Premature trunion bearing wear (1 Viewer)

[mudgudgeon]

These bearings move back and forth constantly, over less than a degree of rotation, as you drive straight, which you do 99% of the time. The grease doesn't get redistributed unless you turn the wheel, and even then not much. Not an ideal situation for roller bearings, which are designed to be rotating, primarily in one direction, all the time. What you are seeing is normal, exacerbated by large tires and offroad use.

I personally use moly grease on everything just because non-moly doesn't offer any advantages, and with that in mind why bother with two types? But for trunnion bearings in particular, moly seems to be a better fit. That being said, it doesn't solve this problem either. They are a wear item. Most people don't notice how quickly they wear because the wear isn't obvious unless you disconnect the steering linkages and rotate the knuckle. As long as they are still tight and no play is felt when rocking the wheel at 6 and 12 while off the ground, I don't mess with them.

My thoughts are similar to this.

There's almost no rotation of the knuckle for the vast majority of driving at anything much faster than jogging speed. A few degrees each way.

I use Moly grease in everything, except wheel bearings.
Moly will provide dinner lube if the bearings end up just sliding, not rolling


I had a knuckle that was almost locked up. Didn't feel it while driving until it was completely toast.
I could barely rotate that individual knuckle by hand. The only time I felt it driving was when I had to drive a succession of tight hairpin turns (switchback??) that required code to fill lock on the steering both ways.

 

[sunrk]

Moly because that's what goes into the swivel hubs and the kingpin bearings are in the same space. I do a lot of full-lock turns getting in/out of where I live, and getting in/out of the work carparking areas. Just remember that the top bearing is not 'bathed' in grease. High off-roading loads, massive tyres, etc. will wear kingpin bearings.

Any time the wheel bearing play at the front is checked, the kingpin bearing play should also be checked.

 

[Rusty Marlin]

There is a US Army test report, findable if searched on Google, concerning the use of Moly grease. In short, don't use it on rolling element bearings. Moly is a flat plate like structure that will wedge under rolling elements and cause them to skid rather than roll. A roller bearing that skids is a dead bearing.

Back to the knuckle bearings
Near as I can tell the "indexing" of the knuckle bearings is normal. The roller bearings are in reality an infinitesimally thin line supporting the weight of the vehicle. Every time you hit a pothole, or otherwise "shock load" your front end that tiny little thin support line rams into the bearing race until enough surface area is created to stop the movement of the bearing into the race. Because the bearing isn't rolling, it creates brinelling lines, ie. indexing points.

I have a lot of experience with this kind of failure mode, just not vehicle related.

 

[sunrk]

Valid point but with kingpin bearings using a different grease for them is practically impossible as when the swivel hubs are assembled they are exposed to a moly greased environment even if the top one is difficult to keep greased.

 

[-Spike-]

Many moly greases are rated for use in wheel bearings. Do some research, then use whatever you're comfortable with. It's unlikely to make much difference either way.

 

[aztoyman]

Spike and BILT4ME both mentioned the number of rollers in the bearings available and I also believe you should choose a set with more rollers if possible. I can give an example I ran into with front wheel bearings.

Sorry not a Toyota but still relevant. I had very short wheel bearing life on a 3/4 ton truck I had. I thought it was the off brand bearings so I bought factory Bower USA made bearings. Not much better. Then I tried Timken made in USA and noticed that the cups were the same but there were more rollers in the cones and more importantly they were longer. Covered the entire race where the others were about 1/8" shorter and ran down the center leaving a lot of area of the race unused. Never had to replace them after that. Many years.

So a quality bearing and proper setup should at least help. I don't know if there are upgrades for heavy use for 80's? I know there are trunnion bearing eliminators for the mini trucks or Marlin Crawler 25 mm bearing upgrade. I don't know if they are even effective on the mini's. I never tried them.

 

[mudgudgeon]

There is a US Army test report, findable if searched on Google, concerning the use of Moly grease. In short, don't use it on rolling element bearings. Moly is a flat plate like structure that will wedge under rolling elements and cause them to skid rather than roll. A roller bearing that skids is a dead bearing.

Back to the knuckle bearings
Near as I can tell the "indexing" of the knuckle bearings is normal. The roller bearings are in reality an infinitesimally thin line supporting the weight of the vehicle. Every time you hit a pothole, or otherwise "shock load" your front end that tiny little thin support line rams into the bearing race until enough surface area is created to stop the movement of the bearing into the race. Because the bearing isn't rolling, it creates brinelling lines, ie. indexing points.

I have a lot of experience with this kind of failure mode, just not vehicle related.

My limited understanding is moly content below 5% is not a problem in roller bearings. Definitely not an expert on this though.

 

[mudgudgeon]

Interesting that the "same" bearing can have a different number of rollers.

I had noticed difference in roller length in the past. Never counted the number of rollers.

I learnt back in the skateboarding days, cheap bearings rarely are cheap.
I had to relearn that with Landcruisers

 

[-Spike-]

My limited understanding is moly content below 5% is not a problem in roller bearings. Definitely not an expert on this though.

That is my understanding as well. High-percentage moly likely has specific use cases, as does low-percentage. I believe Toyota specs low-percentage moly for the birfs anyway, so that's what I use everywhere. What I use is rated for wheel bearings and universal joints. No one on this board ever specifies, we all say 'moly', but we should probably specify as it probably makes a difference.

 

[aztoyman]

There was a thread on Pirate "I think" that talked about the trunnion bearings on the minis. I think there are even bearings with a different angle to the rollers. The ID and OD of the bearing is the same. Steep vs shallow angles. Arguments or "discussions" about which was better as far as thrust loads or something. I just stuck to my KOYO or Nachi numbers.

 

[Squeegee]

There was a thread on Pirate "I think" that talked about the trunnion bearings on the minis. I think there are even bearings with a different angle to the rollers. The ID and OD of the bearing is the same. Steep vs shallow angles. Arguments or "discussions" about which was better as far as thrust loads or something. I just stuck to my KOYO or Nachi numbers.

Those are the 25mm bearings. It’s a super common upgrade for the mini axles, it seems to keep them together. Slee and marlin used them in their race trucks a while back. We don’t see then much in 80s though. The only way to go with the larger trunnions is to run hellfire or front range knuckles and that’s not for everybody

I’ve been talking with the owner of arcworx about making a kit to run the 25mm bearings top and bottom or a 25mm lower with a kingpin upper with stock steering but neither of us are sure if people would be interested

 

[BILT4ME]

Those are the 25mm bearings. It’s a super common upgrade for the mini axles, it seems to keep them together. Slee and marlin used them in their race trucks a while back. We don’t see then much in 80s though. The only way to go with the larger trunnions is to run hellfire or front range knuckles and that’s not for everybody

I’ve been talking with the owner of arcworx about making a kit to run the 25mm bearings top and bottom or a 25mm lower with a kingpin upper with stock steering but neither of us are sure if people would be interested

View attachment 3222081

20 vs 16 rollers in that picture. Of course the one with more rollers can handle more load.

 

[Squeegee]

20 vs 16 rollers in that picture. Of course the one with more rollers can handle more load.

Hints why I’m trying to get my friend to make a way to put 25mm bearings in 80s with stock steering. I’m surprised it hasn’t happened already

 

[NielsC]

So I got the scale today… with the shim that was already there (second thinnest) I got a preload that was too loose.(Around 20N, the range is 25 - 45N.)
1 shim thinner and it was still a bit too loose but better, on the loose side of the specs.
Without a shim I got a preload that is in the middle of the spec range (30N).
I have left it this way, wich I felt might be a little tight, but the measurement doesn’t lie, so lets see if it will hold up longer.

 

[ozarkmud]

I'm absolutely not an expert, and given that this is counter the opinion of most of the people here, it's probably wrong.

I set bearings tight to be sure they've seated, then back off so it's light with absolutely no play. I also don't like to use moly in bearing applications. May or may not be an issue here, but something I am leary of. I think I used a red 'n tacky grease when I did a front axle on a 60, but unfortunately ended up selling the rig after maybe a thousand miles at most.

I'm curious (apologies if you already said) exactly which grease you used, and how the bearing looked when you pulled it.

Motorcycle steering stems can use tapered roller bearings. I've been absolutely shocked by how some have come back from being aggressively notched. Just with an adjustment, feeling perfect again. It's a similar, though very different thing to the knuckles. It might be worth trying this with an adjustment, without doing new bearings. Or adjusting 100 miles after they are first set.

If the grease is too light, I could see it "falling" out of the top bearing faster. Moly could, in theory, also bind up the rollers.

 

[sunrk]

Hints why I’m trying to get my friend to make a way to put 25mm bearings in 80s with stock steering. I’m surprised it hasn’t happened already

What is the spec of the factory kingpin bearings, and won't that require replacing both the upper kingpins and the steering knuckles to use something different?

 

[Squeegee]

What is the spec of the factory kingpin bearings, and won't that require replacing both the upper kingpins and the steering knuckles to use something different?

80 trunnions are a 20 mm pin and yes it would require replacing the upper kingpin and the steering arm

 

[Squeegee]

80 trunnions are a 20 mm pin and yes it would require replacing the upper kingpin and the steering arm

If anybody is interested, the dynamic load rating for 80 series trunion bearings are 7890lbs.

 

[blinkerfluid]

Remember the top kingpin bearings are impossible to get grease to once assembled. The square plug thingy doesn't feed grease to them and is only to top up the grease load inside the swivel hub space on each side. If the swivel hubs are kept very full of grease (remembering they are not a sealed system) some might flow to the top bearings. If during maintenance the top kingpins are taken out it could be possible to inject some grease to feed into the bearings.

It's probable they have lost enough grease that the rollers have worn ever so slightly resulting in 'cogging' as they turn. Replacing the bearings isn't difficult but it's messy and fairly involved.

If you have ever worked on a Nissan Patrol y60, you'll see Nissan used a very thin metal plate under the trunnion bearings - basically the plate goes in first, then the bearing cone is pressed on top - once the bearing is greased and installed that plate doesn't let the bearing grease leak in to the swivel hub (pretty much for life) - it is a neat design IMO and we do the same to the 80s and other vehicles with similar setups at our shop

 

[Kernal]

"a very thin metal plate under the trunnion bearings--- we do the same to the 80s and other vehicles with similar setups at our shop"

@blinkerfluid :

How is this done in the 80 series??

Do you have photos you can post up?