calgutie

iTrader: (3)

So I don't know if an alignment will help my situation but anyways....when I'm driving in a straight line the car handles fine but when I am making slow u turn or making a corner at slow speeds my tires tend to screech and my car doesn't seem to like it....any suggestions as to what could be going on??thanks!

Tuned Performance

iTrader: (92)

http://en.wikipedia.org/wiki/Ackerma...ering_geometry

calgutie

iTrader: (3)

so in other words...i need an alignment??Im sorry if i sound stupid..

iansane

iTrader: (1)

When my control arm bushings were toasted (poly units!) and I would turn around in my cul de sac the car would hop and fidget because the tires were pointing in the wrong directions. Now, they're supposed to point in different directions to a degree, so I can only guess that mine must have been pointing almost parallel?

calgutie

iTrader: (3)

hmmm...so whats they way that i can fix this issue?

iansane

iTrader: (1)

Well on my car I replaced the front control arm bushings (with stiff del a lums) but on your car you're going to have to jack up the front end, roll under and start inspecting things. I would imagine most all the rubber components on your front end are fairly well used?

JamesC

iTrader: (5)

You may find the following info useful:

The following is from How to Tune and Modify your 1982-1998 Camaro by Jason Scott:

"The problem stems from high forces transmitted from the steering box to the chassis, especially under low-speed cornering, such as when maneuvering around a shopping mall parking lot. Fat performance tires present a great deal of resistance at low speeds, which imparts considerable stress into the steering system, and ultimately attempts to rip the steering box from its mounting surface--especially during "full-lock" turns, where steering torque is greatest. Over time, these forces weaken the chassis surface around the steering box and can result in torn metal.

"Whether the chassis is weakened or torn at the steering box, the result is the same--steering actions are delayed while the chassis flexes, leading to unresponsive and erratic steering. Ironically, though the damage stems from low-speed steering, the resulting problem is far more serious at high speeds than low ones.

"It is possible to repair the damaged area, though the best solution is to avoid the problem in the first place by installing a brace that reinforces the steering box mounting area."

The brace is the Wonderbar. Recommended, if your car isn't already equipped with one.

JamesC

SlickTrackGod

It is an incurable defect in steering geometry from the factory. What happens is the inside tire will not steering at more of an angle for a tighter turn radius than the outside tire, THis is a result of the spindle steering arm coming off the front of the spindle making the car a 'front steer" suspension. THe engineering of the spindle and the front suspension hub/wheel offset assembly does not allow for a proper angle of the spindle steering arm to set outward of the balljoint.

As a result of this defect, the car will "climb" on the toe in effect of the turn radius and cause the nose of the car to lift and skip the wheels as it hard u turns. If you back up the car will lower.

Something we all just live with in tight parkinglots

Dean

iansane

iTrader: (1)

That's definitely not false, but it is exacerbated by original rubber control bushings with 30 years of wear. Chances are, if they have not been replaced, there isn't much material there at all and you get a real problem then. With newer, higher durometer bushings you don't notice it as much if at all.

SlickTrackGod

Its more of an issue of worn factory strut mounts changing toe rather than the a-arm bushing deflection.

A-arm bushings when worn and setback has occured does not change toe in forward motion whether the car is straight or turned, worn strut mounts will.

An A-arm bushing even in reverse is not driven by the drivetrain so as not to induce thrust change, so not there is relitively no change from worn a-arm bushings causing this ackerman issue.

Edit to add info- In actuality, a worn A-arm bushing reduces track witdh of the front tires which will reduce the need for ackerman- so in all fairness the worn bushings will aid in reducing this effect in sharp parkinglot turns

iansane

iTrader: (1)

How would worn control arm bushings NOT affect toe when turning? The a-arms aren't going to move in the same direction evenly. Even if by some freak occurrence the bushings wore perfectly symmetric, one is getting pulled out one direction while the other pushed in another direction. I don't claim to have even a sliver of the knowledge you've given here over the years, I'm just commenting on my experience with the toasted bushings on my car. I replaced them and the 'hobbling' or car trying to drive up itself in a sharp u turn all but stopped with no other variables changed.

sofakingdom

iTrader: (1)

That isn't what he said; he ACTUALLY said

(Feels weird defending Dean, but hey, he's right)

In most of these cars, the strut mounts deflect MORE THAN the bushings, and therefore cause MORE OF the "skipping" behavior than the other. Not, the bushings "are all perfect". If BOTH were "perfect", the car would simply scrub the crap out of the tires in those tight turns, but it wouldn't "skip".

His description of the geometry issue that causes it is also accurate. These cars (and ALOT of others as well) all do the "skipping" thing in tight turns. The wider and stickier the tires, the worse it is, because they will REFUSE to slip sideways.

About the best advice one can give for curing the problem is, don't do that any more than absolutely necessary.

iansane

iTrader: (1)

Yeah, he seems to be a polarizing individual with lots of tech.

I wasn't trying to say that strut mounts don't cause this skipping but from this sentence it sounds as if Dean is saying worn a-arm bushings should HELP this skipping issue. Which is what confused me, because that's the opposite of what happened to me.

Maybe I just had a horrid combination but my factory strut mounts deflected very little and the poly control arm bushings deteriorated to such a point that there was almost nothing left. I had factory strut mounts and old poly a-arm bushings. After a number of years this jacking or the car driving up itself was very bad in my cul de sac. I replaced the poly bushings with del a lum and the car felt rock solid and never jacked again. I later replaced the strut mounts and that had more of an effect on ride quality and dealing with road imperfections (they were the raised mounts) but felt like it had less of an effect on handling than the control arm bushings. But that could very well just have been because the a-arm bushings were new it was less noticeable. Again, I'm not saying that strut mounts are not as bad as control arm bushings, just reiterating my experience. If that's a the exception and not the rule then I guess it's good this thread came up.

Either way, the front suspension needs to be inspected!

SlickTrackGod

All I can say is my car skipped voilently in tight slow full lock turns- and you all know how built and solid it was.

Its as bad as my long wheelbase truck with my detroit locker and 12wide tires. Nothing you can do about it, it will skip.

The only thing that reduces this is using toe out on a tight race track. It will improve ackerman and get the inside tire to angle enough to bite and turn the car a little better. The inside tire is what turns a car (people thingk its the outside tire that does this but its the inside tire.) Best example I can give in turning a vehicle is to think of yourself walking and wanting to turn left. ex 1 you will try and push off a wall with your right arm to go left (note the wall makes your suspension{in this case your arm) absord motion and try to force your body to turn on recoil- not real effective). ex 2 is you left arm reaches out and grabs a pole and your body naturally swings in that direction- its is immediately yanked that way. This is what an inside tire does in turning when given the proper bite and angle.
The outside tires just hold lateral grip as the inside tire sets the path. WHen you loose inside tire bite the car will push on corner turn in.

The failed ackerman on the cars is worse as the wheel turns towards lock from striaght position. THe good is that we generally do not have to turn the wheel that far in normal driving at speed. Tire natural slip angles come into play and "create" ackerman. These cars were designed with larger sidewal tires that are more forgiving and will create more slip angle. The lower profile and/or stiffer sidewall tires will not create slip angle and will skip easier. As we modify these cars, this inherent defect becomes worse. I just kept factory 16x8 wheels on my car with factory spec 145/50-16's for that very reason and they worked great as documented on various posts I have put up over the years- but yes my car skipped badly in tight u-turns so a little applied throttle always helped when no one was around.

Insame- A arm bushings really do not move about when worn. They become mashed and deformed and just mainly cause setback abd overall camber and caster loss in adjustment range. I am refering to most cars out there with worn bushings that have been aligned with thoise bushings deformed into place already. Yes if the car remained in the same alignment for 20 years (which it won't) as those bushings wear and deform, then the toe will increase in static and decrease in dynamic ackerman due to tierod and drag link geometry angles as oppsed to the A-arm geometry. So putting new bushings back into there sets the A-arms back up into position which more corrects the steering link marraige to the suspension- however, it still skipped fromt he factory and was never non existent to begin with. With that said, one simple little thing like a worn idler arm will aid you in not skipping- but when all things are in perfect shape? there is no way you will eliminate the poor ackerman unless you refer back to 215/60-15 tires that will "give" and thus "create" there on slip angle to help ackerman.

SlickTrackGod

That last thing I want to add is when you installed your A-arm bushings you may have opted for more negative camber specs and more positive caster specs than previously had- because your car now had more adjustment range with the new a-arm bushings. If this is the case(which I strongly suspect knowing how you were linited with the previous bushings) then you are statically riding on the inside tires more with less scrub radius in tire footprint and less track width in tire footprint.

Both reductions will aid in ackerman.

iansane

iTrader: (1)

I think this is what my mind is having a hard time grasping. I can't fathom how the main pivot of an a-arm won't rotate around when not in a solid bushing. Isn't that the point of running stiffer bushings or hiem joints? I mean, that's how I realized I needed to replace mine. I put up a crow bar and pryed from the kmember to the a-arm and it flexed like crazy which led me to notice the almost non existent bushings.

The adjustment range didn't change between the bushings? I didn't buy offset bushings or anything. And the specs didn't change from the ones I've requested every time my buddy does an alignment (Camber; -1.5* Caster L-4.5* R-5* Toe-.4 or as close to that as can reasonably get). How was I limited with the previous bushings?

And I'm not here to say you're wrong, now I'm just picking your brain.

SlickTrackGod

You are not grasping thrust and setback

Chassis dynamic is one of those things that 99% of car people never fully grasp in a lifetime. It is very complex in though because multiple things are happening in a 3D imaginary vision. Nothing more I can explain on a computer.

What happens to me everytime is I get deeper into a conversation and start showing detailed sketches etc as to what is going on and why peoples choices are effecting things adversely and such and then people take offense to me like I am bashing them.

I see where this is going. I do not want to point out what is wrong on your car, I want to explain wht is done right and your choice to do it or not(THis is a direct statement to everyone, not just Insane)

SlickTrackGod

The last thing I feel a need to add to your initial post Insame is that it makes no logical sense and I will explain why. I personally feel you posted here just to brag about putting Del-a-lum bushing into your car.

If your post about harder durometer bushing helps reduce this OP's probelm then answer your own obvious statement as to why on gods green earth would locking up anything tighter make it track more freely?

I will await an answer- and if you do not understand the depth of the question then there is now point in going any further in this conversation. Please do not take offense to my asking if you do not know the answer becasue most people do not and never will- it does niot make me a superior person to you, though I am clearly more knowledgeable in chassis dynamics but you may make me look like an amatuer in computers- we all have our strong points and weaknesses- so I say this as a helpful person here trying to post factual data so people can make their purchase decissions based off of accrued knowledge- I am not here to make person friends, I am here to share my gift of knowledge and help so it is passed on just as it was passed to me

iansane

iTrader: (1)

I'm sure it would take me a lifetime to understand even half of chassis dynamics. But trust me, you're not going to offend me by saying I did something wrong. This car has been an experiment. And like all experiments, people do them wrong.

However, calling me a braggart IS going to upset me. I was merely pointing out that I had replaced the bushings with something with very little deflection. I am by no means someone who posts just to up my post count or to show off what parts I can or have bought. I think you've come across a lot of that "I bought this! It's the BEST! (but I don't know why...)" mentality, haven't you? I don't act that way. Or at least I try not to! I was just saying they were new, and that it appeared to solve my issue. Which was similar to the OPs. Honestly, I interjected again because I was hoping by telling you and TGO what I had replaced and what the car was doing that you would be able to guide the thread to why new control arm bushings might also solve (or in this case mask?) similar issues. If you don't want to do that, that's fine.

I was not stating that locking it up further was solving the issue. I was suggesting that if the bushings were as far gone as mine were the wheels were in even greater differing angles. But now that I have dug deeper into the reason for this jacking issue it seems that greater ackerman helps soft it? And, in my case I might have been getting LESS angle between the wheels? I apologize if my wording was not optimal here or originally. I didn't mean to infer that harder bushings made tracking easier, just that it kept the alignment specs back where things should be instead of flowing all around randomly.

SlickTrackGod

Sorry, I was away for a few days outta town.

I want to appologize about offending you. I really did not mean it that blatant that you were a braggart. I just ment that I felt you posted up what alot of us do about parts you put in and proud of it. I have a bad choice of words. I too am guilty of bragging- I think we all float our own boats now and then because frankly, who else is going to do it? (Smiles)
Thank you for staying clam with me, I am terrible at expressing myself in type. I have a very sarcastic/playful personality that gets lost in my typing. Ask people that actually know me in person they say I seem like two different people when they read my text.

Anyways. You need to think of the force applied to the bushings when in motion. The front tires are not driven, thus they are pushed back always with road force drag on the tire footprint. This makes for any slop in the bushing to have setback against the worn busing and balljoint will suffer setback in geometry compared to where it should be when in good static position with the strut mount.

The tierod angle off the drag link is more stright as a result of setback (when draglink is in the centered position.) This tierd geometry is unfavorable for the Ackerman. The balljoints forwward as a result of better bushings makes the tieord angle at lock to be more staight which would increase ackerman as opposed to loose it. But so many other factors come into play based on individual alignment characteristics of individual cars that make footprints of the tire vary on track width and angle in various elements of steering. If the bushings at static have minimal setback, but then maxium setback in dynamic motion of the vehcile then static alignment specs no loinger come into play and can have a reverse effect (which is most likely)