What Torque value do you use for the front hub nuts

[Mike929]

I just pulled off my front hub to replace seals and repack everything including some new boots.

I am torquing everything to spec, and was putting on the 12 nuts and new lock washers that hold the spindle to the steering knuckle and ended up stripping one of the nuts and another feels like it is failing. All other torqued correctly.

The TM says that a 3/8 nut with 24 threads per inch should be torqued to 49 ft*lbs.

I am reading the torque value from the catch all page in the TM based on size. Am I mistaken on the torque or do I have a lot of fatigued nuts holding my front wheels on the truck.

I plan to go purchase new nuts for all the bolts, just want to make sure I am not making the problem by over torquing these 12 nuts.

Thanks for any advice,
Mike

 

[gringeltaube]

I always use new nuts, with plenty of loctite 242 on clean (!) studs and tighten to 35-38 ft-lb.

G.

 

[Mike929]

I always use new nuts, with plenty of loctite 242 on clean (!) studs and tighten to 35-38 ft-lb.

G.

Studs are clean, I pressure washed the entire knuckle before remounting on the front axle.

Do these nuts have a specific torque rating that I missed (i.e., do not use the generic torque value of 49 ft*lb listed in the TM), or is this based off of personal experience?


I know when I brought them up to 40 ft-lbs the nuts felt solid, so I am inclined to agree.

I did not use loctite, but did replace the lock washers with new SS lock washers.

 

[gringeltaube]

.....Do these nuts have a specific torque rating that I missed (i.e., do not use the generic torque value of 49 ft*lb listed in the TM), or is this based off of personal experience?..........

Its based on the quality of the nuts one can get.... , plus the fact that studs have seen use and abuse, in so many years, especially on older trucks.

Better to use high nuts + loctite instead of lockwashers, IMHO.

G.

 

[jasonjc]

Per TM 9-2320-361-24-1 dated Aug 2006 25-35 lb-ft.

I've had some of those nuts and studs strip on me too. Some where stripped when I took it apart. Just remember the military HAS to buy from the lowest bidder. They do not always get what they should.

And per the TM you must use lb-ft not ft-lb

 

[DieselBob]

Same spec in TM 9-2320-361-20, page 7-18 that jasonjc posted. I ordered new nuts and washers from McMaster-Carr. Dorman makes the exact replacement studs if needed.

"Install brake plate (13) and deflector (15) on spindle (1) and studs (14) of knuckle ( with twelve
new lockwashers (16) and nuts (17). Tighten nuts (17) 25-35 lb-ft (34-48 NŽm)."

 

[rlwm211]

I checked the older version of the manual. TM 9-2320-209-20-3--1.

The illustrations are the same and the proceedure is the same.
They do not specify a torque and instruct the following:
pg 804 step 4

Using 9/16-inch socket wrench, screw on 12 nuts and lockwashers (6) and​

tighten them evenly.

I would say that this suggests that the technician use their judgement as to how tight theyse should be. While I agree that using loctite is a good idea I would caution that a lot of torque wrenches are not all that accurate at the lower torque levels and a difference of 10% on such a small fastener could cause the stripping that has occurred.

Just my two cents

RL

 

[Mike929]

Dang, I looked through several TMs and missed any specific torque values after a considerable time searching. I found the catch all page of torques which gave me the torque specs that I used.

Thanks for the correction.

 

[rlwm211]

Hey, that's what we're here for!!!!!



RL

 

[Mike929]

And per the TM you must use lb-ft not ft-lb

Dang, I had my torques backward as well.

 

[rlwm211]

Oh, I just had to look this one up...

WHAT'S THE DIFFERENCE between foot-pounds and pound-feet?
Both consist of the same units-a force and a distance-multiplied together.
The physical quantities being expressed, however, are quite different

The product of a force times a distance, as in "pound-feet"
("Newton-meters," for those metrically inclined), is torque

Any physics text or engineering handbook will make the principle clear
and will define force times distancepounds times feet, or ounces times inches-as torque.

To "say it right," remember the universal standard convention that the force comes first; the distance second.

So, is "foot-pounds" meaningless, then? Not at all.
When the distance is named first, and the force second,
the product represents something equally real but quite different: work.

from Wikipedia:
Usage
The foot-pound is an obsolete term used particularly in the United States. The foot-pound is often used to specify the muzzle energy of a bullet in small armballistics, the tightness of a bolt and the output of an internal combustion engine.
The foot-pound can be expressed either as energy or torque. Although they are dimensionally equivalent, energy (a scalar), and torque (a vector) are distinct physical quantities.
Energy

When the foot-pound is expressed as an integral of force and displacement it arises from a dot product. Muzzle energy and the chemical energy released by liquid fuel in an internal combustion engine are examples of the dot product.
Torque

The "Foot-pound" is also the name of a unit of torque (see Pound-foot (torque)). Torque is product of a force vector with a displacement vector and is a cross product. The measurement of a torque wrench or engine torque are examples of the cross product.



Class dismissed.....

RL

 

[Mike929]

Okay, I have removed both hubs and replaced with all new hardware and torqued to 35 "Pound-foot" . While I was at it, I replaced both front brake lines. I had already replaced both brake cylinders, boots, all seals, and repacked everything.

I am one bearing away from completing the entire front axle. I had one race with a mark on it that would have eventually caused the bearing to wear prematurely, so I have a new one ordered that should be here Friday.

Everything else in the front hubs was spotless and barely used. The grease that was in the bearings from the military was new, and no water had ever been in the hub. (no rust on any exposed unpainted iron in cap, axles, etc.

I mainly took everything apart to replace the boots and inspect. Save for the one bearing race, it was all good.

Next stop, I get to replace the T-case with a new rebuilt one that I purchased. When I was changing the oil, I found some metal pieces from a bearing cage. I was going to rebuild my case, but a new one was actually cheaper.

Luckily, all the other fluids on this truck look great. No rust, no water, very little if any wear. After the T-case I should be ready for launch.

The only thing I haven't opened up are my rear hubs, but I plan on singling out my deuce this winter, which means flipping the hubs. I figure since outwardly they look like they have been recently serviced, I will re-grease and replace all the seals when I flip them and do a complete inspection to make sure everything is 100%. This will also let my funds regenerate a little, as all the new parts and new tools have put a dent in my mad money fund.