I had thought that the original torque for axle nuts was 320 ft lb and revised to 250 (ish). And I had thought RAVE was updated, at least the copy I have. I thought wrong. So when I did my overhaul years ago I torqued to 258 ft lbs. That is the original spec. So this weekend when I did my CV swap it was a pain getting the nut free (had to go get all 3/4" drive stuff). During assembly I quickly checked RAVE to verify the torque value and did 258 again. Well later on last night I did more reading only to find out that yes, there was a revision but I was wrong. The over 300 value was newton meters and 258 ft lbs was the original, so back when I did all that work I thought I was going to the revised spec.

So my question is should I keep with the 250-ish value since that is what the bearing has been under for some time now or should I back it off to the new value? My concern is that backing off the bearing that has been loaded up at 258 may cause an issue. But I would not mind making things a little easier to remove the next time I pull the nut. Or should I go to 200-210 for now to sorta meet at the middle....

 

I don’t see how the axle nut torque could significantly impact bearing preload. These are factory sealed hub/bearing assemblies. All of the axle nut torque is applied to the center hub spline. Unless the torque is so high that it deforms the hub, I can’t see how it would matter. Risk of severe over torquing I think would more likely impact the shaft end threads than anything else. That might be reason enough to match your previous torque.

I’m no engineer, but I can’t envision an impact on preload here.

 

I am no engineer either, heck, I never even played on on TV, OR stayed at a Holiday Inn Express........ But I can tell you with absolute certainty that if the axle nut is loose, it will cause premature bearing failure. I was helping my nephew with new front bearing on a 2004 Mini Cooper a few years ago. After just 80 miles it developed a bad wobble above 50 mph. He admitted that he only put them on "hand tight" and intended to torque them "later".

I have a short answer and a long answer.

SHORT ANSWER: the axle moves in and out of the bearing and "wobbles" when it does, thus causing the bearing to wear out sooner.

LONG ANSWER: As it was explained to me; if there is a loose axle nut, the axle will not be supporting both sides of the bearing, the half shaft that is in the bearing will move in or out as you apply or release torque (accelerate/decelerate) because the movement is allowed, it magnifies the gyroscopic effect of the spinning shaft and it will want to move the end that is inside the bearing in a 90 degree direction ahead of the direction of rotation. This gyroscopic effect causes the end of the shaft in the bearing to "wiggle" in the hub as it moves ever so slightly and places a continuous +/- 90 degree shearing load on the bearing. This is the same as a "P" factor in propeller driven airplanes.

You can read about "P" factor in propeller aircraft on the internet. Sitting in the cockpit the propeller spins in a clockwise direction (the top moves from left to right for those who grew up with digital watches) as the airplane accelerates down the runway and a certain point, the pilot will move the controls to lower the nose (raise the tail) this action causes a gyroscopic effect 90 degrees ahead of the direction of rotation thus causing the air plane to turn to the left.

Same thing is happening in the wheel bearing and if the axle is not tight, it will allow movement that will cause premature wear.

Or I could be wrong about the whole thing.
Bottom line is follow the manual and you have a greater (but not guaranteed) chance of success.

Jeff

 

Okay but not talking about a loose axle nut, just the theory of having a bearing loaded to 258ft lbs being reduced to 170 ft lbs. I will just torque mid-way. Still within spec, less concern about having such a large pressure change on the bearings.

 

Original factory torque was set to 300 Nm, later reduced I believe to 230 Nm but information on that was vague at some point. I just do a happy medium when I torque mine to 270 Nm.
Early model years halfshafts required stake nut, later to be redesigned with a crown nut at the wheel bearing torque point. My Timken bearings lasted 160 000 miles on 270 Nm specification .

 

That is correct, changed due to premature bearing failure. My wrench only goes to 210nm so i do that and about 5 degrees more and call it done.

 

When I did the second one a few months later I found the revised spec. I loosened, re-torqued the old one and re-staked. I recall torquing to 170 though.

From Disco3.CO.UK (2010)

Straight from TOPIX (GTR replacement):

3. Install a new halfshaft retaining nut and lightly tighten.

4. Make sure the brake disc and hub mating surfaces are clean.

5. Install the brake disc.
•Tighten the Torx screw to 35 Nm (26 lb.ft).

6. Secure the brake caliper anchor plate to the wheel knuckle.
•Tighten the bolts to 275 Nm (203 lb.ft).
•Align the wheel speed sensor.

7. Install the wheel speed sensor retaining bolt.

8. Secure the brake hose retaining bracket to the wheel knuckle.
•Tighten the bolt to 22 Nm (16 lb.ft).

9. Tighten the new halfshaft retaining nut to 230 Nm (169 lb.ft).
•Stake the nut to the halfshaft.

 

Wouldn't you know it just a few weeks after reading this thread, I needed to change the front bearings on my wifes' LR3. No problem, I have done this kind of thing before. Well the old "while I am in there" bug bit hard and I did a full brake job because ..... well because. As I was installing the hubs, I remembered this thread and rather than hunt for the service manual to get the torque specs, I cheated and just reviewed the info here during installation. The only hang up was I could not find my 12 point socket that fits the brake caliper cradle. I know I had it when I took those things off. I broke down and bought a single 12 point socket for Menards when I was getting some material for a house project. The torque on those mounts is stupid tight and the cheap socket held up just fine.


SO THANKS GUYS -you made a small job just a little bit easier.

Jeff

 

I wouldn’t “split the difference” or back it off arbitrarily—axle nut torque is critical because it sets the correct preload on the Ball Screw Support bearings, and running the wrong preload can cause premature wear or failure; if the revised spec is indeed lower (around 250 Nm / ~184 ft-lb depending on the application), then it’s best to follow the correct updated spec rather than what it was previously tightened to, and re-torque properly rather than just loosening it slightly, because bearings don’t “remember” the old load in a way that makes this risky, but incorrect preload absolutely can cause issues over time, so stick with the manufacturer’s latest spec for proper ceramic ball bearings life and performance.

 

From memory it is 230nm.