Mid motor car question

[m_vice]

For the people that have driven both, is it worth building a mid motor car for off road?
I was planning on making a old / new RC10 mid motor car but not so sure it is worth it.
What is the reason to ad an extra gear to the tranny like on the S2 and the X-6?

[templeofspeed]

The fourth gear maintains 'normal' motor rotation while allowing the motor to remain on the right side. The Tekin mid-motor chassis placed the motor on the left...

[Charlie don't surf]

It's easier to just flip the diff around and the top shaft

[LowClassCC]

as stated above.. when you flip the rear end of a vehicle the wheel will spin the same direction as they did. but since the rear is backwards everything is reversed. you can do one of 2 things. one it to reverse the wires on the motor. pos to neg and neg to pos. this reverses the rotation of the motor. the other way is to add a 4th gear to the transmission. this will also reverse the rotation of the final drive but the motor can maintain its normal rotation.

on the stealth and 6 gear trannies you can just flip the top shaft around and which the side of the trans that the motor plate is on and end up with the same results as the 2 methods described above. the newer transmissions don't have this ability so they have to do things a little more complex.

[m_vice]

Excellent info, anyone experience driving some of these?
I would love to know how it feels in comparison to a regular one.

Thanks guys.

[markt311]

on the stealth and 6 gear trannies you can just flip the top shaft around and which the side of the trans that the motor plate is on and end up with the same results as the 2 methods described above. the newer transmissions don't have this ability so they have to do things a little more complex.

The reason Xfactory added a fourth gear was to move the motor to the right side of the car. That way the rotational force of the motor pushes the rear suspension down, creating more traction. The original Xfactory 2wd had a three gear tranny, and on power and through bumps it was a loose car because the motor was actually trying to lift the rear suspension.

I've driven Paul Sinclair's 2wd buggy, it turns quicker than a normal buggy. It just takes 2 or 3 runs to get used to how you have to drive a mid motor to be fast.

[Mr. ED]

the liower weight on the rear does make them harder to run on slippery tracks

[Charlie don't surf]

However, having a 14oz motor hanging off the rear end of the car may make it slower to react initially to steering input ( like trying to lift 10lbs attached to a 6 ft pole vs straight lift) it also can
cause the car to be very loose from the center off ( like trying to lower that same 10ft pole from 90deg to 0deg, the weight extended past the central pivot causes mechanical advantage ((or disadvantage)) Mid motor cars must have the correct battery & electronics placement to be viable on the track. Also the current X car keeping the 4 gear setup is slick seeing how the outside rear tire is the tire that drives the car off the corner

[SteveK]

Yup, basically what all these guys said; a mid-motor car will be steer much more quickly than a rear-motor car, but it won't be as easy to drive. The placement of the battery also affects weight transfer as well, concentrating it more to the center of the car. The RC10 was pretty much the standard for dirt ovals around here for decades, and pretty much everybody used the rear-motor setup. Mid-motor cars would hook a little more, and weren't as easy to drive. There were mid-motor conversion kits later on, but they stretched the wheelbase which counteracted that.

4WD is another story, because of the way 4WD makes the car react of acceleration, braking, and coasting.

Obviously it's all personal preference, but there is a reason Associated and Losi and Kyosho and pretty much everybody else has used the rear-motor setup for 25 years.

I'm not too familiar with the X Car, but I wonder why they didn't just use the pass-through design of the Stealth, instead of adding a 4th gear to the transmission? The only downside of the Stealth design was that the motor plate was the wrong way around. If you just cut the motor plate flat and drilled a hole in the left side of the gearcase, you could flip the tranny around in the later Stealth trannies as well.

[scr8p]

there is a reason Associated and Losi and Kyosho and pretty much everybody else has used the rear-motor setup for 25 years.

well what is it? don't leave us hangin'.

i don't think a mid-motored 2wd offroad car would be ideal for every track. but i do think it could have it's place. with tire technology what it is today, the weight difference in lipos compared to nimh cells, there's no reason you couldn't get one to hook up and be competitive.

I was planning on making a old / new RC10 mid motor car but not so sure it is worth it.

i resurrected an old c.c. mid motor build i started a couple years ago. i'm putting it together for the 2010 vonats. i'll let you know how it worked next september.

[m_vice]

Thanks for all the info guys. So, an ideal car would be the one that can go mid or rear by switching it around depending on track conditions. I have to analyze this a bit more and maybe start cutting some chassis to see what I can come up with.

Hey scr8p if you have some pics of the mid motor I would love to see it in detail. Or if you have it on a thread let me know.

Thanks.

[Brandon G]

Don't get discouraged about the mid motor buggy. Paul S. was one of the fastest in 2wd buggy with this car here locally. It would hold an inside line like no other.

He let me drive his prototype and it did feel loose in the ass end, but then again, EVERY car of his I drove was like this. It was just his personal preference as far as setup goes. He assured me that the car could be tuned to suit just about every driving style.

I will also say that the new 2wd chassis they are producing is a beautifully molded piece!

[markt311]

I agree with Brandon. And on a blue groove or high traction clay track I think the mid motor car has a ton of advantages over a rear motor car. You don't have to swing that heavy motor as much because it's tucked into the middle of the car.

The Xfactory cars are also much more responsive in the air to corrections, which can be good or bad depending on your level of experience.

[m_vice]

Good stuff guys, how about the wheelbase on mid motor cars. How does this affect the handling? Should this car be a bit longer or narrower than regular?

I started working on it this week and will probable have something to show in the next 2 weeks or so. It is going to be more of an old school design (no comp for the modern ones like the S2 and X-6) but it might be able to keep up. I might be close to an Tekin conversion but nicer, IMO.

This is a pic of the design process. I am planning to use some hobby shelf part so I can repeat the car and I am making some custom parts like chassis and towers.

[Charlie don't surf]

you might have thought about this already, but try to mount the servo similar to a B4 to keep the
weight centered--Very cool project!