Rear hub ass'y replaced: Already going out <5000 miles - Page 3

elsolo · 11-19-2012, 10:48 PM

Quote:

Originally Posted by amc49

I would consider the fact that rolling drum on the last final tighten means that you are exerting torquing force also into the rear suspension in the form of twistup load, that amount of load will be subtracted from your actual nut torque regardless of what your wrench says. Meaning you won't have full torque there....

From like 75 ft. lbs. on up I have wheel bolted on, car on ground, brakes and engine on and someone standing on brake. The only way to guarantee pretty much full torque on nut itself.

What is this twistup load you refer to?

Your torque wrench will click (or display) the correct torque setting, even if the fastener you are tightening is on spring loaded suspension parts that compress under the load of the wrench.

If you put the wheel on the ground to do the final torquing, you are possibly harming your bearings during install. You will not be able to spin the drum during the torquing. Having the brakes on is another issue.

Top-Ace · 11-19-2012, 11:59 PM

That is unfortunate. My wifes 2000 Focus sedan has been running SKF brand rear hubs bought from napa for a long while now, no problems. I dont think motorcraft is necessary, but I know skf makes good stuff.

I did have to sand some rust off the spindle and applied a dab of anti-seize to keep the bearing from fusing/rusting to the the spindle again.

amc49 · 11-20-2012, 04:27 AM

Think manual transmission, the total torque rating is shared by every part the power flows through and divides amongst them. Depending on how you fit the torque wrench in on nut (angle of attack mainly) the rear suspension can deflect some thus absorbing part of it. Same reason torque wrench manufacturers tell you never to put an hand on torque wrench head say using 1/2" fittings and six inch extension. When you load it, the whole thing can swing to one side and risk rounding off corners of bolt/nut. Human nature has you putting a hand on top of wrench head to steady it but doing so affects the torque since some is absorbed by your hand.

A torque wrench is nowhere near smart enough to know if you put all that power into just a nut or into everything else the nut was attached to. It just clicks to an given number. Put a wrench on front wheel bearings already installed say with atx in park, wheel free in air and twist load on the wrench and tell me how much load you just tried to put on the axle and parking lock inside trans, you can waste 25 ft.lbs. quicker than spit there just pulling all the looseness up solid.

I roll disc or drum while tightening maybe to 50+, after that the races have contacted, all you are doing is running up the force holding them together. Balls have done all the centering they are going to do.

If suspension components compress under the load, I assure you they ARE absorbing force, the wrench does not know that, all it reads is 'total' force, not everything force was applied to.

Having brake on does nothing, if bearing already run up partially, the brakes will have an easy .020" in sideways deflection front or rear before anything becomes a problem. At full torque runup you'll do well to get another thou out of the bearing. Even though brakes themselves are a force you are working against they force the torque to pretty much stay right there local to the nut.

Quick test of bearing after done, spin it, if there's a problem you'll know it. The balls better be right or the bearing was scrap to begin with. Never lost a one doing this, in fact they last forever.

***whynotthinkwhynot*** · 11-20-2012, 08:04 AM

twist-up load: he's referring to something else moving besides the nut or bolt you're torquing on. What it would be in this situation is that if you have the car jacked up by the subframe, then the suspension might be absorbing some of your torque instead of the nut. What should be done is that the suspension should be supported by a jack, and you should apply torque in a downward motion towards the jack so that there is no flexing of the suspension that might absorb some torque. If you torque upwards, or horizontally, then bushings or the springs will flex.

amc49 · 11-20-2012, 06:24 PM

There you go, BTDT. There are ways of getting around the issue. Remember the angle of attack I mentioned? Simply a way to use the construction design of surrounding objects to aid you, not hurt you.

Look, there's 15 ways to skin a cat. I started doing this after observing how many times the torque did not seem very high at disassembly time. No way was there 175 ft.lbs. on nut then, maybe as low as 50 in some cases. I started looking for a way to guarantee the full torque amount. It seems to show, at disassembly now years later they seem to be tighter than they were before.

zakkius · 11-29-2012, 10:55 AM

Quote:

Originally Posted by G Ford Fan

the above is 100% correct and I also do just that.

I spin the drum both directions several times as I am torquing the bearing hub nut down.

This helps to seat the bearing properly and is a very important step.

Seems like that would be a very crucial part of the replacement, and I have overlooked it. Let's see if I can get it right the second time around. Thanks!