TOPIC:

I have 2 Mercury at home currently. The one from my friend and mine. Both have deformations in the chassis, making the measurement difficult. There is still some new parts available somewhere in France, and even at reasonnable prices. I decided to order a chassis, and few other additional parts... They arrived yesterday.


That should allow me to work this out more easily. Unfortunately, no shocks. I will try to find some at some point.

I decided to open and model a diff this morning.

First removing the e-clips and ball bearings


Then, 4 screws and it's in parts


The center part is a bit complex...

It will require to identify the number of tooth of each gear, the module. And from this, center will be defined by the geometry, and by gears center distance...

No difficulties for the gear with the plugin inside Fusion 360, they are in module .5 (metric) and the number of tooth is 14 for the outputs and 10 for the two internal gears... I took note of the interdistance between 10-10, and 10-14 and draw a sketch to start to work out the center part of the diff...


The other side is using a similar drawing but is moved as the two internal gears are working togther in the center... Once this piece is done, the other parts are super easy.


It's actually very difficult to show... But I tried to do something



The center piece is also including a side for the belt. MXL025 format, like on the 44B chassis, 37T around the diff.


Once there, I added the ball bearings, the pins, the outdiff and the eclips, and my diff is built (and the real one rebuilt )


Front and rear diffs are the same, they are just inversed. That is also saying there is two belts, and I will also need to see the center diff. But that will be for later...

After the diff assembly, there was an easy part sitting on the desk...


The diffs are mounted in excentrics, and those are used to set the belt tension.


After that, I started to look at the shock towers.


They are obviously highly complex. It requires boolean, and the geometry will be difficult to work out... I made a quick draft for the front shock tower (right side), and I can already tell there will be a second attempt.


This is the type of parts you need to do assumptions about the things. And you have to check at the end the assumptions made about the geometry are right. And in that case, I definitely need to review some of the initial assumptions. In short, the part is not complete, and I'll probably have to redo it from scratch (and it's also probable that I do the same for the chassis halves)...

This afternoon, I did work out the universal shafts... All jointed, with the possibility of movements as defined in Fusion 360. That's much better than when you play with dogbones and try to figure out how to joint them so they actually work with the suspensions...


Those things have a huge amplitude...



I also added the wheel driver


That was fairly easy... There will be 4 of those on the chassis...

Spoiler, I decide to let the difficult parts at the end. Rationale : it allows to have the impression to move on, and I needed some success and to finish some parts, because that's too long without finishing parts... Will focus on the central differential next.

In order to change a bit, I tackled the front shocks today... Spoiler : they are quite complex.

I've put it to parts first.


One thing that caught my attention is the shock piston, which is unusual, at least for me... It's made of multiple parts, and it is quite smart... And I'll try to show why


I modeled the piston and it's parts...


And then I modeled the shock body. There is a slider in it for one of the piston part...


The principle is simple. The disc has a split on one side, and the second part is sliding in the shock body. If you turn the shock body, the small part turns compared to the disc and opens or close the disc opening. I tried to represent this in few pics...




On the top cap, here whitout the hook (which is turning inside the cap), you find numbers. 0 corresponds to the closed opening, while 9 is going to be the highest flow rate.


Both hooks are fixed (top on the car and bottom on the suspension arm) and the shock body can turn around the shock piston, allowing for a smart setting of the suspension dampening effect...



I found it quite interesting

The first variable damping shock. Serpent used a close system 10 or more years after....

I tackled all the remaining transmission parts... Nothing difficult with straight pinion. This is not like bevel gears, it is easy...

The central diff includes a central gear, to satellite, and internal gear running around all of this.



The shaft act to transmit for the front side, while the rear part is transmitted around the shaft. This is a rather interesting setup...


I will have to finish the chassis modeling to be able to show this in place...

Having 2 chassis which were used and a set of NIP chassis halves, I had a bit of comparison of the chassis. Either there was 2 versions, either one has been cut to allow battery compatibility. I'll have to recheck the chassis from my friend...

In anycase, I move forward to finish the right part of the chassis.

I started by the center piece (which was already highly detailed in my sketchs, but required some review, specially when the NIP part is slightly different (and the way it is designed is now making more sense to me).


Then I moved to the front area, where I had to add the mecanism for the steering and the arms attachements.


I also added the arms attachments at the rear (yeah, boolean mastery )


Finally, added the body mounts and the slot for the centering of the chassis...


When there, I contemplated the positionning of the diff with the excentric part...



Then, the left side of the chassis took a few minutes to complete... I started with a mirror, removed the details which were not required and applied the modifications that were required at the left side.



And here we are, we have the chassis ready to receive the transmission... That was good progress, and will allow me to move forward to next parts, and probably start a bit of assembly

Once the chassis, is in, we can play with then transmission...


I started to put the diffs in, then brought the transmission in the design, and noticed I need bearings... Thankfully, they are not much cost in CAD


I added the bearings in, and started to set everything in the right place... After some work, it looks like this...




The center diff  looks like this while we hide the main gear...


Now, it's clearly crowded inside... And since it is difficult to have some springs washer act as spring washers, there is some collision inside my diff... Yes, it's clearly complicated


Another view of the elements (belts will be for later).


I tried to play with motion links to be able to see the movements of the central diff, but I could not get it work, so I decided to give up...

Impressive!

Today, tackled the bumper first... Not much complexity, as it derives from the front of the chassis for the profile and the position of the fixation points...



It was directly added in the overall chassis assembly...


Next was the shock tower. I decided to drop what I did few weeks ago, and restart from the chassis side...


After not so long, I got a part...


But then I noticed I was missing some details. Apparently, there was an option for sway bars... Which was not complex to add to the part, but still it's something I had to do...


Here is the front shock towers on the chassis...


Next, I worked out the rear ones...
First, I draw the side of it, then did some extrusion, and went for a cut of the unneeded elements...


And repeated for the middle plane on the half top side...


Then I took care of the top of the part, which is supporting the wing...


And finally, added the sway bar attachment...


The chassis is now having the shock towers...
 

What is still left to do are the steering components and the lateral decks...
But most likely it will be after Christmas... Merry Christmas to all