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Axle Bearing question

SSDDBRONCO

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So i took out my axle shaft because it has been leaking. Do i just change the bearings that are on it or is there some kind of seal that i need to change as well? Also inside the axle there is some kind of like metal that looks to be a seal should i replace that or just leave it. Is that the one that is causing my axle to leak differential fluid? ?:? Im not a expert at this axle stuff so i really need help;D. Also since i changing my bearings should i dump out my old diff. fluid? If so which one do you recommend? I know i have too many questions but that's what this site is for ;).
Thanks A Lot
 

mortimersnerd

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I'm assuming you're talking about a rear axle. Yes, you should change the bearings as long as you've got it out. Do you know if you have a big bearing or small bearing rear end? Post up the OD of the bearing and we can tell you if you don't know. There are seals involved, which ones are there depend on what type of bearing you're running.
 

DirtDonk

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Yes and yes. Even though the bearings themselves are sealed, it's just to keep the grease in, not to keep the gear oil from leaking. That's done with that inner seal you're probably looking at.
Not sure why it would look like it was all steel though, unless it's just hard and shiny from age. Press your finger down on the inner lip and see if it flexes at all. If so, that's your old seal. If it's fairly hard, that's likely your leak too.
And yes, it should be taken out and a new one put in. Like mortimersnerd said about the bearing, same thing goes for the seal. Even if it wasn't leaking, if it had a lot of miles on it, just replace it while you've got things apart. Since yours IS leaking though, then changing it out is a must.

A common issue when replacing old seals is the new one leaking around the outside. Even though most have that plastic coating on the outside that acts like a glue and sealant, I like to put a bead of silicone sealer around the housing surface before pressing the new seal in. Then rub some clean oil (or gear oil, since it's handy) around the inner lip of the seal before sliding the axle in.
Also check the seal surface of the axle shaft. If it has any groove or wear marks on it at all, dress it up with some super-fine sand paper or emery cloth. Like 400 and up grit.
You want to smooth the surface back down evenly, so that the new seal isn't riding in a worn spot.

Paul
 
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SSDDBRONCO

SSDDBRONCO

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ok here are some pictures to give a better explanation. Two pictures are for the metal seal inside and one picture is the wheel bearing to show any wear
 

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SSDDBRONCO

SSDDBRONCO

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I'm assuming you're talking about a rear axle. Yes, you should change the bearings as long as you've got it out. Do you know if you have a big bearing or small bearing rear end? Post up the OD of the bearing and we can tell you if you don't know. There are seals involved, which ones are there depend on what type of bearing you're running.

Yes im talking about the rear axle. I have a big bearing unless im wrong;D
 

DirtDonk

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Yep, that's an axle seal. In the first and third pics you can see the rubber seal lip inside the opening in the steel casing. The red stuff around the outside of the casing is that plastic seal/glue stuff I was talking about.
Get a seal puller and yank those dudes outta there.

Some people can use picks or screwdrivers or even nail pullers, but they're in there pretty good so a seal puller makes more sense.
You just have to be more careful than you might think, to not mar the machined surface surrounding the seal. If one or both are really stuck in there good, you might have to fight it. And that's when it's easy to gouge a nice scratch in the axle housing.

Paul
 

DirtDonk

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Looks to be large from here too.
Judging just by the axle seal number #51098 (National brand in this case), that's a large bearing setup.

Paul
 
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SSDDBRONCO

SSDDBRONCO

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Thanks Dirkdonk for the help. I got all the parts I need but I have one question does the seal inside the axle have to be pressed or do you just push it in?
 

DirtDonk

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It's "semi-pressed" which means that you can do it, but it's a tight fit.
You don't need to have someone with special tools press it in, but you'll need to carefully tap it in with a block of wood, a properly sized socket, or a seal-installer.

Run it down until it seats in the housing, or, if you have a deep groove in the axle's seal surface, don't run the seal down in quite as far as you normally would. That way, the seal will ride on a different part of the axle and give you a better chance of it not leaking.

Paul
 

mortimersnerd

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Since you've got a big bearing rear, I'd suggest replacing the sealed ball bearing with a tapered roller bearing. They look like the front wheel bearings, if you've ever seen one of those. The outer race is tapped into the housing and the inner race is pressed onto the axle. No inner oil seal is used and the bearing is lubricated by the gear oil. A seal goes on the outside of the bearing underneath the retaining plate. This type of bearing is a little more expensive (around $20 including the seal, if I remember correctly) but has a higher load capacity and likely will have a longer service life. They're the kind used on the big Bronco rear ends. I think I got the one for a '78 Bronco, but don't quote me.
 

Apogee

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Since you've got a big bearing rear, I'd suggest replacing the sealed ball bearing with a tapered roller bearing. They look like the front wheel bearings, if you've ever seen one of those. The outer race is tapped into the housing and the inner race is pressed onto the axle. No inner oil seal is used and the bearing is lubricated by the gear oil. A seal goes on the outside of the bearing underneath the retaining plate. This type of bearing is a little more expensive (around $20 including the seal, if I remember correctly) but has a higher load capacity and likely will have a longer service life. They're the kind used on the big Bronco rear ends. I think I got the one for a '78 Bronco, but don't quote me.

I know you said not to quote you (sorry), but the SET20 tapered roller bearings are not directly interchangeable with the SKF88128RB ball-bearing type due to different inside diameters (1.531 versus 1.563), so you would need to change to aftermarket axles in order to run the SET20 bearings.

As for lubrication, the sealed ball-bearing type are "lubed-for-life", meaning they don't receive any additional lubrication other than the grease sealed inside the bearing during assembly.
 

Bartonatl

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I tapped my seals in with the end of a softball bat. It's all I had that was the right size. And what also helped, I used one of the old seals to set against the new one as I tapped it in. This helped to not screw up the new seal. They bend really easy. Buy an extra!!
 

mortimersnerd

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Aug 25, 2010
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I know you said not to quote you (sorry), but the SET20 tapered roller bearings are not directly interchangeable with the SKF88128RB ball-bearing type due to different inside diameters (1.531 versus 1.563), so you would need to change to aftermarket axles in order to run the SET20 bearings.

As for lubrication, the sealed ball-bearing type are "lubed-for-life", meaning they don't receive any additional lubrication other than the grease sealed inside the bearing during assembly.

Hmmm, I'm running 31 spline axles, maybe that is the difference. I thought I had the A-20 bearings in my truck, but maybe I went with the a-35s from the 76/77 BB rears. Could be a difference with my truck as well, the only thing stock is the rear housing.
 
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