Rear trailing arm bearing - technical question

[rapandi]

Hi team

 

I hope I am not being overly technical here. I have just installed the two bearings on my right side trailing arm. The left one is yet to be done. 

 

I have carried out the calculation as shown below to work out the thickness of the shin and mine works out to be 2.99mm and that’s what I have.

 

 

 

However I have noticed something interesting.... the outter bearing installed appears as below...

 

 

The space between the face of the bearing and the outside lip/edge of the trailing arm is 8.3mm. The seal ring (not installed yet in above pic) is 7mm. This means there will be a 1.3mm gap between the seal ring and the outside bearing. Does it mean the seal ring actually is not meant to touch the bearing? 

 

In the pic below there shows a small gap between the seal ring and the outside bearing. 

 

 

Just want to make sure my understanding is correct and I am not getting this wrong. 

 

Regards

 

Raj. 

[Buckeye]

I would make sure outboard seal face is flush with bearings housing and seal face on inboard side is recessed by 1+mm. 

did you coat sleeve tube with grease and how much?

[Einspritz]

+1 on the seals above.

 

Follow "good practices" for packing the bearings as well as the space between the bearing and the seal. In that way, the grease will be pushed into any remaining voids of the bearing by the insertion of the stub axle and hub.

 

The stub axle / inner bearing / spacer / outer bearing / hub being torqued holds it all together, the seals just seal, most times.

 

HOWEVER, it is really not necessary to grease the whole center section between the bearings; and here is why: The "drop point" specified is somewhere in the realm of 350-500 Deg. F. at which point the grease becomes liquid and then can flow within the axle. The only time that even has the remote chance of happening is if the rear brake shoes heat the drums which heats the hub which heats the stub axle which heats the bearing which heats the grease. Even after a day of track time, the swing arm is maybe warm to the touch. The heat transfer just isn't there.

 

That said, the grease, particularly between the seals and the bearings can serve to keep water out, which is a good thing.

 

I have never seen evidence of the interstitial grease flowing; besides, at 500 Deg.F I think your seals would be toasted.

 

There is no harm in doing what is shown, just no real extra benefit, though grease is cheap.

 

Two other things; remember to brush anti-seize on the splines to make it easier for "the next guy" to remove the hub. And, I am not a big fan of RedLine grease; used it a lot when it came out, but found that it never lubricated the bearings (front and rear) very well.

 

I am moving toward using bearings with integral seals, but packed with my choice of grease, probably Krytox, so I will be experimenting on myself.

 

Either way, you should be good for another 100K miles.

 

Best

[rapandi]

Thank you @Buckeye and @Einspritz for the advice. That clears it up for me!!!

[TobyB]

Yes, leave a little gap between the seal and the bearing.  Grease DOES move around in there-

it may not reach the point of becoming a liquid anywhere except in the bearing itself, but between

centripetal acceleration, bouncing around, heat soak in the pits, etc, having a full reservoir in the hub

keeps the bearings lubed.  If you only lube the bearings themselves, they pump themselves dry in about

8 track hours, and fail.

 

Things I learned from the PO,

t