1005 - 2 Speed Conversion - MCD V4 Models - by Demon RC

[soundman]

this was the reply I got from demon rc when enquiring about brushless 2 speed conversion, he was asking about the shaft from motor to a/b gears and how mcd managed it.
I see how they did it.  The extension shaft mounted to the motor shaft is basically the gas version's clutch bell shaft extended to meet the motor's shaft.  Basically, all you would need is that same extension but from our clutch bell design.    The MCD shaft goes from a 10mm to 9mm to 8mm and then to a 6mm threaded end.  Ours is much simpler.  It's a 12mm round shaft and drops to a 10mm hex.  Instead of a 6mm threaded end we have a 6mm tapped hole.   I could probably draw up the design if I had a few more measurements.   It's not that complicated. 

 

Now, here's the kicker.  It's not something that we would want to manufacturer considering the few brushless setups out there.  We actually might make that conversion kit obsolete with our own conversion kit. which is setup more like the brushless Rampage XBE which is similar to the 1/8 buggy setups but with duel battery packs.  If you would want to pursue machining your own shaft I can give you all the measurements needed.  I would expect that most machine shops would charge right around $90-$150 to machine a single part like that.   

 


James Stergar - Demon RC

info@demonrc.com

 

nice, I'm for it.
I basically played around with some boiler plunger washers until I got the right fit. Then bonded it up on the conversion kit shaft, smoothed it out, and it works..
Do these gears mount up on the original alloy gear carrier?

if so then cut two

if your making the shaft, cut two. I'll take one and spit the cost.

[robw]

I ordered one for my fuelly version, will see how it goes!

just the job for the petrol version

[starefly]

Finally got mine ! 

It is delivered assembled, I only split the parts for the pics.






Nicely made, looks robust. Some very slight play in the shaft, will see how it influences gears wear.

next step-> installation !

[BeatsMe]

Nice... can't wait to see how it goes and hear your thoughts on the running of it over the coming months.  So this will be going into your X4 isn't it??

[starefly]

Yes it is for my X4 !

Forgot to put the weight: 749g

[starefly]

I had a closer look to shaft play, and I was not satisfied by what going on at intermediate shaft level.
I had 1.5mm axial play, leading to gear misalignment and close to gear collision.


So I decided to machine a bit the shaft.


after machining I'm close to 0.3mm which is much better, no more gear misalignment issue

[robw]

that's not good somebody like me would have to send it back for another one or refund, I wont bother with that then.... if I decide to go petrol

[starefly]

So here comes the installation:
1st remove old gear carrier :


Fix new gear plate:
Screw used M4x12 at each extremity (M14x16 is too long), and M4x20 at the center (I put a nut to secure the stuff). Only 3 of the 4 holes are drilled.



Had a problem with the U brake pad carrier (not going far enough), I had to grind a bit the gear plate:


Then wanted to fix brake & radio plate but need to drill the plate to 5mm as they used a bigger diameter. I also noticed a slight misalignment with the gear plate.


Correcting brake plate alignment problem, with an heavy method 


Then installed final gear, but brake shaft flat is not long enough


After grinding:


Fixed the gear but thread is not long enough to put a nut


So installed a additional 10mm washer


2 speed finally installed:


It took me about 4 hours to install it in the car. For some steps I used a mill, but a light grinding with a dremel could be enough.

Positive point I saw is that bearings are made in Japan and not El-cheapo like the one used by MCD and other parts look robust.

Possible improvements (letter to Santa):
- Correct intermediate shaft milling (maybe an isolated case on mine)
- M4 thread on top instead of M5
- 4th hole drilled and tapered
- Longer pins to be better secured in gear holes (there is space for it)
- Alloy 7075 shaft to save weight  ??

Next step: firing it up

[starefly]

Hi All,

I finally had the time to test this  2 speed setting ! I have run 5 tanks in a row on my local tarmac race track.

So far, so good ! Unit is running well! Factory 2nd gear setting is adequate with my setup & race track ! The 2nd gear is passing quite smoothly, there is no major a$$ kick !

Regarding car handling, she looks a bit heavy, I think that I will have to go with a lightweight chassis because my wishbones are not liking it even with black rims:


My only concern is gears lifetime, some of the tooth are already damaged  even if I didn't run it off road. I'm pretty sure that it is coming from shafts machining by not being tightly fitted inside plate bearings.
I don't know if demon is watching this forum, if it is the case, please improve a bit shafts tolerance !

[BeatsMe]

Thanks for the update Marc, very sorry to read of the problems you're having... perhaps get in contact with DemonRC directly regarding the gears.  If you haven't already done so.

On the wishbones wearing out.... that problem has been known for some time, not really related to the weight... more the flex between both the wishbones themselves and the rims. I understand that alloy wishbones do help to reduce this problem.

Here's a picture from when Darksoul Racing was working on their alloy wishbones...

[BeatsMe]

Forgot the related topic link...

http://www.mcdracingforum.com/index.php?topic=2604.0

[starefly]

Darksoul ones seem not longer manufactured, do you think that MCD alloy set will fix the problem ? I will not "eat" the rim instead ?

[BeatsMe]

I was only posting about the Darksoul topic to show you about the previously discussed issues... so, yeah, the MCD wishbones will help to reduce the flexing too 

[starefly]

I have sent a mail to demon to ask them if they can post a comment on the forum as they are sponsor.
let's wait for their feedback

[starefly]

After 2 additional tanks I had a transmission problem, car had some difficulties to run.
Went back home and dismantled the the gears; free wheel was stuck.




The free wheel bearing (greased prior installation) has melted and machined the shaft...
The 30x42x7 bearing oil went out, the sealing seem to have shrink ; the bearing is turning roughly.




The pawl has a significant amount of wearing, shifting works well anyway.






2 speed behavior/shifting is good but the wear rate is too high from my point of view ; after 7 tanks:
- 2 bearings dead
- Gears heavily damage

I don't know if constraints are higher on tarmac (my case) than off road but I'm using a stock 29CC engine ; with a modded engine which delivers much more HP I'm quite Skeptical about the results...
The product is good, but it doesn't look to last very long  ; with some slight modification (shaft tolerances, gears quality) it could be an outstanding product.
I'm ready to put 50$ more in product price and get something robust!