nowinaminute

Nikko F150 twin 540 motor MT Project.

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I love these trucks, the family started off with the Hawg which was a 1/10 monster truck with twin 380 motors and it went on to be the Midnight Crusher, Black Thunder and perhaps most famously the Thor.

The design is in many ways the equal of contemporary hobby grades. New Bright these ain't. The materials and overall design owes much more to the hobby world than it does the toy world. The front double wishbone suspension trumped many an entry level hobby grade monster truck back in the day and the transmission design and quality was very close to your typical Tamiya kit. These trucks came with digital proportional control, interchangeable crystals and took a standard size 7.2v pack. It could easily be argued that these trucks were similar to a hobby grade and just happened do come off an assembly line. They even had full parts support back at the time.

A few years down the line Nikko decided to make a new version by apparently feeding the original truck steroids so the motors grew to 540, the wheels became nearly clodbuster size, the gears were changed to nice chunky mod 1.0 jobs and the spur gear is a novel two part design with internal springs to act as a protective buffe. And of course, the customary huge Nikko bumper got even more ridiculously large.

The result was a big and sturdy monster truck with a surprising amount of power, a tough drivetrain, good ground clearance and off road ability lightyears ahead of anything else on the toy shelf.

This later range of trucks including the "Power 2000" and "Hercules" were the most formidable trucks Nikko ever made and they have bags of potential but one major facepalm of a weakness: You can't fit standard bearings. The older high end Nikko stuff was much more bearing friendly but these trucks have plastic bearings that don't match any off the shelf item.

That's where @Granddad Stinky enters the game with his mad lathe skills! 

I sent a few of the cast metal parts off to him to see if he could reduce them slightly so that standard bearings could be used, if only on the outer axles where the plastic bearings do the most damage by trapping dirt and becoming grinding stones. 

But the more we talked about it the more determined we became to go the whole hog so I recently sent an entire front and rear gearbox off to him so he could try and work his magic.

That pretty much brings us up to scratch, I will update this post and fill in all the missing details when I get more time but the basic aim to to fit real bearings where there were once plastic ones and prevent the truck from slowly eating itself. At the moment I'm terrified of taking them to the beach an places like that even though it's where they are the most fun!

They have so much potential but with spares being thin on the ground to say the least it would be a massive bonus to switch to bearings and not have to worry about parts wearing themselves into oblivion!

It goes without saying that massive props are due to the talented GS, at this stage I'm pretty much just the guy with the vision, throwing Nikko parts and bearings at him and relying on his impressive problem solving!

So fingers crossed he can come up with a workable solution, the rear gearbox is relatively straightforward but the front might take a little more creativity!

Stay tuned!

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There were essentially 2 versions of this later truck. 

The was a "1:8" scale version with the standard wheelbase, this came in both RWD and 4WD versions. The RWD version simply leaves out the front motor and gears. The single motor version is more common than the twin motor, presumably because it cost significantly less.

EfgMsiU.jpg

Then there was the "1:6" scale version. The same chassis but with a plug extension in the middle to elongate the wheelbase. These came with either a Ford F150 body or a Hummer body. As far as I know these only ever came with RWD but converting them to 4WD is child's play and just a matter of swapping the empty front gearbox with one from a 4WD model.

xFKMD7L.jpg

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The original Hawg rear gearbox design was a little easier because the axles were one piece from the diff gear all the way to the wheel, pretty much like a Tamiya Lunchbox etc. But these later trucks have 3 pieces. You have the diff then a hexagonal bar and then on the end of that is a metal stub axle which goes through the end of the gearbox casing for the wheel to attach to.

Where the original models and Lunchbox etc have two bearings/bushings (1 at the wheel end and 1 and the diff end of the axle) these trucks have 3 (1 at the diff and then 2 down at the wheel end, 1 on the outside and one on the inside to support the stub axle and also to stop it sliding out (the stub axle has a lip on the inside end)

This picture shows the approximate stock setup (proportions are way out)

JxPeap2.jpg


My original goal was to just replace the outside bearing, that's the critical one because it's open to the elements. No matter what you do there's going to be wear on the stub axle because with the stock plastic bearing the two parts rub together by design. If you leave it as it is it will wear down the bushing then dirt can get in and the dirt embeds in the bushing and turns it into a grinding stone and ruins the metal axle! If you use grease it would theoretically stop the wear but because it's on the outside it traps dirt and grit etc and before you know it you have the same issue.

At first I was happy to just replace that outer bearing, it meant no more wear there ever again and it would also totally prevent dirt/grit/sand from finding it's way deeper into the box. With no dirt present you can use grease on the inside and make the parts last years. Every time I've stripped down a vintage hobby grade with plastic bearings the inner gearbox ones have usually been ok, it's the outer ones that are exposed to dirt that take a beating. This is the work GS did originally to simply allow the outer bushing to be replaced with a bearing:

fj2TaB9.jpg

After talking about it a while we grew more ambitious. I figured it would be relatively easy to replace the inner bearing too so I came up with this which we both pretty much agreed upon:

JcLVkzY.jpg

That takes care of the outer bearings. Then you have the third inner bearings that sit each side of the diff. This part was a lot easier. An 8x12mm flanged bearing fits right into the stock bearing carrier:

lP9CgNN.jpg

And then the metal "drive stubs" on each side of the diff need just 0.3mm taken off to fit inside the 8x12 bearings!

XPy83SM.jpg

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So far, so good! that leaves just one thing to look at in the rear gearbox, the spur gear.

Unfortunately this became a bit of a sticking point, the gear doesn't have the provision for bearings at all, not even irregularly shaped plastic ones. If the gear was one solid part it would have been easy enough to just cut bearing carriers into each side but this gear is in two parts because it has that awesome shock absorbing mechanism.

At first I thought it would be easy enough to do, just cut a seat into the solid side of the gear and then on the other side there's a sort of tube with a locking disc around it. I thought we could cut the tube down:

f9iEpP9.jpg

And then fit a bearing in the space once occupied but the tube kinda like this:

PGN69kC.jpg

But it had been a while since I took one of those gears apart and I had forgotten how thin that disc was, I don't think it would be substantial enough to hold the bearing by itself and take the entire load on that side of the gear. GS very much concurred with this notion so the idea was abandoned.


At this point I was happy enough to just leave it as it was, there was no way any dirt or crap was getting inside the box now so it should be good for years with some decent grease.

But GS had other ideas, instead of cutting bearing seats, make up our own plastic bushings. Not as good as a real bearing perhaps but it still gives you a sacrificial surface that can be replaced if and when it wears out. His idea is to make a bush for the outer 1/3 on each end of the gear and then pack the inner third with grease to help keep it all lubricated. 

He's going to use Delrin plastic which is super durable but smooth too. It's often used to make actual gears so it seems like it should be good enough to act as bushings.

This is sort of roughly how it would be, bear in mind I'm just trying to visualise what GS is telling me so it may differ somewhat in reality but hope it's near enough:

mwp7ilu.jpg

So, as a result of all those mods there would be bearings throughout apart from the spur gear that will now have sacrificial bushings. And in theory, because there will be no dirt present the plastic bushings should wear away without causing damage to the metal shaft. But even if it did, the shaft is just a plain 5mm rod so could be replace if need be. 


This all basically means that the level of wear will be greatly reduced and the lifespan of the gearbox will now be limited only by how long the teeth on the gears last which should be a good long time as long as they are greased and grit doesn't get in there.

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That's the easy part! 

The front is a lot more difficult. The outer drive cups were a piece of cake, the cups just needed to be reduced to 7mm so 7x11mm bearings could be used on the steering hubs/knuckles/hub carriers or whatever you want to call them.

2uqlhC1.jpg


Everything inside of the gearbox, however, is a PITA! And I personally can't see how do to much without some pretty nasty butchering. This is where I'm hoping GS will pull something out of the hat! 

As with the rear, the most important thing to me is those external bearings. We have the outer ones sorted on the steering hubs but the ones where the inner stub axles go though the gearbox case are going to be tricky because the dimensions of the standard plastic bearings do not come close to matching any off the shelf bearing.

And because of how the inner drive cups are designed, the bearing has to be pushed on over the actual cup because there's a lip preventing it from being pushed on from the other side.

Out of all the metal parts you wouldn't want to really take a lathe to, the drive cup has to be pretty high on the list!

Up15Hy7.png

My first idea was to get a bearing that came close to the inner diameter of the stock one but was 15mm outer vs 13mm of the stock item. This would mean having to bore out the hole in the gearbox by 2mm which would bring it perilously close or even cut into where the suspension arms attach. GS thinks this would be a bad idea and I agree.

FOj6IUs.jpg


So I went back to the drawing board. This is how the part looks in stock form, the red part is the stock plastic bushing:

gvsGleL.jpg

 
So I thought perhaps we can get rid of that pesky lip completely and machine the part down on the other side and avoid taking anything from the cup end:

5SggZnF.jpg


Then you could put on a bearing with an out diameter that matches the hole in the gearbox: No need for butchery!

In this pic the red represents the bearing and the purple would be a metal sleeve to do the same job as the lip did originally:

jGpgRKr.jpg

This is pretty much as far as things have gotten. I don't know if there's enough "meat" on that part to even do what I'm thinking of. And besides that, it wouldn't surprise me if GS came up with a completely different and superior solution that involves half the work anyway!


At the moment he's still working on getting everything together on the rear box so the front box is a little way off for now.

That's pretty much where things stand, as GS feeds info and photos to me I will post it in this thread!

Thanks for looking!

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Update time!

The diff bevel gears needed just a little shaving so that 8x12mm bearings could be used in place of the stock plastic bushings:

oqbXG7z.jpg

8HiPtFK.jpg

The spur gear was a little trickier. There's not enough "meat" there to add recesses for bearings so instead GS came up with replaceable bushings made from Delrin plastic which can be replaced as and when needed:

uWomNu9.jpg

noRpX3e.jpg

PJzCknY.jpg

That just left the part where the stub axle comes out of the gearbox casing. The outer bearing was easy enough, just reduce the stab axle a little so an off the shelf 8x13mm bearing can be used in place of the stock bushing.

The inner one was trickier because the stock bushing is tiered and has two outer diameters. GS put his thinking cap on and came up with a bearing carrier that matches the outer profile of the stock bushing and carries another 8x13mm bearing. Genius! 

6oyhu1Q.jpg

9obVQyk.jpg

954Dz3F.jpg

nNCkSYd.jpg

Q8c1RgM.jpg

That's the rear gearbox done! It will soon be back with me for testing. That's the easy part done with!

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I have completed a test run with the GS spec rear gearbox and it went brilliantly! Smoother, quieter and even seems to get off the mark a little quicker. And of course it is now essentially grit/sand proof so I can run it on the beach till my hearts content! 

I'll try and get some video of it in action soon.

GS is now working on the front gearbox so I can have the same benefits with the 4wd version too. Looks like the front end is going to require some more creativity but nothing he can't handle I'm sure. 

It really is great to know that I can run these trucks without all the wear associated with plastic bushings now, the beach especially as it's one of my fave places to run but causes the most damage to anything that doesn't have bearings. 

I'm hoping by the time summer comes round I'll be able to put twin brushless motors into one and get some cool pics/video of it kicking up big rooster tails in the sand!

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Here's a video of the gearbox in action:
 

I often run it with a 20T brushed or a 3100KV brushless but that's with a lexan shell. I felt it fitting to use a Nikko shell for the first video and to combat the extra top heaviness I downgraded a little to a Tamiya torque tuned. Still gets around quite nicely though!

It works great! battery life seems to be better and it coasts for way longer off the throttle. And best of all I can kick up dirt and sand etc without grinding all the metal parts to dust!

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I still need to pick my jaw off the floor before I post more details but GS has got the front gearbox figured out now too, he just sent me instructions of how to assemble it on my end. I'm really amazed by how he's managed to solve this tricky problem. I can't wait to try it!

These trucks are so fun to drive and while they are obviously not going to give a Traxxas sleepless nights I genuinely feel like they are in the same ballpark as the simpler Tamiya and Kyosho models. The only thing really letting them down was Nikko's decision to abandon standard size bushings any by association, the ability to ballrace them. But thanks to GS that issue is now a thing of the past.

I can't wait to try out the front gearbox and have a fully ballraced 4x4 version!

I have an ambition before the summer is out to take the massive 1/6 one and fit two brushless motors as a sort of one off and get some epic video and photos at the beach. I highly doubt I'd use twin brushless in day to day use, not so much because of build quality concerns but because the chassis is too simplistic to cope but I think at the beach it would be enormous fun, everything handles well at the beach, even my Grasshopper lol. I'm thinking golden evening light and enormous 4 wheel rooster tails!

I'll post pics of how the front box was done soon. In the meantime, here's some pics of one of my trucks at the beach in RWD configuration using the GS Spec rear box:

rl6Ggru.jpg
QW3rIho.jpg
VTbNKMe.jpg
ZlyvmHW.jpg
q12E3s7.jpg
d1UehtI.jpg

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Ok, it's time to try and explain what GS has accomplished with the gearbox, these are his photos which he sent me just so I'd know how to put the thing back together! It has been pretty dramatically re engineered.


First of all, an overview of the parts. You'll notice that the drive cups/outdrives have had the lips machined off as I mentioned in a previous post. That's about as far as things went in terms of me guessing anything right lol!
C63cuf1.jpg

First of all, the stock outer plastic bushing is kept in place but is no longer load bearing radially, it's purpose now is to keep everything spaced correctly axially.
3xQZpaV.jpg

Next up we have a new bearing and a custom made bearing carrier. The bearing is inserted into the carrier and then the carrier inserted into the gearbox in such a way that the bearing is sandwiched between the new carrier and the old plastic bushing.
BAFS0SG.jpg
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This means the outdrive is now supported by a real bearing which will also prevent dirt getting into the gearbox. No more metal grinding against plastic! The old plastic bushing no longer supports the outdrive radially so if any grit gets that far, it won't be grinding away between the two parts like it would before and the new bearing will prevent it getting any further. This part alone left me feeling pretty pumped because my main reason for wanting bearings at all was so I didn't have to worry about parts grinding each other to death!

What came next really had my jaw on the floor though!

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The very first step with the diff is very similar to the rear end, the stub axle or what have you has been reduced slightly so that it can accept a bearing:
2qLT6yH.jpg

Once the bearing is installed, the outdrive is inserted into the diff stub axle thingy:
q0GmiZW.jpg

But the retaining lip has been machined off of the outdrive so there's nothing to keep it located axially. Well it was at this point in reading the instructions that a little pee started coming out of me.....

We now slide the bearing onto the outdrive to reveal a 2mm hole, there's a corresponding hole in the outdrive too:
NKBLYSL.jpg

Insert a Tamiya hex pin and then slide the bearing back accross:
dHp98Y6.jpg

Repeat on the other side and you now have the outdrives locked in place axially by pins which are held captive by the bearings :o:oB)
MLQ80O1.jpg

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And in another stroke of genius, the stock inner bushings are also re-utilised as bearing carriers, making the perfect translator between the new bearings and the original gearbox housing!
keq6f9d.jpg

The diff and spur gear are then put into place, as with the rear end, there isn't much scope for ballracing the spur gear but now that dirt can't get in it's not a really big issue as long as I keep it lubed. And if the bore ever does wear oval shaped like it did on the rear spur, GS can make some replaceable delrin bushings like he did on the back end.
sAMouum.jpg

Et voila, one ballraced, dirt proof front gearbox!
OvYF2vi.jpg

I've already tried the truck a few times with both boxes, it definitely seems to get a little better battery life, accelerates a little better and coasts for much longer now that several points of friction have been eliminated. Most appealingly to me though is that I can use it on dirt and at the beach etc without feeling like I'm taking a big chunk out of it's lifespan every time.

Finally this truck can live up to it's potential. Maybe one day an old Japanese RC designer will browse youtube and recognise his offspring, finally fully realised like he probably intended before the bean counters "streamlined" the design and the factory in Singapore inflicted their QC on it!

Hopefully more video and photos to come soon of it in action with both gearboxes.

Next milestone will be to get the long wheelbase version working on 2 ballraced gearboxes too! 

I want to make a little "GS Spec" sticker to put somewhere on the truck too, such impressive re-engineering deserves recognition!

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It looks quite good when you look back through the photos, I'm glad it all working out. 

GS Spec? 😂🤣☺️☺️

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Very nice work and inspirational! So much so that I have started taking apart my Nikko Thor to modify it!

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32 minutes ago, Bvtrinh said:

Very nice work and inspirational! So much so that I have started taking apart my Nikko Thor to modify it!

Another build thread approaches. 👍

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On 6/13/2018 at 12:14 AM, Bvtrinh said:

I started a new thread here: 

 

Holy crap I missed this lol

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Apparently I forgot to post this video 7 months ago. Only the highlight of the entire thread!

This video features the truck with bearings in both the front and rear gearboxes. Running two Tamiya torque tuned motors. Towerpro MG996R servo, cheap Chinese esc with dual motor outputs and oil dampers from hobbyease
 


 

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13 hours ago, nowinaminute said:

Apparently I forgot to post this video 7 months ago. Only the highlight of the entire thread!

This video features the truck with bearings in both the front and rear gearboxes. Running two Tamiya torque tuned motors. Towerpro MG996R servo, cheap Chinese esc with dual motor outputs and oil dampers from hobbyease
 


 

Look at that thing go, great video. Handles really well! 

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On looser surfaces, it handles surprisingly well considering how archaic the rear suspension is. I think the front end does most of the hard work and the rear is just along for the ride lol. Mind you, with the super long rear arms, it seems like the rear doesn't lock up quite as bad as a Grasshopper/Lunchbox design does. It still locks up at full throttle but it seems to start working a little when you're at 50% or lower instead of needing zero throttle to actually work.

On grippy surfaces, it's top heavy and prone to grip rolling but hey, that's what monster trucks do, right? :D

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It’s always fun to see that beast in action! I especially liked the slow motion around the turn as it appears the truck was drifting! 

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On 2/2/2019 at 2:09 PM, Bvtrinh said:

It’s always fun to see that beast in action! I especially liked the slow motion around the turn as it appears the truck was drifting! 

You can indeed sort of drift it on dirt. Not quite fast and furious style but if you let off the power so the back steps out then quickly hit the throttle again you can get some nice power drifts out of it!

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