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Author Topic:   solid pullbars
LITTLEMAN
Member
posted December 11, 2000 09:00 PM
I AM WONDERING IF ANYBODY HAS RUN A SOLID PULLBAR WITH BIRDCAGES,OR 2 LINK SUSPENSIONS OR IS A SPRUNG PULLBAR THE ONLY WAY TO GO?INTEREATED IN STORYS ON ANGLES LENGTHS AND HOW HIGH TO MOUNT OFF TOP OF REAREND,THANKS

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MOD RACER#93
Member
posted December 12, 2000 09:16 PM
the advantage of running a spring bar vs a solid bar is the spring bar will cushion the shock when torque is applied to the rear end. They both have the same effect on anti-squat. Solid bars are most common on asphalt cars because of available traction of the corners, when used on a dirt car the driver needs to be more smooth on acceleration to avoid breaking the tires loose. Personally i would only run a soild bar on an extermely tacky track or in a limited class where spring bars are not allowed. As far as length that depends on the type of suspention, on a two-link it is detemined by the length of the lower links and on a properly designed z-link the longer the bar the better.


bbracer17
Member
posted December 13, 2000 05:44 PM
I'm running a solid pull bar right now but haven't done all the changes I want to yet. I really like it even on dry slick. Mine right now is mounted 12 inches above the rear end housing and is 40 inches long. I've tried it straight with 15, 18, and 20 degrees angle and I've tried it angle toward the right front at 20 degrees. I think it is actually to long to really work well atleast on 1/4 and 3/8 mile tracks. I'm going to shorten it to about 26 inches and try all the angles again. I know a couple of fast guys that are running solid bars and even more that run the rubber bars that are almost solid.


jammin
Administrator
posted December 13, 2000 06:39 PM
Well....another thing besides cushioning the forward bite is that it allows dynamic weight distribution with the movement. The more it moves in certain areas....the more the suspension can be altered to put weight where you want it when your on the throttle.


bbracer17
Member
posted December 13, 2000 07:42 PM
Jammin is right, if your rear springs are staggered and you use a solid pull bar the car won't increase wedge on acceleration.


LITTLEMAN
Member
posted December 13, 2000 07:56 PM
the sprung pullbar has me wondering how much force is lost in compressing a spring.if lower the pullbar down front and rear ,won't there be less pull on the chassis thus less force applied to the tires trying to break them loose.then i could cushion the lower links,what do you guys think?


Racer 111
Member
posted December 13, 2000 08:00 PM
Go with the spring style.The rubber bushing style there's no way to measure the travel.Most Spring style have a travel rod on them.It is always helpful to be able to measure whats happening.A solid bar sounds like broken mounts to me.


LITTLEMAN
Member
posted December 13, 2000 08:02 PM
quote:
Originally posted by bbracer17:
Jammin is right, if your rear springs are staggered and you use a solid pull bar the car won't increase wedge on acceleration.

I DON'T LIKE THE LOADING THE LEFT REAR WITH THE WRAP-UP OF THE REAREND USUALLY CAUSES A LOOSE CONDITION ON ENTRY.


wfoondirt
Member
posted December 13, 2000 08:29 PM
littlman,lowering both end of the torque link will reduce the amount of anti-squat in the car. You mentioned cushioning the lower links...how do you propose that?


bbracer17
Member
posted December 13, 2000 10:46 PM
Try the solid bar first, its cheaper. Then maybe borrow a spring bar from someone and try it. If you want something in between then use the rubber pull bar. Just play with different angles untill you get want you want.


CUSTOMPERFORMANCE
Member
posted December 14, 2000 12:28 AM

i have run a solid bar with a 2 link, mounted about 13 inches from top of rear and 3 inches back from center, 40 inches long angled about 15-20 degrees. it worked best when track was tacky and didnt work well when dry slick. i have seen guys running shorter ones around 20 inches that seem to have good success. i also have run the rubber biscuit style and it seemed to have better bite than the solid or spring stye but the rubber biscuits wear out and you loose bite. i am now on the spring style and like it, still expierementing with spring rates to find what works best for me, mounted at the same angles as the above types.


LITTLEMAN
Member
posted December 15, 2000 08:12 PM
I've seen a solid pullrod on larson chassis,its mounted to the right of center these cars seem to have good bite when its slick. Does anybody run one of these cars???Seems like information on this subject is hard to find.


wfoondirt
Member
posted December 18, 2000 10:27 AM
Ideally, a soilid torque link would be the most efficient set-up, but on a the monster motor hard-tire modifieds that are out there now its very hard for the driver to keep the car hooked up especially on a slick track so yes the spring torque links are a crutch of sorts, but are normially a necessity on dirt cars. As far as the spring rates on the torque links unless you have the springs staggered, ie lr in front rr behind, i like to run as stiff a spring as i can untill the driver begins having problems getting the car hooked off the corner. If the springs are staggered as mentioned i like to go softer on the torque link spring on a slick track to allow for the axle rotation to add diagonal.
Custom, how long of lower links were you running with the 40" solid torque link?


CUSTOMPERFORMANCE
Member
posted December 18, 2000 07:19 PM
20.5 ON THE LOWER LINKS.


LITTLEMAN
Member
posted December 18, 2000 09:21 PM
I WAS JUST THINKIN....IF THE PULLBAR IS MOUNTED 13 INCHES ABOVE THE CENTERLINE OF THE REAREND,THEN THE LEVER ARM IS 13 INCHES LONG WHICH MULTIPLYS THE FORCE TRYING TO COMPRESS THE SPRING AND PULLS UP ON THE CHASSIS.WHICH IF YOU HAVE A1000 LB. SPRING AND IT COMPRESSES 3 INCHES YOU BASICLY HAVE 3000 LBS. OF FORCE.IF I HAVE A SOLID PULLROD IS THAT TO MUCH FORCE FOR THE TIRES TO TAKE?IF I DROP THE PULLROD DOWN TO THE TOP OF THE REAREND THE FORCE IS CUT IN HALF ABOUT 1500 LBS,HOW MUCH FORCE IS USED UP COMPRESSING THE SPRING?ANY TAKERS??LATER


wfoondirt
Member
posted December 19, 2000 09:29 AM
littleman, i'm not exactly sure what your getting at but lowering the torque link and reducing the angle will reduce the amount of anti-squat. If i understand what your thinkin that by lowering the torque link in an attempt to cushion the torque shock to the tires? A more effective way to acheive this is to soften the spring or reduce the amount of preload thus cushioning the torque shock to the tires without reducing the anti-squat in the chassis. If your idea is to do this with a soild torque link, lowering the bar will reduce the shock to the tires a little but you will probably have to find another way to make up for the loss of anti-squat which in most cases will hurt forward bite, ie more angle in the lower links to create thust anti-squat but that will tend to cause roll oversteer, or you may be able to just put more diagonal in the car, everything is a trade off.


Strokin3
Member
posted December 19, 2000 06:03 PM
Littleman talked about running the LR c/o eliminator in front of the axle and the rr
mounted on top of the axle with a jack bolt.
Will staggered c/o eliminators get me close to the same setup. I have also run a real short biscuit rod in the center to try to get
some indexing of the rear springs when mounted behind the axle. it seemed to work but i'm sure there's always something better.


LITTLEMAN
Member
posted December 19, 2000 06:45 PM
quote:
Originally posted by Strokin3:
Littleman talked about running the LR c/o eliminator in front of the axle and the rr
mounted on top of the axle with a jack bolt.
Will staggered c/o eliminators get me close to the same setup. I have also run a real short biscuit rod in the center to try to get
some indexing of the rear springs when mounted behind the axle. it seemed to work but i'm sure there's always something better.

THAT SET-UP WORKS PRETTY GOOD WHEN IT'S DRY I'VE SEEM IT HAVE A PROBLEM WITH PUSH ON EXIT WITH LIMITED STAGGER ,BUT IF YOU CAN GET ENOUGH STAGGER IT CAN BE MADE TO WORK VERY GOOD ALSO CAN'T RUN AS MUCH LEFT REAR HEAVY WITH THIS SET-UP 20 TO 60 LB. RANGE OR WHEN IT UN LOADS COULD GET LOOSE ON ENTRY.AND DEFINETLY TOUGH TO RUN THIS SET-UP WHEN IT'S TACKY.YOU WILL HAVE TO MOVE THE RIGHT REAR SPRING TO THE FRONT OF THE REAREND TO KEEP IT FROM ROLLING OVER SO HARD CAUSING A PUSH.IF YOU PUT THE RIGHT REAR SPRING ON TOP OF THE REAR END YOU STILL GAIN LEFT REAR BUT THE RIGHT REAR WEIGHT IS MORE STABLE ALOWING YOU TO RUN MORE STATIC LEFT REAR.



Western PA MOD GUY
Member
posted December 19, 2000 10:22 PM
WESTERN PA GUY,THE TORQUE OF THE PULLBAR BRKTS WOULD BE MORE THE HIGHER YOU WENT UP THEM BECAUSE YOU HAVE ALONGER LEVER IN WHICH IS TRYING TO ROTATE THE REAREND LEVER BEING FROM THE PULLBAR MOUNTING HOLE TO THE LOWER LINKS MOUNTING HOLE.


Western PA MOD GUY
Member
posted December 24, 2000 10:29 AM
quote:
Originally posted by LITTLEMAN:
WESTERN PA GUY,THE TORQUE OF THE PULLBAR BRKTS WOULD BE MORE THE HIGHER YOU WENT UP THEM BECAUSE YOU HAVE ALONGER LEVER IN WHICH IS TRYING TO ROTATE THE REAREND LEVER BEING FROM THE PULLBAR MOUNTING HOLE TO THE LOWER LINKS MOUNTING HOLE.


The lever (pullbar) is not trying to rotate the rearend. It's function is to hold the rear from rotating or to control the amount of wrap which is desired. The force is coming from the rear, not the pullbar. The force coming from the rear is transferred up to pullbar. The force would be less powerful if mounted farther away from the centerline of the rear than if it was mounted on top of the rear. The HIGHER you mount the pullbar the easier it would to control the rear from wrapping. If you run a 1000lb spring in your pullbar mounted 13" off the rear and if you cut the mounting hight in half 6 1/2" then you would need a 2000lb spring in your pullbar to control the rearend. The force being transfered is coming from the rearend which it comes from the rear tires, not from the pullbar to the rear


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