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Now I must confess, I'm still not 100% sure about those big tyres.  They look cool enough on the wheels, but they seem to sit a bit close and I think the stance was better with smaller tyres.

I might have another go at getting some stock BFGs over the RC4WD wheels again, and if that works I might just stick with those for now - at £30 per pair it's going to cost a lot for 6 new tyres on a rig that was never meant to be hugely capable.  I might even go crazy and splice some BFGs together to make super-wide tyres for the back.  I don't mind chopping up old BFGs as I have a few sets lying around, they look good, they perform well enough on mud with a cut stagger pattern, and the lettering is classic Tamiya goodness.

Alternatively I have identified some smaller (96mm) RC4WD tyres that should look good, if I save up the cash to buy them.

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I don't usually do these updates late on a Sunday night, but things are going to be a bit crazy over the next couple of days so I thought I'd get this in early.

Workshop Sunday began with a clear blue sky and an unseasonably warm sun beating down on the workbench.  It still hasn't been cleared since last weekend, so it started the day looking like this:

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First thing I wanted to do was experiment with tyres.  I managed to get a newer Tamiya BFG mounted on the deep steels, but the sidewall had an ugly bulge and it just didn't look right.  I them remembered I had some KRT tyres on one of the CC01s that might be worth a try, but although it fitted the wheel well enough (actually it would need gluing because it spins on the RC4WD tyre!) and looks kinda cool as a standalone wheel, it really didn't suit the look of this truck.

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With that in mind, I went ahead and mounted the old Rock Stompers on all 4 deep steels and fitted some old Hyraxes up front, as they are a similar diameter to the Stompers.  The final tyre will probably be a bit smaller, but this is good enough to build the rig from.

sm_PB210004.jpg

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I glued a closing panel onto the back of the cab, and while that was drying, I set to work on the towing beam.  I saw a neat idea on a Wendigo tow rig at the last Bournemouth truck meet, so I went back to the photos to see how much of it I could copy.

I started with some U-section allu.

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I pressed some 4mm ID tube into it to stop it deforming when clamped.  I will probably replace this later with a pulley wheel.

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I cut some more spacers and a length of M3 rod (M4 would be better but I need to mount the shocks on the end of it) and mounted the front of the boom.

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It should probably look a little like this:

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To make the frame for the back, I used some 3mm piano wire that I'd got for making monster truck sway bars.

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I part-bent it into shape before fitting, but had to take the bends out to get it through the boom, then put them in again, hence they're not perfect.

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I wedged a smaller side u-section into the boom to stop it deforming while I used a combination of vice, hammer and brute force to get the wire into a neater shape

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And, fitted!

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One final pic - working on the pickup assembly.  I had a million different ideas for how this might work, but most of it looked great in my head but wasn't going to be easy to make in such small space from bits of alu sheet, section and tube.  Here's what I started with - a brass cupboard hinge, a piece of 1mm sheet and a Tamiya servo post.

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You'll have to wait until next weekend to see how all this goes together, but basically the goal is for me to reverse up to a stricken touring car, slide this plate under the body, then - using a single winch line - lift the plate to secure the car to the truck, as well as lifting the car off the ground so it can be towed back onto the track.  Whether any of this will actually work in practice remains to be seen...

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Bit of a late update from last week.  I was racing on Sunday 28th, so didn't get any work done on the tow truck, but I had some time off work the following day.  It was cold in the workshop, so the first thing I did was stoke up the wood burner for the first time this season and get some warm air flowing around.  I also moved all my stuff from the main workbench at the far (cold) end of the workshop, to the window end by the wood burner.

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Then I cut some drop brackets to hang the lift mechanism from.  This is "photo 2" of the series but was taken a full hour after photo 1 - that's why my days disappear when I'm working on projects with parts made from aluminium!

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Brackets fitted.  Slightly odd angle is proof that even with a pillar drill and a centre punch, I still can't drill my holes in the right place.

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A whole 3 hours and 15 minutes later, I'd built this upright on my pickup assembly.

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Another 30 minutes on top of that and I had two very rough linkages made.

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And finally, a zoomed out rough idea of how the finished article might look

sm_PB290007.jpg

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Friday 3rd December, my new tyres arrived.  These were £16.89 for a set of 4 including free Prime delivery:

https://www.amazon.co.uk/gp/product/B09B362BFH

With a 100mm OD, these should be perfect for the big rig axles.  The existing RC4WD Rock Stomper X/Ts measured just over 100mm and fitted perfectly, the Proline Hyraxes on the front are 104mm and are too big.

Immediately out of the pack, they feel as soft and sticky as anything from Proline or RC4WD, with a realistic tread pattern (I have no idea if they look like genuine Dick Cepek tyres) and some nice soft foams.

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Here they clearly look better than the old Rock Stompers, and are visibly bigger, too.  Uh-oh...

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They actually look closer in size to the Hyraxes...

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The lack of scale detailing on the Amazon specials is obvious when put against the Proline tyres

sm_PC030012.jpg

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Anyway, let's not worry too much about that just yet.  If they fit the wheels and the truck, they have been a real money saver.

Good news - they fit well on the wheels.  There's a bit of a bulge near the rim (I'd prefer the bulge to be further up, like an oldskool balloon tyre) but the foams actually move around on the hub, so the tyre can be positioned for best aesthetics.  It'll probably move around a lot on the trails, though.

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Mounted on the truck next to the RC4WD tyres - there is rolling clearance here, but very only just!

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With two tyres on, they rub.  Not a lot, and only in places due to inconsistency in the tyre shape (most likely due to foam and fitting, not actual badly-made tyre) but bad enough that I can't run the truck like this.  Oh well, that's a job for Sunday...

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Sunday began with my trying to fix Friday's problem.  I needed to space the axles apart to get the tyres on, and I figured the easiest way to do that was to make a new axle hanger.  It's hard to space the axle out at the top because the leaf spring bolts directly into it.  Fabricating a new leaf spring is beyond me, so I'm limited to pushing the bottom out a little bit, or abandoning the leaves altogether and changing to a walking beam or 4-link type affair.

Here's the prototype for my new hanger.

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With the theory proved (albeit not as well as I'd like), it was time to make another bracket and file it to shape.  I used the stock one as a template.

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I even fired up the bench polisher to get a reasonable finish before fitting them.

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Then I turned my attention to the lift mechanism.  I cut two more linkages from the same material as last time, and screwed them together to cut them down to size.

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There was a lot of filing to do, which involved me having to poor water over the links at regular intervals as it was getting hot enough to melt the ally into the file.

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The links should be symmetrical across the length and the depth.  To help get them mostly right, I screwed the blocks, flipped two width-ways and one length-ways.  This highlights where the links lack symmetry.  By filing all the sides and ends until they are smooth again, they should be closer to symmetrical.

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After that, it was time to cut some threaded rod, alu tube, and hang the whole assembly on the back of the truck!

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Tube at the bottom of the brackets should stop the frame deforming under load and make everything nicely rigid.

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Links installed with nylock nuts.  Ideally I'd push some insert into the links, but I don't have anything suitable and can't cut anything to that degree of accuracy.

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All 4 links installed.  The lift assembly rests on the floor just where it should.

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Like the Lighthouse Family, it can be lifted

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OK - now for the real test - does it work when using a winch line?  Note no winch was attached, I was pulling on the other end of the string with mine own hand.

line attached to the servo post:

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line runs up to the beam.  The final product should have a nice pulley here, if I can find one:

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at rest:

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with some tension applied - this is a good thing!  the hook should lift before the assembly does, otherwise the car will roll off the back

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full tension applied:

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RESULT!  It actually does what it's supposed to do!

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After that, there was only one thing to do - try it with a real car!  It's all well and good if it works on the bench, but it's no good if it can't actually pick up a car.

Here's my M03 vintage racer, complete with vintage damage to the vintage body.  No tension on the line, the hook is resting on the floor.  The truck would reverse up to the car here.

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As I apply tension to the line, the hook lifts up inside the body to stop it rolling backwards.

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Continue applying tension, and the lift assembly slides up - no sticking, no locking, no twisting, no falling off - up it comes!

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So there you have it!

I made a thing!  I made an actual thing, and it actually works!

I know this thing was all designed in my head before I started, but there were a lot of potential pitfalls, places where I might never have been able to make the parts, and the areas where parts could have just got stuck or twisted, or not been strong enough, or been too heavy to lift, or just made the front of the car fold up and fall off.  But, it actually works!!

I MADE A THING!!

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Great work! I love it when things are made from some profiles and a sheet of aluminium. 👏

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Lovely work, this is a fantastic design. I wonder if a rubber lip on the aluminium might give a little more grip. Such a cool car.

 

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9 hours ago, Nikko85 said:

I wonder if a rubber lip on the aluminium might give a little more grip

I like that idea!  I'd need to see what rubber I can get that won't increase the thickness of the hook plate too much, as it needs to slide under the body of a beached car.

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An old window squeegee? The triangular wedge shape to get under the car to be collected and then help to drag?

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2 hours ago, Badcrumble said:

An old window squeegee? The triangular wedge shape to get under the car to be collected and then help to drag?

hmm, might me an idea, as long as I can un-collect the car afterwards :) 

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New transmission from Banggood arrived earlier, along with a handful more cheap sliding propshafts.  I'm on the works laptop at the mo, so no pics to share until later, but it looks like it should fit properly and leave more space for shock towers and grille.  I keep forgetting to order the pinions I need to complete the transfer box, and I don't have the budget for a crawler ESC right now, but it might not be too long before I can give it a brief run around the garden.

I keep forgetting that I'll have to do a partial teardown after the initial build, as I still need to put some putty in the rear diff and see if I can unlock the front, as it was assembled in a locked state.  Also need to mod that TLT front to get in more steering angle.

It's all starting to take shape now though - I might be able to start on the interior soon :o 

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Ha - I LOVE this! ...what a cool idea! - and the crane mech is inspired!

I was just thinking about your wheels - did you say you'd got six of those deep-dish RC4WD ones? - because you can always mount the hubs the other way around to reduce the offset (as long as they clear the steering knuckles of the TLT axle of course) - it's what I ended up doing to narrow the track width (approx 5mm per side) when using them on some portal axles:

i-xtZ9p5H-XL.jpg

That way you could narrow the track at the front, but keep the deeper dish at the rear?

Looking forward to seeing this develop - rust it!

Jenny x

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2 hours ago, JennyMo said:

did you say you'd got six of those deep-dish RC4WD ones?

Actually I only had 4 - I originally bought them for the BOM, but they were way too wide.  They've been almost the perfect donor for this - in fact the only real hassle has been getting tyres on them.

Ideally I'd get a set of non-deep wagon wheels for the front, but it's a fair amount of money to pay.  I might see if I can get another cheap set of the plastic steel-lookalike wheels (as pictured above with the Hyrax tyres) as the offset is fairly narrow and they look about right for this sort of truck.  The TLT axle is actually slightly wider overall than the big rig rear with the deep dish wheels installed.  I'll need to fit a fairly narrow hex and a narrow offset wheel to keep it from looking goofy.  If all else fails I can cut a spacer to go behind the deep dish wheels, between the rear part of the wheel and the machined hex.  It probably only wants 2-3mm.  But if I can get narrower on the front, I'll get better steering.

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