Rear axle housing grease zerk question
 

It’s close to brake backing plate on axle housing . WHERE IS THE GREASE GOING..?

Re: Rear axle housing grease zerk question
 

If you have good internal seals it should mostly go to the wheel bearing, otherwise it just fills the axle housings, later v8 cars the fitting was gone, with a 10000 mile regreasing by pulling the drum

Re: Rear axle housing grease zerk question
 

Thanks for your comment ,now I know .

Re: Rear axle housing grease zerk question
 

Here is a video that shows the path.

https://youtu.be/QuDGQ2jByac

Re: Rear axle housing grease zerk question
 

See the Service Bulletin of July 1928, Page 266, Figure 532.

Re: Rear axle housing grease zerk question
 

But with todays sealed bearings, you don't need that grease fitting do you?

Re: Rear axle housing grease zerk question
 

If you look closely at the service bulletin pix, you see that the axel shaft seal lip is facing in toward the differential, that would indicate that the seal is to keep the 600w out of the wheel bearing. And that would make sense... this contrary to the opinion voiced in the video.

Joe B

Re: Rear axle housing grease zerk question
 

Re: Rear axle housing grease zerk question
 

Oh but Joe, the video MUST be correct because it is on YouTube!! http://www.model-a-ford.com/ROFL.gif

Re: Rear axle housing grease zerk question
 

See the attached article.

Tom Endy

Re: Rear axle housing grease zerk question
 

Before I replaced the hub during a bearing replacement I pushed grease through that zerk and watched it come out to the bearing area. You should only give them a couple shots if you ever decide to use them.

Re: Rear axle housing grease zerk question
 

The article from Tom certainly speaks with authority as to the function of the inner oil seal. What remains unanswered is why does the illustration show the seal lip facing toward the differential? The seal lip and garter spring normally face the fluid to be restrained. Note that the lip and garter on hub seal in the same illustration faces the bearing and grease to be retained. Is the illustration incorrect?
Joe B

Re: Rear axle housing grease zerk question
 

Wow, this has been up for 4 days and no comments. opinions! I have been giving the issue of the axle seal more thought. I'm convinced that the axle seal has two functions. The PRIMARY function is to keep differential oil out of the hub and brake assembly. The SECONDARY (co-lateral) function is to divert grease out toward the hub bearing. That's why the seal is installed with the lip facing inboard. Consider which is more critical, 600W in your brakes or a little grease in the differential.

Joe B

Re: Rear axle housing grease zerk question
 

I don't believe the seal is an oil seal, it is a grease seal, and is not designed to keep differential oil from reaching the brakes. I have taken hundreds of rear axle assemblies apart where the seals were totally shot and literally not there and there was no evidence of oil reaching the brakes. The design of the housings are such that the oil remains in the banjo.

Tom Endy

Re: Rear axle housing grease zerk question
 

That was always my thought as well. Maybe obvious enough that it didn't generate any discussion. The grease is free to go to the wheel bearing.

Re: Rear axle housing grease zerk question
 

That was always my thought as well. The grease is free to go to the wheel bearing.

Re: Rear axle housing grease zerk question
 

I had to replace my seals on my 31 because oil did in fact run out from the differential down towards the brakes then on the floor while parked

Re: Rear axle housing grease zerk question
 

That can certainly happen if you have a Borg Warner overdrive installed. All are cottage industry conversions and most use that same grease seal for an oil seal on the stub shaft of the overdrive. It will not hold oil back and will allow oil to migrate into the banjo. Over time the oil level will rise and if high enough will reach the brakes, if the overdrive doesn't starve for oil first.

Tom Endy

Re: Rear axle housing grease zerk question
 

Seals are installed backwards as a pressure release as well. The manufacturer will want the excess grease / pressure to vent into the axle tube versus around the bearing seal and into the brake area. It's done often in industrial applications and confuses new guys who don't pay attention to the drawing. :)

Re: Rear axle housing grease zerk question
 

This is from page 361 of the Service Bulletins.


Rear axle shaft, drive shaft, and rear wheel
grease retainers, part numbers A-4245 and
A-1175, must be installed with the sharp edge
of the leather section of the retainer pointing
toward the part from which the grease would
flow (see Fig. 736). In other words, the rear
axle shaft grease retainer must be installed
with the sharp edge of the leather section
of the retainer pointing toward the differential.
The rear wheel grease retainer must be
installed with the sharp edge of the leather
section of the retainer pointing toward the
bearing in the rear hub. The drive shaft
grease retainer must be installed with the sharp edge of the leather ·section of the
retainer pointing forward on the drive shaft.