Frame / Springs: 1947 M5 rear spring bush removal.

[Aussie Hawk]

I was under my M5 yesterday checking out the next job, replacing all the rear spring bushes. Most seemed a pretty straight forward bolt removal, but the forward shackle point has a nut on the inside the cast boss that's riveted on to the chassis, but doesn't have a normal hex bolt head, it just seems to be a flat head about an inch in diameter. Has anyone pulled these off, I just want to start the job with a bit more knoweldge.

[garyash]

It's easier than it looks at first glance. The head of the bolt is serrated around the outer edge to keep it from turning and the interior of the spring hanger has mating teeth. Support the weight of the axle and spring with a sturdy jack. Squirt some penetrating oil on the head of the bolt and on the nut. From inside the frame, insert an 11/16 socket into the stamped hanger and loosen the 7/16-20 nut, but don't remove it completely. Adjust the jack to remove any up/down side-force on the bolt. Tap the nut to push the head of the bolt free. Then remove the nut and pull the bolt out. This is usually a job for two people in order to unload the axle/spring weight and drive the bolt out.

The parts catalog shows the nut as p/n 264-07, 7/16-18 in section 1519, but the Standard Parts index at the back of the M truck parts catalog shows this to be a 7/16-20 Marsden lock nut. These are castellated nuts with split facets that are locked by the contact of the castellated face against the frame, forcing the facets against the threads. I think these are normally used only once. If you can't find a new Marsden nut of the right size, replace the nut with a modern deformed-thread steel locknut. The Marsden nuts are normally free-running going on, then they tighten when they come up against a surface. That means that the split face goes on first and the smooth face goes to the outside. I suppose you could also use a Nylock-type nut if you are sure it won't move.

You can buy the Marsden nuts on line, like here: http://www.amkproducts.com/bulk2.asp...e=Marsden+Nuts

Be careful with the serrated-head bolt. I've never seen a new one.

[Aussie Hawk]

It's easier than it looks at first glance. The head of the bolt is serrated around the outer edge to keep it from turning and the interior of the spring hanger has mating teeth. Support the weight of the axle and spring with a sturdy jack. Squirt some penetrating oil on the head of the bolt and on the nut. From inside the frame, insert an 11/16 socket into the stamped hanger and loosen the 7/16-20 nut, but don't remove it completely. Adjust the jack to remove any up/down side-force on the bolt. Tap the nut to push the head of the bolt free. Then remove the nut and pull the bolt out. This is usually a job for two people in order to unload the axle/spring weight and drive the bolt out.

The parts catalog shows the nut as p/n 264-07, 7/16-18 in section 1519, but the Standard Parts index at the back of the M truck parts catalog shows this to be a 7/16-20 Marsden lock nut. These are castellated nuts with split facets that are locked by the contact of the castellated face against the frame, forcing the facets against the threads. I think these are normally used only once. If you can't find a new Marsden nut of the right size, replace the nut with a modern deformed-thread steel locknut. The Marsden nuts are normally free-running going on, then they tighten when they come up against a surface. That means that the split face goes on first and the smooth face goes to the outside. I suppose you could also use a Nylock-type nut if you are sure it won't move.

You can buy the Marsden nuts on line, like here: http://www.amkproducts.com/bulk2.asp...e=Marsden+Nuts

Be careful with the serrated-head bolt. I've never seen a new one.

Thanks Gary, you're a Champion, (no pun intended) ;-)