1997 FZJ80 Rehabilitation

[jpoole]

If they look/feel good those bearings probably have/had a lot of life left in them. They could be useful as spares, particularly if you were setting off to parts unknown, but I'd personally prefer to keep a new set of bearings/seals/etc. to do the full job as my "spares". I'm guessing you'd never put a used set of bearings back in, just because.

 

[Wrencher93]

If they look/feel good those bearings probably have/had a lot of life left in them. They could be useful as spares, particularly if you were setting off to parts unknown, but I'd personally prefer to keep a new set of bearings/seals/etc. to do the full job as my "spares". I'm guessing you'd never put a used set of bearings back in, just because.

This was my second thought after the first one of "oh I could keep these". I agree that new bearings would be ideal but I was thinking more of a replacement if you shredded one while away from home and just needed a bearing to throw in there. Not sure how realistic that is... I will probably keep them as a reference/curiosity piece if nothing else. I also have a young son who would love to play with them once they're fully clean so multiple uses on the horizon haha.

 

[Wrencher93]

After disassembling the birf to clean it, I realized I didn't know 100% how to put it back together. So I searched and found a couple threads on the topic. As far as I can tell, this is correct. Please comment if you think it's not. Everything went together fairly easily and the joint has a slight tension but you don't have to force anything. The way it was described on another thread is the cage is "tapered side" out (showing) and the star is "big side" out meaning the larger face (and tapered flanges).

 

[Wrencher93]

All the pictures I just posted are the driver's side minus the knuckle housing. I will have to clean the rest tomorrow (if it isn't raining). I was hoping to get the axle back together today but I had other obligations that got in the way. Soon though, soon.

Oh, and when I zip tied the brake calipers to the coil springs to get them out of the way, the axle to caliper brake lines revealed some really gnarly cracks/rotting. Glad I'm about to swap them all for new.

 

[Wrencher93]

@BILT4ME and @jpoole I searched this but couldn't find the specific answer I needed. Everybody talks about the major components of knuckle disassembly but skips over this. How do you remove the top knuckle/trunion bearing from the cap? The bottom one falls out. Top one is still stuck. I don't want to mar the cap by pounding on it with a screwdriver...

 

[BILT4ME]

@BILT4ME and @jpoole I searched this but couldn't find the specific answer I needed. Everybody talks about the major components of knuckle disassembly but skips over this. How do you remove the top knuckle/trunnion bearing from the cap? The bottom one falls out. Top one is still stuck. I don't want to mar the cap by pounding on it with a screwdriver...

The bearing slides over a "pin" on the bearing cap. If it does not slide off, then you will need to pry under the bearing to pull it off. I would recommend soaking it with PB blaster because it must be corroded of the inner race to the pin. If the bearing cap won't pull out of the knuckle, turn the knuckle upside down and use a long pin punch on the pin of the bearing cap to drive the cap out. Use a BRASS punch if possible. If you cannot find a brass punch long enough, you can use a steel one, but make sure you center it with EACH hit and be careful to not mushroom the pin.

Support the knuckle in a vise or something so the cap is "free" in between the jaws and can drop out when the time comes. If there are any shims under the cap, make sure to re-use them and don't mangle them.

 

[jpoole]

Hey @Wrencher93

It shouldn't take much to get those bearings off unless you've got some weird damage or corrosion going on. I guess that the damage is possible given the scarring inside the knuckle though!

Here's a thread that covers some ideas:

Knuckle Bearing Cap Race Stuck!

Doing a Knuckle rebuild on my 4/74 FJ40 - First time the knuckles have been apart (only 65K miles on the truck) in 43 years! Both the bottom bearing cap and the top steering arm have the inner bearing race frozen on the pin. I was going to heat and beat, to try to knock the race off, but any...

forum.ih8mud.com

​

Personally I'd try the easy/quick options first and only escalate efforts if needed. I've got an old chisel that I use for mechanic work that's small, gently sloped and not too hard/brittle so hasn't shattered in years of use. I'd stick that in the seam and tap it gently in different spots around the bearing to see if I could get any easy movement. Once it starts to move it should be easy to work it off from there even if gentle prying is needed. If the chisel gets no movement then I'd add heat to the mix next and retry. From there I'd consider a puller or other options depending on how it was behaving.

When it's off I'd look into cleaning the surface up so that the fit/feel of the new bearing is the same as the others to help you avoid this the next time around.

 

[Wrencher93]

Thanks, gents. I really appreciate the replies. I now have the knuckle clean so it's easier to see what's going on. I'm going to try gently prying it off before anything more extreme. I was hoping to just leave the cap installed and not remove it - but if I have to I will drive it out with a brass drift and force the bearing off that way.

 

[Wrencher93]

Got one off. No serious damage to the cap but I did scratch it a little around the base of that pin where the inner race sits. I don't see how I could have been more gentle. No corrosion, I just wasn't sure how to go about getting good leverage on the inner race. Ended up using a small cold chisel and gently tapping it between the bearing race and the shoulder of that pin. Then I just worked it off.

 

[Wrencher93]

And now the other is off... should be ready for reassembly after I clean a couple more parts and redress the mating surfaces with some steel wool to remove any gunk.

 

[BILT4ME]

Are you doing NEW knuckle studs on the bottom of both knuckles?

 

[Wrencher93]

Are you doing NEW knuckle studs on the bottom of both knuckles?

Nope. Are they supposed to be?

 

[BILT4ME]

Nope. Are they supposed to be?

Usually a good idea, as they are a frequent failure point.

My trucks PO had broken off one lower right stud and I knew about it. One day I looked under the truck and only one remained and was almost ready to fall out. I screwed it in finger tight and gently drove home.

I then changed all on both sides to make sure none were stressed, fractured, or stretched. They have not come loose in over 90K miles.

There is controversy on torque to set them into the hub and whether or not to use Loctite. Look it up and decide for yourself.

Final nut torque is to be 71 LB-FT. Assemble them DRY (no anti-seize or oil)

 

[Wrencher93]

Usually a good idea, as they are a frequent failure point.

My trucks PO had broken off one lower right stud and I knew about it. One day I looked under the truck and only one remained and was almost ready to fall out. I screwed it in finger tight and gently drove home.

I then changed all on both sides to make sure none were stressed, fractured, or stretched. They have not come loose in over 90K miles.

There is controversy on torque to set them into the hub and whether or not to use Loctite. Look it up and decide for yourself.

Final nut torque is to be 71 LB-FT. Assemble them DRY (no anti-seize or oil)

Thanks for the heads up. None of mine were loose or seemed compromised (of course, the naked eye can really only tell so much when it comes to this kind of thing).

 

[Wrencher93]

When I was sitting in my driveway cleaning everything the last two days (I work slow and have a family. No, I'm not done yet.) I recalled all the times swapping birfs has been mentioned on this forum. Both of mine seemed OK to me, even after completely disassembling them. But - this is my first time tearing them apart and I know that what looks like "mild" wear on a bearing can have significant consequences in terms of actual performance.

Here are some pictures of the wear I found. Any suggestions/cautions based on what you can see?
I'm probably going to reassemble everything today but I don't want to swap sides with the birfs if they appear to already be on the "correct" side.

Driver side:

 

[Wrencher93]

I'll have to take the passenger birf apart again to get pictures. I didn't have my phone handy when I cleaned it. I don't remember seeing anything wild in terms of wear but I'll check it out.

 

[Wrencher93]

Still doing my homework on the birf swapping subject. Trying to figure out where the wear patterns would be given which side of the vehicle the birf was on. Stated differently: would the wear marks inside the bell and on the star be on the "forward" (in reference to vehicle) sides of the openings? So on driver side, on the left hand surface as you look at the installed birf (right hand side of ball bearing track as you look into birf from inner axle side)?

The reason I'm trying to figure this out is I think these birfs have been rotated before because there's some visible wear in both directions. Trying to determine which side has less wear and stick with that orientation.

 

[Wrencher93]

Side note for my own reference: proper bolt size for tapped hole in birf shaft is M8x1.25

 

[jpoole]

I assume that the wear will be mostly from acceleration force as opposed to deceleration force. I assume that flipping them reverses that and lengthens the life of the surfaces that the balls contact.

I'm not sure how much benefit flipping will actually give you and at least in my case when I've had mildly clicking birfs flipping sides made no difference. I'd put them in so that the surfaces with the least wear are engaged during acceleration and hope for the best.

 

[Wrencher93]

I assume that the wear will be mostly from acceleration force as opposed to deceleration force. I assume that flipping them reverses that and lengthens the life of the surfaces that the balls contact.

I'm not sure how much benefit flipping will actually give you and at least in my case when I've had mildly clicking birfs flipping sides made no difference. I'd put them in so that the surfaces with the least wear are engaged during acceleration and hope for the best.

I couldn't find any solid explanation of which surfaces are engaged for a specific direction of rotation. So, I went out in the garage, grabbed a birf, and figured it out myself. The following is my current thought process. Let me know if you see any glaring errors.

To figure out which surfaces will be incurring wear, we have to think about which parts are "driving" which other parts. In this case, the inner axle shaft is imparting force to the star in the birf, which in turn applies force to the ball bearings, who then drive the outer bell and attached shaft, which then drives the drive flange and so on. The relationship is important because it establishes certain points of contact within the assembly. Based on this relationship, I deduce the following area will see increased wear within the birf:

1.) The rear side bearing surfaces of the star
2.) The front side bearing surfaces of the bell
3.) The rear side of the bearing slots in the cage

The words "front" and "rear", as used here, are in reference to the vehicle as a whole with the birfs installed. This is why swapping sides could, theoretically lengthen the life of the joint. They only wear in one direction (unless you do a disproportionate amount of driving in reverse).

Here are pictures of my passenger side birf. You can see here the wear inside the bearing tracks of the bell. As expected, the greater wear is on the left hand side when looking into the bell. The "left" side would also be the front of the vehicle as viewed from the diff in the installed orientation.

This next picture is of the cage. You can see that the larger divots worn by the ball bearings are on the rear sides of the slots. The wear seems to occur on the inboard (closes to diff) edge of the slot.

Finally, this picture shows the wear to the star insert. As explained before, increased wear is seen on the rear sides of the bearing channels. This happens as the star "pushes" the ball bearings into contact with the bell.