Locking nuts on main bearing

[katy]

Anyone using locking nuts on main bearings? I had the pan off to work on the rear main and decided to use locking nuts instead of struggling w/installing cotter pins after getting the 80 ft-lbs set. I used the all metal nuts, not nylock type. Similar to this.

[Flathead]

Locking nuts will affect your torque values. You can use plain nuts with no lock washers, cotter pins or lock nuts. I use grade 8 nuts and never had a problem. You can use plain nuts on the rods too. The plain nuts are also stronger as they don't have notches for the cotter pins.

[nkaminar]

If you want to use the metal locking nuts, measure the torque before they start to tighten the bearings and add this to the required torque.

[katy]

Originally Posted by nkaminar

If you want to use the metal locking nuts, measure the torque before they start to tighten the bearings and add this to the required torque.

I'll try that, if and when there is a "next time". It's back together now and running w/o the previous oil leak. IIRC there wasn't a lot of extra drag on the nuts before they seated.
I'll try a bench test on a new nut to see how much drag there is.

[katy]

Originally Posted by Flathead

Locking nuts will affect your torque values. You can use plain nuts with no lock washers, cotter pins or lock nuts. I use grade 8 nuts and never had a problem. You can use plain nuts on the rods too. The plain nuts are also stronger as they don't have notches for the cotter pins.

Interesting, never heard of that before.
For now I'll stick w/the self locking type as I had to buy a pack of 25.

[J Franklin]

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I have used that type of locking nuts on the connecting rods in one engine and all seems to have stayed together.

[BRENT in 10-uh-C]

Originally Posted by katy

Interesting, never heard of that before.
For now I'll stick w/the self locking type as I had to buy a pack of 25.

While it is likely true due to the crimping design of the nut, ...to your point, where did Ford's Engineering Dept specify what those torque specs should be? So if Ford didn't specify a torque spec, then does that torque spec really matter when using a locking nut?

[nkaminar]

Ford used wrenches of different handle lengths for different applications. That was their torque wench. A man can only pull so much and a wrench with a longer handle means more torque applied to the nuts or bolts.

All modern car manufacturers specify torque values for most of the fasteners. The clamping force that resists load is due to the stretch in the fasteners. The stretch is due to having the proper torque.

[Richard Knight]

I used 100s of flex-loc all steel re usable locking nuts. Mains and rods, As, Bs, and V8s. A mains 75 ft.lb. Rods 40 ft.lb. no problem and always the correct torque.

[updraught]

As far as i can work out, torque wrench specs didn't come out till WW2.

[katy]

FWIW, the turning torque of the nuts w/no actual load came out as 6 ft-lbs.
The 80 ft-lbs value came from the "red book".