Pulls hard left under accel

As funny as it sounds also check rear brake adjustment if a drum is dragging enough it could cause a tank steer issue. This usually is only the case on a drag car in a wheelstand. I agree though on the panhard. I have a similar setup on my coupe and it was always going right under accel. Left on decel. panhard and a steering dampner solved its dancing around when the front end got light!

 

Being a drag racer, 9 times out of 10, when a car moves around under acceleration its the rear end turning the car.I said in an early post, get a four wheel alignment and square the car[thrust angle setting]. Then,with weight on the car[on the wheels] take one four bar link off, starting with the top right bar, and set it so the bolt just goes in neutral, no preload. Do the other top bar next.The bottom bars may have been moved to square the car, they don't preload. When this is done, take it out and hammer it from a stop and see what it does. Good luck, hope ya get it.

 

Ok . . . . I said I was done . . . but here is one last post.

You can fuck with the rear end every which way . . . all you want !!!!
You've had a lot of feed back on that.

You said you've had cars with cross steering & without panhard bars or dead perches, and had no problems.
You might get away with that if the shackles are tight, and can't easily move side to side. But sooner or later they are going to move, and that will probably happen when you're diving into a turn, and the chassis will shift on the shackles and that will cause the draglink to push or pull on the right spindle, and the car will start steering it self and you'll just be along for the ride, hanging on and wondering where the car is going to end up.

That is kind of what you described in your very first post on this thread.

If you have a rear end problem, and I say "IF" you'll have a better chance of diagnosing it if you correct the front end first !

I learned all this panhard bar stuff the hard way when I built my first cross steered '32 way back in the early '70's. Damn near wrecked a really nice roadster & scared the shit out of myself. Took a little studying, along with Jake's help to figure out what was causing the handing problem.

Good Luck !

Pete Eastwood

 

My stock 1963 Corvair Spyderw/posi would pull noticeably under the hardest acceleration it could muster ( a frequent occurence with a 19 year old driver) after the Dunlop SP41 radials wore a bit. Moving tires around fixed it.

 

Have you checked for a broken axle?, It has been mentioned, but you have not ruled it out. also look at your rear locker, if you have one, you may have some chewed up spiders/gears/clutches. I only mention this again cause you haven't said you checked it.
a broken axle or missing spider gear teeth will cause a hard turn under acceleration.

Godspeed
MrC.

 

Hey slinginrods checked in to see how the science project was doing and was checking the pictures again. Question, one shot of the front end shows what appears to be a monoleaf spring, is that spring securely clamped in place or being held in by gravity?
I have teched some vehicles and found that a steering issue was caused by the front U bolt plate bottoming out on the front crossmember before the spring center bolt actually seated in the centering hole, steering the car caused the spring bolt to pop out of the hole and get goofy beacuse the spring pack was not compressed to the frame, turning back the opposite way recenterd the bolt and everything was fine. This is something that you can't easily see and occurs when using short stack spring packs or mono leafs that require a spacer to correctly obtain the compression on the spring in the alignment hole. Just for kicks check to see that the front spring plate is tight and has at least 1/4" gap between the plate and the front cross member flange. If its tight to the flange this could be the magical mystery, the spring is sliding around and you are losing central mounting.

 

The spring is held in place by a plate that is bolted to two tabs welded on the crossmember.no ubolts.yes it is clamped in tightly .i believe we saw it on a SoCal frame but I'm not sure .we just liked the clean looks and we copied it. Btw I plumb bobbed the axles and took measurements the wheelbase is at exactly 106 inches both sides.the axles are square to the chassis as well.took awhile but it was worth the effort.i drove it last night,felt way better.purposely tried to upset the front end over bumps,got a little squirrelly so I'll invest in a deadman .i dont want to weld anything on my. Freshly powder coated frame.(damn nice cars !).just to rule axle sway out.im thinking of ditching the tube axle and going with an ibeam .what do you think? Will I feel any difference? Every bushing is tight and has no slop.feels real good tracks straight .oh yeah rechecked caster 7 degrees.

 

brakes checked fine,mine does the opposite ,hard accel drives left.let off pulls right.damn thing is scary.i wanna beat on this and it drive straight and let off and not have to fight it.i know people drag these cars,are they this hairy?

 

Have you tried swapping the rear tires side to side?

 

Had two different rim/ tire combos on it ,made no difference thanks.

 

He said rear. Swap them side to side. And I am seeing a pattern here. Go back and do what Mr. Eastwood suggested, only. 'Science out' the front end 1st. Correct and safe before pretty.

 

I said I have changed the wheel tire combo out with no change,do you have any suggestions other than Pete eastwoods cheer leader?pay attention son

 

Doc Hudson says turn right to go left

 

Yeah ,maybe just cut off all this traditional front end stuff and convert it to a nice chrome mustang 2setup with a full rack steering,coil overs a sway bar and some 18 inch billet wheels.remember safe before pretty.

 

relocate the engine to the right of the current location.

 

Will do that first thing tomorrow

 

Glad you're making progress. I'd put the dead perch on, forget changing the axle, and I bet you'll have a nice driving car.One other option, use the spring clamp plate as one end of panhard bar mount, the other to a bracket on the batwing. Did this on my buddys car for the same reason, didn't want to weld on the fresh frame. Despite the geometry not being ideal, it works great. Steering is solid and as precise as a straight axle car can be. Good luck, glad its better with the chassis aligned.

 

Post some pics showing the rear links. The body will want to roll on acceleration and you may be getting some rear steer generated by the body leaning.

 

Nice to see you are making progress, That clamp style can be misleading, it looks like everything is tight because the plate is bottomed but the spring is still loose just recheck to be sure. Dead perches are like dead fish, they stink, this is a race car application used as a bandaid to correct a mistake. They also reduce the spring efficiency. The simple solution suggested is a panard rod bracket to the ubolt clamp but that produces a short rod and the arc travel can create issues with alot of suspension travel. The panard rod does not subject it self to excessive loading thus bracketry does not have to be bullet proof. So you dont have to worry about welding on your new chassis you can simply make a flat plate bracket from 3/8" flat that extends level with the axle and mount it with bolts to the rear edge of front cross member. There is a panard bracket made that mounts to the bat wing bolts so that becomes a bolt on and all you have to do is make up a panard rod of the correct lenght and make P-Wood happy.

 

It looks to me in post 38 the car isn't sitting level, like it has a lots of preload in the rear suspension and it leaning to the right.
Is there an antiroll bar as well? Is it loose when you are in the drivers seat?
I'd be looking at the 4 link bars in the rear, something there is under tension or compression and it shouldn't be. Got a buddy with 4 corner scales? that'll tell you.
Sweet car, need to lay some wood into it for sure!

 

man thanks,ive seen some of your work,its killer.those pics were taken before i worked on the four bar and reset the coil overs.it sets level now.my buddy has a rolex 24 hour race car team,im thinking the same thing about scaling it.the upper left bar was under tension ,when we put it together we just set everything even to drive it.i figured it would all need to be readjusted.i do that on every car after about 500 miles ,which is where this one is now.i just never had one do this before.after a breif drive wed night it felt much better.

 

I would lay blame to the handling problem on your rear set-up Put a good 4 link & panhard and enjoy!!!!!! my thoughts only !!!!!

Ol Deuce

 

Took it out today and worked it pretty good.pulled straight and true,guess it was to much preload in the left rear.thanks for everybody's input.oh yeah Pete I'll be ordering a dead perch this week,just to make sure I don't have any other issues.

 

Glad you got it sorted, well done.

Scotty

 

Glad you got it right, but like Dick and I said, try the short panhard bar instead of the dead perch, you'll be happier with the result.If you scale it, for a street car, dont preload the upper four bars to get wheel[corner] weight. You'll be right back where ya started. Most higher hp drag cars want to launch to the left, in other words the right rear tire needs weight taken off of it. You do this by putting negative preload in the top right bar[shortening it]. I'm only talking a couple of flats[1/6th of a turn]. Keep the bars dead neutral, where the bolts slide in easily, and ya got it right for a street car. Same goes for a rear sway bar, make sure the links are neutral for the street. Happy cruising.

 

Yes If You Have A Posatraction Add Some Posi. Additive Go To A Parking Lot And Turn Circles Both Ways.

 

Get on the longacre.com website, there is a whole section on setting up a car for four wheel alignment using strings, straight edges etc. if you have had the rear in and out or if this is a new build it could just be that things are out of square. An excellent reference book is Dave Morgans, Doorslammers a Chassis Guide. It talks all about alignment issues, preload, four link versus ladder bars etc. I would STOP getting on it till you fix it.....driving the piss out of it is not going to make it better, might crash the car and someone could get hurt!