Wheel bearing life extended by periodically repacking?

[Mikes Z car]

Since the front wheel bearings are easier to repack with grease they tend to be greased much more frequently than rear wheel bearings, right? Do front wheel bearings tend to last a lot longer because of this indicating there might be wisdom in periodically re-greasing rear wheel bearings assuming there is a procedure for this? I have heard of a pin injector like used for putting air in basketballs that can be used for wheel bearings, don't know if that might work with an early Z.

Edited July 8, 2014 by Mikes Z car

[240260280z]

It's difficult to get at the rears to re-pack.

Bicycles have passages in the hubs for forcing in new grease that pushes out the old.

I bet this could be done with the rear hubs but the volume of grease in the central cavity is very large. This would have to be filled first in order to use the bike hub method.

[Mikes Z car]

Is there room to put a zerk fitting in the hub or would it bump into something else? I am not sure from what you said if it would be a good idea to even try it.

[Zed Head]

The front bearings are tapered roller bearings, the rears are ball bearings. May not matter.

Seems like the automakers would have installed a Zerk fitting if it needed it. I don't think that re-packing the front bearings is even a maintenance item either. I remember re-packing the front bearings on my 78 B210 a few times but in retrospect I don't think it was necessary.

[zKars]

Here is a pretty good description of how and why wheel bearings fail and the contributing factors.

toyotaoffroad.com/Articles/Projects/Bearing_Failure/Bearing_Failure.htm

There are several points that are relavent to our discussion. Breakdown due to age and heat, contamination, and too much grease are listed issues.

It would be nice to be able to re-grease the rears occasionally and that would no doubt extend their life, but the design and labor required makes it unlikely that anyone would actually take the time to do it.

Note that the advice in the above link refers to front type conical bearings with a separate race and bearing, not sealed rear ball bearings when they talk about periodic maintenance.

Edit: the 71 FSM lubrication Chart has a "change wheel bearing grease" every 30,000 mi..." I'm pretty sure they just mean front... Still, a very short interval. And "Change", not, Clean, Check adjust or supply.

Edited July 8, 2014 by zKars

[Zed Head]

I looked for maintenance information on the wheel bearings but couldn't find it. But now I see that it's also in the Owner's Manual. Since becoming an FSM advocate I almost never look in there anymore. Thanks for the tip.

By 1976, maybe earlier, they were down to 25,000 mile intervals. As your link points out though, one cause of failure is contamination during repacking. It's a dilemma. Probably worthwhile to get one of those grease packing device to reduce handling if you're going to do it.

[John Coffey]

The rear wheel bearings on the S30 last a couple hundred thousand miles with normal road use. How many more miles do you guys want?

[Mikes Z car]

I like to shoot for forever when doing maintenance realizing there might be some unobtanium in that idea. The Toyota Tercel that is my DD went 179,000 on the rear bearings before they needed replacing. I actually had two of those cars back in the old days and the other one went to a similar mileage before the rear bearings started getting noisy.

[grannyknot]

The rear wheel bearings on my 1970 had 150,000 miles on them when I pulled them off during the resto. They were working perfectly but I was replacing everything wearable.

As I remember, the inside bearing behind the seal was open and was packed with some pretty hard grease, the outer bearing was sealed on both sides.

Both or I should say all four bearings where replaced with sealed bearings.

Anyone else find the same thing?

Chris

The rear wheel bearings on the S30 last a couple hundred thousand miles with normal road use. How many more miles do you guys want?

[Mikes Z car]

Thanks zKars for the link to bearing failures and to everyone for the great information.

[zKars]

The rear wheel bearings on my 1970 had 150,000 miles on them when I pulled them off during the resto. They were working perfectly but I was replacing everything wearable.

As I remember, the inside bearing behind the seal was open and was packed with some pretty hard grease, the outer bearing was sealed on both sides.

Both or I should say all four bearings where replaced with sealed bearings.

Anyone else find the same thing?

Chris

Granny, you bring up a couple of interesting areas for a further discussion!

In the article I found, he mentioned a few words about how wheel bearing grease works. It has two parts, a carrier, the heavy thick stuff, and the actual oil that is extracted from the thick stuff that fills and lubricates the bearings.The balancing act is having enough volume of "grease" (both parts) to keep the lube action going for it lifetime. Eventually the grease breaks down and goes hard and waxy. I've seen in lots of old bearings. Hopefully this happens at the end of the service life (150000-200000 miles)

All the stock bearings I've seen only have one integral seal on the outside of the inner bearing, all of the other three bearing faces are open to the housing guts. This implies you need grease everywhere in the housing to keep these supplied. I'm a bit worried about grease life with having bearings that are sealed on all four sides that have a much reduced volume to use. It also makes me think someone before you replaced those bearings.

This all assumes that the total grease in the bearings and in the axle housing warms up and thins out enough so that there isa net flow of grease throughout the space over time. Otherwise what is the point of having (some) grease in the axle cavity front or rear if only the grease in the bearings themselves is doing anything? It hard to find information on "axle grease flow dynamics"....

[John Coffey]

Adding a zirc fitting or penetrating any of the seals to add or change the grease will just create an avenue for contamination. And a sealed bearing is not a panacea, look at Porsche's problems with the intermediate shaft bearing on the M60 Boxster and Carrera engines as a perfect example.

And regarding grease "flow" into the rear hub bearings... I've opened up a few dozen rear hubs and have yet to see evidence of grease flowing into the bearings from a packed housing. I may not be smart enough to see if that occurs but most of the grease packed in the housing has solidified and only "flows" when I scrape it out with a putty knife.

I know packing the housing is a step in the FSM but its not something I do when I rebuilt them. I just use a grease (Wurth SIG3000) that didn't exist back in the 1970s and is orders of magnitude better then what's spec'd by Nissan.

Edited July 9, 2014 by John Coffey