Podguy

I have always wondered why when I go to re-pack wheel bearings the hub is full of excess grease. I have always cleaned out the excess grease first and then hand pack the bearings leaving enough extra grease around the bearings so they would not go dry. I have never had one fail or go dry.

Is there a reason for all the extra grease in the hub?? I would be interested in how others do this and why.

Speedtoys

Less air space in the hub, is less expansion/contraction of the air to blow in/out of the seals with.

On the race cars, Id pack it heavy, and always drilled a tiny hole in the center of the bearing cap to keep the seals from being blown out.

Ive also wondered..when hot, if it doesnt circulate some, and carry away heat.

dr bob

Many WSMs carry specific instructions to not pack the hub. Expanding air will never blow out a seal, and a properly-adjusted bearing won't heat up enough to drain the grease out.

So I flush the old grease out of the bearings and the hub, generally with a paper towel and maybe some solvent. I pack the clean bearings so that all the cavities between the rollers are packed solid, with clean grease coming out the downstream side. That downstream side is packed solid between the cone and the cage. I sometimes smear a layer of grease on the face of the cone so the rollers are completely coated. Then assemble, and adjust clearance to zero preload. No big gob of grease inside the hub, since in fact almost all of that space is taken up by the spindle. Only that thin layer between the minor diameter of the hub and the spindle is left without grease. For the inside bearing, I smear a little grease on the seal lip after installation. But I don't pack the space between seal lip and the inner bearing. Just lube the lip of the seal before it goes on the spindle.

I've never had a bearing fail in service using this method.

Speedtoys

Expanding air can blow a seal. On demand. I cant say for all cars, but if you raced 1st gen RX7s, ya..you betcha. Then you got grease all over your rotors mid-race. Lots of fun. That was part of my theory, at least.

But..that space -is- there on purpose. ?

brianrheffron

The right tool for the job.

http://atoztool.com/270.html

GlenL

How full is full?

With the heat and forces in the bearing the grease needs to fill the hub somewhat. The "excess" also circulates and dilutes dirt, water and metal bits.

If it's full to the point of the seal lip it'll ooze out at speed.

namasgt

What wheel bearing grease do you guys recommend? Does it matter what kind, there are so many options out there.

Speedtoys

Ya..that's not true. Lived lifetimes of blowing seals out on race cars until I left little air, or drilled the cap.

dr bob

I use Mobil-1 synthetic grease in the 14oz tube, and my bearing packer. Option grease is Redline CV2, but the M1 is easier to find at most local parts places. Both are red like the original stuff the factory used. Just in case the concour judges decide to inspect the bearings I guess.

The hotrodders used to recommend a Ford long-fiber grease for their bearings. I use a waterproof marine grease on trailer bearings even with bearing-buddies. In the giant scheme of things, I've never lost a bearing to anything related to the grease itself; I usually added a dose of stupid to cause any failures I experienced, usually in the form of "just a little more snug to take the play out".

I'll leave the experiential discussion of expanding air blowing seals to the experts here. It seems to me though that regardless of what's expanding as it gets hot, grease or air, grease that isn't packed in between the bearing and seal can't be pushed out. I've never had an issue with seal blowout using the air-gap method, but maybe my wimpy brakes didn't transfer as much heat to the hat and hub while racing or towing.

namasgt

Thanks Dr Bob

Speedtoys

Ya..if you're not splitting a rotor cleanly from the hub to the outer circumference (every weekend), you don't have enough heat in em yet.


Spec class fun.

KenRudd

For whatever reason, Mobil can only pack 12.5 Oz of grease into the same tube that everybody else manages to get ~14 oz into.

dprantl

Maybe it's the same volume but it's just lighter

Dan
'91 928GT S/C 475hp/460lb.ft

KenRudd

dr bob

I guess everybody is cutting corners a little. There's only ten ounces of potato chips in a one-pound bag too. Inflation....