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MG K3, TR3 and MGB 3 Brit Classics


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35 minutes ago, rob Lyttle said:

have you got any more information on that?

Well now, I'm on holiday and away from my info, but..... :)

 

The MG Racing Shop in the early/mid 1930s were continually searching for ways to improve their cars' performance, and one way to do that was to try improving the preciseness of the steering gear. Bearing in mind that at this time, the primary steering was by a box containing a worm and peg gear, usually either Marles Weller or Bishop.

 

Normally, driver input at the steering wheel was transmitted to the front wheels via a drop arm on the steering box which swung in an arc left to right, then via a drag link to an arm on the nearside stub axle. This was then transmitted in turn to the offside stub axle by a full width track rod.

 

This system is prone to bump steer, where a deflection at one side, a pot hole or bump, is transmitted via the steering components, to the other side. This has the effect of amplifying the bump in the road, making steering a matter of hope and prayer when at racing speeds. The K3 was capable of well over 100mph, the Q and R-Type Midgets (750cc!) were even faster!

 

What the MG Racing Shop tried to do was eliminate bump steer on its beam axle racing cars, the J4 and Q-Type Midgets and K3 Magnette, by dividing the cross-car track rod.

 

What they did was to fit an idler arm in the middle of the front axle beam, which was connected to the steering box by a shortened drag link. Then a half-length track rod linked the idler arm to each front wheel.

 

The system was only partly successful, as the increased number of spring-loaded track rod end joints added additional potential play.

 

Hope that makes sense!!! And apologies if I'm trying to teach you to suck eggs!

 

Cheers,

Mark

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3 hours ago, 2996 Victor said:

Well now, I'm on holiday and away from my info, but..... :)

So that was all just off the top o' your head, Mark....⁉️🤩

All great information, thanks. I'm going looking for some K3 refurb projects for some Stripped down chassis pictures. I don't expect I'll be able to make anything resembling, I'm at full stretch just making the steering operate.

The old fashioned mechanism you describe--  I think I've modelled something like this on maybe a Heller Delage D8 or similar 🤔 

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29 minutes ago, rob Lyttle said:

So that was all just off the top o' your head, Mark....⁉️🤩

Yep! I'm a bit of an MG MMM nerd :rofl2: 

 

For refurb photos, perhaps you could try the MG Car Club Triple-M Register website. They have a photo archive. The Triple-M Register publishes a Yearbook - I haven't got recent ones but you may be able to search those as well.

 

Also, there was a book published some years ago, K3 Dossier, authored by M F Hawke, which described every K3 built in detail.

 

K3 owners such as Karl Weissman, Mike Hawke, Peter Green, carried out exacting restorations. Peter Gregory built a number of replicas on K1 chassis. There may be photos on the web.

 

I'll see what else I can dig up!

 

Cheers,

Mark

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Here's a useful site: MG K3. It's one of Peter Gregory's cars so most probably a replica built on a shortened K1 saloon chassis. Go to the gallery bit and scroll way down and you'll spot some underside shots.

 

The underside photos show the divided track rod and idler arm quite well, along with the beautiful finned sump! This is probably the most useful:

MG-K3-Special-Peter-Gregory-1933-44.jpg

The bits to look at are just behind the axle beam. The blue-painted oil pump housing is behind the drag link/track rods.

 

HTH :)

 

Cheers,

Mark

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MG-K3-Special-Peter-Gregory-1933-44.jpg

Wow 👌 

Afraid my endeavours look rather clumsy in comparison to that work of engineering Fine Art, but I have one articulated brake plate assembly, 

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Both ends of the axle have a bearing tube attached with my best shot at giving the characteristic camber to the front wheels, and a brass nail is acting as the kingpin. 

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A bent wire steering arm is fitted already in the hope of making something to link the wheels. 

I looked into the possibility of soldering brass tubes to the axle ends, testing with some offcuts from the back axle mod. 

It's an absolute NO...!

Finecast recommend not using solder for assembly as the melting points are quite close. It's much worse than that.... this metal is reduced to a blob in seconds with my little iron, which I don't think is particularly hot. 

So I'm still working with CA 🫣

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The brake plates are being fitted out with a pair of these...

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...basically splitpin shaped items bent in wire and glued through holes. The tails are snipped off when set. 

The kit metal sump is no match for what's pictured in Mark's @2996 Victor photo. I'm doing a scratch modification in styrene. 

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There's no great detail on the underside of the car,not even a tunnel and prop shaft, due to the nature of the kit and material. That's OK but I thought I'd take a shot at improving a couple of things underneath while I'm tinkering..

The carburettor position is getting an update too. Drilled through, made oblong and sleeved with a squeezed plastic tube. 

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Lovely work, Rob, the sump correction is excellent! Great work on the steering components, too!

 

Are you modelling the supercharger? More trivia : for the 1933 cars it would have been a Powerplus No.9 blower.

 

Cheers,

Mark

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On 15/06/2024 at 14:10, 2996 Victor said:

Are you modelling the supercharger?

I've been trying to get something done on those lines but it's all got in a bit of a tangle. Here's where a load of faffing has got me so far...

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Some kind of structure on the front of the sump that takes a drive-shaft for the supercharger. It goes through a clearance hole in the bracket which is an intrinsic part of the main axle. The springs structure in the 1st picture can't go on as a unit--  the supercharger is now in the way. The crossbar to the rear is intended to be removed after fitting and THEN the sump is fitted. It's going to have to go on as 2 separate springs. And before that it's necessary to fix the headlamp/mudguard stay framework--  that crossbar had to be snipped, spread and fitted over the little driveshaft.  Talk about unintended consequences??😜

Anyway,  the steering project has worked. Turned out that when inverted the kingpin nails tended to drop out and I had to make a couple of little stops glued to the brake plates to stop them. 

I've just gone for a plain trackrod and be thankful that it works and the wheels are parallel. 

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I think that's enough fun and games under the front end,  eh?. If I can get the springs fitted and the shock absorbers attached ,I'm calling that bit done. 

Oh hold on... there's some stub axles to sort out without glueing the whole steering structure solid, and a curly oil pipe to replace on the front of the sump  

 

But other than that, what have the Romans ever done for us.....??🤩

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Posted (edited)

While I'm bashing away with the metal MG K3, there's a good opportunity to describe some modification on the Triumph car.  I said previously that while the kit has a good looking bodyshell, it also has some serious toy-like issues. One of these is the interior tub. There's no footwell. It finishes at these arrows,  where the green plastic stops...

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It's just a blank wall. I took the hacksaw to it, leaving the top of the bulkhead intact with the big mounting plate and taking off the bottom ⅔for what would be seen below the dashboard. 

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Floor and walls were fabricated in 0.5mm stock and the tunnel extended forwards to suit. 3 pedals installed on sprue legs-- they went in early in the process. Dimensions wise, all I could do was sketch a bit and take my best guess at how far forward for the new bulkhead wall. It doesn't have to be too slick an assembly on the outside, 

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Featured here are a pair of runners positioned to sit on the chassis. 

The seats don't look too bad bearing in mind that they are intrinsically moulded in the tub as one piece--  the little backseat bench too. So again toy-like, and yet quite a good finish and appearance. I don't know when this was first tooled or by who, but it was a LONG time ago, so well done to them. 

So there we are, a decent improvement to the overall look of the Tr3 🤩

 

Edit,  originally 1960 by Hubley,  and it looks like their first several issues were pre-assembled and sold complete. That explains some of the quirky design features like the big circular mountings that look like they can take screws or plug dowels. 

Well, mine has a footwell now 😎

Edited by rob Lyttle
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4 hours ago, Neddy said:

difference to the interior.

Yeah, I think it's worth the effort in the long run. 

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What can you do with a blank wall, other than paint it matt black?

I realised that the floor pan needed extending back under the rear bench seat and box in the back axle space. Just a bit more 0.5mm plastic...

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For the MG K3 I've decided to go with the blue I used on the little Airfix kit. I like the look of it, but it's Humbrol enamel gloss 14. So it's a brush job. 1st coat over primer has been knocked back and 2nd coat applied. I'll keep going and see what can be achieved. The metal surface is not perfect by any means and tricky to work on with all the extra detail of bonnet straps,  louvers etc 

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I had a go at wiring one of the wheels for the K3, and had a fail--  more of a shambles really 😳--  so I'm doing other things instead. I'll come back to it with a clear head. 

The stub axles are successfully fitted without glueing up the steering. 

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I cut a couple of discs in 0.5mm styrene with tight holes for the ali axle tube and ca'ed it in. Then I glued that onto the brake, keeping glue off the tip of the tube that fits into the brake drum. While the glue sets I kept the steering movement active just in case. 

The front radiator is permanently attached and the whole bodyshell now fits as one unit onto the chassis. 

You'll recall that I had a couple of photoetch MG badges left from the MGB build, I pressed them into service here...

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The one on the rad is an ace 👌. The bigger one on the supercharger housing is a bit of a liberty. Later K3s certainly have the logo on a mesh air inlet and the housing has a more angled shape to match the Octagon shape. I'll try to kill the red paint with black to see if it improves. 

Looking at the exhaust pipe system, it fits OK but I'd quite like to have the up-and-over style that's common on these cars. 

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I don't think the cast metal piece will take kindly to that sort of bending. My best bet is to bend ali tube to run from the silencer to the tail end. If it's a fail then nothing is lost and the kit pipe can go on.

I'm a bit concerned that inside the bonnet is a complete void with nothing for the manifold to attach to. Precious little can be seen through the opening but it might benefit from having something in there. 

I got the 2 fuel caps attached to the top of the tank. They are SMALL!!

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Again some stock plastic came to the rescue. The cap is ca'ed onto a strip of skinny styrene once the bottom face is cleaned up of the sprue attachment mess, plastic trimmed back on one end, and use the other end as a handle to place the cap in position on the tank and glue. 

Then the handle bit can be trimmed off.

So, inching forward item by item 

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On 24/06/2024 at 15:57, rob Lyttle said:

I don't think the cast metal piece will take kindly to that sort of bending.

Wrong....!!

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Visible on the mat is the ali tube version bent up and the fishtail hand built and ready to go. I finally took the hacksaw to the kit exhaust. Knowing I had a viable replacement ready to fit, I thought I'd give the cast pipe a little push, see if it would bend at all.

It loved it 😍 

The disadvantage of bending pipes or tubes is the tendency for it to kink rather than a nice smooth sweeping bend. So I didn't do too badly getting the ali tube to take the S bend. But no such problems of course bending the cast metal and it's looking OK 👌 

I've had to make good the joint I cut, I drilled for a wire dowel into the silencer and into the pipe, nothing glued yet. I also drilled a new hole in the bodyshell above the back wheel to accept the mounting pin towards the end of the exhaust 

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Some heat shield lagging needs wrapping around the pipe before it's fixed in place. 

I can't say how much working this metal would take but there was no sign of fatigue or breaking up as I did this process. 

So, definitely going to stick with the kit piece and keep my ali tube version as a spare 

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Nicely done! If the kit part is white metal, as is common, it should take quite a lot of bending before it gets fatigue cracks.

 

Ian

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Finishing a few details on the MGB build and she's just about done ✔️ 

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That's the knockoff wingnuts all round, wing mirrors, wipers, door handles. 

Wing mirrors got mounted on brass wire and holes drilled in the bodyshell. The little plastic legs and undefined placement with a surface butt joint were just inadequate. 

I found the wipers needed extra effort, especially the driver's side. The tiny pips on the wiper arms wouldn't engage with the holes in any meaningful way. I inserted drive shafts in stretched sprue. 

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That worked for the nearside and a line of acrylic gloss varnish along the blade finished the job. Driver's side has a lot more curvature on the screen to contend with, and in the end I pulled the sprue out and went another way. 

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Here the arm is drilled and the sprue fixed through, leaving a decent handle protruding for my convenience. Then it's fitted and twisted about until the blade wants to rest against the screen. The blade itself needed some extra curvature  added to the plastic to follow the screen shape. 

I've had a fail with the rear view mirror on the central bar, and fogging inside the screen for my efforts. The fogging has mostly been polished away and ready for another try. Apart from number plate decals, that'll be it done I think 😎

Nothing left in that box. 

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  • 2 weeks later...

I'm in the "wheels" zone and it's proving quite challenging.... Some coherent progress with the Triumph wheels arrangements that I'll tell you about later, but this is my current nemesis...

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Back view...

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Holy Moly, what a job. 

This is the 1st one I've managed to get off the jig as a coherent whole. I lost my place and count doing the back face but when all's said and done it is the back. Having got this far noticed that the rim has a castilated look due to the slots--  can you see what I mean on the back view?...

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So then I wondered if a circular ring of the wire would go on the outside edge to get rid of this look,

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Pfff.... easier said than done. But I got this far. In position as the spare wheel...

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I'm thinking that structure on the back to include the number plate etc will help to cover the irregularities when positioned to suit. This sort of thing, as on my Airfix K3. 

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And then try my hand at the next wheel, see if I can do a better job and not stick my fingers together so much. This phone's biometric fingerprint function is struggling to recognise me 

 

This could take a while....

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Just a thought - could you use some epoxy or UV resin to fill in the gaps to remove the castellated look, then file smooth and paint the outer rim when finished? Or is it too small to be trying that?

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Nice work on the wheels, it's not easy!

I just noticed the slope at the front of the MGB bonnet. I hope it's just the angle, but it looks far too steep. The bonnet front is almost flat!

 

I'll have to make a note to check that when I build mine.

 

Ian

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2 hours ago, Brandy said:

the slope at the front of the MGB bonnet.

Now you've got me looking....

I think it's reflection effects, haven't really noticed anything that gave me concern. Nothing that you'd call flat. 

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But have a look at your plastic and tell us what you think 🤔  But for the moment I'll put it down to the shiny glossy finish I've obtained this time!😎😅

 

20 hours ago, Spiny said:

could you use some epoxy or UV resin to fill in the gaps

Well, I could try something along these lines but it looks like another pile of opportunity for messy shambles. I see that Matthew Bacon's Delage has painted spoked wheels which gives a marked improvement on the appearance. I may yet resort to the painted option... the kit has it that they should be painted the bodywork colour 

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If I'm honest I think the wheels look fine as they are, I was only suggesting another option if the castellated bit was still bugging you. If it isn't, stick with what you've done is my advice.

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I think you're wire ring method to hide the back of the wheel works quite well.  Have you tried gently stretching the wire first to remove any kinks?  Then ideally you could wrap the wire around a circular object of exactly the same diameter,  if you can't find one a slightly larger one should still work.  Once wrapped round the tube give the wire another gently tug and you hopefully will end up with a neater circle - Andy 

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