Repeated Hub seal failure for Sterling 10.25"?

david85

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After an E-stop road test yesterday, I found the truck pulls to the driver's side on hard braking. I figured it was no big deal and it was probably just time to adjust the brake shoes, since these trucks are not known for self adjusters working very well.

Today, I pulled off the right rear drum and found a greasy mess inside (pictures to come). I do remember replacing the hub seal years ago but this still seems like a premature failure. If I remember right, it was the unitized 2-piece style seal that has it's own internal running surface. This being the better design, according to what I've read.

I probably don't have time to fix it this weekend but will be shopping for parts for next weekend (probably new shoes and drums too...). I'll inspect further when time permits but in the meantime, does anyone have ideas that could explain a early failure? Do these seals come pre-lubricated? Or is there some other procedure I might have missed when I installed it?
 

chillman88

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I know on my truck, the first one I replaced started leaking again. I put a thin smear of RTV on the axle housing side where the seal sits and it has been fine since.

Apparently the scotseal was too loose on my axle housing.
 

IDIBRONCO

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I need to remember to start doing this myself just for extra protection from leaks.
 

TNBrett

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Not all two piece seals are the same. The ones that you have to drive into the hub can get put in crooked and wear prematurely. I like the SKF 34384 Scotseal Plus XL. It is designed to install by hand, and eliminate install errors.
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chillman88

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Not all two piece seals are the same. The ones that you have to drive into the hub can get put in crooked and wear prematurely. I like the SKF 34384 Scotseal Plus XL. It is designed to install by hand, and eliminate install errors.
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For what it's worth, this is the exact one I used.
 

cbmech

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I'm a heavy truck mechanic, 26 years on refuse trucks, and I won't use anything but National seals. Scott/cr have caused me almost as much rework as stemco. I don't know if they make them for these trucks but the national one piece internal seal, to me are the best in the business. The 3700... are very good, the 3800... series with the lay down lip Teflon seal are much better. About installation if you need to use silicone you've got a problem you should probably take care of
You drive them in until they bottom
 

5 oclock

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Seperate question not to hijack the thread! are there any setups worth the $ for rear disk brake conversions?
 

Booyah45828

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I've had decent luck with the skf scotseals. Definitely use rtv on the hub and axle, especially if there are any nicks or it's a non-perfect surface.

Scotseals don't require to be soaked in a lube. And if it's a teflon seal, don't pre-lube it as it will leak for sure then. I think part of the teflon seal working is a bed/burn in process that won't occur if pre-lubed. I've fixed issues with teflon crank seals, that were greased on install, leaking.

The one truck I did have issues with scotseal failures, actually had a cracked axle stub that finally broke after the 3rd seal job. We actually tried a national seal the 3rd time because I was tired of the scotseals "failing".

As someone prior said, check the axle vent too. A lot of times failed wheel seals and plugged axle vents go hand in hand.
 

david85

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Late update on this by I think this mystery is solved.

The axle vent was indeed blocked. Photos show the problem and solution. A mixture of dust and rust powder blocked the vent port on the axle tube. To prevent this dirt from getting into the axle, I removed the fill plug (jack the truck on one side to prevent spilling), then gently apply a few quick puffs of compressed air while slowly drilling out the blockage at the vent. Once the drill cut through, everything got blown out. Hopefully with minimal contaminants getting into the gear oil.

Funny how I managed to find time to install an E-Locker, but not to inspect the vent port. Priorities...priorities :idiot:
 

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DaveBen

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Be careful with drilling that fitting. It also connects the brake hoses. If you cut/break one, you will lose your rear brakes.
 

david85

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I don't think the brake line passage crosses the vent passage. But even if it did, I used very light pressure to avoid making any metal swarf (the dirt was very soft). I could have turned the drill bit with my fingers but wanted to be quick to make sure there was still pressure in the housing to blow the dirt out.
 

Black dawg

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Would be impossible to get in the brake lines drilling out that fitting. That fitting and brake hose are two separate pieces.
 

Black dawg

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Pretty easy to remove that fitting to avoid dirt and craps getting in the housing
 

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