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View Full Version : 2wd or 4wd - Which Jumps Better?


markwilliamson2001
21-12-2007, 09:47 AM
Having been down to the MK GP it was interesting watching the 2wd buggies and 4wd buggies handling the jumps...

I thought that both cars flew about the same through the air, but the 2wd's had the edge on landing... I believe this to be due to the large amount of kickup that the front end of a 2wd has compared to 4wd, so that if the car lands slightly nose down, you have better chance of landing with 2wd.

Just a thought, anyone else any opinions.

Mark

stefke
21-12-2007, 09:55 AM
I think a 4wd is easier to jump because it's easier to correct in the air.

Lee Martin
21-12-2007, 10:28 AM
4wds easier to correct in the air.......

but 2wds seem to land better...

markwilliamson2001
21-12-2007, 10:35 AM
Interesting what you say about 4wd in the air... Is this because of the 2wd being sensitive to throttle input in the air because of only the rear tyres being driven...?

I always thought 2wd was easier to jump...and land!

Keep em coming.
Mark

stefke
21-12-2007, 10:37 AM
Just simple physics : you have 4 wheels responding to throttle imput and giving a gyroscopic effect instead of 2.

Lee
21-12-2007, 10:39 AM
The 4 wheels are easier to correct because all 4 wheels produce the gyroscopic effect, you can lift of lower the nose very easily, with 2wd its really quite hard to lower the nose mainly because the motor is hanging out the back and there is only 2 wheels being driven, 2wd cars feel pretty dead in the air to be honest compared to a 4 wd

Lee Martin
21-12-2007, 10:42 AM
brushless is better in the air than brushed though!!! i found anyway!!!

stefke
21-12-2007, 10:46 AM
brushless is better in the air than brushed though!!! i found anyway!!!

I'm glad I'm not the only one who came to that conclusion ! People at my local track didn't believe me when I stated the above. I guess the word of the UK national champion will give more weight to my statement now. Thanks :D

Wraggy
21-12-2007, 10:50 AM
I guess the word of the UK national champion will give more weight to my statement now. Thanks :D
he knows nothing !!!!!! lol ;):p

Northy
21-12-2007, 10:55 AM
4wd not so good with a 1 way diff up front though :(

ben
21-12-2007, 11:10 AM
My s4 is quite forgiving if you get it wrong in the air.

lil ben

Lee Martin
21-12-2007, 11:30 AM
1 way's are rubbish1!!!!!!

hehe

Mike Hudson
21-12-2007, 11:33 AM
they are better in someways, and ive always found my 2wd very easy on jumps:p

Nick Goodall
21-12-2007, 11:45 AM
I'm with Lee on the Brushless thing with 2wd, I can make the front of my car smack down almost vertical if i jam the brakes on in the air - they give you soooo much more control!

2wd's have always been better for me, i love the way a 2wd car jumps compared to 4wd - 4wd cars always seem to land heavy to me, even if you get the downsides, 2wd cars are a bit more forgiving really.

markwilliamson2001
21-12-2007, 11:46 AM
Spot on Nick, I agree. You always seem to sum up well what I am thinking!!

M.

Billthemina
21-12-2007, 01:05 PM
they are better in someways, and ive always found my 2wd very easy on jumps:p


well the motors not hanging out of the back on an X-6 so it will be nicer in the air ;) :D

Lee
21-12-2007, 02:38 PM
The X6`s really slap down though, thats what i find , they seem to land like a 4 wheel:mad:

josh_smaxx
21-12-2007, 02:52 PM
At the regional last sunday my car flew better than expected, i have never really driven a 4wd but the way my B4 came down on the jumps and how i can correct it to any possition i want i think is spot on, i was hitting the down ramp quite well nearly everylap on sunday with the nose just a bit lower than the back, it left the jump spot on in my opinion.

glypo
21-12-2007, 03:18 PM
Just simple physics : you have 4 wheels responding to throttle imput and giving a gyroscopic effect instead of 2.

I must admit I found that sentence rather funny. Throttle control in the air is nothing to do with gyroscopic effects. Gyroscopes simply resist movement, through angular momentum itself which is not simple. So by very definition having gyroscopic effect on wheels would just make the car more stable in roll. It's exactly what happens with 1/5th scale bikes, big heavy metal wheels are used to resist roll (lean) and keep the things upright.

Anyway onto the question. Yes generally 4wd is better as people have said. However there are so many factors involved, as movement in the air is controlled by the polar moment of intertia. Things to consider, if you look at just the wheels... then of course 4wd has twice as much rotational control as 2wd. However if you consider in 2wd's the motor and gears are rotating in same direction as the wheels, this isn't always the case with 4wd's. And of course some rotations would provide a positive effect in terms of extra control, and others provide an adverse. It is actually possible to at least match the polar moment of area between 2wd and 4wd if you had a positive result in 2wd and poor on 4wd.

However there is also balance to consider. 4wd is much more symmetrical then 2wd, which will of course help through the air. Compared to the huge asymmetry found in 2wd anyway. And of course in 4wd if you have a one-way in the front you have full throttle control, but only 2wd effect trying to get nose down. So lots of factors, so it's not just class specific but also model and of course setup as well.

Of course pidge is the person to listen to as he does both with amazing results and his sentence seems to some up everyone's findings from practical experience.

Northy
21-12-2007, 03:27 PM
1 way's are rubbish1!!!!!!

hehe

Do you run you B44 full time 4wd then?

G

Lee
21-12-2007, 03:43 PM
full time 4 wheel drive with a rear bar could be the future?:confused:

Richard Lowe
21-12-2007, 04:17 PM
However if you consider in 2wd's the motor and gears are rotating in same direction as the wheels...
Actually on 3 gear 2wd's the armature/rotor spins in opposition to the wheels ;)


full time 4 wheel drive with a rear bar could be the future? :confused:
Noooooooooo, one ways are ace! :D

glypo
21-12-2007, 05:37 PM
Actually on 3 gear 2wd's the armature/rotor spins in opposition to the wheels ;)


Yes of course. I phrased that sentence in a poor manor, sorry. What I'm trying to say is that on a 2 wheel drive the motor is rotating along the lateral axis, the same as the wheels. And that this isn't always the case for 4wd, as in shaft drive 4wd the motor rotates around the longitudinal axis. As obviously within the gearbox each gear is spinning in a different direction, hence I said in my original post that some parts will contribute to the moment of inertia, and some will detract. As you say for 3 gear 2wd (I don't think you can buy belt ones any more?) The rotor in the motor will be opposing the moment of the wheels, as will the idler gear in the box. However the spur, slipper clutch, input and differential all add. It's all about the net difference, hence I said it depends on each model.

In 4wd shaft models the rotor, spur and slipper have no effect on the rotation of the car about the lateral axis (i.e. nose up/down) as they are rotating in the longitudinal axis. Sorry for confusion.

showtime
21-12-2007, 05:48 PM
Jason you're starting to sound like a nutty proffessor :o

i like it :D

josh_smaxx
21-12-2007, 06:35 PM
Sorry for confusion.

:D yep

No i actualy understood that, it makes sense to me..... no idea how mind.