Ref: Ford Escape Shop Manual Volume II

There are two significantly different torque specs for tightening the front wheel hub nuts:

Section 205-04-4 Removal of the Front Drive Half Shafts
In the Installation section it specifies tightening the hub nut to 184 Lb-Ft in step 7.

Section 204-01-6 Wheel Knuckle in the Installation section it specifies tightening the hub nut to 221 Lb-Ft in step 7.

Anyone out there got a clue as to which one is the correct torque value?

Since this may be related to the noise issue mentioned earlier could it be the cause?

About 35k miles ago I replaced the front wheel bearings & front strut packs. Thus I used the spec associated with the front suspension section (ie the 221 Lb-Ft).

On replacing the half shafts I used the spec associated with the half shaft replacement (ie the 184 Lb-Ft). About 500 miles later the thumping developed.

So could the lower value be associated with the thumping I've been hearing?

It takes about 5-15 miles to develop on startup, then it goes away on light load, heavy acceleration or wheel turning. The thumping is in sync with the rotation of the wheels and once per rev (ie 1X rotation).

 

In the 2009 manual it's on 204-01-5 instead and states 221 lb-ft and on 205-04-4 it shows 222 lb-ft. Odd a 1 lb-ft difference! Rear hub nut shows 221 lb-ft on 205-05-1. A chart on 204-02-1 shows it at 214 lb-ft.

The following is part of a conversation that I was included in another forum about a noise problem where wheel bearings were replaced/installed at 214 lb-ft with no problem. Elsewhere they mentioned that the hub nut broke loose at 75 lb-ft. Don't know if the difference between 184 and 221/214 would make a difference as the bearing preload is built into the bearing.

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Picked up a 04 two wheel drive V6 Escape yesterday with 116K miles a super clean garage queen. Driving home on the highway 10 miles all warmed up between 40 and 60 mph a rump rump sound like a tire delaminating at wheel speed as well a whining sound that changes in pitch with speed as well loudness in volume when weaving left and right. I believe the seller wanted to sell this Escape being in fear of expensive repairs. Steering wheel has a slight buzzing vibration feel, I suspect a hub bearings on the way out.
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Turns out on road test the noise is still there, this didn't make any difference.

In the case of this bearing the pre-load is not built into the bearing. The inner races are split and so the pre-load has to be applied to this bearing.

Still, this isn't a onesy-twosy kind of difference. the 221 vs 222 issue doesn't bother me since one can only set a torque wrench so accurately, but ~40 ft-lbs does make a difference.

 

Well, what I meant was that preload is built into the bearing when the hub nut is tightened down. The inner races are split but there probably no way of telling what the gap is, correct? Double bearing sets come in different configurations with a gap "somewhere", you tighten down to close the gap and that's it. Might be a spacer to fill "almost" the whole gap but again, it's tightened till there's no gap but you can't really see if the gap is gone, you have to assume that it's gone. Really doesn't matter if it's 100 lb-ft or 200 lb-ft.

There's a video from a Ford Tech who posts many videos doing a tone ring on a Escape. He doesn't even mention hub nut torque just states to use a breaker bar and says, you'll know when it's tight!

Use to have multi spindle machines that intentionally the preload setting spacer was left out. When they got chatter, etc. on the part(back face on ring gear from a ring&pinion set), release the drive clutch, loosen a locking nut, we had a 10' pipe that two guys would jump on to tighten up the bearing.

 

The "TAH" torque spec is not a good way of doing business. Some years ago I split for a 300 Ft-Lb torque wrench specifically because of the need to tighten things like hub nuts.

Using a "you'll know when its tight enough" rating won't get you to a sure 100,000 mile lifetime on things.

This represents a 20% difference in applied torque (eg 221 vs 184) that's beyond the pale.

Got it on the spacing of the two halves... and yeah... they're inside so you can't measure that gap to ensure it's set correct. Thus I use a new hub nut each time and I clean up threads to ensure the clamping force is as specified.

In the end I didn't think this torque issue would address the problem I'm having, but hope springs eternal. As my thinking has evolved I now think I have an engine/transaxle mount problem. Looks like there are 5 of them so I'll replace them one at a time...

PS TAH = Tight As Hades...
Recall that steel is elastic within a range. The torque spec is designed to remain within that range. Too much applied torque means you could go beyond the limit and deform the steel so that the applied force is reduced. It's like a rubber band: if you stretch it too much is doesn't return to original length and it doesn't hold as well. In the end you could destroy the threads and the nut could fall off on the road.

Somehow a 10' pipe on a breaker bar just doesn't seem a good idea.

 

The 10' pipe was placed on a spanner wrench IIRC. I have been forced to use a drive shaft pipe on a breaker bar, you gotta do what you gotta do!

Yes, always use torque specs when supplied, steel will deform but your talking in tenths of a thousand and this is a wheel bearing your talking about here. The 10' pipe was on a production multi-spindle lathe, all big and nasty. Further down the process where the gear teeth were cut the tolerances are very close and then on to lapping.

 

Do the math for a 10' cheater bar: 100 lbs x 10 ft = 1,000 ft-lbs...

That's that way you break things. What will break here is not the bearing but the threads on the spindle or inside the hub nut. The bearing also will likely fail sooner.

I don't care how big & nasty something is, it's built for a certain clamping force. In this day & age of computer design there is far less margin for error than once upon a time...

Once you go beyond the elastic limit of the metal, it's deformed permanently...
Of course we're talking of thousandths... and one thousandth too much still goes into plastic deformation. You can't pull it back from plastic deformation so it will fail much sooner.

For the rest of the world: A ten foot cheater bar is a Bad, bad idea.

 

Bill, he was talking about multi-spindle machinery. I have sockets up to 5" that have seen well over 3,000 ft-lbs. Not to mention beater wrenches that are designed to be hit with a 20 pound sledge hammer with everything you have. Not everything in the world is car sized....

 

GeorgiaHybrid, I've been around heavy machinery all my life, I know what he's talking of. But there are many, many here who'll misinterpret his words and may act on them.

 

Yeah, impact wrenches that you lift with an overhead crane. Your talking about so-called slugging wrenches.

Ever do any press work? Heating the tie rods with a rose bud torch and tighten the nut with a sledge hammer! Newer one have hydraulic nuts or built in induction heating rods, no torch needed.