ladder bars....what does this tell me?

My car is a strut front with ladder bar rear. Rear shocks are Koni dble adjustable. The car leaves straight, but was wanting to drift left out around 350-400 ft. Not a hard move, just drift enough that you have to "drive" it.

setup on rear : ladder bars and anti rollbar neutral. rear shocks: ext is the same at 4 from loose on both, comp is 2 from loose on right and 4 on left. With them set the same on comp the cars goes left off the line. set 2 clicks apart if leaves straight, just the drift down track.

Yesterday I staggered the rear tire pressure and it went straight, no drift. 7 3/4 left and 7 1/2 right....car ran it's best yet 5.23 @ 133.5 1.15 60' @ 2800 lbs. NA bbf. 15X32 stiff sidewall Hoosier.

What does it tell me that it went straight with the left rear tire just a tad larger? What do I need to adjust to get it straight w.o the tire stagger?

Thanks
David Cole

Have you checked the rollout on the rear slicks? Housing square with chassis CL?

If you have not attended one of Daves seminars I highly recommend it, at the very least pick up his book.
http://www.davemorganseminars.com/seminars.asp

Diddly wrote:Have you checked the rollout on the rear slicks? Housing square with chassis CL?

If you have not attended one of Daves seminars I highly recommend it, at the very least pick up his book.
http://www.davemorganseminars.com/seminars.asp

Have not measured the rollout, but it did it with either tire on the each side. I have swapped the tires to the other side and it was still the same. The housing is square. triple checked with tape and string.

Saw your post on YB also. How many times did you run it when drifting left, and how many with staggered tire pressure? Just want to make sure it wasnt a fluke thing. By adding to the left rear, you are basically band aiding the problem(obviously), so somewhere throughout the car, something is bent/tweaked/loose, etc. Triple check everything, including rearend squareness to car, and everything in the front as well, especially steering.

my car was goen right and i found the front heim bushing was loose.my bars are the chassis works with the big front joint and bushings on each side that also fit in the crossmember holes.the bushings on that side were a little loose in the hole so i tq'd the shit out of the bolt and then backed it off a little,works now.are you running wheelie bars Dave?

I will double check the rear for square this winter. Put the antifreeze in today, will drain fuel system and finish the winterize tomorrow as it's my unheated garage.

The ladder bars are Chassisworks with solid ends. No heims, It's got wheelie bars, but they are just along for the ride. The never hit the ground. They are pretty short and the car doesn't wheelstand enough for them to touch. About 6" is all the wheels are. Needs prob 8" or more for the bars to hit.

I am starting to lean towards the front end perhaps. When I first got it the front was out pretty bad on the toe. Right front was 1/16 in, but the left was more than 1/8". My chassis guy reset it using a sliding metal bar that he made. Had to go back and forth several times and at the end the steering wheel was off. It seems like he made an adjustment to get the wheel centered, but then didn't do the back and forth, side to side to get it perfect again. Might need to put it on a machine to verify the alignment.

Doesn't pick the front up very far. Not a lot of travel in the Strange struts:

curleysracecars wrote:Saw your post on YB also. How many times did you run it when drifting left, and how many with staggered tire pressure? Just want to make sure it wasnt a fluke thing. By adding to the left rear, you are basically band aiding the problem(obviously), so somewhere throughout the car, something is bent/tweaked/loose, etc. Triple check everything, including rearend squareness to car, and everything in the front as well, especially steering.

It's always gone left...several dozen passes, tires sawpped side to side twice no effect. Made 6 passes yesterday with staggered pressure, 5 were good, one went right (think something on the track) but the one right wasn't bad enough to lift.

I'm thinking alignment

i'd take the bars off and see what it does.i put a new strut frontend on my car and also put w/b 's on at the same time.first time out it was goen right and all the preload in the world would'nt help it.i got video from the rear and boy was i shocked! the damn rims looked like they hit the ground when i left and the shocks had to be giving up 3"ext.the other thing the video showed me was the wb's smack the ground,right one first,and unload the rr tire a little and cause it to do the hard right.i know you already have good shocks but when you can,take them off and have a look at them too.i'd also get the frontend checked out.your making more power than me,goen faster with a heavier car,so the ladder bar setup will be a hand full.i've also found that the strut/LB setup can 60' hard without the frontend up much,your 1.15 is faster than my 1.19,but it has a point where it'll come up and get up fast! whats the wheel base on your bird?

If the car is launching left, and the rollout is the same & there isn't anything loose/bent/wrong (or something like side-to-side spring height stagger) it could just need the side-to-side preload tweaked a very little amount. You could try removing a little preload/weight out of the pasinger side ladder bar with the ladder bar adjuster, maybe try removing only a 1/2 wrench-flat or less at first. This should reduce the weight/traction to the pasinger side slick some (and increase the driver side) to drive the car back toward center under load instead of to the left.

If you end up adjusting the preload too far (remove too much right/pasinger preload) the car should in effect "tell you" you went too far by starting to launch to the right. By staggering the air pressure like you did you were in effect shifting the preload around too, but using air pressure adjustment vs using suspension adjustment.

It is also possible that the ladder bars & the anti-roll are fighting each other since they both will (by design) try to fight body-roll on their own. An anti-roll is really more meant for a 4-link, or ladder bars that are mounted real, real close together.

Dave, will a l/b car with a lota power just load the rr tire hard from tq or body roll? the bird is making some grunt! i also thought of something another guy found on his car,one strut was screwing down cuz the bearing plate was rusty and adjusters were'nt locked down good.it would dart bad when he let off at the far end.

cool40 wrote:.....will a l/b car with a lota power just load the rr tire hard from tq or body roll?

Big launch torque numbers & increased rotational torque loading of the RR slick under load (increasing it's weight/traction) happens more on cars with a ladder bar setup, and cars with a 4-link/anti-roll setup. This is because as both are fighting to restrain/control the body roll-over action, that load has to go somewhere, and that "somewhere" is the RR slick.

The increased RR loading effect is less on a 4-link without an anti-roll as the body roll over action/loading is allowed to happen without a direct (solid) component trying to stop it (& transfer that load to the RR side). So while there can still be some increased loading to the RR side on a 4-link without an anti-roll (from more RR spring compression & the 4-link rod-ends finally rotating over far enough to bind-up) it's not an instantaneous "torque smack" over to the RR like with ladder bars or 4-link+anti-rolls. This is why you sometimes see LB/4-link+ARB cars with big torque having less static preload weight on the RR at rest (instead of so called "neutral" preload) to make up for the increased torque loading of the RR under load. This sometimes adds to the confusion when people talk about having/wanting a "neutral" static preload setting. This is because (A) a "true neutral" setting isn't exactly the same for all of the three mentioned suspension types (LB/4-link with/without ARB), and (B) a true "netural" setting isn't desired 100% of the time on every car out there anyway. Some cars can use neutral, and some can't, it just depends on the car's total combo (suspension type, f/r weight bias, available power/torque, etc, etc).

As for the front struts/springs, yes the front suspension can have an effect on rear side-to-side preload. Some people prefer to do the preloading with the front suspension instead of the rear suspension....I'm not a fan of this however. I feel that if a car/chassis is straight & square and there is no issues with the suspension, then the front/rear shocks/struts need to have the same spring height/rate side-to-side, and then use only the rear suspension for side-to-side preloading. But that's not to say that staggering the front spring height/rate has absolutely no place in a drag car......staggering the front spring heights a little can in fact be very useful if the front frame is tweaked/twisted a little.

i was just thinking out loud Dave,lol.thanks.

I don't remember if this has been mentioned yet (brain fart), but is there any good launch video of the T-Bird?

I had this exact issue of overloading the R Rear at launch. When I first built my car the struts were pretty soft for my iron headed CJ motor. When I built the A head 557 it started acting up. On a really good track it would launch dead left. I had the struts rebuilt bact to the original specs. and it fixed it 100%.

David is describing his car as starting to move around well down track, I don't think this theroy would apply, but anything is possible.

No videos yet. I do have an old one somewhere from the previous owner. But, it's at night with a cell phone, not good.

It seems to start it's drift left after the shift, when it's making the most power...the fallback after the shift is right in area with the most hp. With the shocks set the same on the rear it does go left at launch. I run the compression on the right rear 2 clicks softer to solve (band-aid) that.

David,

When you go through the traps and "lift", a lot of the weight transfers back to the front. How does it drive then? Are you really having to steer it? If so, that's a sign of too much front end preload,,,,related to what Dave was talking about.

Charlie

David ,

I know this might not pertain to your situation , but it seems with my latter bar deal the more i throw at it the smoother and straighter it runs .....


later Nick


p.s. ...just spray it

bruno wrote:David ,

I know this might not pertain to your situation , but it seems with my latter bar deal the more i throw at it the smoother and straighter it runs .....


later Nick


p.s. ...just spray it

X2

Davids car is fast without spray.

Charlie....the car drives fine when I lift. It just drifts left when it's making it's best power just after the shift. I shift at 7000, (logger shows 7100 or so) and it falls back to 6400, where the meat of the power band is. The left move is not a hard left, just enough that it will get out of the groove if I don't correct it. This winter I will check the rear end squareness, get the alignment redone and then look at maybe doing some preload adjustments. After having been in a dragster for 8+ years there is a lot to re-learn about this new, totally different animal.

I might spray it sometime later guys.... It's where I want to be right now.....brackets + the ability run the 5.30 heads up classes. Next step would be to spray enough to run the 5.00 heads up. As a 1 guy operation it would be tough to spend enough to keep up with those guys.

Right now my concern is to get this thing where it's on auto-pilot. THEN I'll be able to do some finish line racing.

cool40 wrote:Davids car is fast without spray.

i realize his car is fast , im not saying that its slow by any means ..... his chassis is set up for gobs of juice ....thats all

bruno wrote:

cool40 wrote:Davids car is fast without spray.

i realize his car is fast , im not saying that its slow by any means ..... his chassis is set up for gobs of juice ....thats all

the bbc it had in it needed all the help it could get.lol