Sd.Kfz Rebuild

[Adrian Harris]

This is the old girl I picked up last week:

She has smoke and Benedini sound in the engine bay:

And the switch/fusebox wiring in the rear:

There was no motion pack but I'll be fitting Sabertooth and Syren speed controllers for the main drive and winch motors anyway, to save space.

Adrian.

[Adrian Harris]

I spent today stripping down one side and looking through the running gear. Quite a few of the push on hub caps are missing, so I'll have to write a program for my CNC lathe to generate new ones from aluminium. The original ones are steel and not quite the right shape, so I would want to replace them anyway. A couple of the axles had worked loose and the end caps were loose on a couple of wheels, which is why the whole thing seemed so slack.

I've removed all the road wheels and the idlers and have stripped the paint from them using Wickes generic paint stripper. This is an alternative to Nitromors and doesn't stink or strip the skin from your fingers

It seemed to strip the paint OK but took more effort to clean up than Nitromors, as the soapy water seems to leave a slimy sludge behind. A decent scrub with some green scouring mats in a bucket of water and the wheels and suspension arms have come up quite nicely. A quick once over with a wire brush and they'll be ready for primer and back on the chassis. Once this side is done, I'll flip her over and do the other side.

One thing I noticed is that one of the arms of the front wheel, where the bolt holds the hub to the rim, has broken through the mounting hole, so I'll need a new hub at least.

The other front wheel is currently on the opposite way round, so I haven't found out if this is OK or not yet.

I have noticed the tyre isn't on the rim properly, so it has a bit of a wobble when spinning - probably not enough to notice at the speed these models usually manoeuvre

Adrian.

[Paul Wills]

You've got your work cut out for there Adrian. I find it harder doing a rebuild than an out of the box kit. the wobbly tyre should sort its self out in a pan of boiling water I've still got one to do if I ever stop tinkering with the Tiger

Paul.

[Adrian Harris]

> I find it harder doing a rebuild than an out of the box kit

They are so much harder. I dread finding a frozen or broken bolt, or a stripped thread.

I've loved these half tracks since making squadrons of them from Airfix kits as a kid, so I couldn't pass up this one.

Adrian.

[Peter Silcock]

Adrian I think you will find cellulose paint thinners at £12 for 5 litres much cheaper quicker and easier for paint stripping. Paint will just wash off with a large paint brush. You can reuse a few times as well, but don't use it inside though- you won't be popular.

[Adrian Harris]

Thanks Peter. I've ordered a small bottle of thinners to see how I get on.

The wheels are mostly stripped, as are the hull sides and the rear box are on the way.

Adrian.

[Robert E Morey]

Great find Adrian, I'm sure with your make over and new CNC parts she will be a beauty once again. Would love to find one in the rough - but stripped and broken parts would be a worry. Looking forward to seeing it come to life again.
Bob

[Adrian Harris]

These old kits are a labour of love. I had decided not to buy any more pre-built kits as you never know what you will find but I couldn't resist one of these trucks.

> but stripped and broken parts would be a worry

I thought one of the front wheel hubs was broken and having broken them down and stripped the paint and filler off this turned out to be true:

The beauty with Armortek kits is that a quick email to Monique and I have prices for all the parts I might need.

And then there are the stunning aftermarket wheels from Michal, with Continental tyres and nice chunky hubs.

At the moment I'm torn between the two and can't make a decision as to which way to go.

Adrian.

[Adrian Harris]

Today I managed to get the hull frame stripped down to the basics but there are quite a few CSK bolts screwed into the rails with their hex heads rounded off

Also, two of the bolts which held the motor tray in place had lost their heads. One is flush with the frame, so will probably need to be drilled out. The other is standing proud so should come out with the application of some heat. I've left them all soaking in WD40 overnight.

I found another headless bolt in the rear stretcher but managed to get that out OK after some gentle heating with a MAPP torch.

I'll post some pictures tomorrow sometime, although it looks like being a family day !!

Adrian.

[Adrian Harris]

Finally managed to get the hull parts disassembled and into paint stripping.

Most of the CSK screws came out with some heat and the use of a left hand thread 4mm cobalt drill. I had to swap two of the phases on the inverter on my pillar drill to get it to go backwards for the LH drill bits. A bit of heat and some pressure on the drill and most of the screws came out intact.

Only one proved to be really tricky and I thought I might have to send it off to an EDM workshop to be burnt out. There looked to be an EasyOut or something similar stuck in the hex hole in the head of the screw and nothing would touch it - not even the cobalt drills I was using at the time. I was thinking I might have to send it to an EDM workshop to be burnt out but then I remembered a video on YouTube of someone freeing a stuck bolt by tapping it round with the aid of a centre punch.

With the sacrifice of one Dormer 2mm drill bit, I managed to make three small dimples in the head of the bolt:

These were enough for me to position a small centre punch and with a few smart taps I was able to get some movement. Having the three dimples meant I could drive it slowly round by using each in turn to land the punch. Once the head was proud of the hole, I could get some pliers on it and remove it completely.

Only the stub of the broken off screw mentioned in my previous message above wouldn't come free, so I have punched that out and will countersink the hole, fill it with Durafix and redrill and tap the hole.

Adrian.

[Adrian Harris]

Not sure what happened here but both ends of the rails which hold the winch in place are quite badly bent:

Hopefully a gentle tap with a nylon hammer should get them back into shape.

Once the 7 is back in one piece, they'll be pretty much hidden by the running gear and bodywork.

Adrian.

[Adrian Harris]

I've been getting on with the rebuild, slowly, and have started to get the chassis back together.

I have recently cleaned up and primed the drive casings but didn't want to contaminate the inner areas with paint, so needed to mask off those areas.
Rather than use tape, I decided to create a small shield on the 3D printer, which would drop into the recess. It only took 5 minutes in the CAD program to generate the solid shape and 20 minutes to print:

Once in position, I used a turntable to allow me to rotate the part and get a couple of light layers of primer on:

Once done, just lift out the shield and move onto the next part. When done, there is minimal over spray inside.

Adrian.