crazy handling on freeway

[oh dam]

Ok so my car is pretty much stock as far as suspension goes. I have saggy leafs in the rear and torched springs up front with Gas-a-just shocks in the rear and monroe oespectrum shocks up front. By lowering my car i know ive changed the geo on it creating some bump steer.

On the freeway (or streets) i feel like the steering is really really lose. It isnt tight like my DD(1997 nissan altima) i know its a newer car but im pretty sure the steering didnt suck this bad on my 72. It happens when 1.the road is f'ed up and 2. when im going 75+. It gets pretty scary driving 90+ and the road has imperfections. and it seems to "lag" when i turn. I'll need to turn the steering quite a distance (more than i am comfortable with) before it reacts

but i have other questions and concerns.

1.) With a proper OEM alignment i find that i still have the same problem. although it helped a little.

2.) one time going through a passage on the freeway i had passengers in the back seat (about 275LB worth of passangers) and it seem to "correct" my steering problems. which lead me to believe my problem is the rear. but "stiffer than oem" shocks didnt fix that.

3.) i recently bought some 600LB maier racing coils for the front and going to install them soon with my desired ride height. and going to get some 200LB leafs in the rear (for racing). Will this help my problem?

4.) the bolt that adjusts my camber is bent. can this be the problem? can going with eccentric eliminator bolts help this?

im running out of ideas. bushing have been replaced and it seems like no part is loose. would SFC, sway bars, work?

 

[cudak888]

Any slack in the joints between your tie rods, center link, and drag link?

Have you checked, rebuilt, or replaced the steering gearbox recently?

-Kurt

 

[Don C]

Don't forget to check the rag joint, too.

Tires and wheel sizes can make a huge difference if they aren't compatible. Tread patterns will affect handling, especially if they are directional. Tire pressures can also make a big difference.

 

[droptop73]

Caster will help directional stability. The toe angle is important as well, if it's toe'd outit will want to wander on hard braking. Like has been said above make sure ALL of your steering components are up to snuff. IMO increasing spring rate will not solve your isues and will make your car ride like a truck.

 

[72HCODE]

do you have front and rear sway bars?

these will make a big difference on lowered cars.

OEM settings on the alignment unless they compensate for radial tires is not good.

you want as much caster as the car can tolerate before the tires start hitting the fenders, start with 2-2.5 caster. i recommend keeping the camber at 0

and for the toe in 1/16-1/8

Now you torched the front springs, that doesn't mean they are even in ride height, i would think about going with replacement 620lb front springs with a 1" drop

and while you are there inspect the spring perch. if the rubber is blowing out or cracking go with a roller rocker perch.

additionally they make outter tie rod relocation kits, that drops the angle of the tierods about 1" to reduce bump steer.

Now i went through some of the things mentioned.

on my car i have lowered front and rear springs. I also had a 1 1/4" front sway bar, when i started to drive it, after i rebuilt the suspension and had done a DYI alignment i had Scary bump steer. i had new gas a just shocks front and rear.

first issue was i had poly bushing replacements for the suspension and strut rods. I had nothing but issues with them and swapped them all for OEM style Rubber bushings. instantly i had improvements i got more float out of the suspension and it got a little less scary.

I also discovered my front sway bar hardware for the connector links was WAY too tall this was because the kit was for a stock suspension so my sway bar was riding too high and hitting the strut rods. I got 67 mustang connector hardware to lower the sway bar down and get it level with the lower suspension arm.

I still had bump steer and bought a tie rod lowering kit but never install it because i just could never find the time needed.

1 year later i discovered my made in china suspension rebuild was starting to go south. i had some bushing deterioration and i replaced the parts.

i discovered my new spring perches fell apart as well, i replaced them with roller rocker. now i didn't notice much of a change, but i did notice the strain on my power steering pump was reduced and i seemed to have more steering at low speed.

At this point it was much much better but the rear end was really squirrelly i had an addco rear sway bar sitting in a box because i didn't feel comfortable drilling holes in my rear frame rails at the time, but i figured what the hell and installed it. Monster improvement, the rear end stiffened up and that squirrelly feel went away. Braking was more stable as well.

so first thing i would do is inspect the suspension for worn parts and the condition of the bushings and any play in the suspension.

inspect the spring perches. think about swapping the front springs for something better then just cut stock springs.

look at the alignment numbers again. you want more caster, 0 camber, and 1/16-1/8 toe in. i would start with less and see what happens.

next install sway bars if you do not have them.

some times they recommend -.5 - -1 camber on the tires for performance cornering, my experience this causes more bumper steer so i recommend 0 degrees

think about a outer-tierod drop as a last resort.

 

[oh dam]

Any slack in the joints between your tie rods, center link, and drag link?

Have you checked, rebuilt, or replaced the steering gearbox recently?

-Kurt

the tie rods and ball joints has been replaced and according to firestone no play or slack (if we are on the same page as far as the meaning) the centerlink an drag link have not been replaced so i wouldnt know about that one. The gearbox has been rebuilt and the pitman arm replaced.

Don't forget to check the rag joint, too.

Tires and wheel sizes can make a huge difference if they aren't compatible. Tread patterns will affect handling, especially if they are directional. Tire pressures can also make a big difference.

Where and what is the rag joint? my wheels and tires are 225/40/18 up front and some 275/35/20 in the rear. how do you tell if they are compatible? and explain the tread patterns what should i look for

Caster will help directional stability. The toe angle is important as well, if it's toe'd outit will want to wander on hard braking. Like has been said above make sure ALL of your steering components are up to snuff. IMO increasing spring rate will not solve your isues and will make your car ride like a truck.

interesting because one time i had to make hard and it swerved a little.

do you have front and rear sway bars?

these will make a big difference on lowered cars.

OEM settings on the alignment unless they compensate for radial tires is not good.

you want as much caster as the car can tolerate before the tires start hitting the fenders, start with 2-2.5 caster. i recommend keeping the camber at 0

and for the toe in 1/16-1/8

Now you torched the front springs, that doesn't mean they are even in ride height, i would think about going with replacement 620lb front springs with a 1" drop

and while you are there inspect the spring perch. if the rubber is blowing out or cracking go with a roller rocker perch.

additionally they make outter tie rod relocation kits, that drops the angle of the tierods about 1" to reduce bump steer.

Now i went through some of the things mentioned.

on my car i have lowered front and rear springs. I also had a 1 1/4" front sway bar, when i started to drive it, after i rebuilt the suspension and had done a DYI alignment i had Scary bump steer. i had new gas a just shocks front and rear.

first issue was i had poly bushing replacements for the suspension and strut rods. I had nothing but issues with them and swapped them all for OEM style Rubber bushings. instantly i had improvements i got more float out of the suspension and it got a little less scary.

I also discovered my front sway bar hardware for the connector links was WAY too tall this was because the kit was for a stock suspension so my sway bar was riding too high and hitting the strut rods. I got 67 mustang connector hardware to lower the sway bar down and get it level with the lower suspension arm.

I still had bump steer and bought a tie rod lowering kit but never install it because i just could never find the time needed.

1 year later i discovered my made in china suspension rebuild was starting to go south. i had some bushing deterioration and i replaced the parts.

i discovered my new spring perches fell apart as well, i replaced them with roller rocker. now i didn't notice much of a change, but i did notice the strain on my power steering pump was reduced and i seemed to have more steering at low speed.

At this point it was much much better but the rear end was really squirrelly i had an addco rear sway bar sitting in a box because i didn't feel comfortable drilling holes in my rear frame rails at the time, but i figured what the hell and installed it. Monster improvement, the rear end stiffened up and that squirrelly feel went away. Braking was more stable as well.

so first thing i would do is inspect the suspension for worn parts and the condition of the bushings and any play in the suspension.

inspect the spring perches. think about swapping the front springs for something better then just cut stock springs.

look at the alignment numbers again. you want more caster, 0 camber, and 1/16-1/8 toe in. i would start with less and see what happens.

next install sway bars if you do not have them.

some times they recommend -.5 - -1 camber on the tires for performance cornering, my experience this causes more bumper steer so i recommend 0 degrees

think about a outer-tierod drop as a last resort.

i have stock front sway bar no rear sway bar.. OK so things i have and what i have planned. i already have the 600LB front springs just waiting to be installed. I have 200lb leafs that i'm going to order soon. I have the 1 1/8 in front sway bar and thinking about 3/4 rear sway bar. I need sub frame connectors so that's next on my list. Also in the near future is the tower brace and pan-hard bar with torque arm. also few questions. you mentioned the tie rod relocating kit. what is that? is that the "bump-steer kit"? if not how useful is that kit? and how useful is the "adjustable strut rods" because as far as i know they are already adjustable. also i plan on getting roller perches. also should i go with poly or rubber? seems like you dont like rubber. also with all the upgrades and so forth how can i determine what is the best alignment? and how can i know if my parts will be compatible with one another.


I will try and find the paper for the specs on the alignment. i am not home but ill try and find it when i am

 

[MotoArts]

If you have wheels and tires that are closer to stock, put them on and take it for another ride.

If not, find someone with a good set that you can borrow.

Then come back and let us know what you find.

My 5.0 is stock, and tight as a drum underneath. Car has custom subframe connectors, X-brace and chromoly 3 point strut tower brace. The braces themselves improved the car immensely (it is a convertible). Has new(er) OE style struts/shocks, and OE alignment.

I went from the stock 15x7's on it, up to 16x7's. Ride quality deteriorated a bit, but handling improved by the same.

Replaced those with staggered 17x8 and 17x9's with some fat 50 and 55 series Michelin rubber without changing anything else.

Handling is sorta OK at extremes, but it is a GIANT handful on a straight open highway. It follows the troughs and peaks in the asphalt like never before.

It is scary bad.

I absolutely hate it.

In my case, a realignment to suit the wheel/tire might fix it, might not.

 

[oh dam]

hmmmm interesting..so the size of my tires can be the cause. is realignment the only way to help compensate? i dont want to buy other wheels. i like how it looks.

 

[Don C]

"V" shaped tread patterns are usually directional and having them on backwards will affect handling. Too much air pressure will cause the tires to pull onto ridges and grooves in the pavement. Too low can cause a lag in the steering.

I agree with 72H, OEM alignment specs are for bias ply tires and need to be adjusted for radial tires. Further adjustments are likely needed to compensate for your tire/wheel choice.

Sometimes different tread patterns on front and rear tires just don't work, almost as bad as having a mix of bias and radial tires.

Ever wonder why you see so many used 18-inch and bigger wheels and tires for sell on Craig's List? They might look good to some people, but if the suspension isn't designed for them they can handle poorly and people switch back.

TireRack has a lot of information:

http://www.tirerack.com/tires/tiretech/techpage.jsp?s_kwcid=AL!3756!10!3308524027!30371467972&ef_id=Up84xwAABCgh1pac:20131217145000:s&techid=9

 

[Jeff73Mach1]

If your springs are shot, nothing is going to help until they are replaced. Bad shocks will cause significant handling problems.

Front suspensions in good shape will handle reasonably well. Not new car, but they should neither be scary nor unpredictable. Rear sway bar should remain smaller than front sway bar to prevent excessive oversteer or the tendency of the car to want to swap ends suddenly.

Since you will be changing the front springs, you'll be in a position to inspect everything else in the front suspension

 

[oh dam]

"V" shaped tread patterns are usually directional and having them on backwards will affect handling. Too much air pressure will cause the tires to pull onto ridges and grooves in the pavement. Too low can cause a lag in the steering.

I agree with 72H, OEM alignment specs are for bias ply tires and need to be adjusted for radial tires. Further adjustments are likely needed to compensate for your tire/wheel choice.

Sometimes different tread patterns on front and rear tires just don't work, almost as bad as having a mix of bias and radial tires.

Ever wonder why you see so many used 18-inch and bigger wheels and tires for sell on Craig's List? They might look good to some people, but if the suspension isn't designed for them they can handle poorly and people switch back.

TireRack has a lot of information:

http://www.tirerack.com/tires/tiretech/techpage.jsp?s_kwcid=AL!3756!10!3308524027!30371467972&ef_id=Up84xwAABCgh1pac:20131217145000:s&techid=9

the thing that i never understand is people say i have a tall tire. but it really isnt much different from a 17 in rim or 16. depending on the tire you chose. I have about a 26 in tire. i similar tire in 17 in rim will be about 25-26. I mean does the size of the rim make that much different? even if the overall height is similar?

If your springs are shot, nothing is going to help until they are replaced. Bad shocks will cause significant handling problems.

Front suspensions in good shape will handle reasonably well. Not new car, but they should neither be scary nor unpredictable. Rear sway bar should remain smaller than front sway bar to prevent excessive oversteer or the tendency of the car to want to swap ends suddenly.

Since you will be changing the front springs, you'll be in a position to inspect everything else in the front suspension

ya that was one of my questions since my springs are in bad shape, can that be a problem as to why it handles like it does. someone said no and you say yes. so im a little confused.

 

[MotoArts]

I maintain that the ONLY way to be sure is to change ONE thing at a time, then drive it.

Don't just throw a bunch of stuff at it all at once.

I can say that when going back to my 15's, my car rides and handles (normal street driving) like new again. If I were autocrossing or open tracking, lap times may show the tradeoff.

I assume the sidewall compliance (or lack of) makes some of the difference.

I had "tire rejection" happen on a motorcycle as well.

A 1985 Ninja 900, designed for bias tires, had narrow 3" wide rims. Back in the early '90's, radials came available. Few companies made them in sizes that fit the narrow rim. One style of Michelins fit, and were a HUGE improvement in braking, handling and overall bite. Unfortunately, I could smoke a front bald in one day of open track riding. Replaced them with similar sized Dunlop Sportmax, and the bike totally refused to turn, even at street speeds. It was dangerous enough that I took them off and replaced them with the Michelins again.

Have since used the same Dunlops on other bikes with no problems.

Just hard to say why this particular bike rejected them.

 

[Boss1Ray]

You are getting some great info here. I agree and say start with the tires. Get with someone and borrow a set to see how your car acts.

I remember a really slick 71 Ford pickup that I thought had some real suspension problems. A friend at a tire shop said he would change out my tires for another set (they were like new but used). It completely changed the truck, for the better. I was amazed. We speculated a couple of the other tires had some belt seperation issues.

Good luck!

Ray

 

[oh dam]

hmmm interesting.. is it because the diameter of the wheel? or is it because of the width? I am due for new front tires any way. any you recommend? as far as brand and type. not size. Ill just have to ask around for a favor to borrow wheels temporily.

 

[droptop73]

If you really want to sort out the "whys and wherefores" of what the car is doing at speed I'd recommend the book "Chassis Engineering" by Herb Adams. He goes into several types of chassis design and how everything interacts together. It takes a few times through the book and diagramming the suspension points to really get a handle on what the car is doing.

The main issues we deal with when changing things, (like ride height, wheels, tires, swaybars and springs) is deviation and concerns from changing basic suspension angles like scrub radius, roll centers and camber changes. Wider tires and wheels and their accompanying backspacing changes and sidewall stiffness can definately have an effect on how the car tracks at speed.

 

[oh dam]

Thanks so much much guys. I just wanted a general idea of what to do but you guys went more into detail!. Slowly but surely i am going to make sure everything is tight and not worn out as i suspect some parts are. Time to put my engineering skill into test and measure the geometry and rule out what is correct. But one quick question. Can someone go into detail the elements of alignment and their functions? i have a general idea of all, but would like to be schooled so i can develop my perfect alignment specs to my pleasure.

 

[72HCODE]

like others have said the tires make a big deal, the modern trend is a very low profile tire large rim. they tell you tighten everything up, lower the car, etc. you end up with something almost Undrivable, these older cars need a certain amount of floating to compensate for design.

what works on a race track isn't good for the street. fast steering response and quick handling on paper sounds good but it makes for a twitchy very loose car on the street and you do not want that in traffic.

but as others have said change one thing at a time. inspect the joints for play, there will most likely be no play in the linkages.

the shocks are fine, what will come into play is the springs and the sways and if you will be in ride height range of an alignment, you can drop a car too much, at that point you would need to rethink the mounting points on the front suspension to the shock tower and relocate things 1" to keep the geometry.

for a quick explaination. you have Camber, Caster, and Toe in-out

read this

http://www.ozebiz.com.au/racetech/theory/align.html

for indepth information

now when you lower a car you usually take it out of a factory set geometry range. all cars have a certain amount of bump steer.

bump steer is unwanted movement of the tires when a suspension is compressed this is due to the suspension layout of an upper and lower A arm setup and how equidistant the top and bottom Arms are. usually you have a longer lower A arm and a much shorter top. that causes the suspension at extreme down range to toe-out the front tires and usually massive negative Camber, so you hit a bump and the freaking car all of a sudden veers off to the left or right depending on how off center the bump you hit was to the center of the chassis.

the other end of the spectrum is you lift the front end up and you get massive toe in and positive camber.

so they set the suspension in an acceptable range of motion, when you lower a car or raise a car you come out of that comfort zone which is why you get wacky handling on modified cars. either you have to raise the car slightly or adjust geometry on some linkage to minimize it or the suspension has to be redesigned to work.

you want the car as neutral as possible on the street for a bunch of reasons, emergency handling, tire wear, MPG, rain, bumpy roads, speed bumps.

as for a perfect alignment there is no such thing. Amazingly you can have 2 cars exactly the same next to each other with the same alignments and one will be better then the other. this is because of manufacture tolerances. this is how you could end up with a lemon, somebody welded something in 1/32" off and now the car will not align correctly.

here is where that float i told you about comes in. there is the old joke you must of bought a friday or monday car.

when they built the cars on friday everyone wanted to go home and on monday everybody was hung over so the tolerance was worse at the start and end of the week during production. you would seriously see a 1" difference in tolerance on some cars.

the engineers sort of knew the human error factor and built it into the design. they knew the rubber bushings and large profile tires took up alot of error in assembly. also you had bias ply tires which reacted differently to road input. so the cars floated along the road the handling was sluggish and slow but predictable. later you come in and want it Light, tight and right, and well all the problems get exposed. so you have a limit to how low you can go and what a car will tolerate.

some of our cars can tolerate +4 degrees of caster, some barely +1 the more caster the better with radial tires.

camber is easy you want it 0 as much as possible through the range of suspension travel so you set it at 0 at ride height knowing as the car moves up and down it will float between -1 and +1 of range.

toe in usually between 1/16 - 1/8.

the problem comes when a car is lowered too much, then you set all those numbers at ride height but suddenly when the supension is moved you have wild variations in camber and toe +5 to -5

but first check for a mechanical issue with joints, then make small changes and go for a drive, if you change the springs you will need a re-alignment in camber and toe. the caster shouldn't change unless you swap bushings.

the rag joint can be the source of some issues and should be looked at

a car can also have frame damage that prevents a good alignment or rust damage, obviously rust is a major issue but on our cars the shock towers can roll inward and cause all kinds of suspension problems those shock tower braces are very important and most people are missing them in the engine bay.

 

[oh dam]

Ya my rag joint has some play in it.. I replaced my gearbox recently. does a "rebuilt" gearbox come with a rag joint or not? i had a buddy's shop do it and i dont know if they touched the rag joint.

 

[auron73mach1]

there is the old joke you must of bought a friday or monday car.

when they built the cars on friday everyone wanted to go home and on monday everybody was hung over so the tolerance was worse at the start and end of the week during production. you would seriously see a 1" difference in tolerance on some cars.

I had to look it up real quick, my car was built on a Thursday! Dodged a bullet on that one for sure.