WHEEL LUG NUT TORQUE

[PT81PlymouthPickup]

Anyone know what the correct lug bolt torque should be on the 1/2 ton pickups with original wheels? Most modern cars I believe are close to 100 foot pounds, but I'm thinking that's too much for our wheels?

[billrigsby]

 

Nothing in my Dodge manual, but....

Proper torque

[JBNeal]

On p.49 of the B-3-B owner's manual, it mentions that "wheel lock nuts should be tightened to a torque of 375 to 425 foot-pounds", with the same statement made in B-1 and B-2 manuals.  In my opinion, that is extraordinarily high for the lugs and suspect of some kind of information mixup that was never corrected.  The manuals have a list of specifications in the back that list air inflation pressures, but not lug torque.  So I fall back on what I was told by several old timers when I was a kid:  get as tight as possible with the 4-way lug wrench, since that might be the tool used to swap out the spare on the side of the road

[RobertKB]

1 hour ago, JBNeal said:

So I fall back on what I was told by several old timers when I was a kid:  get as tight as possible with the 4-way lug wrench, since that might be the tool used to swap out the spare on the side of the road

 

Great advice! That's all I ever do with the old rims. If you've ever tried to undo lug bolts or nuts that were tightened with an big impact wrench you will understand the old timers' advice!

 

New rims/wheels are different and should be torqued down and often retorqued a hundred miles later although I've never had an issue with retorquing.

[PT81PlymouthPickup]

1 hour ago, JBNeal said:

On p.49 of the B-3-B owner's manual, it mentions that "wheel lock nuts should be tightened to a torque of 375 to 425 foot-pounds", with the same statement made in B-1 and B-2 manuals.  In my opinion, that is extraordinarily high for the lugs and suspect of some kind of information mixup that was never corrected.  The manuals have a list of specifications in the back that list air inflation pressures, but not lug torque.  So I fall back on what I was told by several old timers when I was a kid:  get as tight as possible with the 4-way lug wrench, since that might be the tool used to swap out the spare on the side of the road

Yes, that's either a mix up or is referring to something other than lug nuts or bolts. I know that a 1/2-20 (which are what mine are) would strip the threads long before 375 foot pounds. I'm familiar with the old timer feel method, but thought it might be useful to have a torque number for those that might not be, or out of practice. What started me on this quest was that the feel method was failing me a bit. On my new modern rear wheels it was very positive and after checking with my torque wrench was about 85lbs. The original wheels which I am running on the front seemed like I could keep tightening almost like the steel in the wheel was flexing? After reading a bunch of stuff on threads and lug nuts etc. Lots of variables can affect torque, such as material, plating, lubrication, etc. I did put some never seize on the threads. I was hoping someone might have some torque numbers that would be useful for our original wheels.

[TodFitch]

The 1944 MoToR's Auto Repair Manual - Eighth Edition says the wheel lug bolts for 1935-42 Plymouths should be torqued to 58.5-66.5. Odd that they give an 8 ft-lb range with 0.1 accuracy on the end points. But basically I’d interpret that as 60 ft-lbs.

 

For a 1/2 ton truck of that same era that has very similar running gear to the car, I am guessing the values would be the same.

 

That said, like @JBNeal, I tighten mine with a four way lug wrench and not a torque wrench. First, just snug when on the jack. Then final after the wheel is on the ground. I do a star pattern on the tightening as my father taught me but can’t say that it is necessary. I also marked the socket on the wrench that I actually use on my car with some tape which makes is faster for me to pick it up and put the correct one on the wheel bolts.

 

Side question: Back in my engineering classes we used “foot pound” when talking about torque. At least that is what I remember. Nowadays people seem to say “pound foot”. Multiplication is order independent so the result is the same, but I wonder when and why the popular nomenclature for torque changed. Anyone know? Or is my memory totally bonkers and “pound foot” always been used.

 

p.s. Just checked some of the old manuals. The 1936-42 Plymouth factory service manual just says "pounds". The 1946-48 Plymouth factory service manual says “ft. lbs.” So my memory is not totally bonkers.

[Plymouthy Adams]

my old Motors manual uses pound/ft. specifying the "X" value....but in general most all folks just say ft. lbs.....it is not something that trips the average torque wrench user up for sure.   I still default 1/2-20 to 85....never lost a wheel yet, never broke a stud...still mount wheels with a 4 way.....but always use my torque wrench....if along the road...first order of business at home...get the spare off and the right wheel back on....then torque proper. Along the road even at 1/2 grunt is enough....

[JBNeal]

I looked in the B-3-J/K owner's manual and it has the same paragraph for dual wheels as the much smaller trucks, so I'm guessing that paragraph is more accurate for the larger trucks.

 

Looked at my better 4-way wrenches, and they measured 18" across.  Doing a rough calculation, if 200# was applied to the 4-way, the resulting torque would be 150 ft-lb.  Older 4-ways usually measure shorter across, resulting in less applied torque.  This falls in line with the other documented values cited. 

 

From what I recall from one of my elder engineering professors, foot-pound was used predominantly before the advent of the metric system, where torque is measured in Newton-meters.  Doing a simple conversion to English units yields pound-feet.  Either usage is correct as they derived from the same equation, but foot-pound can be thought of as the older or American presentation

Edited April 11, 2021 by JBNeal
added words that fell off of the page

[kencombs]

11 minutes ago, JBNeal said:

I looked in the B-3-J/K owner's manual and it has the same paragraph for dual wheels as the much smaller trucks, so I'm guessing that paragraph is more accurate for the larger trucks.

 

 

First thing I thought when I saw that 375ftlbs was duals for 8.25/20 tires.  That is pretty normal for Bud types.  Someone somewhere probably wrote a truck manual and that page go copied into smaller versions.

 

Here is an interesting truck lug chart for anyone who's interested.

https://cbsparts.ca/admin/bulletins/Tech Spec Rec Nut Torque.pdf

Note the 8hole Chrsyler line

Edited April 11, 2021 by kencombs

[Plymouthy Adams]

that is a truck chart.....not so much a pick up truck chart where 1/2-20 was the morn....I do have a truck here with 9/16 60 degree studs....and I do go 125 ft. lb. looks like I should up it a bit to at min 135

[Los_Control]

I see true torque specs as very important for critical components ... Heads, internal engine parts rods,crank etc...

Born in the 60's, working in the industry in the 70's. Wheel torque was never discussed ... I think it was the 80's before wheel torque was discussed in my memory ...  ?

 

It was the mid to late 70's after the gas shortage that people started buying import cars, then by the 80's realized the cheaper thinner brake rotors would warp if not torque properly. Then proper wheel torque became a major topic .... shops had to start replacing rotors if they over torque a wheel & warp it.

 

100# torque sounds just about max for a rattle gun in good condition. I do not think it is to high, except if you are on the side of the road changing a flat with no cheater bar.

100# would not damage your wheels or your drums if in good condition .... most rattle guns have a zillion miles on them and only reach 80# before replaced.

 

Into the 1990's, the tire shop we used a 1" impact gun with a 3/4" air hose just for it. For semi trucks. Get them girls on tight!

There was no discussion on proper wheel torque for a 1990 peterbuilt.

 

My only point is, any vehicle built in the 50's maybe 60's & earlier, the wheel torque was "TIGHT"

Was the cheaper off shore parts from the 70's + that we started thinking about wheel torque.

That applies to American cars, the British & other offshore cars were not common at the time and follow there own rules  <--- @Plymouthy Adams

 

Edited April 11, 2021 by Los_Control

[Plymouthy Adams]

we started paying attention to wheel nut torque with the impact disc brakes were making on the market....of course those shops that did not care about their customers and their cars continued the heavy handed gorilla tactics they knew oh so well.....Most British and other foreign cars were so far ahead of America and disc brakes at the time....these rules were quickly adopted......these specs and patterns for work habit are for a reason....just not to tick off some slap happy so called mechanic...but for sure it did do that a lot also....they needed to fall by the side and lay in the ditch, not the car they working on....

[PT81PlymouthPickup]

A young fella I know whom works at the local Tires Plus shop tells me they are required to torque all wheels on cars to 90 to 100 ft. pounds. I assume that's a policy to prevent broken studs and stripped nuts and also more importantly to be certain they're not too loose. I'm sure these tire places have an occasional law suit? I remember my dad telling me one of the young mechanics who worked for him had spun the lug nuts all the way down by hand and then forgot to tighten them with the impact gun. The customer didn't get very far before the wheels almost came off the car. Luckily, she was an understanding sort. Mistakes occasionally happen even by good people. My dad told the young mechanic to never run the lugs down to the wheel by hand. Just start them and then finish with the impact gun. This way it's obvious that they are not tight. Once experienced with a 4 way wrench or an impact gun you can get a very good sense of proper tightness by feel and or sound of the gun. In the hands of the inexperienced bad things can happen.

 

On my 39 Plymouth my feel is telling me that my new rear wheels are good at 85lbs, but the original front wheels feel tight at around 65lbs. Thought this a bit strange.

[Los_Control]

I agree with everything you say there .... Back when these American cars or trucks were being used as daily driver they were so over built that wheel torque was a non issue.

 

While in the early days the 30's - 60's the Jaguar, Mercedes, Porsche,  There is many others but they built things one way.

They won many races because of their design.

 

Here in USA, we overbuilt everything. We made sure a brake drum would not warp from being tight, it would last longer then expected useful life.

It could be turned and re-used.  Same thing with every aspect of the car. Heavy & overbuilt. ..... A modern car is way safer then a old 50's car.

 

Again my point is, on a older 50's American  vehicle I would not be concerned about wheel torque.

I would be interested more in the pinion bearing, the axle bearings .... A lot bigger fish to fry then the wheels.

For over 40 years we have been told about wheel torque ... it just never applied at the time to cars born on this side of the pond.

 

Just now, PT81PlymouthPickup said:

On my 39 Plymouth my feel is telling me that my new rear wheels are good at 85lbs, but the original front wheels feel tight at around 65lbs. Thought this a bit strange

I have to agree 

[TooManyIrons]

In the past I owned a couple of M35 2.5 6x6 trucks and the spec for the lug nut torque was 400 ft-lbs.  I have been using the same lug nut wrench and impact socket from my M35 trucks on my 1939 TF-37, so while I have not looked up the torque specs for the Dodge, I would not be surprised if they were to be in the 375 - 425 ft-lbs range.

[kencombs]

I agree with most of what’s been mentioned.  One exception is max torque with an impact.   My ingersol composite 1/2” will do lots more than 100.  Lots more.

I’ve broken 1/2” grade 8 studs testing it out. Even my 3/8 will exceed 100. 
 

interesting thing in the truck chart is the wide swing in specs with the same size studs.   Nut type, seat type and center register type seem to be the biggest influence.  Well, that and truck load expected.

 

my local Walmart seems to be the best of all the local tire guys at wheell install.  They hand start, run them down lightly with a gun, torque, then drive a figure 8 around the back lot.  After that the torque is rechecked by the supervisor. Walmart of all people!!

[1949 Wraith]

Back 70-80 years ago cars and I imagine cars and 1\2 ton trucks had bias ply tires and tubes that probably failed fairly often. Hence the use of the spare tire, no one is going to release highly torqued lug nuts on the side of the road with the common straight or star lug wrench of the time. I doubt local garages of the time just used a grunt when tightening rims .Probably around 80ft lbs? I know I never used a torque wrench when I was young.

 

Anyway nothing to worry about with our Chrysler products, as left wheel lugs have reverse treads tightening when we drive?

[Plymouthy Adams]

10 minutes ago, 1949 Wraith said:

 

 

Anyway nothing to worry about with our Chrysler products, as left wheel lugs have reverse treads tightening when we drive?

 

 

and yet, the modern car with the absence of this feature continues to defy this mystical force....?

[TodFitch]

30 minutes ago, Plymouthy Adams said:

and yet, the modern car with the absence of this feature continues to defy this mystical force....?

 

As does my '33 Plymouth which came from the factory with only right hand threaded wheel lug bolts. When I first got my car I knew that Chrysler products had left handed wheel studs/bolts on the one side. I nearly split a gut trying to get the bolts loose on the one side, fortunately using hand tools so I didn't ruin the hubs.

 

For reasons way beyond my understanding, the 1931 Plymouth had left-hand threaded studs on one side of the car. They stopped using left handed fasteners for that by 1933 then started doing it again in 1940. Why the on again, off again approach to this?

 

Nearly busted a gut again when I acquired a '63 D200 pickup truck. Someone had swapped the drums from side to side and I didn't look closely at the end of the studs to see the "L" marking. Just assumed the drums were on the correct side and boy they did not want to come off regardless of how much force I tried applying.

[Plymouthy Adams]

I also have seen these items swapped side to side...I have seen where folks have done upgrades to many B-body 8 3/4 axles to have right hand on all corners (I did the same as my compilation had right hand thread front rotors...) when messing with the old and used and handed down...nothing is written in stone....a buddy, husky guy, swore he wrong them water pump bolts off just using his hand.....I feel he forgot to mention the grunting.....man came into the shop one day wanting a piece of 3/4 flat bar cut....Oz said hand me that, I can bite that in half.....

[PT81PlymouthPickup]

Never having worked on anything bigger than a 3/4 ton pickup truck and after reading through all the comments, I'm curious as how one achieves tightening nuts and bolts on heavy duty trucks? I can't believe a human with a wrench could exert 300-400 lbs with a wrench unless it was 10 ft. long? I'm guessing heavy duty impact wrenches?

[kencombs]

3 hours ago, PT81PlymouthPickup said:

Never having worked on anything bigger than a 3/4 ton pickup truck and after reading through all the comments, I'm curious as how one achieves tightening nuts and bolts on heavy duty trucks? I can't believe a human with a wrench could exert 300-400 lbs with a wrench unless it was 10 ft. long? I'm guessing heavy duty impact wrenches?

It’s not as hard as it sounds. 3/4” drive breaker bar is normally at least 24” long, some even longer.  So, 200 lb guy on the end is 400 ftlbs.  

[John-T-53]

1/2"-20 = 55-60 ft-lbs, w/ greased threads.

 

Fine threads require less torque than coarse thread to achieve the same clamping pressure. 

[PT81PlymouthPickup]

3 hours ago, kencombs said:

It’s not as hard as it sounds. 3/4” drive breaker bar is normally at least 24” long, some even longer.  So, 200 lb guy on the end is 400 ftlbs.  

Sounds hard to me!  Lols! ?  I only weigh 180 lbs

[kencombs]

41 minutes ago, PT81PlymouthPickup said:

Sounds hard to me!  Lols! ?  I only weigh 180 lbs

Just use a 3' bar or a cheater on a shorter one.  3' at 180 gets you to 540ftlbs.