Ultima LWB

[XLR8]

Potential failure at the post screw location.
I noticed this as I was cutting the upper chassis plate but it was too late to change it.
I should have made this wider.

[Coelacanth]

I actually think you might be fine there...the upper deck "skeleton" shouldn't be taking the brunt of the abuse anyway, but you might get it a bit more sturdy by bolting it down with a countersunk screw inside a conical washer, instead of just a screw...that might disperse any vibrations to a bit greater surface area.

[XLR8]

I actually think you might be fine there...the upper deck "skeleton" shouldn't be taking the brunt of the abuse anyway, but you might get it a bit more sturdy by bolting it down with a countersunk screw inside a conical washer, instead of just a screw...that might disperse any vibrations to a bit greater surface area.

That's an excellent suggestion!! I was thinking about laminating a small piece of G10 in this area (as a kind of washer) but I like your idea much better.
I don't have any of those conical washers but I think I can make something similar on the lathe.

[XLR8]

Been making great progress and I have most of the new chassis parts finished.
Here's how I configured the lathe to make conical washers. This allows for all three operations (drill/countersink, chamfer, and part) with one setup.
The washers actually came out better than I'd expected. Pics to follow soon.

[XLR8]

Chassis parts are finished and have been assembled for a test fit. I’ve gone ahead and made some G10 shock towers to replace the stock aluminum ones (these will be dyed black).
The stanchions and bellcrank posts were turned from some 3/8” magnesium rod that I’ve had laying around then they were clear coated to prevent corrosion.
The "kickup" plate is 0.090" 6061-t6 aluminum bent 25 degrees.

In an effort to reduce steering slop, the steering tie bar pivots directly on M3 screws rather than on ball-cups (it seems that every ball-cup connection introduces a small amount of looseness into the steering system).

The bellcranks and tie bar are threaded then screwed together with some clearance remaining between the two parts. This is just a test fit but when these parts go together during final assembly, I will apply a small amount of thread lock just under the head of the screw to lock it to the bar and prevent it backing out. The screws will pivot in the nylon bellcranks. I’ve done this on a couple RC10 runners and it seems to work reasonably well. It’s important to use a sharp tap and thread the holes perpendicular to the part and parallel to each other so they don’t bind as they rotate. The resulting connection seems to be very smooth, spins easily and has no slop.

The front bulkhead from the donor car for this project was in very rough condition; some of the screw holes were stripped or oversize from a PO having used the wrong screws. I’ve filled these holes with JB Weld, drill and trapped them but the part still seems a little dodgy to me. I’m hoping to buy a new replacement bulkhead when the re-released Ultima and its spare parts become available.
A motor guard and a battery strap are next.

[radioactivity]

Nice Doug!

Attention to detail, Definition- When the color of your cad matches the actual color of chassis
I really like this build. Craftsmanship at its best, like always.

Chuck

[XLR8]

Nice Doug!

Attention to detail, Definition- When the color of your cad matches the actual color of chassis
I really like this build. Craftsmanship at its best, like always.

Chuck

Thank you Chuck.
I probably enjoy the design process as much as the actual build so I tend to invest more time into the 3d model than is really necessary.

[XLR8]

The motor guard is finished (.060" aluminum).
I have an original Ultima motor mount plate but it's bent and has a stripped screw hole so I've gone ahead and made a replacement using the same .090" aluminum plate material used to make the front kickup plate.

A simple battery strap with some scratch-made thumbscrews.

[mikem65d]

Doug,
You do indeed do nice work.
I'ts a pleasure just to read thru this thread.
Makes me want to buy a lathe and follow along.

[XLR8]

Thank you Mike.
I've had this lathe since the '80's and before I got it, I would attempt to turn parts using an old drill press. Needless to say, the lathe does a much better job.
This lathe is completely manual so making parts takes me a lot of time (it doesn't even have reverse). Even the simplest part seems to take hours to finish but for me it's a very satisfying way to spend the time.

So I've taken some time away from the LWB project to work on the new re-release Ultima. Actually, I was thinking about swapping the vintage gear box with one from the new car. I've assembled both boxes, fitted my scratch made motor plate to the re-re box and was preparing to install it on the chassis. Then, I happened to pick up the vintage box to find a tool that I was needed and I couldn't believe the difference in weight; all those metal gears in the new box certainly adds a lot of mass. I don't have a scale so I can't report the actual weight difference but it's similar to the difference between a 5000mah NiMh vs. a 2S lipo. Anyway, I'm going back to the lighter vintage box for the LWB car.

I will be swapping the rear hub carriers though since the new ones have replaceable inserts for adjusting toe-in (2, 3, and 3.5 degrees). A stock Ultima has about 1 degree toe-in.

[Dadio]

Inspirational , so tidy and professional looking .

[DennisM]

Looking very good - nice project.
Have You considered putting in a Lethal Weapon?

[XLR8]

Looking very good - nice project.
Have You considered putting in a Lethal Weapon?

Thank you!

Hmmm. No, actually I haven't even considered an aftermarket gear box but now you've given me something new to consider. I'm gonna look into it.

[XLR8]

So, while awaiting arrival of the last few parts needed to finish this project, I'm thinking about body shell, paint, decals, etc.
I really like metallic silver color for a car. Both of my 1:1 rides are silver but for some unknown reason, that color has never found its way onto any of my RC's so I think it's time to correct that.
I've been experimenting with colors and graphics and hit upon the direction I'm going with this one.
The base color will be metallic silver and I have a reproduction Ultima Pro decals set from MCI with the yellow and apple green colors replaced with white and dark gray respectively. It's nice that the fine folks at MCI allow color substitutions - and at no additional cost.
As a preview, here's a quick rendering from the cad drawing.

[Mr. ED]

Wow Doug! That's advanced modelling right there. I don't think I'd manage the body like you did.