So I finally had the opportunity to drive my car on the freeway and some longer windy 2 lane roads, as I cruised up I-80 through the mountains on the way to Reno.

The car feels great, EXCEPT when I hit a bump, the front feels like it wants to dart... Even at 20 MPH, bumps make it feel unstable (not just really big bumps, but enough to be felt easily in the car)...

I have had other Chevelles lowered with stock components (stock arms and BJs), and never felt an issue like this...

I have stock spindles, SC&C Stage 2 setup, and the car is lowered with "stock" Eibach springs... Alingment specs are based on SC&Cs recomendations.

Otherwise, the car is a joy to drive. The AGR steering box feels good on the road, great feedback...

My only gripes are lack of an Overdrive and the headers/trans pan close to the ground. I have 3.70 gears, so I only cruised about 65-70+ MPH (3000-3300 RPM)... Oh, and a whacked the front spolier coming out if a driveway. :D

Have you tried giving Mark @ SC&C A call, one of the reasons I chose them was because of the information that Mark has stored in his head over the years.

I seem to recall that there was a thread started thatcovered this awhile back. Maybe do a search for it "SC&C stage ll"?

Could be a scrub-radius issue... what are your wheel offsets?

What is your toe set at?

Could be a scrub-radius issue... what are your wheel offsets?

What is your toe set at?

Here are the alignment specs...

Camber, Left -0.6 degrees and right -0.5 degrees...
Caster, Left 5.0 degrees, and Right 5.5 degrees,
Toe-in, 0.17 L and 015 R...

The wheels are 17X9.5 with 5.5" BS, so I guess the offset is 0.25"

Feels great otherwise... The "bumps" I was hitting are probably 1"+ deep, so most of the drive was fine, just a few spots... Some bridge approaches, and on a side street, I think there was some pavement settlement from some recent street work (lateral sewer pipes replaced, so kind of like a small, reverse speed bump that both front wheels hit almost simultaneously)...

Hmmm... backspace should be fine, toe-in is good too. :confused:

Hmmm... backspace should be fine, toe-in is good too. :confused:

Thats what I thought... I have had extremely lowered cars in the past, with stock suspension/spindles, and never had an issue. In this case, I thought the Stage 2 pieces should improve bump steer (compared to a stock setup)... So I was a little surprised/baffled when I hit the first bump...

I would question the alignment!
time for a second rack IMHO

I would question the alignment!
time for a second rack IMHO

What in the alignment would be the likely culprit (toe, camber? caster?)...

The car otherwise handles great, and feels great on the road, tracks straight, steering wheel is centered. Only the bumps.dips upset it... In a 130+ mile trip, maybe 4-6 times I felt it ( except on the one local street at 20 MPH, where a series of 4-5 dips, felt it every time).

Before the alignment, I had really bad toe out, and it also darted ( even worse), but you could actually see the toe-out condition when comparing the front wheels...

AFTER the alignment, I did tighten all the pivot points at home ( 60 ft-lbs?, per SC&C instructions)...

Camber, Left -0.6 degrees and right -0.5 degrees...
Caster, Left 5.0 degrees, and Right 5.5 degrees,
Toe-in, 0.17 L and 015 R... Camber, Left -0.6 degrees and right -0.5 degrees...
Caster, Left 5.0 degrees, and Right 5.5 degrees,
Toe-in, 0.17 L and 015 R... Camber, Left -0.6 degrees and right -0.5 degrees...
Caster, Left 5.0 degrees, and Right 5.5 degrees,
Toe-in, 0.17 L and 015 R...

Not that it matters or is causing your problem but, you only want that half degree caster adder on your right side to offset road crown. If you spend any time in the left lane there isn't any point in itt. Without thinkinking i put a .25 adder in mine. next time I'm settng them even (I spend too much time in the left lane, passing!)

back to your darting
more importantly; am I reading this correct?
Toe-in, 0.17 L and 015 R...
is that each side? is that degrees? not inches right?
When I put my sc&c stage 2 in my 71 chevelle
I inadvertantly set my toe at 1/8" in and it was darty on the highway
changed the toe in to 1/16 inch (in) and its a dream to drive.

set up on my 71 is
Camber, Left -.25 degrees and right -0.25 degrees...
Caster, Left 5.0 degrees, and Right 5.25 degrees,
Toe-in, 1/16 in
Wheels and tires
Front 17 X 8 with Nitto 555 245/40R17
Rear 17 X10 with Nitto 555 275/40R17
good luck

Camber, Left -0.6 degrees and right -0.5 degrees...
Caster, Left 5.0 degrees, and Right 5.5 degrees,
Toe-in, 0.17 L and 015 R...

Not that it matters or is causing your problem but, you only want that half degree caster adder on your right side to offset road crown. If you spend any time in the left lane there isn't any point in itt. Without thinkinking i put a .25 adder in mine. next time I'm settng them even (I spend too much time in the left lane, passing!)

back to your darting
more importantly; am I reading this correct?
Toe-in, 0.17 L and 015 R...
is that each side? is that degrees? not inches right?
When I put my sc&c stage 2 in my 71 chevelle
I inadvertantly set my toe at 1/8" in and it was darty on the highway
changed the toe in to 1/16 inch (in) and its a dream to drive.



Perhaps thats the problem... I'll have to go look at the spec sheet again.

Another thing, measuring toe-in in inches... There has to be something missing, where is the measurement taken from ( i.e. 1/16" per foot from wheel centerline, etc. Wheel diameters and steering linkage all vary by vehicle/tire)... So how would that relate to degrees? I figure I could probably loosen the tie rods, and spin the adjusters and even amount of turns ( and even use the threads on the tie-rods to estimate how much I was changing the "toe" setting)... Pretty sure the toe was in degrees, as I know 0.125" would be 1/8", and I wouldn't want more than that...

As for the caster, the tech set it that way for road crown (I gave him a sheet with the specs I wanted, based on the SC&C specs). I usually drive on 2-lane roads and city streets, and with 3.70 gears and no OD, I don't spend much time in the left lane


BUT,

I went back to this thread:
http://www.chevelles.com/forums/showthread.php?t=269738&highlight=alignment
and my specs are similar to Mike/Stealth71's ( I think his toe was 0.14 and 0.13)

Aother thing, toe-in in inches... There has to be something missing, where is the measurement taken from ( i.e. 1/16" per foot from wheel centerline, etc.measured from front of tire and back of tire.

Assuming 26" tires, your toe measurement comes out to 0.141 inches. It does vary by tire size, but it really doesn't have to be an exact science... close really is good enough.

Most of the fancy machines read toe in degrees... us cheapskates doing it in our own garages with basic tools need to take measurements in inches.

Could be the shocks? Did you lubricate upper and lower control arm bushings so they move freely? If they are dry against the metal/frame, that would make the suspension act goofy if they are binding.

Unless the alignment is not what the specs say bumpsteer per se is not the issue. the Stg.2 eliminates about 80% and almost all of it in the regular range of travel. That`s easy enough to measure and hardly changes car to car. There are LOTS of other variables it could be though from the particular set or brand of tires to a loose wheel bearing or steering component to excessive toe in.
The thing is we can`t help you if we don`t know you`re having a problem... ;) Give us a call and we`ll help you trouble shoot it. The first thing I`d do is check for excessive toe in and check the tire pressure. Second thing I`d do it recheck the alignment. We had a guy call earlier this week who`s car was "professionally aligned". The sheet they gave him said +5 caster but after rechecking they found it had been set to 5* NEGATIVE caster by mistake. :yes: Now, there`s a problem... LOL! Mark SC&C

Unless the alignment is not what the specs say bumpsteer per se is not the issue. the Stg.2 eliminates about 80% and almost all of it in the regular range of travel. That`s easy enough to measure and hardly changes car to car. There are LOTS of other variables it could be though from the particular set or brand of tires to a loose wheel bearing or steering component to excessive toe in.
The thing is we can`t help you if we don`t know you`re having a problem... ;) Give us a call and we`ll help you trouble shoot it. The first thing I`d do is check for excessive toe in and check the tire pressure. Second thing I`d do it recheck the alignment. We had a guy call earlier this week who`s car was "professionally aligned". The sheet they gave him said +5 caster but after rechecking they found it had been set to 5* NEGATIVE caster by mistake. :yes: Now, there`s a problem... LOL! Mark SC&C

The steering linkage is all good, the tire pressure was set for 36 psi, the wheel bearings were checked a few days before ( I was preparing for the road trip), same wheels and tires were all on the car prior to the swap, although I did drive the car about 40 miles with really bad toe-out, not sure if that messed the tires up ( I plan of replacing them anyway, just trying to put it off for a while.

I haven't driven the car since, been kind of busy...

Honestly, I was kind of dreading calling Mark, because as I recall, he talks alot, and so do I! That could mean alot of time on the phone... :D

I'll try and look at the toe ( roughly, tape measure), and see where it is, ball park... I'd guess that caster should also be able to be eyeballed ( at least in regards to neg/positive)...

Not sure if I screwed anything up, as I never asked the tech to tighten the bolts on the bushings... i did that myself after I got home... maybe they were loose enough to give false readings...

I'll do some more investigation before I waste marks time...

Depending on your tires, checking to with a tape measure can be easy. With my nitto 555s there is a nice staight tread line; easy to find and check the difference, front to back.

Tony you can get a whole lot closer on alignment with basic tools than you might think.

Tell ya what: I work over here quite close to you now ;). You have the car jacked up with the front wheels off, provide a cold one, and we can knock off a sanity check in about an hour (allowing time for the cold one). You probably have my contact info. already :beers:

Depending on your tires, checking to with a tape measure can be easy. With my nitto 555s there is a nice staight tread line; easy to find and check the difference, front to back.

er....... I meant check toe with a tape measure!! doh