Mid motored Cougar 2(ish)

[yorak]

I have rescued a few Cougars from the bin myself. Currently I have one runner, two restoration projects with 99% of the parts but no time nor drive to complete them (Cougar mk1 and C2 Works) ...

... and a pile of parts. This pile, and especially a Cougar 2 chassis that some previous owner had ruine... I mean improved by lightening it by drilling some massive holes into, and all this mid-motored crazyness of yesteryear, got me thinking... and then wildly acting upon these ideas.





From other projects I also had some spare spares: Traxxas Bandit forearms and hubs, Traxxas nitro 4-tec transmission and electric 4-tec ball-diff, Traxxas GTR shocks, 4x4 Slash battery holder, and some miscellaneous parts. I started to put these together and this pretty abomination was born. I have tried to keep the spirit of the Cougar 2: belt drive, angled front wishbones, telescope driveshafts and so on, but cannot stop to wonder: at witch point this stops being a Schumacher and I should post to the Traxxas subforum instead.

The buggy has a super low CoG and will have an option to run the motor in 4-positions (CCW, CW next to rear bulkhead, CCW and CW mid motored ala Schumacher KF), so I might be onto something here.

Next I need to cut an aluminium motor mount and brace, fix them to (and) the middle-bulkhead, a mount for the battery holder / top deck at the front, and a better fitting turnbuckles and ball studs. Not too much and I'm really looking forward in finishing this.

edit: 10/2017 Fixed the links, thanks Dropbox for breaking them.
edit: 1/2018 Added the images as attachments because some members were unable to see the photos.

[Mr. ED]

Now that's something i like seeing around here. Keep it up.

[Typpo]

Nice idea and use of parts.

[bully]

Very cool

[Retro rc]

Very cool yorak! Love my Cougars have a few c2works and team buggies and will be starting a ground up new parts c2 works with carbon chassis soon. Just waiting on the chassis as the moulds are being done very soon.

[Mr. ED]

Now that's something i like seeing around here. Keep it up.

A small PS I wanted to add: I really really like the quality and style of your pictures

[yorak]

Now that's something i like seeing around here. Keep it up.
A small PS I wanted to add: I really really like the quality and style of your pictures

Thank you for your kind words Mr. Ed. Also thank you Typpo, bully and Retro rc for your positive reception for this abomination.

Because my day-to-day life has just been reformed into a mess, and I managed to catch a cold, there has been no workshop time, and therefore, no progress.

What little I've been able to do was on a computer. Some of you are probably already familiar with so called parametric design as a way of doing CAD, but for me this was the first time, as it sounded like it could help me in designing the motor mount plate. In parametric design you do not twiddle pixels (or vectors), but instead you define constraints like "this circle is exactly 32.1 mm from that line" or "the vertical distance between these two holes is 22.0 mm". A picture of the result below. My project, or "C2KF" as I've started to call it, will have and option to run a extra shaft that together with some random gears from the parts box reverse the rotation direction of the supur. This allows me to choose the rotation direction of the motor.



For the general shape of the motor plate I found my just discovered parametric design skills inadequate, and so I had to resort to vector drawing. I tried to capture some of the spirit of the original Cougar motor plates, but I'm not entirely happy. Any ideas or comments?



Regarding the pictures: thanks, the trick is to overexpose the shot, and if you are in a low light environment, like I was, to use a tripod.

[Mr. ED]

If you use a belt and pulleys instead of the spur and pinion you can inverse the motor rotation without changing the motorplate and extra gear.

[yorak]

If you use a belt and pulleys instead of the spur and pinion you can inverse the motor rotation without changing the motorplate and extra gear.

Hmm.. Correct if I'm wrong, but that would warrant an RC innovation "direct drive motor", where the pulley is on the motor axle? Nothing wrong in that, as it WOULD be interesting experiment. Gearing would just be a matter of changing the pulley. Advantages are clear, less weight, less spinning mass. You would need to use double pulley system though, to get the gearing low enough.

But now I got sidetracked (again). Scribbles in my notebook tell me that:

• belt drive =~ 3 gear transmission
• 2 belt drive =~ 6 gear transmission

Unfortunately I cannot see how the rotation direction can reversed using belts. Mr. ED, do you have a design I could stea... I mean study?

I also managed to get some workshop time on Monday. In addition to a CF rear shock tower I cut for another Cougar 2 that is my runner, I made the first prototypes of the motor mounts. They are made from plywood, so they are not functional but purely for fitting and seeing if the design needs to be overhauled. It is easier to work on softer materials first, because the idea never works on the first time. Some pictures will follow when I manage to fit them on the car. It is advised not to hold your breath.

[DennisM]

Using belt pulleys and a belt instead of the spur and pinion will reverse the rotation of the gearbox as it sits originally.
So when You turn the gearbox 180 degrees on the chassis to make it a mid motor, it´s going to be running in the right direction.

Running belt pulleys on the motor is nothing new. I know Hirobo did it on their swb 4wd´s in the mid 80´s
1/8 onroad goes further back.

[Mr. ED]

If you use a belt and pulleys instead of the spur and pinion you can inverse the motor rotation without changing the motorplate and extra gear.

Hmm.. Correct if I'm wrong, but that would warrant an RC innovation "direct drive motor", where the pulley is on the motor axle? Nothing wrong in that, as it WOULD be interesting experiment. Gearing would just be a matter of changing the pulley. Advantages are clear, less weight, less spinning mass. You would need to use double pulley system though, to get the gearing low enough.

I wasn't suggesting to run a belt from the moter to the diff, though I admit having done that already on a touring car. I used a very low KV brushless moter to compensate for the altered gear ratio. The 'other' disadvantage is that a 1 tooth gear change on the 'pinion' pulley has a much larger effect than usual and therefore makes 'fine' tuning impossible.
What I suggested was to replace only the spur and motorpinion by 2 pulleys and 1 belt. Keeping the gearration about equal isn't that complicated then: as long as the pulleys are simimilar diameters as the original pinion and spur. The toothcount on the belt plays no role.

Unfortunately I cannot see how the rotation direction can reversed using belts. Mr. ED, do you have a design I could stea... I mean study?

2 wheels touching will turn in opposite directions, but 2 wheels connected over a belt run in the same direction.

• belt drive =~ 3 gear transmission
• 2 belt drive =~ 6 gear transmission

I think you're on the right track but make it too complicated. Let me explain:
Let's say your diff needs to spin ClockWise (CW) to run forward.

• On a direct drive car= with the motor pinion running direct on the diff, the motor would have to turn CounterClockWise (CCW) to go FWD. Got it?
• Now what happens in a '3-gear': diff CW => idler CCW=> topgear CW => spur CW => pinion and motor CCW
• And in your traxxas gearbox as is: diff CW => belt CW =>toppulley CW => spur CW =>pinion and motor CCW
• For a 4 gear: diff CW => idler1 CCW=> idler2 CW => topgear CCW => spur CCW => pinion and motor CW
• My suggestion:diff CW => innerbelt CW=> toppulley CW => spurpulley CW =>outerbelt CW => pinionpulley and motor CW

The difficult thing with building your home-made 4-gear or whatever gear-on-gear solution, is that you have to make it very precise. If you don't the gears will either bind or wear out quickly from too much lash. With belts you don't have to be that precise, and you can use a belt tensioner if needed or go 1 tooth bigger if it's too tight.

[Headling]

Bit of a thread bump, did you ever use/race the car, looks great btw!

[yorak]

Bit of a thread bump, did you ever use/race the car, looks great btw!

Thanks for the interest Headling. Life has been quite busy and the project has been on hiatus. Since my latest post almost a year (!) ago I've made some prototype motor plates out of plywood, ensured everything fits - and then the project has been laying in a box. However I will definitely pick this project back up in the near future. I will post here when there are any advances. I promise.

[Headling]

I know the feeling!! My rc10/yz2 took a while to get it completed, well worth the effort!!

Good luck with the build

[MegaMousegGW]

Hyper Drive used to put out a complete set of pullies that replaced the pinion and spur gears. I used to run them on my older RC-10, and my first Cougar. Just had to move the motor plate to the other side of the transmission to make them work in the rear motor configuration. Haven't seen any of the pullies for a while now not even e-bay has them the last time I actually looked for them. Only bad thing about the belt and pully system is you had to be dang sure the tension was right or you could wear out the belts or pullies real fast.