poor handling on highway

[montanass]

so i'm getting tired of chasing my car around going down the highway. It seems to jump from one side of the rut(s) to the other, making it quite a handfull and takes away from the fun of driving.

My setup is:

69 el camino
BBC- 2" lowering springs, stock spindles, 18x8 front rims 255/40R18 (f)- 18x10 295/35R18 Rear

all hotchkis components, sway bars, lower conrtol arms (rear) edelbrock adjustable upper control (rear), etc.

I'm just wondering if this is common with larger wheels and low pro tires, or if i should start looking into this a little deeper.

thanks

[Vince@Meanstreets]

a bit more info needed;

alignment specs?
brand of tires being used?
steering linkage new or old? worn components
steering box new or old? worn components
tire pressure?
what speed?
front suspension new or old? worn components

[wmhjr]

I'm just wondering if this is common with larger wheels and low pro tires, or if i should start looking into this a little deeper.

thanks

No, it is not common.

[sweetstang68347]

A couple of thing that come to mind are the amount of caster in alignment and bump steer. But yeah...

a bit more info needed;

alignment specs?
brand of tires being used?
steering linkage new or old? worn components
steering box new or old? worn components
tire pressure?
what speed?
front suspension new or old? worn components

[montanass]

Tires are toyo t1r, 28 psi, alignment is set to "factory specs" (had it done at les Schwab). Steering components are factory origional. I have a poly bushing kit in the plans, and tubular upper and lower control arms. I've been waiting to do the bushing kit until I get the control arms since I'd have to do those bushings anyway. Also a quick ratio steering box is in the plan book... However since a new house and other things are taking up most of my fun money I have to be patient.

[Bryce]

Dont quote me on this. But weren't the factory specs set up for bias ply tires. I know the 65 falcon mustang specs were for bias ply tires.

What are the factory specs. I bet you have very little caster, (the reason you bought the tubular control arms was to increase positive caster). I would also guess you have positive camber. You want the tire to be in at the top, that would be negative camber.

[wmhjr]

There's your problem. Factory specs are worthless once you've changed geometry using different spindles, ball joints, upper and lower control arms. You've changed your entire front geometry and need to align accounting for it.

[Proforged]

There's your problem. Factory specs are worthless once you've changed geometry using different spindles, ball joints, upper and lower control arms. You've changed your entire front geometry and need to align accounting for it.

Since he hasn't changed his spindles or ball joints, the front end geometry is the same as stock.

At the minimum, I would recommend replacing all of your control arm bushings, the idler arm, pitman arm, tie rod ends, and center link. Tall Upper and Lower Ball Joints will allow you to run a more aggressive alignment, but you will likely need tubular upper control arms to get the positive caster you need for highway handling.

If you install tubular upper control arms and tall upper and lower ball joints, here are some alignment specs you can use:

Camber: -1/2 degree
Caster: +5 to 5.5 degrees
Toe: 1/16" total toe-in

If you can't swing the above components right now, bring your car back to get it aligned as close to these specs as possible in the meantime. Dialing in the camber and adding positive caster will help your handling situation some.

[JKnight]

He hasn't changed any suspension components yet, including bushings. I would suggest replacing all your bushings and whatever suspension pieces you are looking to do, have Les Schwab do a more aggressive alignment, then evaluate the handling of the car. 40 year old bushings are going to make that car do all kinds of crazy things going down the road.

Also, why are you running only 28 psi?

[wmhjr]

He changed to 2" lowering springs. Geometry is changed.

[GregWeld]

Since he hasn't changed his spindles or ball joints, the front end geometry is the same as stock.

At the minimum, I would recommend replacing all of your control arm bushings, the idler arm, pitman arm, tie rod ends, and center link. Tall Upper and Lower Ball Joints will allow you to run a more aggressive alignment, but you will likely need tubular upper control arms to get the positive caster you need for highway handling.

If you install tubular upper control arms and tall upper and lower ball joints, here are some alignment specs you can use:

Camber: -1/2 degree
Caster: +5 to 5.5 degrees
Toe: 1/16" total toe-in

If you can't swing the above components right now, bring your car back to get it aligned as close to these specs as possible in the meantime. Dialing in the camber and adding positive caster will help your handling situation some.


REALLY? New control arms per his post... and lowering springs... and you're saying nothing changed...

His first mistake was taking it to Les Schwab and not discussing these changes - and the second mistake was the tech not recognizing the changes and accounting for them.

Further - my guess is the steering box is "loose"... and the bushings are old etc. BUT the tech should have discussed all of that with him (and maybe did).

"Hunting rabbits" on the road is no fun - and can be downright dangerous when the roads get wet/slick. I say take it back to Les Schwab - and ask for a tech that understand suspensions not just how to read specs from a book.

Hope it gets better for you!

[JKnight]

I think to this point he's just done the lowering springs. Control arms are on his list of what he'd like to do, but hasn't yet.

I would think worn out bushings throughout the front suspension and the worn steering box Greg mentioned would contribute more to the wandering he's experiencing while trying to go straight down the highway than the springs would.

[wmhjr]

I read the op as the car was ok on the highway, but after lowering and big wheels and low profile tires it got much worse.

[JKnight]

Hahaha, this thread is like the telephone game.

Bottom line is we're all pissing into the wind trying to guess until we get more clear and detailed information.

I would believe that the wider tires and stiffer sidewalls would expose the weaknesses in the suspension bushings and tolerances that caused the wandering and darting. With tall profile skinny tires I can believe that these weaknesses might have been masked to some degree.

[GregWeld]

Sorry - Yes you're right -- I misread the lower control arms - he changed in the REAR.... Not the front. The ADD got me...

Either way -- he needs to go back and have a good honest discussion with the TECH....

[Hotchkis]

so i'm getting tired of chasing my car around going down the highway. It seems to jump from one side of the rut(s) to the other, making it quite a handfull and takes away from the fun of driving.

My setup is:

69 el camino
BBC- 2" lowering springs, stock spindles, 18x8 front rims 255/40R18 (f)- 18x10 295/35R18 Rear

all hotchkis components, sway bars, lower conrtol arms (rear) edelbrock adjustable upper control (rear), etc.

I'm just wondering if this is common with larger wheels and low pro tires, or if i should start looking into this a little deeper.

thanks


Montanass – it sounds like there must be something worn out or loose in the front suspension components. Check all the ball joints, tie rod ends, idler arm, pitman arm, and steering box. Your car should not be wandering that much if the alignment is good.