Help with trailer rear bearing replacement

wolfee

Seaman
Joined
Aug 20, 2007
Messages
71
I think I screwed up installing the rear bearings. When you take the hub off and punch out the rear bearings, the seal comes out as well. When I put new bearings & rear seal in, I noticed there is free space between the rear bearings and the seal. Instead of installing the rear seal flush to the back of the hub, I tapped it flush to the back of the bearings. So if you look at the back of the hub, the seal is maybe 1/4 inch inside the hub. Also, the hub-kit(2) that I purchased came with two rear seals each and the seals have the rubber seal at different diameters. I went with the wider seal but not sure which one I should have used. Any help appreciated.
 

JimS123

Fleet Admiral
Joined
Jul 27, 2007
Messages
7,993
The bearings bottom out on the shoulder of the spindle. The seal should fit tightly on the rear part of the spindle. They both go in different places.

If you have a 1/4" space, the seals probably aren't working. The proper seal is the one that fits.
 

RMClark

Petty Officer 3rd Class
Joined
Jul 19, 2020
Messages
92
Did you remove and replace the old bearing race as well?

As for which inner seal size to use, I'd go with the choice that allows you to slide the seal on the spindle with light pressure, but has no side-to-side play when on the spindle. I hope that makes sense. If there's any side to side play, grease will easily come out of that gap.

If neither seal is suitable, carefully measure the spindle using a dial caliper and go find a seal that will fit the spindle with the inside diameter for the rubber seal and also fit the hub. You may have to go to a parts place specifically for the seal.

On my trailer, the hubs and spindle accept the bearings that I can find just about anyplace. However, the only seal I can find that fits the spindle well is a specific part number at NAPA, and I have to order those. It's just what I gotta do.
 

JimS123

Fleet Admiral
Joined
Jul 27, 2007
Messages
7,993
Just as an aside, seals and bearings have part numbers. I don'y buy "kits", I simply replace what I had. Also, I always buy spring loaded double seals. They seem to hold up better.
 

wolfee

Seaman
Joined
Aug 20, 2007
Messages
71
Thanks for the quick answers! I did not replace the race. The kit came with bearings, hub, wheel nuts, and 2 seals per hub. (different diameters). Every video I've seen showing the rear bearing/seal shows space between the rear bearings and the seal. That's what threw me off. I continued tapping the seal until it seated itself against the bearing, then slid the hub on. I also think I used the wrong seal because the smaller diameter seal slides along the spindle while the other one is wider, more in line with the location of the bearings. If you know what I mean. Sucks, but I need to redo this.
 

dwco5051

Commander
Joined
Sep 14, 2008
Messages
2,336
I noticed there is free space between the rear bearings and the seal. Instead of installing the rear seal flush to the back of the hub, I tapped it flush to the back of the bearings. So if you look at the back of the hub, the seal is maybe 1/4 inch inside the hub.
The seal should be flush with the hub. By pushing it in an extra 1/4' you now have machined bare metal that will rust and interfere with installing a new seal the next time and having it fit properly. It is easy to drive a seal into its seat flush. Without having the proper tool it is possible to damage it seating past that point.
 

jlh3rd

Chief Petty Officer
Joined
Jul 10, 2017
Messages
424
"When you take the hub off and punch out the rear bearings, the seal comes out as well"
....normal...I've never come across any setup that allows removing inner bearings without removing the seal....
...as stated...the seal is to be flush with the hub....
 

BillWilliams

Seaman
Joined
May 23, 2021
Messages
68
As dwco5051 stated, the seal should be flush with the hub. There will be a gap between the seal and the inner bearing. As far as seal diameter goes, you want the seal to ride on area "B" in dcwo5051's drawing. Like RMClark said, the seal needs to fit onto that spot with a little effort because it needs to keep the grease in and water out. Definitely should not fit sloppy.
 
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