The Stovebolt Site Forums The Shop Area Engine Shop Spring U-Bolt Question

I am starting to reassemble my 54. I noticed in the assembly manual that there are not any lock washers at the u-bolts that attach the springs to the axle. I checked the TF assembly manual and it is the same as the AD setup. This does not seem right to me. But I also know GM had an excellent engineering staff. And they would not leave out the washers to save fifty cents on these trucks.

My question; is there an engineering reason why the washers should not be installed? Having the nuts just grind into the holes does not seem right to me.

Any thoughts from the engineering crowd?

The usual practice is hardened thick SAE washers, then tall nuts.
Occasionally with some blue thread locker, at least the u-bolts on a 2005 Freightliner suspension and rear axle I used on one of my trucks had loctite on them, and it was a new takeout, no miles.

I don't think I would use lock washers, as they can split and fall out, same reason you don't use them on rod bolts. Re tighten them after some driving a few times, then you should be good to go. Or get them really tight the first time with some thread locker.

I just tightened the ones on my 48 6400 a few days ago, I put neverseeze on them, as I will be taking them off in the future to add shock brackets, I don't expect them to loosen on their own though.

Grigg

Greg,

Thanks for the reply. I was thinking the same; that the locks could brake and cause a "problem". My new u-bolts did come with 8-hardened SAE washers. The assembly manual shows only 4-SAE washers; they are used as spacers between the lower shock mounts and the axle. With the 8 new washers and 4 old washers I have enough for the assembly.

I have driven thousands of miles in worn out old ADs and TFs and never had a problem with the axle coming loose. I did have the drag link come off the pitman arm at freeway speed in morning rush hour traffic once. That is a great story. It is amazing I lived through that "life moment".

In a lot of cases the nuts are not perfectly round in the thread bore and don't vibrate loose, I have also seen nuts that were punched on one face with a center punch to make them grip better to prevent them from vibrating loose.

They usually rust on solid after a month or two anyway.

Use a torque wrench to tighten them down. Don't guess it, you'll be suprised at how tight they need to be. Then the natural stretch of the bolt also keeps it from coming loose.
Scott

Thanks for the comments.