Eotz

Hi.

A link to Awesomatrix website:

Awesomatix USA: A700 Evo

I see that the front differential is placed on a floating support, and this support is fixed to the bulkhead just with 2 screws at the inner side of the car. Right?. Pretty interesting.

I have to check my design to see if I can fit something similar. My idea is to use the same bulkheads front and rear, but problably I will change it.

Thanks.

Papi

It's not visible in those cad, but differential is not fixed to bulkheads at all. That support is mounted to "top deck" tube, which is mounted only to motor mount (with floating support in the middle of chassis). It's easier to see here:

https://www.thercracer.com/2014/02/awesomatix-evo-aluminium-chassis-build.html?m=0

​​​

Eotz

For a better understanding, I have just download the cars manual.

Eotz

Let´s assume that the transmission shaft turn is along the X axle and the differential turn is along the Y axle. When the differential gear receive the rotating movement of the shaft gear (turning in X), we can consider that the torque steer moment, is transmitted to the front differential making the Y axle of the differential to turn around the X axle. In other words, the differential Y axle turns on the YZ plane. Right? Or the movement of the front differential have more components?

See the sketch below:

gigaplex

iTrader: (2)

The differentials aren't involved in the torque steer problem. The main cause is uneven contact pressure on the tyres due to the moment of inertia of the drivetrain and rotor applying an equal and opposite moment on the chassis. The problem was far worse in the brushed motor days as the armature has a much higher moment of inertia than brushless rotors. Tamiya attempted to address it with some of their transverse motor layouts, at the cost of complexity and drivetrain efficiency.

Oleg Babich

The "torque steer" is not correct term here. "Torque twist of chassis" is more correct.
FFG eliminates the torque twisting of chassis.

Please check these videos:

Eotz

The problem is the torque of the motor is transmited to the chassis causing torque twisting of chassis. Right?. Awesomatix created this floating system, but as I see at the videos from Oleg (thanks mate), the floating system absorbs all the chassis tweek in general, not only the motors torque twisting. I think that if we manage to dampen the torque in the differential movement, it will not be transmitted to the chassis. At least it will be reduced.

DesertRat

iTrader: (2)

You are over-thinking it. The Awesomatix system just isolates the twist of the chassis and front gearbox from each other, its actually pretty simple in concept.

Eotz

DesertRat

iTrader: (2)

Its quite simple, when the pinion gear in the front gearbox applies a torque to the ring gear, that torque is felt by the chassis. Because the chassis isn't flat anymore, it twists the front suspension relative to the rear, this puts crossweight in the car where the right front and left rear tire have more weight on them than the other two. Add in a little tire slip that we always have, and even when holding the front wheels absolutely straight the car will pull to the side under power.

Eotz

Exactly. The question I made myself, is how the torque arrive from the shaft to the chassis? As you say, when the pinion of the shaft, gear in the front gearbox, the differential, applies the torque to the ring gear, making the differential turn because the teeths, but also making the differential roll along the X axle (See the sketch I made). That is how the torque is transmitted to the chassis, causing all the negative effects that you describe. From the pinion gear to the differential ring gear, the differential to the bulkhead, and the bulkhead to he chassis. So theoreticalli, damping this X roll at the differential, at least, we can reduce the impact of the torque on the chassis.

gigaplex

iTrader: (2)

The shaft pinion only puts an upwards or downwards force on the diff gear (z axis), it doesn't directly apply a moment to the diff. Since the diff gear is off center, that's what's producing a net moment on the diff. There's also some minimal torque applied to the gearbox via the friction in the bearing holding the pinion shaft.

Papi

Look up "torque tube" - it's solution of this issue in real cars. It'd be interesting to see that in RC

Eotz

4k4m3

As someone looking for this same info nearly 3 years later for a Rookie/Series/Fun race debut (and 25 years after dropping the hobby as a teen...), I wanted to say thank you to the members who participated in the original thread. Very informative.

Sadly, not much seems to have changed in the last 3 years, despite a seemingly endless supply of new Kyosho Fazer MK2 models, a new entrant (?) with the Carten T410 (from Taiwan) and the new 4tec 3.0 moving to a 1/9th scale. Here in Europe, the old Yokomo SD is putting up a good fight and refuses to die, but everything else looks pretty dead or on life-support (HPI RS3 Sport 3).

I'd love to see new mid-range models from the JP brands or some EU newcomers.
(that A700 was just so beautiful!)