Jeep project underway

[Mike K]

I managed to almost finish the pivot bolts. I don't have a U.S. standard NPT 1/8 tap for the zerk grease fittings so I used a 1/8 BSP tap - I will lose points at the concourse but I will say its a field fix 1/8 BSP zerk fittings are available at most auto shops here.

The dividing head I made myself to Harold Hall's design. Harold has had many books published and he is the doyen of the hobby engineering scene , he must be getting close to 90 these days .

I have a 48 tooth gear on the dividing head. To machine the bolt head flats you divide 48 by 6 = 8 notches for each flat.

[Lynn Eades]

Mike, without the pin locking in the hanger, the pin movement will occur between the hangers and the pins. This will happen rapidly because the surface area is relatively small. Not only that, but the fix is difficult because your hangers are riveted to the chassis.
The whole idea is for the movement and wear to occur between the shackle pin and the spring bush which is set up for greasing at that point. Also the bushes are an easy replacement along with the pins.

Note that the nuts for the shacle pins are castleated so as to be located by a split pin. This leaves some free movement at the ends of the bushes relative to the hangers. This helps to prevent spring breakage.
Maybe you could try an interfearance taper and step at the pin head? Just a thought.......

[Mike K]

Hi Lynn

The original design is flawed. With the original setup in good condition , the bolts will rotate after a very short period of use. The rotating happens because the bolt splines damage/enlarge the reamed holes , this hole damage begins the process of the elongation of the holes, and it becomes worse as time goes on. A much better method of preventing the bolt from turning is what the Dodge WC vehicles have, that is, a protruding flat section on the outside face of the hanger, the protruding face locks one of the bolt head hex faces in place.

As for floating bushes, the problem with that is, if there is any amount of wear in the bushes or bolts , a yawing or sideways movement of the whole front axle will occur. The yawing action will actually add to the elongation of the holes in the spring hangers. At the other end of the springs, the threaded U shaped shackles don't have enough rigidity to hold the axles in the correct aligned position , those shackles have some wobble , even when new. I am not a automotive engineer , these are my theories .. my theories might be wrong but on the practical side of things, I've seen more than one WW2 Jeep chassis in otherwise excellent condition, with badly elongated spring hanger holes

[Mike K]

This is a good instructional video on how NOT to install your jeep pivot bolts The bushing is loose in the spring eye for a start . And those spring washers

You can see the hanger hole is too large for the bolt anyway

https://www.youtube.com/watch?v=A70wHVerz2k

[Mike Cecil]

Yep, pretty dodgy method in that video, Mike. I suppose, given the limited service life span that the GPW and MB were designed for, the method of preventing the pivot bolts from rotating was cheap, easily installed and sufficiently robust, so 'good enough' in the circumstances. I doubt the designers envisaged that MB and GPWs would be still employed by armies well into the 1960s, or that civilians would be trying to rebuild them nearly 80 years later.

There are possibly plenty of improvements that could be made to various parts of a jeep to make it more robust and longer-lasting. The chassis came in for some officially-promulgated strengthening while in service by the addition of 'T' pieces at the rear, and the steering bell-crank received an added web, for example.

Nice job on the bolts: very skillful.

Mike

[Lynn Eades]

Unfortunately Mike and Mike, there are lots of "how to" You tube clips that demonstrate less than "best practice" info. I guess if the bush was longer and was locked in the hanger and you didn't mind wearing the spring eye that would do? (except that no grease gets to the right place)
I note that my replacement bolts have an 1/8th gas thread in them (and it appears) like the one in the You tube clip. He has used an NPT zerk. (very loose)
His use of the spring washer, is to fill the gap, other wise the nut floats around under the split pin. I used a flat washer.
All in all, that clip fails at all points. As you say, "How not to".

[Mike K]

The Ford factory drawing of the jeep spring hanger: the inside width dimension should be a few thou under 1.7" . After measuring the repro hangers I have, I discovered they were wider by quite a margin. I managed to press the sides inwards to the cortect width using a hydraulic jack.