Jeep project underway

[Mike K]

Made a start on the jeep spring pivot bolts. I can buy these from RFJP but the postage is high and I would prefer to learn some new skills.

This is a learning project for me, it involves turning, thread cutting, the use of a dividing head and thread tapping for the zerk grease fitting. I chose 4140 chrome moly alloy because it's a strong material, is easy to obtain and is relatively easy to machine in the tempered state .

First step is: turning the stock down to 9/16" ( .5625") and threading the ends to the correct N.F. thread pitch. I prefer the old HSS type single point tools that you grind to shape yourself on a bench grinder . The modern carbide insert tools, well, there are endless types and it is a never ending process finding the correct type to suit .

[Mike K]

I managed to do the threads on the pivot bolts. Single point thread cutting on a lathe is a somewhat meticulous job . If you lose concentration for half a second, the process usually ends in horrible mess.

Wrap the work piece in a piece of cut up Alu drink can and the chuck jaws will not mark the work piece !

[Philliphastings]

Hi Mike K,

Just curious how do you go about broaching the interference fit neck of the pivot bolts.

I have a good grasp of the more basic machining but broaching in such an inaccessable spot must be very tricky ?

Cheers

Phill

[Mike K]

Originally Posted by Philliphastings

Hi Mike K,

Just curious how do you go about broaching the interference fit neck of the pivot bolts.

I have a good grasp of the more basic machining but broaching in such an inaccessable spot must be very tricky ?

Cheers

Phill

Hi Phil

The short splined section of the bolt that is located right up against the bolt head . I believe they designed the bolt like that in order to prevent the bolt from turning in the chassis hanger, in others words, to lock the bolt in place . The splines bite into the chassis hanger hole as you tighten up the nut and draw the head up against the hanger.

I don't like the method myself, it is actually a bit of a bodge . Problem is: The splines really make a mess of the reamed hole. If you have to remove the bolt a few times , the hole ends up being torn and messed up. The hangers are only made from 1/4" plate which is a design flaw.

Not easy to replicate that splined section in a hobby workshop, you could knurl the area which will create a raised pattern. I am not off roading this jeep , it will be OK to leave the bolt head as a plain finish.

If I did buy new bolts from RFJP, I would have machined off the splines before fitting his pivot bolts.

[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

[charlie fitton]

"I don't like the method myself, it is actually a bit of a bodge . Problem is: The splines really make a mess of the reamed hole. If you have to remove the bolt a few times , the hole ends up being torn and messed up. The hangers are only made from 1/4" plate which is a design flaw."

Might I suggest that you could weld a tab on to the Hanger plate to stop the Bolt from "working" and therefore restrict the wear to the bushings?

[Mike K]

Long term saga with the front springs .

My jeep came with the 1950s Aust. post-war made springs.

I later on found a couple of WW2 era front springs , in very bad shape.

Purchased 2 new front springs from a vendor here.

Ok the story:

Repro front springs look very little like the WW2 era springs: leaves are thicker, no bevel on the edge of the leaves, the clips look all wrong, the centre bolt is a joke , how people can sell junk like this !

Pulled apart the WW2 era springs. Hmmm some deep pitting is evident , sagging too and one main leaf end is bent badly. Wear is evident where the leaf ends move and dig into the next leaf.

So I made up a spring pack using the new repro main and 2nd leaves and the rest are the old original WW2 leaves . I had to re-arch the old leaves in my pipe bender. Had to bevel the edges of the repro main and 2nd leaves .

Now make new Willys style spring clips..... the originals are .110" gauge . All I can find here is 3mm flat bar, but it is the correct width .
Lots of filing cutting . Had to make a die to press the dot into the clips and heat up up the metal cherry red .

Very hard to get a tight radius on the 3mm bar ,so my old trick, you cut half way through and bend, then weld and file the radius ...do this 24 times for 2 springs

Also had to machine up new centre bolts , out of good steel, not the plastic stuff the repro bolts are made from. The bolt head needs to be a good fit in the spring saddle .... which is usually worn to a oval shape.

Been working on these springs for over 2 years ..... not finished yet.

I have become rather fed up with the poorly made and expensive repro parts ..I now make my own parts when it is feasible to do so.

[Mike K]

Is there anybody out there who is considering buying a new Chinese cast L134 engine block ?

https://www.youtube.com/watch?v=d9yfaRZ0nSw

Metalshaper is the guy who knows his vintage jeeps.

I read a report on these Chinese blocks , the valve guide bores are out of alignment, the bores are not perpendicular to the camshaft, that would explain why the valve stems and guides are very worn after only 3k miles of use. .