Hirobo Bearcat SS - Let's start something else...

[silvertriple 3558]

Long pending update...

The model did not correspond perfectly to what I had in hands... I had few review of dims, more than once without finding the culprit...

In the car I had some standard servo which I'm used to have on many cars. This time I took the servo (Graupner C505) and measured it... And in fact, the servo I used as a reference is not proper. Servo length is too long (about 1.5mm) and the servo head is in real more closed about the left end by 2mm...

I'm assuming I searched for nothing and my model is correct...

Few details remain to do : making sure the walls of the gearbox are printable (I need to make sure I have always 1mm thickness everywhere), and review the diiferential case as I have a small doubt (I need to make sure it is right as it is the same for both Zerda and 44B (I don't have one yet, but I hope to find one at some point)...

Once this will be done, the files will go on Thingiverse after some prints for checks...

[silvertriple 3558]

I don't know why I got this appearing in my items proposals on Amazon, as I did not searched for that whil looking for some cables for the printer... But it appears that pulleys are easy to find in 20T and 16T GT2, and it is the same for timing belts in GT2 in different dimension... That may be a very good reason to consider doing another diff and another Pulley in GT2 format for our Hirobos...

[silvertriple 3558]

The gearbox halves were not printable in their original state if I refer the minimal 1MM thinkness requested by most of the printers

I reviewed the walls to get that proper.

And once done for the first half, I did it for the second one...

There is few remaining notes in my todo list :
- review the diff case : I have 1 mm doubt on the pulley position I will need to recheck
- find a solution for the top shaft bearings : initially the bearing (no ball bearings) are 6x15x5. There is no ball bearing of this size. I woulld think to do a 1MM thick printed washer (6x15x1) to complement a ball bearing

I'll do this later within this week, and once done, I'll extract all the stl files, unelss I decide to do a Powergrip GT2 version of the transmission, which means it will take slightly longer before I come to the stl extraction stage (not too much longer, that said :-)
 

[silvertriple 3558]

and to remove all possible confusion :
- ball bearings for the shaft in the gearbox 4x13x5
- ball bearings for the rear wheel axle : 6x15x5
- ball bearings for the diff : 9x17x5

[silvertriple 3558]

for the wheel axis, using the proposed method on rc10talk and flanged bearings in 6x10x2.5,

That will do it, and i'm likely to have just the bearing needed for this in one of my boxes :-)

Need to check if I need to adapt something for the shaft  4x13x5 bearings or not...

[silvertriple 3558]

Within the last straight line for the Hirobo Bearcat SS push to Thingiverse...

It's currently about finetuning and test print...

I started by trying printing a topdeck section to check my chassis measurements. The print failed multiple times, and therefore I stopped trying and just checked the dimension from the elements which were on the bed at the last fail.

Good news is that it is corresponding... I worked then on the printer to get the bed cleaned and to level it again to get prints working again. I still have an issue in a specific area of the bed that I can't explain, and it doesn't allow me to print the top deck as it hits that area...

I then printed the left part of the gearbox (not the modified one but the original one)

The target here was to check the correspondance with the original  right side of the gearbox : it matches and the inside dims are right as well. With the left side, I was also able to check the fitting of the motor plate (perfect), and the fitting on the chassis (perfect again).

I launched a print of the bonnet as I do want to see how it looks in real and how far it is from the original one...

During the prints I did work a bit on the differential : I wanted to check it is right, and rechecked dimensions. I won't print it now, but the diff should work. I'm planning to do a full Powergrip GT2 version of the gearset as well (should be printable even for the small pulleys in MJF PA12 glass filled).

Then I decided to focus on the front knuckles. The axle is inserted while hot with pressure. It works ok, but once you get a nut locked on it or too tightly torqued, it goes with the wheel once you are trying to unscrew it. I have a brand new set of knuckles but I want to provide  a solution for those who are not able to find new knuckles...

Basically, using a M4 bolt, we should be able to replace the axle easily. I reviewed the plastic part of the knucle to work with a bolt inserted in it...


Once this was done, I just reinforced by extending the diameter around the axle.

I may still do additionnal mods to include M3 holes instead of M2 for the pivot balls... But at least I made some progress today...

[silvertriple 3558]

The bonnet is printed, and while it is not perfectly exact reproduction, it would do it for any Bearcat SS, Bearcat or Tomcat owner without bodyshell (I did not saw any reproduction for those anywhere).

it would require a bit of finish and probably a print with a finer thickness, but it's definitely better than nothing. 

And would you consider this good enough?

[silvertriple 3558]

Files are now on Thingiverse : https://www.thingiverse.com/thing:5567895

I plan to update with PowergipGT2  gearset at some point, in addition to the files I put on Thingiverse today... Happy Hirobo Bearcat/Tomcat repairs !

[silvertriple 3558]

The weather was nice this afternoon, with a warm and sunny Sunday. I was outside, and I decided to start the clean up of the Bearcat SS...

First action was to put the bonnet, roll cage and rims in glanzer. I removed the stickers later on as I forgot that...

Then I focused on the rest... Plastic chassis parts, transmission and metal parts...

I have one suspension axle requiring a bit of massaging...

And I will have to find a solution to replace the suspension axle fixations... Some were missing. That said, I may have a solution for this

And the glanzer bath is working. I can tell as it becomes darker after one hour bath :-). This is there for at least 24 hours, perhaps more. I'll have a look tomorrow when back from the office.

At the end, the parts are definitely cleaner

Some good progress today...

[silvertriple 3558]

The Glanzer is miraculous. It made the job. The bonnet, rollcage and rims are back to their original color.

There si still a bit of work on the rims, and I need to check what I have to put on the rims in the tire department, but that should not be too much issues...
I guess I'm getting closer to rebuild this car :-)

[silvertriple 3558]

For the axle, i decide to use a tool. I believe I could have use a stone, but I just used a Hammer to fix it. 

I'm questionning myself on using the front original tires and rears from Kyosho Scorpion 2014. I'll try a method to get the front tire flexible again (not sure it will work, I got this hint from someone - i'll try tonight and we'll see). I have already a set of Scorpion's rear tires, and I'll have to order a driver on ebay to finish this car...

[silvertriple 3558]

Looking at the state of the tires, I had nothing to loose to try things (dimension from the Sand Super of Kyosho Scorpion 2014 are ok for both fronts and rears, which means I have a plan B).

Started the process with some general purpose WD40 applied in and out of the tires and some massaging so they absorb it. Then I decided it would worth to remove the paint and put the tires for 48hours in a glanzer bath (the same I used for the bonnet and roll cage). Remove the tires from the bath today, and rinse them with hot water and rubbed  to remove the traces of glue.

Here is the result so far:

Tires have gain some flexibility (a lot compared to when I started this). Once dried, I used some cyano to insert in the cuts (one of the front tires had a an issue on that aspect).

Next: another wash with hot water and soap, and then once dried another round of massaging with WD40... It seems it is going to work...

[silvertriple 3558]

I'm expecting some ball bearings delivery this afternoon. I should be able to start rebuilding it.
Here is the plate after the cleaning operations. Tires are still in progress, but I'm not sure I'll use them at this stage.

I started the shocks, as I don't have the bearings yet for the gearbox...

This step is done. The shocks are basically very similar in essence to Tamiya CVA, but the springs are way too hard...

I may change them later anyway for a set of four (Tomcat setup) based on Kyosho legendary series shocks (but not now).

[silvertriple 3558]

I finally got my bearings... I will have to get 4 MF106 for the rear axles tomorrow, but in the meantime, I can start.

Step one, put the gearbox together... I had to get help regarding the screws to be used as they are not documented in the manual (the car originally came with the gearbox assembled, and the screws are not even defined in exploded views). You may note that I used a new Motor plate. The original was bent, I unbent it, but it is still a bit bent, resulting in chassis torsion. Because of this, I decided to use a new one.

The Beaarcat SS manual doesn't really defined the way to adjust timing belt tightening. With the Tomcat and Bearcat, there was a set of parts (Hirobo TM-28) allowing for precise tightening of the timing belt depending of the pinion used. And by the way, it explains why there was two holes on the side of the slot for motor fixation.

The belt cover takes place. It's a new part again. I had to get one to confirm some of my assumptions : my Bearcat SS came with a bent motor plate. The belt cover was bent on it's under side. I model it without the bent as I thought it was coming from the bent motor plate. The new one confirmed my assumption was right.

Next is the upper arm plate. I simply turn it so the top side looks nice (there is marks on the bottom side, they were on the upper side before).

Rear arms assembly. You may note if you know the car that I did not assembled the carriers due to the missing bearing I'll get tomorrow.

And they joined the chassis... And here I just noticed a half millimeter discrepency in my model for the chassis, as the distance between the two fixation holes is reduced from .5 millimeter from the rear fixation holes which result in a bit of toe-in on the rear side (I will have to correct this).

The upper arm plate joins the chassis, just before the gearbox. I added the upper arms here, because there is no way they get in place without removing the belt cover (I'm not sure the guy who have written the manual build the car :-) )

I added the rear shock tower next, before my wife asked me to free the table...

Next steps will be tomorrow, hopefully...

[silvertriple 3558]

I had hope to find some MF106K bearings today thanks to a friend at the club, but it did not work... I've ordered some. In the meantime, i've taken bearings 6x15x5 for the rear axle carrier to continue this build...

The wobble is definitely present, and the MF106K bearings will allow me see the difference when they arrive (mid November).

I quickly installed the carriers and upper arms and went back to the instruction manual sequence... I did not succeed to get the dog bones as clean as the rest...

Which means next come the rear shocks.

Rear end is almost finished, which means we go on the front. The weight balance is clearly at the rear end. On the front we start by preparing arms support and front arms and we assemble them.

and they join the chassis. two screws are used at this step for each side and it will be completed with a third one when adding the bumper at next step. I had to change the bumper screws by metric ones as the thread was dead on the left side...

After the bumper comes the monoshock. I just noticed than I have missing damper bushings and it explains some issues I had with the rear joints while I put the rear shocks in the model. I temporarily used nuts to solve this.

Next is the front uprights... with some M2 balls... I kept those like this for one single reason : I'll put an old vintage servo with palstic head, and it's probably better for its survival :-)

Next is to put all of this in place. The tie rods will require some work : they are too short, I'll have to replace them...

And comes the steering servo, and the very bulky servo saver, installed on top of the servo horn...

The servo is installed under the top deck with double face tape and some plastic collars. I installed the receiver as well.

And all of this joins the chassis, in which I installed the ESC. The motor is not plugged yet, I need to install some connectors at the end of the cables...

And we are almost there : it's now time to get the side of the roll cage mounted... Ilooking at the screws, I decided to use M3  screws for the roll cage as a mix of self tap 2.6 and 3 was used previously.

The roll cage is the last part to assemble...

And we have a Bearcat SS...

Tires are not glued, they will be changed once I get the proper one. And the setting of the front is not good as I need to replace the tie rods... But it looks promising.

I will need to put all the stuff remaining in a small box. To be able to take benefit of the current big box to start another project (Zerda :-) )

[silvertriple 3558]

I shared recently my files with @optimaforeverand he applied some of his secret magic :-)
Here is a few pics he allowed me to share with you

On the real side, I still need to source a set of front tires, and some metal parts to replace the tierods to finish this car...

[silvertriple 3558]

As the Bearcat SS is not over yet, the box is not available yet to start something else... I'm not going to create a new thread to the Zerda until I actually tear down the car, and it means I need to have the box free for this...

But since the wheels are in a bag, next to my desk and i had a few minutes while some stuff was printing, I took measurements and...

The I modeled the tire as well. It's pretty simple, because it is quite similar to the one of the Bearcat SS in the design, except it is narrower...

At the end, I have a Zerda Wheel in Fusion 360

Hopefully the remaining stuff missing for the bearcat come soon, so I can start a new thread :-)

[silvertriple 3558]

Trimed the driver, put new tires on, change the rods that where too short... And it looks almost new

I still need to connect the motor, to paint the driver figure and add some some stckers and that will be done... But in the meantime, the project box is free, which means I'll be able to tear down two Hirobos :-)

[silvertriple 3558]

It took about 6 months!
The motor is connected, and I do not have any other car as silent as this one... Except that when I run it in the leaving room to check the trims, the dog is barking :-D

I still need to paint the driver figure. I intend to have this car ready for this season vintage events...

[silvertriple 3558]

Small step again... Really need to think how to make this driver figure...

Not sure yet about colours and decoration (yes I procrastinate :-) )... But this is required anyway.

[silvertriple 3558]

I did prepared the paint yesterday evening... But I just noticed that my black PS can was almost empty...

Today, once back from work, I decided to gamble on the fact that the can content was enough to do what I need and that was the case as the end... And the can is now really empty...

Few minutes later the paint is over...

I will perhaps add a few stickers, but I really like it this way...

[silvertriple 3558]

There was something missing on this car...

Added lettering on the tires, but was still unhappy...

So I decided to  add leds, and I designed led holders... The side one is printed in TPU, the rear one in ABS (and it relies on the same principles I already used in the past)....

It's much better with leds... But somehow this is missing a wing...

[silvertriple 3558]

Finishing touch...

Ready to run

[silvertriple 3558]

As mentioned somewhere else, I got a second Bearcat SS today...

It came with a box, the original driver, a few missing bits (steering rods - but I need to check inside the box), a broken bumper... Speaking about the bumper, there is an home made one made from a metal plate (3mm thick) which is quite nicely done but very heavy...

Maybe a way to reduce the willingness of the car to go wheelie with the sbsolute power of its 540 silver can :-)
 

[silvertriple 3558]

I had the TPU in the printer, ready to roll (and dried as I just printed a sample of 44B rock'n Vega Bumper), so I thought about printing a Bumper to replace the missing one for the Bearcat SS n°2.

The overhang makes it is not perfect...

But for a runner, that will do the work...