View Full Version : MR-03 with IRS (independent rear suspention) - Suggestions needed

2012.08.22, 09:42 AM
Crazy thoughts and wanting to create something.
Let's call it a long term project.

I would like to fit the rear of a AWD to a chassi with MR-03 electronics.

I think that would mean a new chassi to be able to place the motor and batteries.
I think I would need the widest rear transmissionparts available and the lowest. So that "any" body can be fitted over the transmission.
I think I need some good dampers for the rear.
In the front I would like the narrow front with wide wheels, meaning something like double a-arms or like the adjustable reflex front with long a-arms.

I would try to make the chassi as narrow as possible.
But I think I need help on the rear pod first.

What options for the AWD is there out there, that you can use to race with.
Is low and wide.
So that I can make my own 2WD racing car with IRS....

2012.08.22, 11:06 AM
good luck with that. why not just take the front diff out of an awd? i feel you would have so much time and money invested to get some fabbed up that the benefits would no be worth it. just my opinion

2012.08.22, 11:11 AM
Thats so true and so not fun and so not challenging.


2012.08.22, 11:23 AM
The way I see it (and I've done some investigating) is that it'd be difficult to incorporate a motor so close into an IRS rear awd pod.

My thought is that instead of that concept, you redesign both a PN rear 03 pod(multi platform pod would be best) and a RWD diff to have axle cups for swing shafts from an AWD.

By modifying the rear pod bottom and top plate, you could mount SAS lower and upper arms. Making a RWD diff use out drive cups might be difficult....

Good luck...keep us advised of any progress!

2012.08.22, 11:34 AM
ah, this is some new information to me.
Why is it a problem getting the motor so close to the pod?
Isn't it possible to attach the pinion to the motor?

2012.08.22, 12:16 PM
Thats so true and so not fun and so not challenging.


the challenge would be to try and drive it. ive never had any luck with an awd.
good luck on your project

2012.08.22, 12:23 PM
Thanks man!
I probably going to need all the luck I can have so...


2012.08.22, 12:28 PM
have you thought about trying something with the buggy. it is a great platform

2012.08.22, 12:32 PM

Maybe I will check it out.

I want to make a racer, so low cog is vitale.
I want independant rear suspention.
I want speed like the GT Mod class.

I'm not sure what I will end up with or if I make it all the way.
But this might be something I can do for fun.

2012.08.22, 12:46 PM
ah, this is some new information to me.
Why is it a problem getting the motor so close to the pod?
Isn't it possible to attach the pinion to the motor?

If you look at the awd platform, there's a large pinion driving a big spur leading to a small secondary spur drive working the awd diff. All of those ratios convert the motor rpm into useable drive at the wheels. A small pinion directly to awd diff wouldn't give a good drive ratio.

2012.08.22, 01:09 PM
As cowboy pointed out you'll need to keep the original pinion/spur or something similar to achieve the proper gear ratios. While you're at it rotate the motor 90 degrees so its in the same orientation it is in the mr03, this will help reduce tweak and will improve on power rear grip.

As far the original awd car itself, I've driven many other peoples and not liked them much, mine however rocks and can do a faster lap time then any mr03 I've seen/driven.(it is more work to drive at times though)

2012.08.22, 01:17 PM
How many T is the gear on the differential?
and on the gear directly to the differantial at the back?

What gear ratio would you get there?

Why can't you fabricate a motor mount in the center?

I like the DWS rear since it got a lot of adjustment.
I thought I had to get a SAS, but maybe not. I donŠt know much about these cars so...

Love your feedback guys.
But remember, I'm not going to drive a AWD!
I want to do it the hard and stupid way, so that my mind gets something to do.
Not something out of the box....


2012.08.23, 04:33 PM
I don't know if you are already familiar with this info I'm going to post, maybe someone else on the forum knows what I'm talking about and can tell you even more details >>> A couple years back, maybe even 2007.. Or maybe 2008-2009 --- There was a Hungarian or Turkish company called TGR that produced a hobby-grade carbon-fiber RWD chassis called the Sinister. (RWD, with solid MR02/03 axle). OK, now - The Sinister you might be familiar with... But this is where it gets interesting.....

I saw at a race/display one time TGR unveiled EXACTLY the kind of RWD chassis with a fully-independent rear suspension system very similar to the Atomic AWD SAS rear independent suspension. Looked like a P28 or MRCG with an alloy SAS L&R independent rear suspension, Rear wheel drive only. And 1/28th scale like MR's and MA010's :)

The TGR new chassis' fully independent RWD suspension was all billet aluminum with carbon base plate and lots of carbon goodies.... ; The main chassis just in front of the "SAS" Rear end, the middle of the chassis Where the batteries would go, that middle section was flat carbon and low very much like color0's excellent MRCG chassis. The front had kingpin MR02-style knuckle left/right suspension if I remember correctly... It was a prototype that TGR I think*was trying to get into production, but TGR dissolved shortly after that event (I can't remember when/where the event was though, sorry)....

Also, I remember seeing the hybrid "front-MR02/Rear AWD-SAS" TGR chassis for sale on ebay a long time back, probably the only (or one of the only) protoypes. It was a sweet design though.:D Maybe you can look around the web for pics, that might help you find the answers you seek in order to build the I.R.S. MR03 chassis you are talking about :D

Good Luck!

2012.08.23, 05:08 PM
cool info
Didn't know this!

2012.08.25, 02:09 AM
Haha that was a long time ago, Felix. I remember the eBay listing as well, a silver alloy SAS bolted onto a custom carbon chassis. Wasn't GSR, TGR or P28 as far as I recall.

The whole issue with using an AWD rear end is the 90deg power transfer that is required to use the AWD differential. That turns the motor into a bad north-south orientation (torque steer) as well as ruins the gearing choices and reduces power transfer efficiency. And unlike in 1/10 Mod... even in Mini-Z Mod we care about laying down the power efficiently. To get it right, you have to keep the motor where it is now, and somehow drive a differential that has a much larger footprint. It's going to be very difficult to either 1) make the rear IRS compatible with a direct-drive differential, or 2) adapt the AWD diff to accept parallel gear drive (think 1/10 off-road, or the 3racing FGX). Belts are no good here, they work in 1/10 but they're not optimally flexible for 1/28 scale usage.

2012.08.25, 03:12 AM
good points.

Have someone teste how much torque steer you will get?

2012.08.30, 08:23 AM
[QUOTE=color01;435796]Haha that was a long time ago, Felix. I remember the eBay listing as well, a silver alloy SAS bolted onto a custom carbon chassis. Wasn't GSR, TGR or P28 as far as I recall.

If anyone would remember that chassis, I would think you'd be one of the few color0 :D

2012.08.31, 12:01 AM
How about using a o-ring as drive to the rear axle, I think it was TGR that had that option for the mini-z diff?

2012.08.31, 01:04 AM
MK2kompressor had one of those belt drive units but it sucked -- the O-ring has to be preloaded to transfer power (of course), which drags a lot on the motor. A proper, toothed belt would work but it has to be the super-flexible kind to wrap around 1/28 pulleys efficiently, and that doesn't come cheap.

2012.08.31, 06:02 AM
How about the 3Racing Sakura FGX solution then?
Isn't that possible on this car?