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DeadMeat666

Converting 4WD to RWD

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I'll try to keep this short, because I have a lot to say about this, but I will leave it to those with more experience than me to chime in.

What would it take to make a TT02 Type-S drive reasonably well in rear wheel drive? I've been all over the net looking into this topic, and it's been raised here and there a few times, with the common consensus being that it's generally a bad idea and the car will handle like poop. 

BUT, cars like the M06 and the M08 do exist, and seem to be doing fine RWD, so what's the huge difference between a TT02 and an M08 that makes it such a bad idea to attempt setting up the TT02 for RWD?

Please if you could be so kind as to elaborate if you have insights on this.

Cheers,

DeadMeat

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The problem is the weight balance you’ll struggle to get enough weight over the rear tyres to have anything like decent grip. 
 

if you look at the m06, the motor is way out back behind the back wheels, and the battery is pulled back against the gearbox. 
 

if you look at the m08, the motor is just in front of the back wheels and the battery is hard against it. Both of these cars are built from the ground up as RWD. 
 

a TT02 is designed from the ground up to be 4wd therefore the weight balance is more mid centric to make it easier to drive. What you’ll find is you’ll struggle for rear traction, it’ll want to loop out all the time. If your cambers are out even slightly it’ll just constantly loop one direction and push the other. Getting some extra weight behind the back wheels will be critical to getting some traction then sorting out the overall weight balance left to right to help keep it going straight. 
 

the other thing that will help a rwd conversion is modifying it to have way more steering throw as you’ll need the extra turn in to be able to catch that back end. 
 

if you just pull out the front and centre driveshaft you’ll quickly come to realise it’s pretty hopeless without further adjustments.
 

Juls

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Having driven (or rather, tried to drive) an M04 and made an attempt to make it handle, I can say that you need a LOT of weight over the rear wheels. A TT is a rather well-balanced car, which is what you want for a 4WD car, but not RWD. Contrary to 1:1 scale RWD cars you'd need about an 80/20 split rear to front to get a RWD car to do anything.

Look at an M06, with its motor and gearbox hanging out the back. That was done for a reason. An M08 has the motor inboard again, but moves all the electrics and battery back. Look at RWD buggies; same deal.
Now look at succesfull FWD cars like an M05 or M07, or a FF04 Pro. No weight at the rear, everything over the front wheels. 

You could probably convert a high-end TC into a RWD car if you flip the rear gearbox/diff around and move everything back. Basically a Frontie-conversion in reverse. xD

EDIT: @Juls1: *high five for posting at the same time, saying the same thing*

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Thanks guys, very useful info here. That does raise an interesting question though: If a 50/50 weight distribution works well for 1:1 cars, why do 1/10 scale cars need a 20/80 weight split for them to be feasible as RWD cars? Is it because the amount of grip from scale tires is not proportional? Will wider/softer rear tires help here?

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It's mainly weight vs contact patch which gives way lower grip than you might expect proportional to scale. A full scale saloon car, even a light one from 10-20 years ago weighs 1300kg. 10th scale weight would be 130kg. In reality they are more like 1.3kg, 1000th the weight. Wider rear tyres would help. It took me ages to get my rwd rally car working, and that's based on a rear motor buggy, but i could get different width wheels that would suit. HPI used to do 32mm wide rear wheels which would help. Schumacher do touring car sized minipin tyres called SST, with 20mm fronts and 24mm rear, but they are glued on dull race dish wheels. 

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not so long ago i looked into doing this myself too. i researched a bit around and seems like the general opinion is that a conversion wont work as good as an chassis developed as RWD, or you would need to put a lot of work into it making it run somewhat ok, and it could still end up not being satisfactory. so i ended up buying an Yokomo YD-2TC which is a onroad RWD chassis. i havent built it yet, but im curious to see how it drives.

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