MMV Challenger: Carpet Kitty

[8rad]

I have always wanted to build a "Topcat on steroids". So with mid-motor all the rage these days and my local track switching from dirt to carpet the time seems right for a "Topcat mid". I have been thinking about this for a while and collecting parts.

The backbone of the build is a custom 2mm aircraft grade aluminum chassis that I cut, bent and drilled myself. It just came back from powder coating yesterday.

[Coelacanth]

That looks like a great project for this build-off. It's gonna be fun seeing everyone's creativity and what they end up with!

[8rad]

So basically I am going to mock this up. Overcome any obvious problems and then tear it down and rebuild it with a bunch of new and trick parts to complete.

I mounted the transmission and noticed one big problem. The tranny sits on a severe angle. This cuases the rear bulkhead and shock tower to lean into the middle of the car a little too much for my liking.



So, I made a nylon block to sit under the tranny. Now, there is a slight angle still but not enough to notice. This also seals up the bottom of the tranny to prevent dirt from getting in.



I then added a rear bumper/skid plate I made from nylon and bolted it down.





And mounted the front.

[8rad]

The mockup continues! Everything seems to be going together well. No glaring issues. I am starting to collect parts for the most ambitious part of this project which is to modernize the drive train while keeping the belt drive. I plan to use a B4 diff and cvds mated to a pro diff belt pulley.

Stay tuned!

[tim.sanderson]

Looking good. I'm looking forward to seeing this build completed.
I have a thing for mid motor conversions. Especially custom jobs.

[Coelacanth]

Looking great so far, I like the rear skidplate.

[8rad]

So I finally had a chance to work on the most ambitious part of this build. The drive train. I wanted to use a B4 diff so I could replace the rings and balls from the LHS and not have to scour the bay for parts. I wanted to keep the belt drive so I set upon making the B4 diff fit in the belt pulley.



Looks like this may actually work!



I drilled out the center to install the B4 center bearing.



And assembled.



The fences would not fit over the B4 slipper plates but since I will be running on carpet dirt is not an issue. So out comes the dremel and CA glue.



And voila! Belt drive B4 diff. YAY!

[CAT3K]

Really good job on the diff

I like that the rear axles are going to be inline rather than trailing. Are you going to run B4 CVD's as well?

Paul.

[8rad]

I dont know yet. The problem is I dont know what arms and carriers I will be using so its hard to know what length of CVD to get. I am going to mock up some Losi hub carriers and see if I can nail down a length. Most likely it will be B4 CVD's.

[8rad]

So the bearings finally came in from Boca. I had to order special bearings to fit the B4 out drives and the Schumacher eccentrics. There was a little play in the diff from side to side but 2 1mm shims solved that.





I also got the Schumacher Cougar SV saddle pack holders. They are already made, look awesome and I got em cheap. A clear choice over custom made. Now to rig up some posts.

[CAT3K]

Those SV saddle lipo holders look like they will work perfectly with this.

Is there any fouling issue with the motor plate/spur gear and the bodyshell? It looks like it might be a bit tight in there.

Paul.

[8rad]

Is there any fouling issue with the motor plate/spur gear and the bodyshell? It looks like it might be a bit tight in there.

There will certainly be a clearance issue. The body will fit over everything but the slipper shaft. Not wanting the marshals to lose any fingers I will need to rig up a gear cover of some sort. I think for the MMV build-off I will go sans cover and just trim the body normally.

[Coelacanth]

I wouldn't worry about it too much, 8rad...your build is further along than mine, I don't think Barney has a hope in hell of being complete--body fitted & painted and the whole 9 yards--before the end of November. Your car is coming along nicely, I like the gearbox & diff modding.

[8rad]

So the mock up is done.

[Coelacanth]

Sweet! I wonder...are the rest of you guys participating in this MMV buggy competition probably going to look upon your eventually-completed projects with more pride, more "sense of ownership" than you do with other builds, due to the extra work & frustration & attention-to-detail that you don't really need with other "by-the-manual" builds?

That's what I'm thinking, anyway. Nobody is gonna have cars like these!