knuckle stud thread

[80t0ylc]

......Just a point of clarification, the FSM lists 53 ft-lbs as the torque spec for 6T Hex head bolts (Studs were not listed). I spent a few hours searching for a torque spec for studs and not bolts and was unable to come up with anything. Also called a few of my engineer buddies but none of them were aware of any torque spec table for studs either. Closest we came was a torque spec for an unknown material/class 2 for 1/2 inch bolt was ~40ft/lbs. I had asked about this as the knuckle appears to be cast, however the 40ft/lbs was for a bolt and not a stud.........

There may be a bit of difference between the '97 FSM and the '94 FSM Standard Bolt Torque Specifications (although I can't see why). My '94 SBTS section is 2 pages. First page is a chart which lists Hex Head Bolts, Hex Flange Bolts, stud bolts and welded bolts with a chart to identify each for the purpose of determining the class of each. Second page lists the specified torque for each class from 4T to 11T. The break down for each class is by diameter, pitch, and whether it's a head or flange bolt. Flange bolt is a higher torque rating, so using the head bolt rating is leaning to the conservative and IMHO more accurate rating for the stud bolts. I also believe if there was a deviation to this standard for the knuckle studs, Toyota would have published it in the FSM in the Suspension/Axle section. Especially owing to the fact the change in design from the old style (pressed in studs) to this newer, more versatile style.

 

[mmuthart]

Shame on me...somehow I've been missing this common issue and have never once checked my lower trunion studs (knuckle studs), probably cause I had no idea where these knuckle studs were.

Well, now I know. Was wheelin' on Sunday and during a break noticed gear oil splattered around the inside of my pass side tire. 1 of 4 knuckle studs were GONE. The other 3 were loose. (Obviously a fairly common problem after reading this thread.)

QUESTION: Is it expected that gear oil will leak when the steering arm separates from the knuckle?

I tightened up the 3 remaining studs/nuts but gear oil continued to slowly leak the entire trip. Sitting at home now for a couple days, the leak has stopped. I haven't checked the fluid level, maybe it's just low now.

I have a full birf rebuild kit . Do I use it or can just replace the studs and be good? My birfs have not been rebuilt yet and were doing just fine. Gear oil was staying clean (no mixing with grease) and no leaking.

 

[Cruiserdrew]

Shame on me...somehow I've been missing this common issue and have never once checked my lower trunion studs (knuckle studs), probably cause I had no idea where these knuckle studs were.

Well, now I know. Was wheelin' on Sunday and during a break noticed gear oil splattered around the inside of my pass side tire. 1 of 4 knuckle studs were GONE. The other 3 were loose. (Obviously a fairly common problem after reading this thread.)

QUESTION: Is it expected that gear oil will leak when the steering arm separates from the knuckle?

I tightened up the 3 remaining studs/nuts but gear oil continued to slowly leak the entire trip. Sitting at home now for a couple days, the leak has stopped. I haven't checked the fluid level, maybe it's just low now.

I have a full birf rebuild kit . Do I use it or can just replace the studs and be good? My birfs have not been rebuilt yet and were doing just fine. Gear oil was staying clean (no mixing with grease) and no leaking.

The inner seal is now junk so you'll need to pull it all the way down and rebuild it. The bearings may have been damaged as well, so you need to do the full job.

It will also give yo a chance to install all new knuckle studs-the new ones from Toyota are very nice with the Torx drive head.

 

[mmuthart]

The inner seal is now junk so you'll need to pull it all the way down and rebuild it. The bearings may have been damaged as well, so you need to do the full job.

It will also give yo a chance to install all new knuckle studs-the new ones from Toyota are very nice with the Torx drive head.

Thanks for the advise Andrew. So did the inner seal go first, causing a leak, which in turn caused the studs to loosen up? Or did the leak come after the studs loosened up? You know, the old chicken before the egg argument...

 

[Cruiserdrew]

Thanks for the advise Andrew. So did the inner seal go first, causing a leak, which in turn caused the studs to loosen up? Or did the leak come after the studs loosened up? You know, the old chicken before the egg argument...

The nuts on the studs loosened up. You need to check those periodically especially when going off road-make it a habit to check before you go and at the end of each offroad day. It can save you a lot of pain.

 

[breadbox]

I bought my truck and was unaware of the way the steering was hooked to the front end. It was kinda wondering when I got it and would do some weird stuff on hard breaking, but I just thought it was the tires. Until I stopped at a stop sign and pop, no steering at all, looked under the front and 2 were missing and 2 had broken off, the drivers side had all 4 still.

Got Toyota replacements and red lock tighted them in, I keep checking them cause I am worried they will come out but so far they have not moved at all.

I am relieved to see this thread cause I thought I was the only one that this happened to, now I can see it is a little more common.

 

[Tools R Us]

The seal may or may not be damaged. The first time mine came loose, I drove ~100mi home before finding it, torqued them, refilled with grease and that lasted about 2 yrs before a stud broke. The studs didn't stay tight well, they were damaged and one finally broke. In your case it doesn't matter, the studs need to be replaced, so replace the seals at the same time. Once the studs have been stressed like that, they will never hold full tension and will continue to stretch, loosen.

 

[snowwolf]

All this happened to me too, I was lucky too.

I metal locked my new type studs in, that was 100k ago with no problems since.

 

[mmuthart]

Okay, I'm still not clear on something:

When this happens (steering arm separates from knuckle), WILL IT ALWAYS LEAK GEAR OIL (like mine did)??

I'm just not familiar enough with what's going on inside to understand this. Could the steering arm fall off and no gear oil leak out because that inner seal is still doing it's job?

 

[Tools R Us]

Okay, I'm still not clear on something:

When this happens (steering arm separates from knuckle), WILL IT ALWAYS LEAK GEAR OIL??

I'm just not familiar enough with what's going on inside to understand this. Could the steering arm fall off and no gear oil leak out because that inner seal is still doing it's job?

They can come slightly loose without significant leakage. If cought quickly the seal maybe saved, but most likely the studs are damaged and should be replaced. If driven until very loose, it will always leak, the knuckle is forced out of alignment, pushing the axle out of alignment more than the seal can compensate for.

 

[mmuthart]

If driven until very loose, it will always leak, the knuckle is forced out of alignment, pushing the axle out of alignment more than the seal can compensate for.

Okay, thank you, this is making more sense now. Say my inner seal was good (leakage stopped), couldn't I just replace the studs from the bottom of the knuckle without any dis-assembly and be good?

 

[Tools R Us]

Okay, thank you, this is making more sense now. Say my inner seal was good (leakage stopped), couldn't I just replace the studs from the bottom of the knuckle without any dis-assembly and be good?

Maybe, my intertardweb magic crystal ball is broked! the important things are: The studs stay tight, the seal isn't excessively leaking and the knuckle contains the proper amount/type of grease. If it meets all of those, most likely it will work.

 

[corsair23]

Okay, I'm still not clear on something:

When this happens (steering arm separates from knuckle), WILL IT ALWAYS LEAK GEAR OIL (like mine did)??

I'm just not familiar enough with what's going on inside to understand this. Could the steering arm fall off and no gear oil leak out because that inner seal is still doing it's job?

IIRC don't the threaded holes for the studs go completely through/into the knuckle? I just did my front axle service last October (including replacing the PS knuckle) so you'd think I would remember

Assuming they do, and one or more of the studs come out then I see no way that you won't have moly grease leaking out...especially if you are already mixing gear oil with the moly due to a damaged inner axle seal and assuming you don't catch the problem right away then as Kevin states the inner axle seal will soon be damaged/destroyed and you'll have moly grease/gear oil goo leaking out.

If the studs and or nuts loosen, then IMO you'll still have leakage but it will be past the trunnion bearing and not as severe as it will coming out an open stud hole.

 

[mmuthart]

IIRC don't the threaded holes for the studs go completely through/into the knuckle? I just did my front axle service last October (including replacing the PS knuckle) so you'd think I would remember

Assuming they do, and one or more of the studs come out then I see no way that you won't have moly grease leaking out...especially if you are already mixing gear oil with the moly due to a damaged inner axle seal and assuming you don't catch the problem right away then as Kevin states the inner axle seal will soon be damaged/destroyed and you'll have moly grease/gear oil goo leaking out.

If the studs and or nuts loosen, then IMO you'll still have leakage but it will be past the trunnion bearing and not as severe as it will coming out an open stud hole.

My leakage appeared to be clean gear oil. It does not appear to have been mixing with moly grease.

 

[corsair23]

Okay, thank you, this is making more sense now. Say my inner seal was good (leakage stopped), couldn't I just replace the studs from the bottom of the knuckle without any dis-assembly and be good?

What if the leakage stopped because all or most of your gear oil and moly grease leaked out? I think you said you had the parts so IMO I'd just fix it right now (full axle service including new torx head studs, cone washers, and nuts on both knuckles etc.)

Get it fixed, keep an eye on the studs/nuts, and don't worry about it for a long time to come

 

[Tools R Us]

My leakage appeared to be clean gear oil. It does not appear to have been mixing with moly grease.

The gear oil leaks out through the knuckle chamber. The knuckle chamber should be 1/2-3/4 full with moly grease, if you leaked clean gear oil, the knuckle was empty.

 

[mmuthart]

Okay, thanks guys. I'll tear it apart, take a look, and rebuild it.

 

[Mike Shull]

Use heat to remove LockTite to help in the disassembly.

I check these every day on the ...."I did not used to believe in Locktite, since it would make a broken stud hard to remove. However, now I am convinced they break infrequently enough, that LockTite on balance is probably beneficial."

 

[timer00]

I check my studs maybe twice a week since I am always checking something on the Cruiser due to my obsession with keeping it in top shape since its our primary vacation / backup vehicle.

I rebuilt the front end myself 3000 miles ago or so and they are still tight. I did the hammer trick with knocking on the control arm every few turns to make sure the arms bolts/washers weren't binding up with the control arm etc. Hopefully they don't go nuts and sheer off or loosen on me but that is why I check them twice a week.

 

[mmuthart]

My passenger side knuckle assembly as been rebuilt for a couple weeks now. Only one surprise, the missing knuckle bolt wasn't just missing it was sheared off. I had to drill it out.

This was my first rebuild so I really took my time and made sure I didn't screw anything up. I used red loctite on the new studs and nuts as well. Used loctite on the 2 top trunion cap bolts as well.

She seems to be doing fine after a few hundred miles. My only concern is the lack of any visible grease (see pic.). I'm tempted to pump in some more moly but don't want to overfill. Thoughts?

The only thing missing from the FAQ instructions on the rebuild was the final assembly of the wiper seal kit, although it was fairly intuitive I suppose (not talking about the order but the bolting it up). There was a small gap between the knuckle and final retainer ring in some places, it looked normal due to the uneven edge of the retainer ring but I didn't like it, so I put silicone around the edge (see pic.).

Oh, one more note: I got the Marlin inner axle seals but ended up using OEM after finding a thread not recommending them for the AWD 80.