Rear wheel bearing repack result. (1 Viewer)

[IdahoDoug]

Continuing with the "My family's out of town so I'm doing major maintenance." theme, I repacked the rear wheel bearings and put new axle seals in on the 93. It has been 51,000 miles and I was kind of surprised to find the left side rear bearing again with no trace of grease. I put a Toyota seal and Mobil 1 grease in back then, but it's looking like the recommended 30,000 interval makes sense - especially if you're going to carry loads.

I noticed the original Koyo bearings have a "high cap" stamped in them, indicating a heavy rating - nice to know. I don't remember noting that back in October, 2000 when they were repacked at 90,000 miles.

 

[cruiserdan]

The left side was also washed on mine. I suspect it has something to do with the longer shaft. Was there any sign of grooving on the shaft sealing surface? The SST that sets the seal dictates the seating depth. I wonder if the seal could be seated a bit deeper to get the lip out of any groove in the shaft?

 

[IdahoDoug]

Funny, I was cognizant of that and pleased to find the sealing surface in perfect shape. It kind of seems like the seal doesn't put much pressure on the axle shaft, actually. I did the 97 last week and on reinstall felt like the seal didn't provide much resistance. It had the same pattern - left bearing washed cleaner than the right one.

I did have some scoring on the place the inner wheel bearing seal rides on the axle housing, however. No evidence at all of water intrusion from this, however, and my 80 is often axle deep at boat ramps.

DougM

 

[cruiserdan]

On Kane creek this year we were in water above the bottom of the doors and I could hear it rippling under the floorpan as we traversed about 100 yards. I drained both diffs afterward and the oil in both ends was perfect. The rear wheel bearing seals are very well designed.

 

[IdahoDoug]

Yeah, rears are easier to design watertight - no knuckles to deal with. Nice to know you've never seen evidence of water, either.

DougM

 

[alia176]

I just did the rear bearings two weekends ago and noticed the same thing. They were both washed out with oil. However, the bearings were Timken so there must've been a wheel bearing job in the past life somewhere. Ofcourse a set of brand new Koyo High cap went in. Love that three prong tool thing!

 

[cruiserdan]

The Timkins were OEM.

 

[elmariachi]

The left side was also washed on mine. I suspect it has something to do with the longer shaft. Was there any sign of grooving on the shaft sealing surface? The SST that sets the seal dictates the seating depth. I wonder if the seal could be seated a bit deeper to get the lip out of any groove in the shaft?

Do you know how far in past the lip of the axle housing it seats the seal?

 

[cruiserdan]

I don't remember. It's been about 2 years since I did mine. I'll have to get the installer out of my tool box and look at it.

 

[elmariachi]

I don't remember. It's been about 2 years since I did mine. I'll have to get the installer out of my tool box and look at it.

Tim (tarbe on Mud) and I did ours a month or so ago and I think we only seated them flush with the outer lip because that's where they when removed. But your idea about seating them deeper to avoid wear grooves is interesting. Let us know what the SST says.

 

[IdahoDoug]

Agree with Jim. My 93's original seals were flush, and so were the original 97 seals I took off. Easy to push in farther - I specifically looked at the last ones I did yesterday and there's about 2mm of space behind them before they hit a machined edge and a taper.

DougM

 

[MrZumma]

I just did a rear re-pack yesterday and the seals were flush. The Timken bearings were lightly washed in gear lube and the grease in the hub cavity looked dried and cracked on the surface. When I scooped it out, the grease underneath the surface looked fine. It probably has been there since the day the truck was assembled.

Have a question about the pre-load. One notch on the locknut is to line up with one notch on the spindle. After setting the bearing preload to 43ft-lbs and backing it off to finger tight, I noticed I was 3 or 4 degrees from the closest notch on the spindle. To get to the closest notch, I had to back the lock nut off to less than finger tight, but that let the hub spin a little too free for my judgment. So then I tightened the nut to the next notch and that made it too tight for my comfort level. I elected to back off a little from the finger tight scenario as I could not shake the hub and that was where it was set when I tore it down. What is the best practice when this scenario presents itself?

 

[IdahoDoug]

Personally, I feel you should have gone for the tighter setting. Somewhere I recently commented on this (last 3 days), but these bearings loosen when hot, which is when I want the roller bearings and races perfectly aligned. I'll accept a bit of tightness while they warm up, which is a very small percent of use vs when they're warm/hot. Truly these are massive and overengineered bearings, so I don't think you need to worry too much about making that loose/tight choice as long as you did several cycles of tighten/spin grease around before arriving at that decision point.

I think it's a bigger sin to leave things so loose that the inner race will spin on the spindle than it is to have the bearings run a bit warm as the rear spindles are not replaceable (part of the $$$$ axle housing) like the fronts ($$) are.

Overall, I think you're fine - all the more so if this truck is simply driven vs used to haul a heavy trailer or carry heavy rear loads routinely.

DougM

 

[e9999]

ah, just had to deal with that same issue with a trailer axle. Put 50 lbs on as preload, backed out. But when finger tight, if I backed down to the previous notch I could just feel the play in the wheel. So I went the next notch up, which was about 10 ftlbs. No more play and a tad tight but I figured it would loosen up. So that's what I used. (More comfortable doing experiments on the trailer than on the main truck of course....)

 

[IdahoDoug]

With ya on that one. I'll especially be more inclined if bearings/races are new because I know they'll quickly break in and loosen a bit. Repacking existing ones obviously means the tolerances are already what they'll be for the life of the bearings, so more looseness would be tolerated. Should have added that to my above post to help Marty breath easier!!

DougM

 

[e9999]

well, I also screwed up cuz I mixed LHS and RHS big bearing on the trailer axle and didn't feel like reopening it all up so left it in and thought it might loosen even more...

 

[flintknapper]

The left side was also washed on mine. I suspect it has something to do with the longer shaft. Was there any sign of grooving on the shaft sealing surface? The SST that sets the seal dictates the seating depth. I wonder if the seal could be seated a bit deeper to get the lip out of any groove in the shaft?

I just did mine today, and was careful to look for any wear on the axle shaft.
Mine had no groove, but a very faint shiny spot where it makes contact with the seal.

This mark was on the last 1/8" inch of the sealing surface before it tapers down.
My seals were seated flush with the spindle and IF I'd of had a groove I would have had to move the seal outboard to avoid falling into the groove or moving off of the sealing surface. In other words...you would need to seat the seal less than flush with the spindle.

The boss for the seal inside the spindle measures about 1/2" in depth before it tapers. The seal itself is about 3/8" thick...the problem is: the sealing surface is only about 7/16", so you're stuck with moving the seal outboard if you want to avoid a groove in the axle shaft.

 

[MrZumma]

Thanks Doug. I am not too worried as there was no evidence that the inner race was spinning on the spindle. I did spin the hub a half-dozen times in each direction during the bearing pre-load process. However, it makes me rethink the interval for repacking the rears while they are running a bit loose. I will more than likely replace the bearings then anyway.

Thanks again, your input is appreciated.