Hirobo 44Bs and Zerda :)

[silvertriple]

I wondered if it was moulded or hot pressed out of sheet. Reliant on the upper belt cover for some stiffness. On one zerda I have some metal angle reinforcers on the castor angle. I don't think they're in the manual. May have been an afterthought accessory or third party mod.

Looking at the fixation of the roll cage, it was definitely injection molded...

[silvertriple]

On Thursday, after some Fusion360 issues, I started to put my Zerda parts together. It's somehow mandatory to be able to tackle the belt cover part, the top deck and the roll cage.


And then I started to work the belt cover. First with a projection of all the part, a few extrusions and sketchs later, It was there...


The fact is that with the slots rather than plain simple circle holes on the front of the chassis, you have to take into account for the possible range of possibilities for the belt cover to fit in. Apparently, looking as some measurements at the front they did, but the single fact the front fixation point is not a slot shows they did not went to the end of the thinking (i replace the circle by a slot)...

I then continued to put the part together...


But there was a problem...


It seems I used a wrong reference point to measure the front of the chassis (I actually measured it under the chassis, while I sketched the inside of the chassis). This is a mess
But it was actually worse than this. Even modifying the timeline, I was not able to get my chassis back together because the shell did not work anymore, and I did not understood why (sometimes it happens).
Long story short: after mutiple tries, I started back the chassis from scratch, and replace component in the file so I can review the belt cover...

It took me a few hours to deal with this. This morning after midnight, I finally had my chassis and belt cover together and lining up where it should. &nd I continued to put parts together...


Then I tackled the top deck (it's bent, rather than flat on the rear side, but it is how it should be).


Next I tackles the roll cage (with the position of the front brace deducted from a picture provided by my friend Ryo)


Here is where I am, currently.


Remaining part left :

• front shocks supports, and the brace linking them

• Number plate and support

• Zerda C-hub

For all the other parts, I have them already... This should not take much time

[Dadio]

That's bad luck with the chassis , sometimes there's just no fixing things and with Fusion you often don't know why you can't fix it ? Glad you get it done in the end , it's looking good
One day your going to have to computer animate a race between all your CAD model cars

[silvertriple]

That's bad luck with the chassis , sometimes there's just no fixing things and with Fusion you often don't know why you can't fix it ? Glad you get it done in the end , it's looking good
One day your going to have to computer animate a race between all your CAD model cars

I saved the file... I don't like when I don't understand, so I'll retry differntly later. I don't mind breaking the initial file as it doesn't have any more dependancies in the design...

And for the computer animated race... may be that cost less in parts

[silvertriple]

There was few parts remaining to deal with, and in particular the C-Hub...

I decomposed it in few parts I modeled and then assembled the bodies...





After the assembly and body removal, here is the result



I did a last adjustment (after the mirror, and replicated the same with L on the left one)


Then I pusued the assembly (the front shock tower was not finished, but I needed to check something)


And actually I had two mistakes on the roll cage


Which I corrected quickly...


Then I completed the hideous front bendable towers


Remains to do in terms of models :
- the belt cover and the rubber glove which comes with it.
- the shocks (I need to check the dimension again and what I have in the parts...)

I also need to add the suspension arms to the car to finish it, but I may keep this for later...

[Dadio]

Again the hub carrier is fairly complicated , doesn't look to bad at first until you really study it , I remember several attempts to get the cut out for the knuckle steering arm right .

[silvertriple]

Again the hub carrier is fairly complicated , doesn't look to bad at first until you really study it , I remember several attempts to get the cut out for the knuckle steering arm right .

It's fairly complicated, yes, but once decomposed it i's fearly logical and easy (seems my brain is wired to work out booleans, I see the parts this way, actually when I look at them, the plan to build them is just a derive of this at the end...).


I've added the knuckles and pivot already, and they work as expected with angles fairly similar to what you obtain with the real assembly, so I should not be very far from it...

[silvertriple]

Yesterday, I also modeled the number plate and their support


This morning, I decided to deal with my last key part to model (all other parts missing in the assembly have a existant occurrence in one of the models, being the Bearcat SS or one of the 44B, shocks put aside): the pulley belt cover.

I have one new and one slightly damaged, and the parts assembly fusion 360 as reference.

First I set everything I need into one single file, and set one single sketch to define the key elements.


Then, there was two possibilities :

• model it as it was provided by Hirobo. I doubt they all the element so clearly established in a 3D plan at that time, and their approach was likely very empiric, with large tolerances. The way it is make it is in no way watertight or dirt tight, not sure this is the good option

• Second option is to make it in a way it will work better for that aspect, which is exactly what I'm going to try to do here

THere might be few details still to deal with here, but it may look like this at the end...


Or with the tie rod sock (targeted for rubber resin print - 1mm thickness)...


I made it the pulley belt cover1.5mm thick, so I could consider a proper printing (transparent resin maybe a possibility). Ultimately, it would look like this, with the upper part taking over the gearbox to make it as close as possible...


Need to deal with the shocks... I'm missing few informations to be able to complete them :

• piston length front and rear

• shock bodies length for front and rear

If you have samples and could do the measure, it would be helpfull...

[silvertriple]

I put additional elements inside the model...

Arms, upper arms, hub carrier and wheels


Once there, I could not stand the white rims, and dyed them in red


It is obviously better this way

Then I focused on the rear. I adjusted the slot position for the ubber sock on the belt cover. It is now fine and the arms can move up and down without risks to collide with the cover... The rubber sock looks weird in this contect. but I won't play with more joints to get it working properly (the modeled part is not flexible, while in reality it would be, like the springs).


The upper arms required quite a bit of adjustment, another proof the guy who defined the lengths in the manual likely did not built the car (way too long).


I also added Steering servo and steering ords... It explains why the top deck of the zerda was recut to fit the servo head...


Still missing : shocks (I put aside the driver figure or the nuts and screws I did not add in the model).

Edit :
I moved the servo at the farest possible point on the rear. It's better, the steering rods length indicated are still off, and it stills collide with the top deck... I may modify the belt cover so it doesn't collide anymore, but that would mean a Zerda re-release

[threesheds]

The upper deck post triangular piece raises the deck and standard size servo usually fits. Have you referred to the
Options in the manual re deck bending and cutting recesses? But there's several possible mods to steering with different servo savers which might be improve with changes to the servo mount on the upper belt cover. I think the assymetric steering rods are frowned upon by many owners.
You've got the skills to redesign this aspect which might be helped by having the buggy built to original spec and looking at changes. My early posts show a different servo saver but I can only roughly modify with a hammer and nails!

[silvertriple]

The servo used as a reference is not a big one : it's pretty standard... That being said, I checked quickly with the chassis, belt cover and upper deck, and it almost collides everywhere, so the model is prettry much aligned with this, and the manuel as well

At the end, this looks like empiric fixing . somehow, I find it quite surprising, as on the 44B-LWB, they almost got it right. There was actually not much to do to make it right. And on the Zerda, they could have maintained a similar arrangement as well with the servo saver (except maybe if they considered the chassi was too flexible for this)...

Looking at the timeline, I believe the 44B-SWB came after the Zerda, as they made some pretty effort to get the servo head centered (another way to have a better geometry, even if I think the 44B-LWB with an additional lever on the left side with a secondary link would have been perfect...

[threesheds]

Shock data.
Piston shaft lengths 41mm and 33mm x 3mm
Piston head 7.5mm dia
Cylinder barrel 38mm plus 8mm fixing head
Dia 10mm wall thickness abt 0.5mm
The oil passing around the piston instead of through holes is a poor point in design. So is the method of fixing seals in the cap. And shafts wear by rubbing against the cap.
Anything else just ask

[silvertriple]

Thanks,
I just landed home after a week of work travel, and I will use this tonight.

[silvertriple]

thanks to @threesheds, I have now some nice shocks for my Zerda


I put them on the car next. Apparently, It really needs a pivot ball... and Fusion 360 doesn't like my joints (I did a shortcut and did not put screws in, and apparently, it would need again something else than a revolute joint)...


Not much an issue, this virtual car won't run, even vitually

For the Zerda itself, the target is to get it running, but the idea is to rely on Kyosho legendary series shocks...

[silvertriple]

I've been very quiet today... This is because I spent most of my time today in Fusion360...

First, I adjusted the walls of the 44B bath tub to get them lining up with the belt pulley cover... The fact is, it is really easier to mesure on the Zerda, as there is no différence between top and bottom distances. I was sure for the Zerda, but not so sure for the 44B. This is now lining up properly.



I included .5 recess where the holes need to be done to line up with my belt cover (I still need to do one minor check on the pulley belt cover and the front profile of the rear gearbox... I'll do this at some point when I can use the printer...

After this, I started something else. I have no body shells for the 44B, it is time to make at least one. I've decided to work out one simplified for the Hilux (I have not much hope to find one new or repro).

Started by the front


It is a bit brute, and it's not possible to do more than this with my method (relying on solid and shell), as the shell doesn't work when I apply fillets... That being said, I may use this to set a basis for a mould.

After a lot of work, I finally got something looking like a bodyshell...


And I can even put it on the chassis


I then took care of the accessories I have at hand


Then ther was the roll bar I did it based on proportions I saw on pictures...


At the end I applied esome materials property, and I had my bodyshell ready to put on the car.


And some pics to end this :





That was fun... The bodyshell at least allowed me to do this. I still have a part somewhere to model : it's the motor rubber cap. Looking at how complex the exercise to build such a bodyshell, I'm not sure I'll model the Rock'n City bodyshell (especially considering that I don't have it in hands)... Next ; print tests and rebuilds (no ideas about when)...