FrontEngineDragsters.Org Forum
Technical => Roo Man's Room => Topic started by: ss4 on February 06, 2014, 11:25:21 AM
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Not planning to run wheelies, but if I find the need I would like to have the mounts on before painting. would anyone share photos of what they have done. I am looking at a 3 bar design the would have 2 bottom bars and 1 top bar. I am concerned however if a bar were to break it would come through my back. thoughts?
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Check out Dragster supply on line they sell a awsome kit at a great price give David Beard a call.
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I would think you would want to do it the opposite way with the single bar on the bottom . I also think you would be better off starting out with the bar on the car . You can always take it off later .
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FWIW I agree with Bill's statement above. That is the voice of experience speaking. You want the two bars on top and it is best to go out with the bars on the car. I have almost flipped one over backwards without bars. Not fun! I'll let Roo have the last word...
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ss4,
Please watch this video...
http://www.youtube.com/watch?v=eySjAE0jjRo&list=UUWvCR8VLjbqZegUQp9DSEiw&feature=share&index=5
I do have the wheelie bars, an old two-wheel design. It didn't help at all that I left them in the trailer!
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We chose to go with single top bar and two on the bottom with a wide stance at the wheels. The tabs on the chassis are 1/4" thick with 3/8" grade 8 bolts, bars are 1 1/4" .065. Very stout and believe me we use them every pass, never had any issues with this set up.
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I depend on some flex in my wheelie bar setup. If they were too rigid the car would lift the front end, hit the bars and then drop the front and upset the car. Length, angles and pipe size will determine how the wheelie bar works, along with car balance/ballast.
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I use a three bar single wheel package with the single bar on the bottom where it is in tension. Weld clevis and 3/16" tab at the chassis end, about 6' from the frame to the wheel. Most of mine have 1.125" upper bars and 1.125/1.00 for the lower with the 1.125 on the chassis end and the 1.00 on the slider. I usually use the same McKinney adjuster as the big show guys as it can quickly be fine tuned on the start line without a wrench. As George noted some flex in the bar will stop the car shocking the chassis if it hits at the step.
(http://i156.photobucket.com/albums/t18/aussierooman/IMG_0322-2.jpg)
(http://i156.photobucket.com/albums/t18/aussierooman/McCuistiondragster199.jpg)
Here is the same basic package on an altered.
(http://i156.photobucket.com/albums/t18/aussierooman/IMG_8043.jpg)
Roo
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This is what Roo Man did on mine. It was done after the body had been built because I was going faster. I originally ran without one.
The first shot is actually at the same track, but at a different time.
The second is at our local track
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thanks for all the great input. so are the mounts single or double shear? hard to see in the photos
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Single attachment point, double on the wheely bar
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thanks for all the great input. so are the mounts single or double shear? hard to see in the photos
I use a slotted weld clevis so there is no adjustability of the lateral wheel location to get messed up.
Scroll down this page to see them at the bottom of the third photo. http://www.neilparks.com/chassis/tubing.htm
Roo
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This would be toooooo much flex.
(https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-frc3/t1/545126_420676704620464_178850716_n.jpg)
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Single top bar is a no no, if the mount ever broke, you will get speared! Two upper bars, single lower, length about 1/3 of wheelbase, bottom attach point even with lower frame rails.
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Take a look at the pic (red car) in Roo's post. I could be said that if one or both top mounts broke the driver could also be injured. To make a truly safer set of bars, you would want to move both upper bars out to the widest possible point on the chassis. mounting the lower bar - bars- even lower than the driver to more avoid any injury there. remember in a crash the lower bar might not be in tension. We will be keeping ours the way they are. I am not telling anyone how to make their bars as anyone who does so could be making a big mistake. Keven just posted a pic as was asked for by the OP. Keven nor I would want it to be a "you should do it this way" reply
In line with the driver being injured by bars entering the drivers compartment, I agree with SFI making changes to wing mounting over the drivers head. Perhaps wheelie bar mounting will be next in line for change.
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Van, I very sincerely hope you are not a statistic SFI uses to make change. George
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Van, I very sincerely hope you are not a statistic SFI uses to make change. George
OK George I have given my idea on a safer way to install wheelie bars, Why don't I see at least a drawing of your safer idea ? I do not see two bars directly behind the driver as any safer. I also hope that your idea doesn't become a statistic.
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I see the two as lot safer. Odds are if brake they will split and go outward.This would leave me in the middle instead of the bar in the middle of me. JMO aqnd probably worth less then 2 cent.
I am mounting mine with top 2 bars to frame rails right at kidney bars.Hopefully never to break but id something stupid happens and back end hits something and breaks them I figure they will be deflected away from me. I am running lower bar to center bar ,almost to rear end(high chair car) putting it on sam plane as lower frame rails/Using 1 1/8 mainly with sleeving and adjuster on bottom bar. Hoping that after get it tuned and weight where it needs to be I can basically run w/o bars.
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Van, I bought our car with the bars as they are in the picture posted. They are about 5' long. I run them about 2" off the track. I expect the top rails to flex and with that the bars function is more than a travel limiter. In fact I may change the top rails to allow a little more flex. As you can see by the picture ,the car works pretty well when we are on a good track. George
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I like the idea of the clevis instead of the side saddle mounted rod end, especially pointing at my back. Thanks for all the input.
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my thought would be a plate at least between the 2 seat bars. similar to a door plate on a roundie round car.
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my thought would be a plate at least between the 2 seat bars. similar to a door plate on a roundie round car.
I think you and a few others on here are overthinking this. Go to a Cackle car show and walk down the row of cars and look at the single bar sticking out used to push the cars around the pits and to push start them. some make tripods but most are just a single bar that may not have any bracing. Just do a good job on the quality of parts,welding,fasteners, tubing, and you should have nothing to worry about. Weld the tabs directly in line with the bars for max strength. Make the tabs fill the clevis to eliminate bolt shear. My clevisis are huge, do NOT use the little ones made for steering linkage.
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Here are some pics of the wheelie bars I made, not saying saying this is how to do it, just that it's how I did it. 2 upper bars, one lower, all 1'' .120 MS DOM, 1/2" bolts at spherical rod end attachment points, left-hand / right-hand threads on the uppers to allow lateral adjustment, double shear everywhere. Two machined side plates at the wheel end, spaced apart by the caster, an aluminium spacer, the upper tube rod ends, (and spacers) and lower tube attachment / spacer blocks flat on the sides and contoured to fit the diameter of the lower bar, which is sandwiched between them, with two 3/8" bolts thru all. Not clearly visible in pics, but the rear side plates have two attachment point options for the upper tubes. Rod ends at both ends of the upper tubes loads them purely in compression, unless a crash situation whacks them sideways or elsewhere. The rear tube upper attachment as shown has the upper tube centerlines passing somewhat above the wheel centerline, the effect is to bow the single lower bar upward when the wheel hits the track. The lower mounting hole for the rear of the upper bars makes the upper tube centerlines pass thru the wheel centerline only slightly above it, so the bow effect is less if the wheel is loaded upward, but it's still somewhat springy.
I asked a friend of mine who has some involvement with fuel cars and such, what he thought about the design thinking, he said I was overthinking the thing, (I heard that somewhere recently). The whole setup is certainly more clunky and heavy than what fast cars are and have been running, but it was fun to build. And it certainly resists wheelies in a smooth way.
On the safety side, I completely agree that two upper bars have to be better than one, in the event of backing the thing directly into a wall or something. No one can predict every possible angle of impact, etc., but I think the top-heavy triangle mounting gives me the best chance of not having tubes through my torso or up my... well, ya know...
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Better pic, crossbar connecting the upper tubes added since the above pics to resist twisting of the wheel from any side loads. Hope I'm not boring 'Yall.
John
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Not at all.
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I'm designing mine at the moment. Had the same concerns with a single point up high. I don't believe I'll ever break a bar or mount on a launch, my concern would be going into the wall backwards. I feel as though in any other form of motorsport something like a suspension upright or an aerofoil etc would be designed to shear in a safe way and detach but I can't figure out how you could apply this safely to a wheelie bar ?
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thanks for the detailed posts. Guess I better get my steel ordered. So mild steel or moly?
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mild steel for trailors and tractors Moly for race cars.
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C/M .
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mild steel for trailors and tractors Moly for race cars.
Chris You sound just like Frank!!
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Thanks Bill. I have been compared to lots worst.
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I'm pretty sure Frank would say "Ti" for wheelie bars!
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Frank says Ti for everything. Frank can afford Ti heck his exhaust is titanium. Mosr here are po folks heck spelling it hurt my bifold.
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Mine were MS, but if I had it to do all over again, they'd be CM. Unless my rich Uncle Frank bought me some Ti.
John
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Currently my broke Uncle Sam is screwing me out of my Ti play money.
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Yea it would be nice if everytime we needed more racing money we could take it from everyone in america rather they liked it or not.
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Last time that I checked titanium tubing was about 34 dollars a foot ! A little too expensive for me !
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Was at local chassis builders today had set sitting there out of titainium and told me it was 42 per foot so my thre bar set 6' long would b3e about 800 bucks just for tubing.
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When I was running the fab shop at JFR we were paying $2 per inch for 3/4" x .060 on the secondary market.
Roo
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If jr fuel I guess I could see it.Small motor needs all the weight savings you can get.I still would not spend the money until I had done everything else to cut weight and make every ponie I could then I would go to what I call this extreme.
Any one know what weight savings would be for say single wheel 3 bar 6' long wheelie bar?
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If jr fuel I guess I could see it.Small motor needs all the weight savings you can get.I still would not spend the money until I had done everything else to cut weight and make every ponie I could then I would go to what I call this extreme.
Any one know what weight savings would be for say single wheel 3 bar 6' long wheelie bar?
Not including the wheel bracket and any mounting hardware (spuds/ clevis etc) the steel tubing comes in at around11.34 lbs and the Ti is 8.205 lbs so the total savings is probably going to be less than 5 lbs.
Roo
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.003 light cost nothing and weighs "0" lbs
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Roo and dre, From what I can see, 'yall must take lots of breaks to be on this site as much as you are, and I'm sayin that like it's a good thing... Jeez, to calculate weight differences and such and answer sometimes dumbass questions from me... I appreciate you guys.
John