Mack drive hub axle studs pulling threads

[Art_H]

My '77 RS600 seems to be stripping the drive hub studs for the axles. Not sure why this is happening. The Mack dealerships solution was to drill and heli-coil for fine thread bolts.

Is this a common issue?

Maybe an actual gasket (vs only silicone) between the hub and the axle shaft would give a better friction surface and bite to resist movement?

Thanks

 

[kshansen]

The only time I have seen problems like this on our Macks is when someone removes axle cover and the studs come out with the nut then someone is too lazy to remove nuts and tries screwing them back on with an air wrench. Then the nut spins on the stud before the stud is all the way in and stud only gets a partial thread engagement which then fails. Same problem with wheel studs!

This assumes the guy assembling it does not go crazy with the silicone and lets it cure before he tightens the nuts.

 

[RZucker]

I agree with that about the studs coming out with the nuts. Myself, I will only use the proper gasket. Or Locktite gasket Eliminator on axle flanges. I consider silicone to be a lubricant in this application. And make sure the wheel bearings arent loose.

 

[oceanobob]

When I use a thin gasket with permatex in the little can with a brush, there is no leakage & no movement. When I use the other products such as silicon or whatever the stuff is, there are leaks which I blame on movement.

 

[Art_H]

All good info. Wheel bearings being key...

What Permatex in the can w/ brush?? There are a couple kinds.

The Locktite 515 looks like a good option and it even endorsed axle use.

Any thoughts on repairing the hubs with poor stud threads?? Some that were pulling out, I used JB weld, and they seem to be holding well.

 

[kshansen]

All good info. Wheel bearings being key...

What Permatex in the can w/ brush?? There are a couple kinds.

The Locktite 515 looks like a good option and it even endorsed axle use.

Any thoughts on repairing the hubs with poor stud threads?? Some that were pulling out, I used JB weld, and they seem to be holding well.

JB Weld is great stuff BUT I don't think it will hold up to this application. I would lean towards a properly installed Thread insert such as Heil-i -coils.

 

[Nige]

I wouldn't trust JB Weld in this application either - too much at stake if it fails. Bore hole well oversize and fit inserts which are then drilled & tapped afterwards, or Helicoil would be my suggestion. If you're looking at more than 2 studs per hub I'd also think about scrapping the hub and fitting a new one.

Also I'd be putting something on the studs at the time of first installation to try to ensure as far as possible they stay put when the nuts are removed.

 

[RZucker]

If theres enough metal around the holes I would use solid inserts with the locking keys.

 

[heymccall]

Are the split/ tapered "cones" still present? Does that rear call for them?