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11/04/2012 3:32 pm  #1


wheelie bar talk?

what have you guys found in wheelie bar testing. some like the 5 inch max, some shorter. how about 6 inch for outlaw stuff? width wise i would think wider the better for stability but i do like the narrow look for scale reasons, but is stability sacrificed. thoughts?

 

11/04/2012 4:25 pm  #2


Re: wheelie bar talk?

I have found that 4 1/2 to 5 inches from axle works the best , have never tried real wide as try to keep them out of the main glue path ,also ( I doubt if it makes a diffrence) the further the wheelie wheel is futrher out from center line of  chassis if there is any twist at launch (lifting right rear tire) left one touches first, will try to steer the car out of the slot..that is my story and I am sticking to it.. P.S. I tried scale length on HO scale drag cars , VERY unstable compaired to full length allowed..

 

11/05/2012 8:41 am  #3


Re: wheelie bar talk?

ahhh, wheelie bars.... The longer they are the more forgiving it will be on wheelie bar height. My personal opinion is that wheelie bar construction is the most important part of a car, and the accepted practice is that we build them backwords and upside down from what they should be from a pure strength aspect.

 

11/05/2012 7:47 pm  #4


Re: wheelie bar talk?

Billy your givin up top secret stuff. SHhhhhh! LOL

 

11/06/2012 5:06 am  #5


Re: wheelie bar talk?

Nothing secret about it, you just have to think about in the correct manner.

 

11/06/2012 11:58 am  #6


Re: wheelie bar talk?

Might be fun to try a scale bar length would be what? about 1/2" behind the rear bumber and width just enough to clear the braid,would look good but will it work ?

 

11/06/2012 4:37 pm  #7


Re: wheelie bar talk?

well on 1:1 drag cars longer bars are made to hit softer but we are talking 5-8 inches off the ground. A slot car wheelie bar is pretty much on the ground from the get go.  I may try a chassis with removable bars that come on and off and try lengths 2 inch 3 inch 4 inch 5 inch and see what the affects will be.  of course a 16d will react different than a 20.

     Thread Starter
 

11/11/2012 11:41 am  #8


Re: wheelie bar talk?

In my opinion and experience, wheelie bars are a very tuneable part of the car that can have alot of effect on how the car leaves. The motor/tire/gear combo used plays a huge part in how you set the wheelie bars up. If you try different diameter wire, and lengths of that wire, it will pay off.

Without spending a ton of time on all the variables, just start  here:

  1. Measure the distance from your axle centerline to your guidepost. Now make your bars this long when measured from the front of the motor box to the wheelie bar axle centerline. This is typically between 4-5 inches.
  2. Use .055 wire for the lower rail, and .047 for the upper. After soldering in the lower rail, bend about 1/2 inch of the .047 wire so that it lays flat inside your lower rail while the other end is is place where it will be soldered to the chassis. Solder this wire in place.


You can then experiment with wire sizes, lengths of the bars, and you can even make the bend in the upper rail longer or shorter to soften or strengthen the bar. These wire sizes work on grp12 to grp27 motors, so it won't be too far off even if you dont do anything else to them. Lowers out of .047, .055, and .063 as well as uppers of those sizes can have you testing wheelie bars for weeks if you want to. It wont be nearly that tedious to find a good combo though.

Last edited by Steve B (11/11/2012 11:44 am)


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
 

11/12/2012 7:52 am  #9


Re: wheelie bar talk?

think of the wheelie bars as a big triangle, which is what they are...ok now think about how pressure is applied to the bars and now think in a push pull manor, which piece of the bars is getting pushed against and which is getting pulled. The piece that is getting pulled against does not need to be very strong ass you can pull a lot with very little (think of pulling a rope) and the piece that is getting pushed against should be very strong (think of pushing a rope LOL) thats my theory and I am sticking to it!!LOL to further confirm this...look at big cars with single wheelie bars...which side has 2 bars and which side only has one.

 

11/12/2012 6:15 pm  #10


Re: wheelie bar talk?

This is how i built my last class cars

MM/PS  Ky Trash Inline chassis .082 tubing mains .082 tubing struts .072 bottom wheelie bars  Quad 20
A/FC  WRP Sidewinder chassis .062 wire mains  .072 tubing struts  Quad 20
P/M WRP Sidewinder chassis   .062 wire mains  .072 tubing struts   Quad 12
T/S  WRP Sidewinder chassis  .062 wire mains  .072 tubing struts   Quad 20
F/M T/R Sidewinder chassis   .062 wire mains   .072 tubing struts  Quad 12
PS/T  WRP Sidewinder chassis  .072 tubing mains .072 tubing struts  Quad 12
SS/A  T/R Sidewinder chassis  .062 wire mains   .062 wire struts   Single magnet 20
GT/D  DRS  AA/FC Sidewinder one piece chassis converted with Champion pan  Modified S16D
D/S  Ky Trash Sidewinder chassis   .062 wire mains  .072 tubing struts  Speed FX 16D

Last edited by Rex W. (11/12/2012 6:16 pm)

 

11/13/2012 5:28 am  #11


Re: wheelie bar talk?

It is all just theory, but lets see if you can agree with this on wheelie bar stress,
a. The lower wheelie rail never see's "compression" stress
b. Without upper rails the lower rails see "bending" stress
c. Upper rails see "compression" and "bending" stress
d. As soon as we add an upper rail the lower rail becomes a "tension" type stress and the lower rail can see "bending" stress if upper rail is not strong enough.
If this can be agreed on then to make the strongest, lightest wheelie bar design we would have larger rails for the uppers and can get buy with much smaller for the lowers. When I designed my new chassis I designed them with only one lower rail for the bars and they have been just fine with whatever power you wanted to throw at it.
Now, front rails is a whole different topic LOL

Last edited by billy (11/13/2012 5:29 am)

 

11/13/2012 8:55 am  #12


Re: wheelie bar talk?

I'll just stay with my theory that to build the strongest and lightest possible wheelie bar you need to make upper bars much larger and then you can make the lowers much smaller.
Speaking of wheelie bars, how long do you think a car is on the bars during the course of a pass??? talking about .900 or faster

 

11/13/2012 11:04 am  #13


Re: wheelie bar talk?

lots of great info and thinking here! really makes you think about the forces and what is going on during a run.  People say a car goes on the bars the 1st half and aero plants the nose the 2nd but is there a way to really know. I am sure tons of variables can/will change it.

     Thread Starter
 

11/13/2012 1:34 pm  #14


Re: wheelie bar talk?

Thats what made MM/PS so good is its a inline chassis & lots of guys can't figure em out.

 

11/13/2012 8:41 pm  #15


Re: wheelie bar talk?

I always arrived at my wheelie bar sizes through testing. Too soft would just be slow and arc the braid. Sometimes the car would just be jumpy too. Too stiff would need too much glue and a wide tire just to hook up. And then you would have to drag those stones all the way down the track.


Knowledge does not equal Understanding, and the Truth is the Truth, no matter what you think of it...........
 

11/14/2012 5:00 am  #16


Re: wheelie bar talk?

Marty wrote:

billy wrote:

I'll just stay with my theory that to build the strongest and lightest possible wheelie bar you need to make upper bars much larger and then you can make the lowers much smaller.
Speaking of wheelie bars, how long do you think a car is on the bars during the course of a pass??? talking about .900 or faster

Four to six revolutions of the tire depending on the glue up of a car that runs .500 on .062 short times.

All the cars I have messed with...fast hardbody's... I beleive they are on the bars for a lot longer than you would think
case in point....car arcing braid on big end and hits the glue and skips over it straight into the box, lower the bars...arcing stops and stops perfect. I have seen this scenario many times over with cars.
I really enjoy everyones different theory's on car construction and how a car acts durring the event of the pass, we all know there is 100 ways to skin a cat and none of them are incorrect, but I find it more interesting to the thought process behind the theory's ,which it is all theory until we have the technology to actually ananlyze what happens to the car and chassis during the course of a run.
At the end of the day if this makes someone new to building to think differently and sometimes outside the norm then this would be the greatest accomplishment.

 

11/14/2012 7:03 am  #17


Re: wheelie bar talk?

I know you have probably more hard data than anyone, how far down the track did you film??? I would be more interested in the back half of the track as the front half as this seems to be the hardest part for most people to get a handle on..at least with hard body stuff. The lexan body's with duckbills and large rear wings are a lot more forgiving IMHO.
Braid arcing at or near the finish line is always an interesting scenario (not talking braid burning NEO or Cobalt stuff), why does it happen here and not at the starting line where the most torque variables come into play? The simplest, stripped down explanation is seperation of contact between the braid of the car and braid of the track, but if the body aero is planting the nose then you would think this is planting the guide also??? But why does it often fix this problem when you tighten the bars????? If we can answer these I think it would be a big help to a common problem for a lot of people.

 

11/14/2012 7:48 pm  #18


Re: wheelie bar talk?

Marty as usual you just made the light bulb glimmer. . No wheelie bars ,Hard body ,wonder why a big grilled 66 GTO body with large (1 1/16 X .500) tires and the front end an 1/8th of an inch off the track ,takes flight about 10 FT from the finish line with 50 Grams of lead added ,and a Corvette or Ferrari ,low to the track,runs 9"s at 70 Mph ,Back to the drawing board

 

11/30/2012 10:54 am  #19


Re: wheelie bar talk?

I have found out by running the wheels wider and even in the glue with the bearing wheelie wheels that are coming out the stabilaty of the car is much even than with others that I have ran.  I am not saying that others doesn't work to ones choice.  I have been testing these for a few weeks and have found out that they are running the car with closer times and tighter MPH.  It takes the complete package to do this so with all of the great bulders out there all should pick up more.  The legnth of the wheelie wheels I have been doing jusy about the max and even on a shorter wheel base car the longer will work better.  The wider the path even if in the glue with the bearing wheels it is much even from side to side movement.  Good luck all and great racing.  KEEP AN EYE OUT FOR THE NEW WHEELIE WHEELS and neo magnets for the c cans that are long or shortened ot the euro cans and a few other items coming out later.  The wheelie wheels should be out in a couple weeks and the new magnets before Christmas.  HAPPY HOLIDAYS TO ALL AND GREAT RACING.

 

2/25/2013 6:07 am  #20


Re: wheelie bar talk?

Been working on short bars any where from 1 1/2 to 3 inches from axle , they seem to work fine on SLOW cars or Soft launching BB20 ,next test Grp 20 -1 1/2 inch length bar to axle in a hard rail dragster ..may be a few weeks till I get to a track..but will let you know what happens...

 

3/15/2013 8:50 pm  #21


Re: wheelie bar talk?

Well,to be SHORThttp://cdn.boardhost.com/emoticons/embarrassed.png
 short bars are a painhttp://cdn.boardhost.com/emoticons/shocked.png
 increased sensativity to heigth and alignment , slam down harder on launch and rebound quick..Back to the drawing boardhttp://cdn.boardhost.com/emoticons/sleep.png

 

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