Why Grease should not be used in a Steering Gearbox

[BRENT in 10-uh-C]

Over the years, the topic of using grease inside a Model-A gear box has come up here. When I was a kid, its use was always a forbidden sin when someone asked about it at the club meetings. I think things have changed during those past 50 years of club meetings, but some are still adamant that it is a no-no to use grease in the gearbox. Maybe we can discuss it here again??

So in a typical mindset regarding Model-A gearboxes, there are low speed gearboxes and high speed gearboxes. For reference, the rear axle and the transmission on a Model-A are high-speed gearboxes. The steering gearbox would typically be considered a low-speed gearbox. In between are items such as the electric windshield wipers, window regulators, and maybe another item or two are low-speed gearboxes by definition.

From what I know about it, a high-speed gearbox typically uses a lube instead of grease so-as to cool the components such as bearings, bushings, and to remove the heat from friction created by two gear teeth rubbing against each other. In a slow-speed gearbox such as a steering gear box, a windshield wiper, or a window regulator, the friction on the bearings or the teeth (worm & sector) are not as prevalent where cooling from a lubricant is necessary.

So why did Henry's engineers choose to specify/install 600 W lube in lieu of grease? My theory is because at that time there was not an "extreme-pressure" grease invented, and so the 600W lube allowed the Sector teeth and the Worm gear to be 're-lubed' or replenished after the lube had been sheared off of the teeth during a turn while driving. Today, there are several available extreme-pressure greases that likely would have exceeded the needs for those Engineer's application. (For those who live to watch things discussed on YouTube, there is a channel called Project Farm that has produced several videos regarding the topic of greases.)

So here comes the question. Recently there was a discussion regarding Penrite grease along with a suggested alternative 00 Grease available at John Deere tractor dealerships and also at a local tractor supply store. I had looked at this product maybe a year ago and what I was told is not all "Corn Head" greases are high-pressure greases. It was explained that I should ask each manufacturer about recommended applications, ...and the brand I chose to go with is Champion's 00 lube which supposedly has the additives and the make-up that we would need in a Model-A gear box application. While we have begun to use this, unfortunately we have not been using it long enough in a Model-A gearbox to know whether it will be better than 600w over a longer term (20k-30k+ miles). Time will tell I suppose.

There is one area that I have concerns with in using this is (-unless you have a L28-29 7T sector housing.) the only way for the sector bushings to receive grease for lubrication is during the assembly process. If you study the gearbox housing, you will find it has provisions for lube to enter the sector housing, and the sector bushings are designed where galleys are present to transfer the lube to keep the sector shaft lubricated. So the question is, when using extreme-pressure lubricants in this area does the lubrication stay on the bushings to provide continual lubrication? I say it doesn't. Especially if someone has converted to roller bearings in lieu of sector bushings (-which is a whole different controversial topic!).

One other thing to note; when I rebuild a 7-tooth gearbox I typically re-machine the end of the steering shaft both internally and externally. I like to only remove enough material to remove any damage and then polish it with a worn crankshaft polishing belt. I then make a new lower bushing using oil impregnated bronze material (Oilite) and pack it full of the extreme-pressure grease during assembly. I figure if the grease gets pushed out, the oil in the bearing material will take over the lubrication process.


I welcome your comments or opinions on this, but my take on this is the Penrite and the Champion greases are likely suitable for using in the gearbox however they really do not provide enough lubrication for the sector shaft in its housing. Therefore an alternate method of lubrication needs to be used in you are using grease in the gearbox.

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