USMC67300
New Member
Why did MOPAR and other car manufacturer's put left handed threads on the driver's side? I found this out when doing my front brakes last night on the 1967 300.
Reverse Threads on Driver's side, i know rookie mistake
- Thread starter USMC67300
- Start date
Chrysler (and other manufacturers) engineers were wrapped up with the theory of lugs nuts flying off the left side so left hand studs were used. When mag type wheels were becoming popular it was difficult to find left hand thread mag type lug nuts. I don't know for sure but I think the left hand threads were pretty much gone by 1973. My 1973 Challenger had front disc brakes and right hand threads on the left side of the car.
polara71
Old Man with a Hat
1970 was supposed to be the last year although I have had some early build 1971 Polaras with left hand threads.
Didn't Mopar offer front drum brakes up to 1972 and then went to front disc brakes on all 1973 models?
has2bmopar
Senior Member
I believe this was a heavy transition period, but I have seen '73 B-bodies with drum, and my '74 Power Wagon was still drum also.
As far as the left hand threads, '70 was supposed to be the last year, but I'm sure there was some spill over, like Dave has witnessed.
Forces encountered on countersunk lugs, especially when braking do tend to want to loosen lugs on the left/driver's side of a vehicle.
On passenger vehicles the safety factor was likely surpassed by the bitching factor of common (innocently mechanically inept) people that were first introduced to left hand threads on the side of the road with 2 broken studs aleady to their credit. The hub fitting the wheel opening properly is important to keep side loads off of the lugs.
Trucks however stayed left hand thread on the left side, regardless of make, until fairly recently when they changed to piloted style lugs, where there are no side forces on the lug nuts/bolts.
As far as the left hand threads, '70 was supposed to be the last year, but I'm sure there was some spill over, like Dave has witnessed.
Forces encountered on countersunk lugs, especially when braking do tend to want to loosen lugs on the left/driver's side of a vehicle.
On passenger vehicles the safety factor was likely surpassed by the bitching factor of common (innocently mechanically inept) people that were first introduced to left hand threads on the side of the road with 2 broken studs aleady to their credit. The hub fitting the wheel opening properly is important to keep side loads off of the lugs.
Trucks however stayed left hand thread on the left side, regardless of make, until fairly recently when they changed to piloted style lugs, where there are no side forces on the lug nuts/bolts.
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USMC67300
New Member
Thanks, I thought it did have something to do with the "nuts" backing off when operating. Luckily i didnt snap any, but two are tested to a couple hundred flb's
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Left Hand Studs
Chrysler Products and General Motors used Left hand
studs in the '60s... it made for a lot of errors in busting studs & ruining hubs, worse yet..... it was a dopey thing right from the start -- but back then car manufacturers were always looking for gimmicks, some which failed miserably.....
Put this one in that same pile -- fire those "engineers" -- oh, they're already passed on. Then give them R.I.P. ..............
s_dancing2:
Chrysler Products and General Motors used Left hand
studs in the '60s... it made for a lot of errors in busting studs & ruining hubs, worse yet..... it was a dopey thing right from the start -- but back then car manufacturers were always looking for gimmicks, some which failed miserably.....
Put this one in that same pile -- fire those "engineers" -- oh, they're already passed on. Then give them R.I.P. ..............
s_dancing2:
has2bmopar
Senior Member
You mean those dopey dead engineers that kept wheels from flying off of all makes of semi's and straight trucks for 80-90 years or so?
It is a shame, as there could have been so many more dead people to mock.
The only gimmick that I see that failed miserably is someone disrespecting engineers that used fact, not theory to save countless people from a violent end.
Here's an idea and something that well educated people do... Open a real book once in a while, and don't try to survive in the land of fiction.
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1966-300
New Member
Just so I am clear, as I have not yet removed the tires from my 1966 Chrysler 300. Am I to understanbd that on the drivers side they used LH thread lugs? I honestly had NO IDEA this was the case. Lefty Tighty, Righty Loosy? Is that the case for ALL? I have a shop manual and can find nowhere that it mentions this nice to know little tidbit.
azblackhemi
Old Man with a Hat
Yes if nobody changed it the left side studs will be left hand thread. You should be able to see a "L" stamped on the end of the stud.
My advice is if they are left hand threads convert them over to right hand threads while you got the wheels off. It's an inexpensive and easy conversion.
bluefury361
Old Man with a Hat
commando1
Old Man with a Hat
Always hated that term "righty tighty - lefty loosy" It changes depending from how you view the nut. Plus it makes one sound so girly man.
Left handed threads: Clockwise to loosen.
Right handed threads: COUNTER-clockwise to loosen....
This is Commando1 and I approve this rant.
Left handed threads: Clockwise to loosen.
Right handed threads: COUNTER-clockwise to loosen....
This is Commando1 and I approve this rant.
commando1
Old Man with a Hat
So you don't have to say "righty tighty - lefty loosy" in front of other men. :hehe:
All right hand threads...just my opinion.
polara71
Old Man with a Hat
They are there for a reason, if its not broken, leave it alone.
bluefury361
Old Man with a Hat
Uniquely Mopar .....
Although there were other auto manufacturers who used left hand thread lugs they are usually looked upon as a "old mopar thing".
Now and then when I need a tire mounted or something..... I get a big kick out of the look on face of the kid with the inpact when I tell him the left hand lugs are reverse thread.....! It's a "yeah....right" look of disbelief and then the amazed look when he figures out it's true.
But then it dosen't take a lot to entertain me
Although there were other auto manufacturers who used left hand thread lugs they are usually looked upon as a "old mopar thing".
Now and then when I need a tire mounted or something..... I get a big kick out of the look on face of the kid with the inpact when I tell him the left hand lugs are reverse thread.....! It's a "yeah....right" look of disbelief and then the amazed look when he figures out it's true.
But then it dosen't take a lot to entertain me
polara71
Old Man with a Hat
Apparently not........
70NPORT
Old Man with a Hat
oooh, boy.
commando1
Old Man with a Hat
or I can go to my local NAPA who happens to keep left hand nuts AND studs in stock...
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