'67 half shaft u-bolt

[Leif A.]

Can someone please give me the size of this bolt. GM #3843384. Someone in the past failed to peen over the French lock. Something else to check while under the car.

[Gene M.]

Re: '67 half shaft u-bolt

7/16” fine thread

[Larry M.]

Re: '67 half shaft u-bolt

Agree.........but specifically 7/16 x 20-1-1/8 Grade 8. Paragon and others have them. You hardware store may have something as well, but the 1-1/8 length may be an issue unless you cut it........and Grade 8 is tough to cut.

Larry

[Leif A.]

Re: '67 half shaft u-bolt

Thank you gentlemen. They're all loose back there. 60-90 lb ft sound right?

[Gary J.]

Re: '67 half shaft u-bolt

Check the assembly manual it should have the torque values. I am not at home to check my chart.

[Larry M.]

Re: '67 half shaft u-bolt

Thank you gentlemen. They're all loose back there. 60-90 lb ft sound right?

Chevrolet Service Manual says 75 ft-lbs. Lightly oiled. A regular steel French Lock will begin to deform at torque below the spec. Use stainless steel French Locks ( a bit hard to find, but available) and/or a bit of never-seize just under the bolt head.

French Locks only go on one way/orientation to allow you to get a solid socket on the bolt head. Otherwise you will have difficulty. Check the others on your car for correct orientation, or correct orientation is is shown n Chevrolet Service Manual pictures.

Larry

[Richard G.]

Re: '67 half shaft u-bolt

Since they were all loose all the bolts are now suspect.
To be on the save side I would replace all of the them.
BTW; you can see the French Lock deformation in the direction of tightening the bolts. Just like Larry predicted.
This may not be a lock tab failure but an under torque situation.
After a Corvette is put back on the road, after servicing the axles, I recommend they be checked for torque after 50 miles.
Then bend the tabs over. SS tabs sound like a great idea.

Rick

[Leif A.]

Re: '67 half shaft u-bolt

Thank you everyone. Last evening I ordered 8 new bolts and 4 SS french locks from Paragon. I was going to ask about a touch of Loctite blue...thanks Larry.

[Richard G.]

Re: '67 half shaft u-bolt

For those that don't know, Loctite blue is the stuff for "service removable" items.
I think it's a great idea. Works better than the french locks.
Only down side it you will not be able to re-torque them.
But not much because they will not come loose.
Rick