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Author Topic:   PULL BAR ?
dirtslinger66
Dirt Maniac

Total posts: 200
posted August 28, 2004 12:37 PM  
As the track gets slicker do raise the pull bar on the frame or lower it?

mod70
unregistered Total posts: 200
posted August 28, 2004 04:22 PM           send a private message to dirtslinger66   Edit/Delete Message   Reply w/QuoteBBBBBB
I believe that lowering it (more angle) will allow more travel and a softer effective spring rate. But I'd like to see somebody else confirm this.

66RACER
Dirt Full Roller

Total posts: 26
posted August 28, 2004 06:17 PM  
IF YOU RAISE IT ON THE FRAME, IT WILL PULL THE REAR END IN AND LET THE CAR ROLL MORE, TO HELP ON THE DRY SLICK TRACK.

oldfordmod
Dirt Full Roller

Total posts: 46
posted August 29, 2004 09:47 AM  
The small angle the pullbar makes with a line pependicular with the ground determines the amount of weight the rearend receives from the pullbar(as measured with an angle finder). The compression distance in the bar x the spring rate of the damper = the force in the bar(easier with a spring bar). This force x the cosin of the angle = down force on the rearend(cosin 90 = 0, cosine 60 =.5, cosin 45 =.707). Move the pivot point on the rearend left or right to change the load on the rear tires (tighten or loosen). This effect only applies under acceleration.

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 29, 2004 09:54 AM  
I've played with the angle it doesn't seem to be helping. Cars EXTREMELY loose when I get on the gas.

LF 750, RF 850
LR 225, RR 250
49.5% cross, 58% rear after feature, 51% left side, 4-link Left, Z-link Right, Left rear spring behind, Right rear on swing arm.
Afco push/pull 1050# pullbar

mod70
unregistered Total posts: 200
posted August 29, 2004 10:43 AM           send a private message to dirtslinger66   Edit/Delete Message   Reply w/QuoteBBBBBB
Your numbers don't look like they should be too far off, I'm starting to wonder if it's a geometry thing. Are you running the rear square, and where are you measuring from to check it? Where is your upper link mounted left to right over the rearend?

oldford - huh? weze speekin dee eenglish here. Sorry man, but I didn't understand a word of that. I left my math degree in my other britches. (left my other britches at the party) (left the party in a haze)
what were we talkin about?

sdracer12
Dirt Maniac

Total posts: 180
posted August 29, 2004 11:32 AM  
More downward angle to the front on the pullbar will give more traction quicker, but run out sooner. ie. lowering on the frame in front will give more bite.

What kind of angle is in the bar now, mounting point to mounting point?
What are your bar angles, 4 and z?
Which tire brand?

Some quick suggestions to fix a loose off:

1. More crossweight = LR drive off
2. More LR bar angle = more drive off
3. Less stagger, but will tighten all of corner
4. Less RR bar angle = more LR drive, tighter exit


oldfordmod
Dirt Full Roller

Total posts: 46
posted August 29, 2004 12:54 PM  
Sorry bout dat, its pushdown man, tha moe angle in da bar, tha moe pushdown on tha tires.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted August 29, 2004 01:38 PM  
go 275 on the spring behind, and maybe a 225 on the rr and it will fix most all of the problem, also less bar angle in right side rear bar, and front bar, and add more angle to the lr bars.

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 29, 2004 04:45 PM  
LR upper bar 18* 15 1/2" long
LR lower 7* 20 1/2 " long

RR front 16*
RR back 8*

pull bar 17*

zeroracing
Dirt Forum Champ
Total posts: 1875
posted August 29, 2004 05:22 PM  
take angle out of rr bars.

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 29, 2004 05:35 PM  
I dropped the front bar one hole and put the rear bar in the top hole and it still is very loose on the gas. I can only drop the front bar one more hole and I took all the angle out of the rear bar that I can.

avenger 11
Dirt Forum Racer

Total posts: 88
posted August 29, 2004 07:39 PM  
dirtslinger66,I think you are running a metric front end,and if that is the case try going up about 200 pounds on your front springs and watch what happens.A friend of mine described exactly what you have,he stiffened his up and started winning features.

[This message has been edited by avenger 11 (edited August 29, 2004).]

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 29, 2004 07:48 PM  
mines a Jet Mod and it's built on the Big Impala Frame.

avenger 11
Dirt Forum Racer

Total posts: 88
posted August 29, 2004 08:15 PM  
My mistake,is that the front springs the Jet recommends?

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 29, 2004 08:33 PM  
Yes it is. I had a 650 & 750, then switched to a 750 & 850 and it didn't really make much difference.

Dirt-Tracker
Dirt Maniac

Total posts: 182
posted August 29, 2004 08:39 PM  
I always had to run alot of left rear in my jet car. 180#

------------------
"Somedays your the dog, and somedays your the fire hydrant!!!"

www.geocities.com/albertson28racing

paulickr
Dirt Maniac

Total posts: 110
posted August 30, 2004 10:24 AM  
i dont change mina at all, i run an 800lb pullbar spring and it lets the rear react better with not much tire spin and looseness.
i have been told that moving it slightly like an inch toward the left rear helps.

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 31, 2004 01:58 PM  
After looking things over AGAIN I noticed an 1-1/4 lead in left rear...would that cause me to be loose while on the gas?

[This message has been edited by dirtslinger66 (edited August 31, 2004).]

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted August 31, 2004 02:24 PM  
was that 1 1/4" lead at static ride height or was that with the LR at full drop?

MikeN
Dirt Full Roller

Total posts: 27
posted August 31, 2004 02:29 PM  
HOLY POOP YES!

mod70
unregistered Total posts: 27
posted August 31, 2004 03:27 PM           send a private message to MikeN   Edit/Delete Message   Reply w/QuoteBBBBBB
Ya-huh! That would almost certianly be the problem. You can talk pull bar angles and springs all you want, but none of it will make up for bad geometry in the rearend. Heck, I've gone to a solid pull bar full time and I have no problems even on dry slick tracks. Ya just gotta foot it right.

dirtslinger66
Dirt Maniac

Total posts: 200
posted August 31, 2004 05:53 PM  
yes,that was at ride height.

foolish farmer
Dirt Roller

Total posts: 7
posted September 02, 2004 05:22 AM  
I watched you some Sat. night, and that much lead on the LR would explain what your car was doing. I would try around 3/8 lead at ride height, and try a little more cross..

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted September 26, 2004 11:45 PM  
on our 2 link cars weh ave ran as much as 3 inches of static rear steer on a half mile...
the more trail (lr in front of rr or rr behind lr) you can run and car not be tight in the center the better you will be coming off...

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