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Re: Unique Suspension

Posted: Tue Dec 05, 2017 5:14 pm
by bluewormx
I read a recent thread about touring car manufacturer representation at a recent ETS event, and if I recall correctly Awsomematix was the second most abundant chassis behind the xray cars.
XLR8 wrote: Mon Dec 04, 2017 8:22 pm Agree, the tranny is a fascinating design. However, knowing that bevel gears are less efficient at transferring power than straight cut gears, why do you suppose they are utilizing three sets of bevel gears where only two sets are required (one at each end of the center drive shaft) if the motor was mounted longitudinally? Is it due to the torque reactive nature of the motor's armature and how it could affect handling?


There is a reason that the motor is transverse it is because acceleration of a longitudinal motor causes a gyroscopic effect on the chassis and make it roll to one side. Not a problem in 1/10th buggy’s but apparently an issue in touring cars.

Re: Unique Suspension

Posted: Tue Dec 05, 2017 5:29 pm
by Mr. ED
One of the trf touring chassis has similar set up i believe. Though i tvink the motor is more forward 'midship'

Re: Unique Suspension

Posted: Tue Dec 05, 2017 8:22 pm
by XLR8
bluewormx wrote: Tue Dec 05, 2017 5:14 pm I read a recent thread about touring car manufacturer representation at a recent ETS event, and if I recall correctly Awsomematix was the second most abundant chassis behind the xray cars.
XLR8 wrote: Mon Dec 04, 2017 8:22 pm Agree, the tranny is a fascinating design. However, knowing that bevel gears are less efficient at transferring power than straight cut gears, why do you suppose they are utilizing three sets of bevel gears where only two sets are required (one at each end of the center drive shaft) if the motor was mounted longitudinally? Is it due to the torque reactive nature of the motor's armature and how it could affect handling?


There is a reason that the motor is transverse it is because acceleration of a longitudinal motor causes a gyroscopic effect on the chassis and make it roll to one side. Not a problem in 1/10th buggy’s but apparently an issue in touring cars.
That's interesting and seems to be a very reasonable explanation but I'm curious why the gyroscopic effect wouldn't be a issue for all types of RC cars. BTW, the motor in the B64 and perhaps other serious competition off-road cars is mounted longitudinally. Maybe it's due to the fact that off-road cars naturally roll and pitch as a result of an irregular track surface while on-road cars don't typically roll because they run on flat surfaces; the motor's gyroscopic affect is more apparent while running on a dead flat surface. Still, this raises an issue so I think I would prefer all my cars have a transverse mounted motor regardless of track surface. Considering my mediocre driving ability, I need all the help I can get. :lol:

Re: Unique Suspension

Posted: Tue Dec 05, 2017 8:30 pm
by jwscab
The way the motor is laid out the motor torque will help load the chassis to improve forward bite. Rather than torque side to side and upset the tweak, it essentially pushes down on the front tires.

It's definitely unique but that doesn't always mean better. Lots of links and adjustments are hard to keep consistent.

Bevel gears aren't any more inefficient than 'regular' gears if designed correctly. Hopefully the main drive bevel is not part of the spur gear.

Re: Unique Suspension

Posted: Tue Dec 05, 2017 9:40 pm
by RC10th
Easiest way to see torque steer in action is with a shaft drive drift car

Re: Unique Suspension

Posted: Tue Dec 05, 2017 11:43 pm
by TRX-1-3
jwscab wrote: Tue Dec 05, 2017 8:30 pmHopefully the main drive bevel is not part of the spur gear.
Looks like it mates to the spur with some lugs that go in the holes around the spur center.......

Re: Unique Suspension

Posted: Wed Dec 06, 2017 12:19 am
by XLR8
jwscab wrote: Tue Dec 05, 2017 8:30 pm The way the motor is laid out the motor torque will help load the chassis to improve forward bite. Rather than torque side to side and upset the tweak, it essentially pushes down on the front tires.

I see. I reckon it's the same logic behind the addition of a fourth gear in the gear boxes of modern mid-motor buggies. So, flip the motor to the side of the car that will allow torque from the anticlockwise spinning armature to add loading to the front of the car. Makes perfect sense.

It's definitely unique but that doesn't always mean better. Lots of links and adjustments are hard to keep consistent.

Definitely incentive there to keep the car off the barriers.

Bevel gears aren't any more inefficient than 'regular' gears if designed correctly. Hopefully the main drive bevel is not part of the spur gear.
As I understand it, if the bevel gears are straight cut (axis intersect) they will transfer power more efficiently than if they were say hypoid cut (axis don't intersect; i.e. spiral cut like gears in full size vehicles) since the mating surfaces of the teeth don't slide together as they engage. The bevel gears in the illustration do appear to be straight. I've noticed a trend in shaft drive RC's where the teeth on the crown gears have gotten very narrow. I'm guessing this is to save weight and to improve efficiency. BITD in stock classes we trimmed the width of our spurs to be very narrow in an effort to try and squeeze a bit more speed. Looking back, I think the affect was more psychological than anything else. I certainly wasn't good enough to notice the difference.

Re: Unique Suspension

Posted: Wed Dec 06, 2017 10:26 am
by Phin
I'd like to see how a shaft drive with the motor position of an anglewinder slot car would work out.

Re: Unique Suspension

Posted: Wed Dec 06, 2017 10:50 am
by jwscab
yes, pretty much. bevel gears however can be straight cut or helical. The hypoid gearset is where the axes don't intersect and they lose efficiency due to the offset axes. the helical gearset is harder to make but creates a stronger gearset due to multiple teeth meshed at the same time.

XLR8 wrote: Wed Dec 06, 2017 12:19 am
jwscab wrote: Tue Dec 05, 2017 8:30 pm The way the motor is laid out the motor torque will help load the chassis to improve forward bite. Rather than torque side to side and upset the tweak, it essentially pushes down on the front tires.

I see. I reckon it's the same logic behind the addition of a fourth gear in the gear boxes of modern mid-motor buggies. So, flip the motor to the side of the car that will allow torque from the anticlockwise spinning armature to add loading to the front of the car. Makes perfect sense.

It's definitely unique but that doesn't always mean better. Lots of links and adjustments are hard to keep consistent.

Definitely incentive there to keep the car off the barriers.

Bevel gears aren't any more inefficient than 'regular' gears if designed correctly. Hopefully the main drive bevel is not part of the spur gear.
As I understand it, if the bevel gears are straight cut (axis intersect) they will transfer power more efficiently than if they were say hypoid cut (axis don't intersect; i.e. spiral cut like gears in full size vehicles) since the mating surfaces of the teeth don't slide together as they engage. The bevel gears in the illustration do appear to be straight. I've noticed a trend in shaft drive RC's where the teeth on the crown gears have gotten very narrow. I'm guessing this is to save weight and to improve efficiency. BITD in stock classes we trimmed the width of our spurs to be very narrow in an effort to try and squeeze a bit more speed. Looking back, I think the affect was more psychological than anything else. I certainly wasn't good enough to notice the difference.

Re: Unique Suspension

Posted: Wed Dec 06, 2017 4:54 pm
by tamiyadan
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Re: Unique Suspension

Posted: Fri Dec 08, 2017 12:27 pm
by EvolutionRevolution
tamiyadan wrote: Wed Dec 06, 2017 4:54 pm the Tamiya TL-01 had the Worst Torque Steer of any chassis i have ever driven.
That chassis was one of the worst in several other ways too - integrated shock mounts that result in you having to replace the chassis halves when a shock mount breaks, anyone?

Re: Unique Suspension

Posted: Fri Dec 08, 2017 3:57 pm
by tamiyadan
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Re: Unique Suspension

Posted: Fri Dec 08, 2017 4:44 pm
by Dadio
Hypoid or helical gears are used in full size cars for strength and more quiet running , straight cut are more efficient but way more noisy , typically the reverse gear in a manual transmition car is straight cut and you hear a distinctive whine when reversing that you don't hear in forward gears , helical gears have an overlapped transition from one tooth to the next and this keeps the noise down plus they have a larger surface area that gives a greater service life and strength .