Mystery wheels

[Glen Plumridge]

Slowly stripping LP2A hull number 4425 and gradually getting parts and supplies together.
Only have the diff assembly to remove from the hull before I can get it sand blasted and get paint on the internal section.

Most parts have come off fairly easy and look like they will free up with a little work and lubrication.

Used the, weld a nut to the stud method to remove sheared off bolts and that worked well for the most part. Some impact after the weld cooled also helped the more stubborn ones.
Only have one threaded lug that was not recoverable.

First engine ended up being only good for parts as one of the cylinders was too far gone to re bore and putting in a sleeve is a last resort, so back on the hunt for an engine to rebuild.
It was only cheap so I got a heap of spare internals from it anyway.
The gearbox has freed up OK so might have a win with that one.

Tried a few methods of unseizing some of the worst track sections.
Soaked in citric acid solution. not much changed
Heavy hammering and flexing. not much changed
Sat the track section on a low temp fire and then worked over it with hammer once cool. This got all of the seized links moving and allowed the pins to be punched out. Pins were heavily pitted.


Found a place with 7/16" 4140 round bar so there will be new track pins if the trend continues of finding poor condition ones in the tracks so far.

Were pins hardened to a known rockwell number?


Getting some paint organised so I can protect items once they are reconditioned.

[David Herbert]

Originally Posted by Glen Plumridge

Sat the track section on a low temp fire and then worked over it with hammer once cool. This got all of the seized links moving and allowed the pins to be punched out.

Glen,
The trouble with doing this is that it is likely to make the material of the links very brittle. That does depend on what they are made of and I do not know the metallurgy of LP track but most tank/carrier track that I have worked with is fit for display only if it has been heated. If you break a track at speed you nave absolutely no control of what happens next.

A much better way is to submerge it in a bath of molasses for a few weeks. As this is a very slow process it will gradually eat the rust from inside the hinge joints in a way that a faster chemical process won't. It will do no harm at all and is cheap if smelly. A plastic 'wheelie' type garbage bin is ideal as a tank as you can get a reasonable length in and it has a lid to keep the smell in and vermin out. There are various threads about this on the forum.

David

[Lynn Eades]

David, does M.C.I., B.S.S.309 mean anything to you?
Is it Malleable Iron ? That is a spec for British track links from Feb.1944.
They tried all kinds of brews with Nickel etc in the early days, but settled on a std brew, I imagine the Australian link was made of a similar brew.
I can't locate any info on the pin, but recall it was heat treated?

[Glen Plumridge]

I think of it this way, if track links were pure cast iron, then they would be brittle in it's normal state either hot or cold.

"Malleable cast iron" means it has had heat treatment up over 900 C to change the grain structure.

In my opinion as a welder / metal worker, heating up to around 200 C would have minimal, if any affect on the grain structure. Especially if they are cooled gradually and not quenched.

If you were to get them glowing red hot and then dump them into a tub of water then yes, problem.

The temp of the fire was around the same as if you were cooking on a cast iron pan. That sort of temperature doesn't make the pure cast iron pans brittle so I don't think the effect on track links is as bad as might be thought.

Having said that, I do accept that there is potential for a problem to arise if the metallurgy is not what we expect and will try the chemical options for a bit of a longer period to loosen links in future.