2wd but 4 wheel braking?

[AntH]

If I was to race such a car at a BRCA 2wd event, would it be allowed?

How? Imagine a Cat K1 with a one way layshaft, but with the one way bearing operating in the other direction....

[racingdwarf]

I think there can be no drive of any sort (drive shaft) to the front wheels. so a breaking system would have to be totally disconnected from any sort of drive or 4wd system

[Welshy40]

Originally Posted by AntH

If I was to race such a car at a BRCA 2wd event, would it be allowed?

How? Imagine a Cat K1 with a one way layshaft, but with the one way bearing operating in the other direction....

Get rid of the one way bearing in your 4wd and you will have 4wd braking. 2wd i doubt will be legal if you add disc brakes all over as they got very strict when someone came up with a traction control device fitted to a car years back.

[mark christopher]

http://www.rctech.net/forum/electric...nt-brakes.html

[SlowOne]

Providing that the brakes are operated by a servo that you control, and there is no trickery inside the car (sensors, ABS, etc.), then they are legal. I can't understand why you would want to do it as the additional load from braking will limit the load the tyres can carry for steering.

The front tyres are the narrowest so they can't take much braking force before locking up, whereas the rear tyres are wider and have more weight over them so they can brake much harder without locking up - and we already have brakes on the rear axle through the motor.

But since it is there, and it can be done, why not?

[mark christopher]

Pete pretty sure you can not use a third channel in off road, so would need to run off the speedo port via y lead

[dale]

Reversing the one-way bearing won't be sufficient. If you do this there will still be a tiny amount of drive to the front (since the bearing has some friction) so it would just be a really crap 4wd and not legal for 2wd.

You would need a separate electric/mechanical front braking system.

It does seem like it has potential. The front wheels on any real car do most of the work under braking, as the load transfers to the front and gives that end the most grip. It's why we have disks on the front but can cope with crappy drums on the rear.

You'd need to run different front tyres to make the most of it; the skinny ribs we run on the front of a 2wd aren't going to be much use under braking.

Then the question is how much performance is lost due to the added unsprung weight, plus the WD change that will happen with the weight of this system over the front end.

[andybulmer]

[hi. after asking this same question with paul worsley at a national. "if the front wheels are not driven (as your first quote suggests) then this would be within the rules as they are write at the moment"
my car was a kyosho lazer fs2 with the oneway bearing reversed.

QUOTE=AntH;777152]If I was to race such a car at a BRCA 2wd event, would it be allowed?

How? Imagine a Cat K1 with a one way layshaft, but with the one way bearing operating in the other direction....[/QUOTE]

[jimmy]

Not being a point and squirt type of driver - I can't imagine anything worse. I don't even want front brakes on my 4WD!!

[jo90]

What are brakes ?


If this refers to a video thats been on facebook recently the conversion the guy did is really cool...but i doubt the BRCA will go for it.

There have been different things over the years, more noticable (and mentioned above i think) was LRP's traction control they debuded at a worlds back in the 90's. It got slammed so hard the apes felt how hard Jeurgen got slapped

[Pacman]

Originally Posted by AntH

If I was to race such a car at a BRCA 2wd event, would it be allowed?

How? Imagine a Cat K1 with a one way layshaft, but with the one way bearing operating in the other direction....

Technically this would count as having 4 driven wheels, only that the front are being enabled to drive in reverse. Therefore not legal.

The following I found in the BRCA rules on their website:

23.1 Two wheel drive cars (2WD) are those having only one pair of driven wheels on the same axle. Either the front or rear axle may be driven. Four wheel drive (4WD) cars are those having all four wheels driven.

Check the BRCA rules for any other ideas, but ultimately you would still need to pass it by the BRCA first even if you do find a loop hole:

23.12 The use of sensors fitted to wheels, lay-shafts or suspension units to aid traction control or active suspension is prohibited. The use of the third channel parameter on a receiver is limited to external power supply only (no signal circuitry allowed).
23.13 The 1/10th Off Road Committee are empowered to legislate at any time against any new equipment that in the opinion of the committee detracts from the essential skill of the driver controlling the car during racing. Manufacturers, importers and others are therefore strongly advised to consult with the 1/10th Off Road Committee before investing in technology that may be ineligible.

[David Church]

The way the guy did the brakes was with 2 servos and small disc and calipers,I spoke to Paul and even showed him the article and he said he couldnt think of any rule that would mean it wasnt legal.
Of course sensors are illegal, but a mechanical system would be allowed, now this was Paul saying what he thought he could remember, I gave him a link to the article and he said he would look at it, but he was impressed with what was done!!!
There will be interviews up on rc-area soon and I ask Paul in an interview.

[jimmy]

I thought unless the guy is using a wiperboard speed controller and a mabuchi 540, then two servos was against the rules.
You aren't allowed to have more plugged in - unless this has changed - in which case it opens up a lot of options for many new designs . Micro servos adjusting links or somehow stiffening the outside dampers during hard cornering. It's a free for all if it's true that you can run more than a steering servo.
Advanced electrics braking each of the 4 wheels individually to maintain stability and enable faster cornering like the prodrive car - gyro for counter steering, flip-over mechanism to put the car back on its wheels quickly if it rolls. Engage and disengage the actions of a centre differential.

[k£v!n]

The interview mentioned can be found here...

http://youtu.be/60g4zKlFAf0

[mark christopher]

Originally Posted by David Church

The way the guy did the brakes was with 2 servos and small disc and calipers,I spoke to Paul and even showed him the article and he said he couldnt think of any rule that would mean it wasnt legal.
Of course sensors are illegal, but a mechanical system would be allowed, now this was Paul saying what he thought he could remember, I gave him a link to the article and he said he would look at it, but he was impressed with what was done!!!
There will be interviews up on rc-area soon and I ask Paul in an interview.

does this rule not mean you can not put those servos operating the brake on the third channel?

23.12 The use of sensors fitted to wheels, lay-shafts or suspension units to aid traction control
54
or active suspension is prohibited. The use of the third channel parameter on a receiver

is limited to external power supply only (no signal circuitry allowed).

which he is definatly doing

"I am using a Futaba 4PK to control my Durango which is a 4 channel controller that also has a menu to use the third and fourth channels to control brakes which automatically mixes those with channel 2 which is the throttle/rear brake."

[jimmy]

It ain't legal Dave, or I'll eat your hat.

[terry.sc]

Originally Posted by jimmy

I thought unless the guy is using a wiperboard speed controller and a mabuchi 540, then two servos was against the rules.
You aren't allowed to have more plugged in

There is nothing in the rules that limits how many servos you have in the car.

The pertinent rule is:
23.12 The use of sensors fitted to wheels, lay-shafts or suspension units to aid traction control or active suspension is prohibited. The use of the third channel parameter on a receiver is limited to external power supply only (no signal circuitry allowed).

As long as they are driven only from the two steering and throttle outputs on the receiver and no external sensors are used there is nothing limiting how many servos you can use.

If someone want to use a servo for front wheel braking there's nothing stopping you doing that but the only control of it must be from the throttle output shared with the ESC, so you can't have it so it can vary brake balance between front and rear when running.
If for example you wanted to use servos to stiffen the springs/dampers during hard cornering you can technically do that, but it will be doing the same whether you are going really slow or flat out, there's no way of the buggy sensing how hard it is cornering.

Of course the BRCA has put in rule 23.13 so if the committee thinks you are adding driver aids they can ban it whether it's legal or not.

[AntH]

T[QUOTE=andybulmer;778432][hi. after asking this same question with paul worsley at a national. "if the front wheels are not driven (as your first quote suggests) then this would be within the rules as they are write at the moment"
my car was a kyosho lazer fs2 with the oneway bearing reversed.

So you have raced this Lazer with reversed one way at 2wd BRCA events and got through scrutineering? Was it any good?! I assume it would need lots of setup work to get it to drive ok. I think if a decent setup was found it could be an advantage.... If you think about it, the almost disappearance of one ways in 4wd proves it. 4 wheel braking is more of an advantage that a slightly sharper turn in. Anyway, to be honest my main problem is my driving..!

[SlowOne]

There is nothing to stop anyone doing this. Two receiver connections allowed - use the Y lead. Driven wheels - I think not! Where is the engine/motor driving the front wheels? Driven, by definition, means that there is an energy input to the wheels that creates a force to which there is an equal and opposite reaction. There is no energy input to the front wheels, they are being used as a means to allow conversion of the kinetic energy in the car to heat energy.

As Terry points out above, 23.13 might sink you if in the Committee's opinion...

Hope your hat is tasty, Jimmy!!

[AntH]

Originally Posted by SlowOne

There is nothing to stop anyone doing this. Two receiver connections allowed - use the Y lead. Driven wheels - I think not! Where is the engine/motor driving the front wheels? Driven, by definition, means that there is an energy input to the wheels that creates a force to which there is an equal and opposite reaction. There is no energy input to the front wheels, they are being used as a means to allow conversion of the kinetic energy in the car to heat energy.

As Terry points out above, 23.13 might sink you if in the Committee's opinion...

Hope your hat is tasty, Jimmy!!

Is this not the same difference? Both methods (via driveline or front brake discs) apply a braking torque to the front wheels.