
Rusty, fair enough. Similar to my career, just FYI. But why buy a higher price fluid when better is to be had? Certainly I understand finding a source that is easier, which can be a person's cost-effective solution, so I get that can be reason enough. But, I wanted to make sure other readers have some data (which I do believe is relevant and hopefully useful). Cheers!
[img]/images/groups/vccamember.gif[img] Member #56408
Sorry for the delayed response. I got the '37 back on the road this weekend so have been driving it as well as doing a late spring cleaning in the shop.
You are not going to create any problems using corn head grease. As I noted above, most of us will never wear out a steering gear in these older cars. So here we go with a longer answer.
I do think a thinner grease is a better solution. Until recently I thought the corn head grease was the hot trick based. There are many posts in multiple forums including tractors that promote it. Some of them refer to a video of the corn head grease and the way it flows in a regular gear box.
I started digging deeper when I took the steering gear in my '37 apart to rebuild it. I had filled it with corn head grease abut 2 years (2000+ miles ago). My observation is that it had not flowed as I expected in this application. There was a large pocket that matched the movement range of the sector gear.
As you know the steering gear in a '37 is nowhere near as sophisticated and technically advanced as that in a '41. It operates by direct contact between the teeth on the worm gear and the sector gear. That is by nature of the design a high friction interface.
Even so I was surprised how little wear there was on the gear contact areas. I know there were many years that the gear box was essentially empty. The real wear was in the bushings that hold the sector shaft. My conclusion is that those wore quite a bit more due to the lack of lubrication. Based on what I could measure and observe I would have taken 80% of the play out of that steering gear by just replacing those bushings. I had both a NOS shaft and sector so I did replace them anyway.
So back to the lube in the box. After doing more searching and reading I confirmed what many other have stated. The trick with the steering gear lube is to have a good extreme pressure lubricant that flows readily but will not leak out past the sector bushing and the felt or cork seal. It needs to flow enough that some will get to the bushings.
I was not satisfied with the "flowabilty" of the corn head grease. And that makes sense to me now. A steering gear never generates heat like a regular gear box. So it will not thin out and flow and cling like the video shows. If you put a small glob on a piece of metal it will not flow or self-level at room temperature.
There is also a clue in the 1937 shop manual. It states that the steering gear should be filled with a mineral oil with a viscosity rating more like applesauce than pudding. (It gives technical guidance in terms of Sayboldt Universal Seconds.)
That is why I chose the Penrite with the NLGI 00 rating rather than to refill with JD corn head grease at NLGI 0.
Now that I re-think this whole scenario I think the smart guys are the people like Gene and Chipper and others who have mixed their own concoction. They mix a good EP gear oil (maybe 85W-140) and a good NLGI 2 grease to give them a mixture that slowly pours(maybe using a ketchup squeeze bottle) into the steering gear. After a few days check to see if it has leveled out in the gear box. If it has leveled out and is not leaking out, you have the right mixture.
If I ever do it again I will probably use my extra tube of corn head grease and mix my own.
Based on my experience the most critical part of the steering gear is the outer bushing. It gets lube from a passage around the inner bushing and maybe a teensy bit that might flow past the inner bushing. Since there is NO seal outside of the outer bushing only viscosity will keep the lube in the steering gear. Hence the need for a self-leveling lube. Yes 140 or 85W-140 will work to lube the parts but it also will run out so makes a mess and you have to keep adding lube when you remember. It is the remember part that is the problem with that solution.
For those interested is attached an article on a seal that can be used to hold lower viscosity lubricants for steering boxes. The original article (attached) appeared in the November 1963 G&D. As you can read the page also deals with axle seals. I have not checked to see if those numbers are still stocked.
