Marui Samurai 4WD - Another SilverTriple's journey...

[silvertriple]

Hi everyone,

Recently a project I had in mind materialised... The Marui Samurai 4WD was one of my dreamt cars when I was 15 years old. I never got one back in the time. This car looked awesome and aggressive. It maybe the most beautiful roll cage buggy of those times, ahead of the Javelin (which is still very nice and totally among my favorites).

For the technical specs :

• 4WD

• 3 Differentials

• Chain transmission

• 1070g !

And what is really awesome is its look. It really looks aggressive, with bigger diameter rims and low profile tyres on the front, and some smaller rims and bigger tires at the rear end. And the driver figure is much more realistic than what it was on Marui's Hunter and Galaxy...

Few press articles I found out while searching for information (not exhaustive list - I'm still searching for more)

• Marui Samurai Test track - Radio Control Model Cars - March 1986 : https://www.overrc.com/vintage/documentation/archives-de-mike/Marui%20Samurai%20MC.pdf (source: www. overrc.com)

• Marui Samurai - Radio Race Car International - April 1986 : https://www.overrc.com/vintage/documentation/archives-de-mike/Marui%20Samurai.pdf (source: www. overrc.com)

• Marui Samurai Track test - Radio Control Model Cars - July 1986 : https://www.overrc.com/vintage/documentation/archives-de-mike/Mauri%20Samurai%20MC%20Track%20Test.pdf (source: www.overrc.com)

• The Samurai 4WD (french) - Auto RCM - February 1986 : https://www.retromodelisme.com/article_page/1589/samurai-4wd-marui.html (source : retromodelisme.com)

• Marui Samurai Banzai! (french) - Auto 8 - February 1986 : https://www.retromodelisme.com/article_page/4227/essai-samourai-marui-marui.html (source : retromodelisme.com)

Long story short, searches were active on "Marui" in many places for ages before even I started my Hunter project. And I saw some Samurai going thru... Until I decided it was time...

• Few weeks ago, I contacted someone in the region where I was born and where my parents are still living. For the small story, the guy posted some pics of his Samurai on a group asking question on a car he was considering as he'd like to be able to use it without the fear of breaking something, and that was the day of my 50's anniversary... We discussed and it appear thru the discussion that the guy knew my uncle, and he accepted to book the car for me for a few months. I asked my father to go and buy the car for me, but was not sure how long it would take for him to do...

• Decided it was time to find some parts for a project, found one set of rear plates for almost nothing and ordered them, intension was to tease about the car on some forums

• A Marui chassis is always a thing to bother about when you start a Marui project. @Dadio was selling one of his modeled chassis on ebay, he gave me the link and I was alone to bid on it.

• The day I received the chassis, one good friend in another forum contacted me to proposed me a Samurai with a broken chassis, as he knew that I was that in mind. Having a chassis already, I thought the chassis was made for this one, so I decided to go for it

The first of the two Samurai arrived home last week, with a Galaxy roll cage and few parts.


It's not complete, but I don't mind. This is a project, a new journey, and will keep me busy for some time, which is definitely what I'm looking for

Yesterday, after getting the Nichimo Spirit FF down to parts, I decided it was time to do the same with the Samurai to have a more precise idea of what was needed for it.










Status at the end of what is missing or need rework :

• Left and right chassis to replace (Thanks @Dadio to the rescue)

• Middle Front Bulkhead broken

• Gearbox damaged with a lot of play for the center diff (I believe the car was probably running forward in RWD and backward in FWD )

• Rear right arm slightly damage where the pivot ball is placed. Luckily, it seems that I can just inverse the arms to get that back to work

• One of the front Knuckle is damaged (again a thread which was damaged)

• Missing a roof, and roll cage requires work

• Driver missing

On the good side : not everything is bad, and with the play on the gearbox, I feel very lucky having none of the gears to replace...

And there is also the second Samurai I'll probably not have in hands before Xmas. In any case, this is one of the new background routines I'll regularly post about in the next few weeks/months...

That's all for today!

[Dadio]

Looks like you've lost part of the bearing seat for the sprocket output , the same thing happened on one of my gearboxes , I designed a fix pictured below , happy to share the STL .

Can't wait to see another Samurai back on the road

[silvertriple]

Looks like you've lost part of the bearing seat for the sprocket output , the same thing happened on one of my gearboxes , I designed a fix pictured below , happy to share the STL .
gearbox repair v4.jpg
Can't wait to see another Samurai back on the road

Well, I guess this will be helpful
Thanks Gav

[silvertriple]

Ball bearing size is today's question...

The Marui manual is not really explicit regarding the ball bearing size (and some may be quite specific). So if anyone can route me to the proper size information, it would be very helpful...

Thanks

[naushad]

https://www.bocabearings.com/products/74-005-19183?make=TOKYO+MARUI&model=SAMURAI

[naushad]

The rear gearbox is a weak point of these great looking buggies. A complex piece. Look carefully for any cracks and significant wear - especially the underside.

[silvertriple]

The rear gearbox is a weak point of these great looking buggies. A complex piece. Look carefully for any cracks and significant wear - especially the underside.

Yeah, I can tell already, no need for more detail inspection : there is cracks, and a lot of play for the center diff (up and down, making the main diff gear in contact either with the front gear either with the rear gear). In short, I'll have to replace it, and I'm getting organized for this...

For the bearing, I found out the same, but I got two different informations for the wheel axles :
8 in 6x10x4 or 8 - 6x10x3 : I will have to check which dimension is the right one.

[silvertriple]

Forgot to post about it, but a front mid bulkhead arrived for the Samurai (Thanks again @Dadio )...


Other parts are for another project (Wild One, with less toyish led buckets - but that is another story)...

[silvertriple]

As I  reached my parents place,



I finally succeed to get my hands on my second Samurai, which I had requested my father to catch up few weeks ago... It's in decent condition and I'm very happy with it...

[silvertriple]

Detailed inspection of the second Samurai without getting it down to parts for the moment (have enough in the queue to work out at this stage before starting this - and the first Samurai is still waiting for parts)...

I took benefit of the weather to take some pics...




The driver is in, but he will require some work... I'll decide what I do with it once in parts : cleaning and rebuild or remove the paint, repaint and rebuild...


The roof mounting will require a slight revision... TX/RX are working.


The front body mount is broken and will require replacement (the STL is on thingiverse, that will make it)

The front damper is having a step when moving. I will check once down to parts and cleaned up (the one from the other Samurai is dirty but seems to work much better). The piano wires acting as spring for the front suspension may require replacement, as they can play a role in the step.

The chassis is marked by usage, but is in proper condition (no apparent sign of cracks)


The left half gearbox is damaged at the place where the motor support goes (the screw is in the Samurai box)...


Other elements :
- The linear MSC is in the box, and I don't know if it is working. I will have to test it. In any case, its fixation plate is absent (I may have it with the other samurai, which would allow to reproduce the part in 3D printing if needed).
- There is an ESC to run it (Hobbywing Quicrun 1060WP), and it is directly glued with tape on the accu pack
- The rims are marked, but I have seen other in much worse state. Tires are worn out. I will need to find a solution for those.
- Differentials are working perfectly. Small details, and I don't know if it is a question of settings or a problem, this will be seen once the gear box is tore down : the rear is driving front, but the front doesn't drive rear (I think it may be link with the center differential setting, but this will need check later on).

[naushad]

Looks good, but don't be surprised you find more cracks in the chassis and rear gearbox. Just how Marui plastics are...

Check the condition of the front diff...you can sometimes find small micro cracks as the screwholes for the diff halves are unusually close to the diff casing. Shouldn't be a big problem for a runner build.

Dampers are prone to leakage...get yourself lots of generic fibre washers.

[silvertriple]

Well, first, it is in much better condition that what I expected from the pictures I initially got before deciding to ask my father to get it.

And as for the damper, one would say that a damper working properly is leaking anyway

And regarding Marui plastic, my own experience (1985-1987) with a Hunter I used and abused a lot says that they were not as bad as everyone tend to say about them. To my understanding they were on par with the ones from Tamiya and Kyosho (my Hunter would have been broken very differently otherwise - and as matter of fact, I broke a DT03 chassis in conditions where my Hunter in 1984 did not). That being said, they become brittle when there is loctite around (the Galaxy I got was definitely in this case for the shock towers). And there is another parameter that affects the plastics : age and storage. I believe that lot of people are rediscovering Marui, and get old cars, but the storage of most of them did not help. Plastic doesn't like to get cold storage, neither temperature changes. A lot of those cars were badly stored, and that definitely doesn't help... And it is the same for Tamiyas and Kyoshos (the one in plastics) of the same period. What may have saved a lot of Tamiyas is actually their scale look and hardcore fans storing them on shelves (but get one stores in a non heated area, and you will see the same issues)...

I would love to see Marui re-releasing their cars, and even in their initial format and materials, I think they would be as good as the Tamiya re-released cars...

[Dadio]

I can't speak for other Marui cars but I'm not sure I agree that the Samurai was as robust as it's Tamiya or Kyosho period equivalents , the chassis is pretty poorly designed , further the quality of the moulds for the chassis is quite poor ,if you look at the back of the chassis parts where they are hollow it all looks quite roughly done in the moulds especially compared to Tamiya or Kyosho who both had superbly finished moulded parts.
If you compare the Frog Chassis and Samurai chassis they look roughly equivalent and ask how many Frogs broke their chassis , I can't remember a single broken Frog chassis .
I'm not trying to knock the Samurai , it's one of my favourite cars but its reputation is fair .

[silvertriple]

I can't speak for other Marui cars but I'm not sure I agree that the Samurai was as robust as it's Tamiya or Kyosho period equivalents , the chassis is pretty poorly designed , further the quality of the moulds for the chassis is quite poor ,if you look at the back of the chassis parts where they are hollow it all looks quite roughly done in the moulds especially compared to Tamiya or Kyosho who both had superbly finished moulded parts.
If you compare the Frog Chassis and Samurai chassis they look roughly equivalent and ask how many Frogs broke their chassis , I can't remember a single broken Frog chassis .
I'm not trying to knock the Samurai , it's one of my favourite cars but its reputation is fair .

Design wise, there was all sort of issues at that time... And I saw Frogs with broken chassis as well. But I believe it's not really comparable. Tamiya made more than 50 models by end of 1985 while Marui did 10. While Tamiya has learned of the mistake of their model, Marui designers were trying to catch from the mistakes of others, with success in some areas (Hunter/galaxy gearbox is vastly improved when compared to the Holiday buggy (which is clearly the inspiration for the Hunter on this area), somehow, even if it is still have some quirks). And I still believe the problem was not the quality of the plastic (none of the press articles of the period mention issues in this area, while they do for Hirobo or Nichimo)...

The plastics were not the issue. There was issues in the design, either by lack of experience, by targeting a lower cost or by willingness of going too far in the "light is right" moto directly inspired by Colin Chapman... Lot of things which are easy to spot with the return of experience and the possibilities of nowadays' techniques... And this is true in all activity...

I can spot other examples of this in Motorbikes area. I ride a MV Agusta, and at some points back in 2012, designers decided to change something in the rear wheel driver when they introduced the 3 cylinders bikes: the direct impact of this was to reduce the cost... It dramatically reduced the reliability of that part to the point you could not reach the range of the next programmed maintenance... They would have kept the initial design made in the nineties when they designed the Ducati 916 (the company was named Cagiva at that time and the 916 was an infant of Cagiva design center), and this would never have been an issue... Long story short, MV Agusta reintroduced the original design for that part in 2018, after a lot of issues by the customers (which were actually doing that by themselves with aftermarket parts in the meantime)... What last 6 years for a brand like MV Agusta would have been an affair of weeks for a brand like Yamaha or Honda with a much bigger distribution... That may have been the same on that aspect for Marui versus Tamiya and others...

[silvertriple]

The different sizes is a key particularity of the Samurai.

I'm trying to recap here the different options:

First with original rims.
1. You may search on Thingiverse, someone put some stl for the tires, printed in some flexible TPU filament, they may be a valid option...
2. However, I may have found a much better solution IMHO
Front : T693 | Block - Front Tyres - Blue - CAT (pr) | Schumacher RC Racing (racing-cars.com) (https://www.racing-cars.com/wheels-tyres/off-road-tyres/block-front-tyres-blue-cat-pr-t693) - 2 inches, min block tires (same dimensions as the front Samurai tires)
Rear :  Rear Tire(Medium/2pcs/w/Inner/Scorpion2014）SCT002MB - KYOSHO RC (https://rc.kyosho.com/en/sct002mb.html)- mini block tires, same dimension as the rear Samurai tires...

Then other alternatives requires new rims or designs not too much different between front and rear.
1. You may consider similar diameter tyres such as Hotshot tires, Alien8 sells Samurai like wheels for Hotshot tires (shapeways) - and it would be probably much better to get front and rear to get the same design
2. Other solution is to use at the rear Kyosho Turbo Optima re-release wheel set (2 inches, large) and front from Kyosho 4wd Optima (jcracingproducts.co.uk : https://www.jcracingproducts.co.uk/wheels/kyosho-optima) with tires from Kyosho (the front version for the one used on the Turbo Scorpion re-release which is used on the Kyosho Dirt Hog (2.2 inches, 4WD Front)...
3. In last ressort, you may use any 4WD Hex Wheels with an adaptor (some exists on the Shapeways, and there might be even some on Thingiverse if you have the capability to print).

Obviously I prefer a combination that keep the particularity of the rims diameter difference which is key in the Samurai design.

Now that being said, you should also consider that the tires are participating to the dampening, and changing the size of the rear tire profile may lead to some damage to the shock towers... The best options is maybe the one using the original rims and tire sizes.