I swapped the tires from my 73 F350 to my 73 F250 and vise versa. The left rear on the F350 had left handed threads, can anyone explain why? Of course I didnt notice this till after an hour and a half of trying to get them off and applying heat to them then saw a small L stamped in the center of the stud under the paint. The rear axle is a HD Dana 70 and is stock. Is that normal for these trucks? Sure glad I just got an impact wrench for xmas otherwise I would have no arms left.

 

I know Mopar used left-hand lugs on right wheels back in the 60's (and maybe other decades?). Strange, for sure. I don't think there's really much of a reason.

 

I believe this practice is GVWR dependent, at least in Fords case, the idea was to keep the lug nuts from coming loose, left hand threaded lug nuts on the drivers side would work with the centrifugal force of the rotating wheel, therefore keeping the lug nuts tight, at least in theory anyway (this was generally done on both front and rear drivers side wheels).

 

Ok thanks for that info. I would of never thought of that but stranger things have happened.

 

Most medium and heavy-duty trucks also have left-hand threads on one side. As you found out, always look for the 'L' on the stud. Many older (pre-70s) pick-ups, trucks, and even cars had them as well.

From Wikipedia:

Some cars made prior to about 1960 used left-hand and right-hand screw thread for different sides of the vehicle to prevent loosening. It was later realized that the taper seat performed the same function. Modern vehicles use right-hand threads on all wheels.

 

I learned that same lesson not long ago myself.

 

I have had a couple of them and thats normal for the 1 ton 79 and down. I think they changed that in the 80's

 

My 78 F350 1 ton dually 10,000 gvw dana 70 built in Oakville, Ontario,CDA in sept 78 is right hand thread. Have had a 75, 78, 84, 90 F350 dually cube vans and 72, 75, 78 conventional chassis F350's and can't seem to recall ever having left hand thread but sure do remember splitting rims, backs still sore.

 

1967/83 F350 rear wheels have right/left specific studs and nuts. SRW's use different lug nuts than DRW's.

No Ford Passenger Car had left hand thread lug nuts/studs.

 

My F350 was built/sold as a cab and chassis so maybe that had something to do with it.

 

Doesn't make a dang bit of difference if it's a: Cab & Chassis, Styleside or Flareside pickup, Stake or Flat Bed, or whatever. If it's an F350, it has right/left specific rear wheel studs and nuts.

Post 8: Member has forgotten, is actually referring to front wheels, as no 1967/83 F350 rear wheels have right hand only studs/nuts.

 

My 1974 F350 is a dual rear wheel cab & chassis, and it does have L hand threads on the LR brake drum. However the LF rotor does not. That said, I bought the truck in 1988, so its possible that the rotor may have been changed before I bought the truck.
Back in 1975, I owned a 273 4 barrel 4 speed 65 Plymouth Valiant. That is when I discovered that Chrysler products used left hand threads on their vehicles in the 60`s. It came to as soon as I snapped off the 3rd wheel stud........

 

my 78 f250 dana 60 rear has 9/16 left hand studs on driverside and smaller studs on front dana 44 so you need to keep 2 lugwrenchs in the truck to change a tire. my 83 f350 has 9/16 studs all the way around with lefthand on drivers rear.