FrontEngineDragsters.Org Forum
Technical => Roo Man's Room => Topic started by: janjon on June 03, 2013, 08:10:32 PM
-
So, single wheel, one lower, two upper tubes. 1" x .094 MS DOM tubing. 5 feet out from the mounting tabs on a 150" WB FED. 1/2"-20 threaded rod ends at the ends of the upper tubes, one end right-hand thread, the other left-hand. This to be able to center the wheel in the tracks of the more forward tires and adjust height also. So the uppers need to be able to be turned independently and together to do this. The single lower bar similarly has the same right-hand rod end mounted to tabs at the front. Problem is, set up like this, you can grab the caster and tweak it a bit one way and the other. And looks like to me, if the car launched a little bit crooked, this steering input would be a bad thing, not a good thing. There has been mention of tying the upper bars together (somehow), and using a McKinney adjuster on the lower bar for height adjustment only, but I still don't have a clear picture of how that whole setup would look. Please see the attached picture, and anyone's thoughts and opinions are welcome.
Thanks, John.
Well he;;, the pic.s too big, try to snedit tomorrow.
-
My Roo Man built wheelie bar has two fixed upper tubes and one adjustable lower tube for adjusting the wheel height.
-
Mine same as Glenn's. Not sure what tube he has. Im going with 1.250x.058 wall. I was going 1.125 but was because of material I thought I would have,now that I have to buy I'm stepping up little. Might hit Roo Man up on the 1" thing.Maybe if shorter bars ,if going long (mine are 6') I would be worried about them at 1" tube.Jusy my thoughts.sure Rooman will have better input.
-
I usually use 1.125 x .058 or 1.25 for the upper bars and 1.125 for the major part of the lower with 1" for the slider to allow the bar to be pinned up higher for towing around the pits. I use a weld clevis at the chassis attachment points and at the bottom I use the McKinney wheel bracket which also has a welded mount for the bar. When I build the bar I run a string down the centerline of the car to locate the wheel. The clevis that I use at the top mount is made for a 1" tube so I weld it to a short stub and then slip that into the 1.25. That allows me to line the wheel up on the string by sliding the main tube on the stub and once it is aligned then I weld the slip joint. On some cars which hit the bar hard I add a cross member about half way between the chassis and the wheel to keep the top tubes from bowing out under load.
My desktop 'puter at the shop has had a modem failure and the laptop that I am using does not have all of my photos loaded on to it so I am unable to post photos at this time. Glenn may have some of the installation on his car.
Roo
-
As far as the wheelie bar steering you at the launch, it can be a major deal. We fought this for a few rounds one time. A friend showed me how to center the wheelie bar wheel with the slicks and the launches were back straight as an arrow. Comp Eliminator class will give you a first hand look into interesting wheelie bar designs and how they work. Pretty cool when they launch at 9000 rpm. Lol
-
I usually use 1.125 x .058 or 1.25 for the upper bars and 1.125 for the major part of the lower with 1" for the slider to allow the bar to be pinned up higher for towing around the pits. I use a weld clevis at the chassis attachment points and at the bottom I use the McKinney wheel bracket which also has a welded mount for the bar. When I build the bar I run a string down the centerline of the car to locate the wheel. The clevis that I use at the top mount is made for a 1" tube so I weld it to a short stub and then slip that into the 1.25. That allows me to line the wheel up on the string by sliding the main tube on the stub and once it is aligned then I weld the slip joint. On some cars which hit the bar hard I add a cross member about half way between the chassis and the wheel to keep the top tubes from bowing out under load.
My desktop 'puter at the shop has had a modem failure and the laptop that I am using does not have all of my photos loaded on to it so I am unable to post photos at this time. Glenn may have some of the installation on his car.
Found this one.
Roo
I'll take some pictures next time out at the track, looks like rain this weekend.
-
All the tubes on mine are .875 od. x .058 chrome moly. The wheel is out about 5' from the mounts. The uppers do bow up some after 10 or 15 runs. Theres a slip tube in the bottom for towing and I have slip tubes in the uppers about a foot long to adjust height. I also have heim joints. There are all right hand but its easy to pull the pin and spin the whole tube. I found with mine if the bar is centered or it doesn't hit the bar solid its headed to the right. I need to offset the wheel about 1.5 in. the the left to get it to go straight. I allways thought mine were a little on the light side. But you 1' .094 bars sound a lot beefier than mine.
-
Thanks, All, for the replies and input. 'Tis particularly interesting about offsetting to the left... mine has right and left hand threads on the upper bars, so I would be able to move it side to side as well as up/down as necessary. One other question, any opinions about using aluminum rod ends in the upper bars? They will be loaded in compression only. The lower bar has a steel rod end at the front attachment, and double cross-drilled thru-bolted at the rear.
-
I dont think I would be comfortable with aluminum ends. I'm barely comfortable with moly ends in mine. Even though they are in compression I would be concerned where the the load is at an angle on the upper mounting point at the chassis.
-
Im all for saving weight but some times its just better to go little heavier and be safe. Call Frank Parks if theres a safe lite weight piece he has it. Warning he is out spoken and may tell you your nuts.
-
Use C/M.
-
George and wideopen, I'm gonna go with your advice. I would still stand by my statement that the rod ends would be loaded in compression only, and the mounting tabs could be subject to some angular load that might rip them loose, as long as theyre only subject to getting hit on the launch, but crash situations could, I guess, rip things loose and possibly send them spearing through the seat back area and into the driver. That's my concern, anyway. I'm gonna upgrade, for more peace of mind if nothing else...