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What have I done? - Tamiya TNX 5.2R restoration. Everyone, say hello to "Rusty"

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If you know my collection you will know that I like Tamiya Nitro. Maybe an understatement with approx 250 Tamiya but what I love is the restoration challenge. During lockdown I decided to get a runner of all the major Tamiya off road nitro kits and the TGM-04 TNX 5.2r is the last one I need. With the TGM kits that I dont run this will be the 14th of these monsters to join my collection.

Now, it would be fair to say that I also like a challenge! I find it really hard to look away from Tamiya nitro kits that are down on their luck....and this one really is. It's clear that the kit was used, probably abused and then sidelined for time to take its toll.

So a little about the kit itself first. The TGM-04 chassis TNX 5.2r first hit the streets in Dec 2006 as kit number 43530. The last in a line of Monster truck iterations that would carry the TGM chassis designation it basically took all the Proline developed hop-ups from the TNX 3.0 and rolled them into one. Tamiya fitted the Force .32 engine badged as the FR-32FX and added the usual body, wheels and radio gear. These make great trucks but they really didn't get any further development and as we all known brushless power soon started to overtake. Tamiya released one extra kit with some bling in the 49460 Champagne Gold Version ( restored one here: https://www.tamiyaclub.com/forum/index.php?/topic/88767-49460-tamiya-tnx-52r-champagne-gold-restoration/& ) and then the Nitrage came along. Since then nothing.

Now, the one that I will be restoring popped up on Ebay and went on the watch list. First impressions aren't too bad are they!


Wrong body, dirty, a little scruffy etc. But my oh my things get worse...


Tyres are all dry rotted


Steering parts are all rusty


Underside is the same


Engine is a bit rusty!



and lastly a full chassis shot.


As ever...the plan will be too restore as much as possible and make this into a runner.......Stay tuned she is on the way to my house and I paid £63.

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12 minutes ago, KEV THE REV said:

You have the skills to make it live again . Great project 

I would rather restore this than build a new kit to be fair.

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First update. What's my plan of attack? Normally when I see kits like this I will assess the pictures and make some assumptions. These are my thoughts on this TNX


Clearly I need to make some decisions on the price I will pay and a return if it all goes horribly wrong. Even with the truck being as rusty as it is I can get my initial return back. Just the Fuel tank alone would sell for approx £30 so with all the other bits (wheels, gearbox, diffs, Tamiya branded servos and RX) on it I could make the initial outlay back. However, thats not why I purchased it.

What needs doing?

Lots obviously. however if we then break "lots" down it makes a little more sense


It will need a complete strip. The cylinder head looks slightly squashed but that will straighten, clean up and then be painted in high temp satin black. Once stripped everything will go in the Ultrasonic and then be inspected. I really dont know what the engine will be like inside but I am presuming its locked up. Once apart I can check it over but at a minimum all screws, gaskets and the front and rear bearings will need replacing. The FR-32FX has a composite carb body so that will help with the corrosion of its internals. The metal parts of the carb will be cleaned back to bear metal and then chemically blackened again. The engine is missing its rotostart so that will need replacing. The manifold and plastic muffler are missing but I have them already.

Plastic Chassis Parts

All will be stripped and washed and once clean inspected. I have already ordered some new chassis bars as the ones on the kit have some large holes drilled in them. Restoration or otherwise a new set is £8. I also think that the rear body mounts will be replaced, they are badly bent and the holes have been enlarged. There is also evidence of a philips wood screw in the picture!

Metal Chassis Parts

Stripped, cleaned in the ultrasonic and then assessed. All of the black effect parts like the rollbar/handle will be stripped back to bear metal and then chemically re-blackened. At this point its an unknown.

Fuel Tank

Cleaned in the Ultrasonic. Looks good from the pictures. Primer is intact


I have a spare if all goes wrong but it will be stripped and cleaned. Time will tell what the inside is like.

Front and Rear Diffs

Much like the gearbox, stripped and cleaned with new bearings being fitted


They actually dont look bad in the pictures. Stripped, cleaned and the rebuilt at this point but I may need to replace the shock shafts depending on how rusty they are.


Stripped, cleaned and new bearings. Steering rods and ball joints will need attention though!

Chassis plate

Cleaned and then assessed. Dont want to replace it so will work to make it as nice as possible even though it has at least one spurious hole. Maybe strip the faded blue off and polish silver.


Remove old tyres, clean wheels. Fit new tyres....I hope. Risk will be if any of the rims are cracked.


As a runner the RX will be replaced however all the rc gear will be checked and tested. The servos are usually pretty resilient so should be ok. I am planning to have to replace the switch and AA battery box. 


All will be replaced with hex head button screws. The TNX uses lots of 3mm x 12 screws and as 100 new ones are just £6 its not worth spending any time trying to restore them. As its a runner I am not super fussy about original Tamiya screws. I save that OCD for the shelf queens and I have two TNX 5.2's already that fill that gap.


Sounds easy doesn't it!

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2 hours ago, matisse said:

oooof, that needs some love

It certainly does...

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Rusty turned up last yesterday and he certainly lives up to his name. Had a quick look over and apart from being rusty its basically complete. Body went straight in the recycling. Tyres are glued on but should free from the rims which will be reusable pending no issues with the hubs.

Engine was only held on by one bolt and so came off the chassis easily. Its seized but what I could see from the exhaust port showed the inside (that I could see) wasnt rusty. Sprayed it internally with WD40 and sprayed the outside bolts etc as well.

Transmission turned over with no issues once the engine was free and Rusty  rolls across the floor with no odd sounds.

Pictures and more work to come.

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That looks like a fun project!  GL with the restoration.  


Hello, Rusty~!  :D

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8 minutes ago, Willy iine said:

That looks like a fun project!  GL with the restoration.  


Hello, Rusty~!  :D

Thanks, parts are already arriving (screws etc) so progress should be quick.

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So a long overdue update on Rusty! Work and life have slowed things down a bit but managed to get a few things done.

After quite a bit of work i had to admit defeat on the original engine. Not total defeat as I will explain but the engine will never run again. Having soaked the engine for a week I set about dismantling it with a view to clean the parts and then assess them. The engine stripped down pretty well but despite every trick I know the piston, liner and crank would not break free and unsieze them selves. The engine was very rusty inside so I have taken the view to recover what I can and work from there. I also do have a number of FR-32 parts so will see what I can build. Sometimes they are just to far gone!

Engine head has been saved. It was sanded, the bent top fin re positioned and then painted with high temp paint. I use heat and a spacer to bend the fins as they are easily snapped. The spacer stops the fin below from bending etc.


Happy with how that has come out and looks presentable again for a runner. It did look like this


The rest of the engine was then recovered. Carb, backplate, screws, flywheel, clutch and clutch bell. The clutch bell and flywheel have cleaned up ok. The clutch bell was then chemically re -blackened.

I then raided my spares box and found a crankcase and replaced the bearings in that with new ones and purchased a used crankshaft on ebay. The crankshaft was cleaned up and fitted. The Tamiya labels from the original engine were removed and added to my new build crankcase (it wasnt a Tamiya branded crankcase) and the carb after cleaning was fitted. The flywheel and flywheel nut from Rusty went on but cant yet be tightened up.

The engine now looks like this


So some engine progress but nothing on the chassis yet. I have got a used exhaust and have been getting together some other parts ready to strip Rusty down.

More to come soon hopefully. The next thing I need is a new Piston and Liner

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An amazing save on this, it looked fit for the bin to me 😂

Did you soak the engine in WD40 or did it sit in a bath of something else?

The engine head has come up really well, do you use a blow torch to heat the metal? 

Lots of great info and tips in your threads for restoring older R/C 👍

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2 hours ago, Grumpy pants said:

An amazing save on this, it looked fit for the bin to me 😂

Did you soak the engine in WD40 or did it sit in a bath of something else?

The engine head has come up really well, do you use a blow torch to heat the metal? 

Lots of great info and tips in your threads for restoring older R/C 👍

Thanks, its getting there. some more challenges on the chassis though!

Engine was soaked in a mixture of diesel and acetone. still didnt budge.

Heatsink was indeed heated with a blowtorch, just enough to make the metal less brittle when you bend it.

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So a long awaited update.

With a week off work I started to take "Rusty" apart.

This was the starting point


and it was clear that it would need a good clean!


After about an hour I was left with...


Radio Gear


The more specialist screws


Metal parts that will need some love!


Plastic parts and larger assemblies like the diffs and gearbox



Wheels. The tyres will be scrapped and the rims reused.


A pile of scrap parts. All the standard screws are being scrapped as they are simply not worth expending time on relative to replacement cost. The plastics are either damaged, cracked or have holes in.


and a mess....sorry Mrs Acprc!!


So now its just (he said casually) a case of sorting everything out and putting it back together, simple!

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That shouldnt be like that!


Diffs have been stripped, cleaned, fitted with new bearings, regreased and rebuilt. The shaft that had come loose has been pressed back in and slightly peened to hold it in place. A known weakness of these cars however good design actually means it wont fall out when it does come loose.

Plastic parts


Metal Parts


and rebuilt


Steering arms have been rebuilt with nice new bearings instead of the plastic bush.


Remember the rusty bits?


Cleaned off on the scuff wheel on my bench grinder/polisher then degreased


Then chemically re-blackened. Happy with the end result and perfect for Rusty as she will be a runner





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"Rusty".....but not quite as much as before!

Managed to plod on with the parts restoration to get rusty back looking fine again.

Gearbox got stripped cleaned, new bearings and fresh grease. Clutch plates were fried so they also got replaced. No damage at all inside and apart from some corrosion on the input and output shaft the gearbox was fine.



Started rebuilding the plastic parts onto the diff and bulkhead assemblies front and rear. These were then fitted onto a new chassis plate. I had hoped to save the old one but after cleaning it it was cracked and bent at one end. I could of hammered it flat but a new one is just £34 and now its coming back together the chassis looks better for it.

Fitted a new EU CE label. I made these a few years ago for my TGS fleet restoration and they look good on the restored cars.


Fuel tank cleaned up well and was fitted with new rubber washers.


One of the 11mm Ball connectors has a damaged head so I need to source another which means I cant fit the final arms on the rear yet. Tamiya dont sell them separately but Kyosho have some 11mm so I will try them first.




The engine with its new piston and liner was test fitted. Still need a starter system and a muffler spring. I have the exhaust from my spares box and the mount is on the chassis ready.


Gearbox fitted in nicely and linkages back in place.


The radio gear was tested and fitted. The RX will be replaced by a modern 2.4ghz unit but the servos should be ok. The steering servo was a bit slow and the screws had some corrosion but once opened it had no corrosion inside. I think it was just in shock having been used again!

So now Rusty looks like this!


Need a few more parts etc but slowly getting there. Oh.....and found a body in Japan. Rusty will be sparkling! This is the body from the Champagne gold edition and is in very good condition apart from a couple of scuffs. Perfect for a runner.


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Some progress during the week.

A member of the Facebook TGM group sent me a used 11mm ball connector and a used battery box lid. This meant I could fit the last of the suspension arms.


Shocks were checked, refilled with oil and refitted


New front bumper and skid plate fitted


New rear fitted as well


So Rusty now looks like this




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3 minutes ago, Grumpy pants said:

An impressive transformation - it’ll need to be renamed from ‘Rusty’ to ...

Thanks, I think he will stay as Rusty

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Small update before some progress over this weekend.

I knew I needed a starter for Rusty as he didnt come with one fitted. Started the search knowing that they usually run for £79 and up but oddly got a stock hit on Amazon UK.

£25 later and within two days this arrives. Only one they had and no other Tamiya for sale. Rusty now has a starter and it will be fitted this weekend.



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A few more jobs done

Front body posts fitted


Rear body posts fitted


Starter built and fitted


Fuel lines fitted with an extra filter and Exhaust mounted


Filter mounted (needs an OEM foam really)



Progress, job lefts to do are:

Fit steering arms and rear arms

Fit manifold spring (when it arrives)

Fit silicone exhaust coupler with ty-wraps

Battery box, switch, RX and battery box lid

Set up electronics

Wheels and tyres

Fit body (when it arrives from Japan)


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So about a year after my last post i was moving Rusty about and realised I had never finishes the thread! Shame on me. Rusty had the new steering arms fitted, the manifold spring and silicone exhaust coupler. I added a new battery box and a modern 2.4ghz RX.

The original wheels had the tyre remains removed and then had nice new tyres fitted. The wheels actually cleaned up nicely but took some time. The Champagne Gold body from Japan had a light clean but was very good.

Rusty has over the year been run a few times and after some steup appears to be fine. Today, Rusty looks like this.





Thats Rusty done...onto the next one.

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