Pulls hard left under accel

My 32 pulls hard left on accel,if I get on the gas hard.i looked at the rear four bar( triangulated) it looks ok.when I drive normal it's fine.butif I accelerate hard from a stop or on a slight sweeping left turn it tries to change lanes.scary.any body else run into this? I have to fight it. Then it'll whip to the right.the rear is not breaking loose,it just drives hard left.i have a 4 inch dropped axle ,spring over front end.with a maval steering rack in place of the vega box.alignment is 6 deg caster and 3/16 toe in.it will not self correct either .any ideas? Thanks

 

Sounds like the rearend is loose and allowing it to shift so it is steering the car. Not a front end issue. The extra torque is allowing the rearend to move so it is not perpendicular to the car. Look at your four link ends for slop.

 

If your running a chevy motor thats your prob...to much power. Try a ford motor!!!

 

^^^^^^^^^^^^^^^^
ha ha nice one
has it always done it or is it new. maybe your torque is unloading the frone end cousing it to let the axle swing (do you have a front pan hard?) also what arre you running for a front set up (hair pins split wish bones parrallel four link)

 

What rear end set up are you using ?
Get a camera and have someone stand behind the car and make a recording of how the car looks from a hard launch . Then you will be able to see how the rear sags and dips on one side more than the other . If you have a good 4 link rear then that's a simple fix with some adjustments of the bars .
Take the picture a few time until the car launches straight and not to the left or right . If you don't have a camera , have someone that knows what to look for stand behind the car .

Retro Jim

 

Did you have a four wheel alignment?

 

Are you sure your chassis was not set up by an oval track crew chief?
Rubber or poly link arm bushings?
If they are rubber, change them to poly.
Was the rear end narrowed?




oooh, oooh, one more to 1k

 

A front panard bar could help. As the front of the car raises under hard acceleration, the steering input changes when the chassis goes up and the wheels don't.

 

The rear end is a winter v8 quick change.with coilovers and a triangulated 4 link.the ends are poly and have no slop.relitivly new build.hair pins on the front.no panhard bar.socal shocks.p&j steering arms.maval rack steering. Im leaning towards the rear being out of adj.right now everything is adjusted evenly.pinion angle is 3the degrees down.I have the right rear coilover adjusted tighter than the left.the car seems to twist the left front when accelerating.frame is boxed and has a tubular center section.was built on a fixture.it is not off.

 

what are you running for tires? Last time i had this problem it was because I had radials up front with bias ply's in the back. Less noticable with skinnies up front, but when i put the wider tire up front it turned into one scary ride.

 

Your bars are adjustable, I had a similar problem with my 4 link set up. Mine went to the right so I shortened the upper right bar. If yours goes to the left turn the upper left bar in a turn or two and try it. It takes a little testing but my car comes out strong and straight now.

Pat

 

edit: never mind...may have been addressed above since I was writing


Could the difference between an open diff and a posi type diff possibly cause this?

 

Today I set the coilovers even.then I loosened up the drivers upper bar and the whole chassis just evened out.I ended up about 5 turns out to get it to line up wth the bracket so I could slide the bolt in and out.raining here so I haven't tested.thanks for the responses.

 

With that type of steering, & without a front panhard bar (or a dead pearch) the car will never be predictable in it's driveabilty. Put a properly installed panhard bar on it before you wreck it.
You'll probally find that also will "Fix" all your rear suspension problems!

 

Check the roll out on the rear tires, drag cars will all ways pull to the low tire....

 

It must be set up for circle track racing if when you floor it, it wants to go left....

 

Reduce your toe in to just under 1/8".
If too much toe in when your chaissis is under load it could be putting a lot of weight over one front tire and if that tire is not pointed straight enough it will grip and head the car off in the direction of the toe in.
I had that trouble with cornering and toe in...it gave me agressive over steer!
Do the easy stuff first.

 

3/16ths is excess toe-in. From earlier treads, it sounds like an unequal 4-bar rear loading also could induce steering effects.

 

Listen to this man. He's probably done more of this type of work than 100 of the rest of us. Listen to this man.

 

Please pardon me if I missed it, but.. What's the "back story"? How long have you owned it? has it always done this? what type of material in the joints? any adjust-ability? Have you "squared" the chassis? first things first... In my opinion..

 

Worked on a model A that did a very similar thing we fitted a rear sway bar & it cured the problem

 

It has a dead perch.

 

X 2 for me and what kind of HP are we talking here???

 

Possible case of bump steer. When the front end lifts under acceleration, it acts like a "reverse bump" if you will, moving the steering to the left. Especially noticeable with side steer cars with high caster. As the axle follows the arc of caster, it effectively moves forward and back, making the car (and your steering wheel) think that the drag link is "longer" or "shorter." Since I'm having difficulty describing this phenomenon, here is a diagram (angles exaggerated for illustration):

 

I think it is time you posted some pic's whole setup and stance...

A picture tells 1000 words!

 

Maybe totally off base but are both axles engaging? Had a new truck come from the factory with one axle too short to reach the pumpkin. Easy check is if it steers the other way under hard de-cellaration using only gears, not brakes.

 

What side is the dead perch on ? (it makes a difference)

 

A dead perch is better than nothing, but a properly installed panhard bar will give the best results for correct steering geometry. Unless steering geometry is correct, you will forever be giving away optimum driving and handling characteristics.

 

I believe that your front steering is okay. Your rear axle torque twist is causing the wheel base to decrease on the left and increase on the right side. This is due to the upward or downward angles of the 4 link bars. Engine torque is causing the rt rear frame to drop and the left to lift up. The rear axle is then trying drive under the left side. If your upper bars a too short or the lower bars are too long, this along with bar angles up and down, this can be a mess. Remounting the lower bars to be parallel to the ground will likely solve the torque steer.

 

Lower bars are parallel to the ground.the left upper was adjusted too tight and the rt rear coil over had way too much preload causing the left rear to squat and pull to the left.it has a posi and the bars were out of adjustment causing the pull under accel.as far as the pan hard bar in the front,I have never used one .while driving the handling seems fine it never felt like it was in the front end ,the steering is responsive and I don't feel alot of body roll or any kind of "looseness". I may still install one to see how much difference it makes.