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What is the recommended lug nut torque

Thanks

Jack,

For your '48 3100 with original 7/16" x 20 studs and steel wheels, lug nut torque should be between 70-80 ft lbs. If you are using a wheel different than original steel style (like cast aluminum), you should confirm what that wheel manufacturer specs are and go by their requirements.

Hope this is helpful.

Dan

I have a 49 3100 6 lug 15" tires on steel wheels. My hand written maintenance notes say 50-60 ft lbs. Looked in my maintenance manuals but couldn't find the reference. I must have seen it somewhere but can't say where.

50-60 ft lbs seems pretty light. Everything I've seen has lug nuts around 90-100 ft lb, but a generic bolt torque chart [boltdepot.com] recommends about 55-60 ft lb on a 7/16 diameter bolt. I think the tapered seat on the lug nuts create more resistance, so a higher torque would logically be required to get the right bolt tension.

If someone has an era-specific owner's manual, it would likely be in that.

Did they even have torque specs back in those days? I realize they do now, but I always had the impression that back then you just cranked them as tight as you could, so they didn't come loose.

Thanks guys

I know 90 is too much because that’s when it broke

Torquing last of all 4 wheels

Looks like a clean break

Factory wheels

I’m going to go with 75

I checked the owners manual for my ‘52 and could not find it listed anywhere. I believe I went with 70-75.

Yeah, that torque them down till they break and back off a half turn method doesn't really work very well.
I'd say 75 ft lb would probably be fine.

Interesting that the owner's manual doesn't have anything.

Nor does the FSM.

The way I deal with situations like this is to tighten the nuts with the lug wrench that came with the vehicle instead of using an impact driver or air gun. It's nearly impossible to over-tighten lug nuts using the tire iron manually unless you're Arnold Swarzeneger.

After all, what farmer in 1950 was riding around with a torque wrench in his truck? He tightened the nuts as tight as he could by hand with the tool provided.

Anyone that uses an impact wrench to install lug nuts needs to be drawn and quartered.

Guess I'm in trouble!!
For 40 plus years I've used 90 psi with my air wrench on all cars/trucks, from Volkswagen to 4 wheel drives, of normal size and never had a problem. Maybe a couple studs.
Also, at 90 psi, my young daughters could break the lug nuts loose.
Yes, bigger trucks get more attention.

I laugh at places like Walmart who has psi set so high they know the torque wtench will click.
When I delivered parts commercially for Advance Auto I delivered most all studs and lug nuts to the same place.

Just my .02 worth.

I agree with Kevin and Otto, I always hand tighten to final torque whatever that may be?
Also make sure the threads and nut faces are lubed. I know the race car pit crew have their impacts calibrated to a certain air pressure and torque.
But that don't apply to us. Yes spin them on with a impact till they touch, then either hand tighten or use a torque wrench to the final torque.
Never hammer down with a impact because you really don't know what torque it is at!

Don

According to the '54 SHOP MANUAL, torque for lug nuts should be 50-60 ft lbs on 1/2, 3/4, and 1 ton; 250-275 ft lbs for 1 1/2 and 2 ton using a self-locking nut that requires this high torque. Don't know if the other shop manuals are close to the same as the '54 but it's on pg 10-9 under fig 21.

S2

Thanks, Stewart

Finally something definitive. There's nothing at all in the 48-51 shop manual. That should pertain to 47-55 3100's.
Interesting, I just looked at a 55 2nd series shop manual and it specifies 45-65 ft lb for 1/2 tons. That's on page 10-12. It specifies 65-90 ft lb for 3/4 ton and 1 ton, and 250--275 ft lb for 1-1/2 ton and 2 ton.

Sort of off subject but the shop manual for the 55.1 IS the 54. They just added section 7, pg 140 to cover the "Hotchkiss drive system" for the 1955 modified 3 speed transmission. So, 4 paragraphs.

S2

I agree!

On lugnuts just use the SAE torque chart. that is plenty. On modern stuff higher torque values contribute to ability of the whole vehicle to stand a crash. Even the fragile bumpers are made to wad up in a crash,so maybe you'll be able to hobble away !!

klhansen Remember when the tire shops would torque the lug nuts so tight you would bend the tin wrench that came with the vehicle along the road on a tire change ??