Prepping for steering knuckle rebuild - question on birfields

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Good afternoon Mudders,

I recently purchased an 86' HJ61. Been hearing a pop/clunk from up front (front left maybe), usually when turning. I jacked up the front end and did the 12 & 6 o'clock test and noticed some play/wobble in the front left tire. I assume that means a bearing has gone. I also hear some noise when spinning both front tires freely.

I ordered a knuckle rebuild kit & tie rod end kit, and have been picking up the tools I'll need. *I'm not a mechanic but sounds like this is something I can handle.

My question is if I should be concerned with the birfields?

From what I understand, a birfield going out creates a clicking noise? I haven't had any clicking, just the occasional pop/clunk.

*I noticed in the old repair records there was a note of a leak (diff fluid getting into the knuckle I think) on that same front left wheel, and the note mentioned it could be a bent axle. That was in 2014 shortly before it was imported to the US. The previous owner said he hadn't noticed any leak since he bought it in 2015. He seemed honest but there's also some faded fluid drip marks on the inside of that tire. Could be from that leak from 2014 though, as the owner I got it from had only driven it around 20k miles since he bought it so I assume they're still the same tires.

I am hoping to keep my costs to a minimum, but don't want to skip a step I should just do since I'm already getting in there. I'm not sure how long birfields last, and if I should just replace them, or if since I don't have any clicking I should hold off and just inspect them before spending the money.

Thanks for any help. You guys rock!
 

OSS

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The noise is probably a dry worn out wheel bearing. No biggie. Replace the set and lube them up and you’ll probably be good.
The birfield joints only get used when driving in 4WD. If the cruiser rarely uses 4WD, the birfield joints likely are good as new - though they could use a cleaning out of the old grease and reapplication of new grease.
A little axle gear oil leaking out past the oil seal on the ball of the knuckle isn’t a big deal. Just means it’s time to replace the inner axle oil seal.
 
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If you keep blowing axle seals it could be that the axle is worn out where the seal seats or it could be the trunion bearings going out and or not properly shimmed/aligned. If you go in that deep make sure you keep your shims in order and you check that it’s all aligned or you’ll blow seals real fast.
 
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That too. But if your shims are off and the birf isn’t aligned then the seals won’t seal properly whether you use marlin eco seals or OEM.

I’ve gone back and forth and discovered I need the SST to set the trunions up correctly.

I bought a knuckle rebuild kit so it sounds like I'm going in deep.

Is the marlin seal crucial? I think my kit has a japanese/oem seal

What do you mean about alignment? I'm still learning this process. It looks like I need a spring scale gauge to test the bearing load and adjust shims as needed. Is there something else I need to do in there to align the birf, etc, or do you just mean setting the bearing load? I do not want to miss an important step.
 
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I bought a knuckle rebuild kit so it sounds like I'm going in deep.

Is the marlin seal crucial? I think my kit has a japanese/oem seal

What do you mean about alignment? I'm still learning this process. It looks like I need a spring scale gauge to test the bearing load and adjust shims as needed. Is there something else I need to do in there to align the birf, etc, or do you just mean setting the bearing load? I do not want to miss an important step.
The spring scale is for setting wheel bearing preload. You do need that unless you’ve done it enough times to know “the feel”... last time I did it I just went by the instructions and made sure it felt right. But I’ve done it a couple times in the past.

The trunion bearings and the spacer shims align the birfield joint in the knuckle. If there is too much slop the axle shaft will bounce around in the housing allowing the inner seal to fail. Likewise, if the birfield isn’t aligned properly it will put slight pressure on one spot of the inner seal and cause it to fail prematurely. The shims are usually setup for the individual knuckles. They are there to compensate for slight variations in the casting/machining process so that you can get everything aligned with the proper specifications. They are usually good to go once they have been set by the factory, but depending on what’s happened in the past, you may not be able to rely on the shims being correct. You will be provided with a set in your rebuild kit should you need them.
Read your FSM several times. Removal of the trunion bearings and races can be done with a brass drift/punch. BRASS!
F900AB4C-6A07-4A6F-99C0-5BEC69B752DF.jpeg
Here is the SST for setting the trunion preload. This is the step I’m speaking of. You CAN get by without going through it as long as you keep track of your shims and they aren’t damaged. If you feel the need to go through this step you won’t find that SST anywhere. There are some people on this forum who have acquired that tool and they will gladly loan it to you for a reasonable fee, but you’ll have to ask around. I also think trail tailor was making that tool for a while, but I’m not certain if it’s available anymore. Like I said, you CAN get by without it, but if you keep blowing through inner seals or your steering is drifting too much you may need to reset the preload on the trunion bearings using the SST and new shims. Heck, there may be a method of doing this without the SST but I haven’t come across it.
F1B78287-C951-460A-AA81-13ADB5523C1B.png
 
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The marlin seal is not crucial. The OEM seal is very good quality. But, if there’s a substantial groove worn in the axle where it seats to the OEM seal you will get leakage. The marlin seal is thicker so it seats on a different portion of the axle shaft that the OEM seal allowing proper sealing surfaces and keeping oil from migrating down the shaft, into the knuckle, and into the locking hub.
 

Spike Strip

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If your seals are wearing out quickly, it's most likely (but not absolute) that the birf is not centered in axle housing (due to position of knuckle) and thus causing uneven wear on the seal. The SST above is necessary for getting it all aligned if it's been fubar'd in the past.

Marlin Seals are double-lipped Very Heavy duty version of that seal. I would never do another front axle rebuild without them.

OE seals are fine if you have no issues.

You might be able to Rent/Borrow the SST from someone on here. Most only use them once or twice in a lifetime.

You will also need a 12" caliper.
 
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The marlin seal is not crucial. The OEM seal is very good quality. But, if there’s a substantial groove worn in the axle where it seats to the OEM seal you will get leakage. The marlin seal is thicker so it seats on a different portion of the axle shaft that the OEM seal allowing proper sealing surfaces and keeping oil from migrating down the shaft, into the knuckle, and into the locking hub.

Oook, I figured there was more to it. Looks like I need to pour over the FSM a few more times. I haven't seen any youtube videos go over this detail.

Thanks!
 
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There is s bit of a learning curve while you’re in there your first time. It seems intimidating at first but it’s mostly just the mess you make cleaning the grease out of everything. It’s generally a fairly standard maintenance procedure that anyone owning these trucks must learn to do, lest you pay an arm and a leg for someone else to do it. Once you see it all broken down and put it back together it’s all pretty simple.

Pro tip, when removing cone washers use a brass drift on the top of the stud with the nut backed off just to the top of the threads to protect them. Don’t pound on the side of the housing or you could warp the hole making things difficult or impossible to reassemble. You can see here on my hub where someone in the past did just that. Luckily it’s not bad enough to cause issues, but any more and I’d be SOL. The same goes for the trunion cap.
5A7175A2-4577-4FF8-BFCF-F56B3203737F.jpeg
 
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Thanks to CPS432 for the huge write-up, and everyone else's input. I think I'll order some marlin seals just to be safe.

Being a new owner I can't really speak to how long / how well the axle seals have been holding up.

Sounds like unless there is a concern of something being misaligned, I should be able to put the shims back in order and avoid re-alignment?

I'm tempted to do the rebuild (without the SST for birf alignment) and unless the seal shows some unusual wear on one side just go ahead and replace the seals etc and close it back up? I mentioned before the previous owner claimed he's seen no leaking out of either knuckle, so hopefully that'll be all I need.

Worst case: I see a leak coming out of a knuckle after rebuilding, and have to dive back in and put in a new seal and align the birf?

Thanks everyone!
 
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Thanks to CPS432 for the huge write-up, and everyone else's input. I think I'll order some marlin seals just to be safe.

Being a new owner I can't really speak to how long / how well the axle seals have been holding up.

Sounds like unless there is a concern of something being misaligned, I should be able to put the shims back in order and avoid re-alignment?

I'm tempted to do the rebuild (without the SST for birf alignment) and unless the seal shows some unusual wear on one side just go ahead and replace the seals etc and close it back up? I mentioned before the previous owner claimed he's seen no leaking out of either knuckle, so hopefully that'll be all I need.

Worst case: I see a leak coming out of a knuckle after rebuilding, and have to dive back in and put in a new seal and align the birf?

Thanks everyone!
I’ve done this 4 times and I haven’t messed with the SST. A little oil in the knuckle isn’t going to destroy your truck. But if it’s weeping shortly after you button it back up it would be wise to go back in and check your trunions and probably reshim everything. It’s actualky kinda fun once you know what you’re doing. Since I’ve owned this truck long enough and done knuckle work enough I feel I should have the SST just to be right on the money. But you’re more than likely okay to skip over that part. Just keep your shims in order.
 
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I’ve done this 4 times and I haven’t messed with the SST. A little oil in the knuckle isn’t going to destroy your truck. But if it’s weeping shortly after you button it back up it would be wise to go back in and check your trunions and probably reshim everything. It’s actualky kinda fun once you know what you’re doing. Since I’ve owned this truck long enough and done knuckle work enough I feel I should have the SST just to be right on the money. But you’re more than likely okay to skip over that part. Just keep your shims in order.

Yup I'm actually quite excited to dive into this thing. I haven't done any real wrenching in years, but I used to replace races/wheel bearings in our work trailers all the time. Really looking forward to getting my hands dirty and familiarizing myself with all the steering components.

Thanks again for all the help!
 

CruiserTrash

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I borrowed the SST and still wound up using the exact shims as before. Probably good to go through the process from a conceptual point of view.

As for the preload, I had somebody with experience helping me (more like overseeing, they let me do all the dirty work). They let me fight with the spring scale, go back and forth probably a dozen times, before they finally tightened it up by feel and said "it should be like that". Once you get the feel it makes a lot of sense ... tight but loose, no play but also no undue resistance to motion. Ever tighten the hubs on a bicycle wheel? Like that.

To answer your first question, we cleaned the birfs in and out without disassembling them then gave a good look over for wear. We also rotated them around to feel that the internals weren't messed up. They passed the test and I've had them reinstalled for about 9 months with no issues.
 

Gretsch

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I borrowed the SST and still wound up using the exact shims as before.

Every instructional video I have seen that goes through the process of aligning the birfs with the SST, goes through everything only to re-use the same shims as before. I opted out of this step for this reason and just re-used what was there. So far no issues. I used the Marlin seals as well. Much better than the OEM stockers I pulled out of there IMHO. The lip they have on those ensures you get things aligned properly. I got an original Toyota OEM seal installer on sale from one of the vendors on here. They had a few left over from days gone by and were selling them cheap so I jumped on it. Might have been Trail Tailor. Highly recommend a seal installer tool if you can get one. Made short work of installing the seal straight. No games and no leaks. HTH.
 
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When you clean the birf out and it’s all dry and you’re inspecting it, there is a probability it will get “jammed” up as you’re moving it around without grease. Pack grease into the bearings and it should losen up. Those things are really quite tough and pretty hard to break, though they do.
 

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