Jacki&GeneZ16

Please help me pick a better alignment, needed per a SCCA instructor who drove my C4 recently. I'm getting as much seat time as possible in my 1987 Vert that has 152K miles.

What I'm working with: automatic with standard suspension; within past 1.5 yr: all new polyurethane bushings, new Bilsteins and wheel bearings, replaced all U-joints, best gear shop says the differ looks & feels great, balanced drive shaft, I replaced swaybars w/VBP 30mmF and 26mmR. Soon: Hoosiers A6 275/45zr16 on stock 9.5x16 wheels for autocrossing.

84-96 Autocrossing Suggested Specs
VBP
Front Camber 1.5-3*neg, Caster 4-5*pos, Toe 3/16" out
Rear Camber .75-2.5*neg, Toe 1/16" in

Guldstrand
Front Camber .25-.75*neg, Caster 2.5-4*pos,Toe 1/16-1/8" in
Rear Camber 0-.36*neg, Toe 0-1/16" in

From CF Larry
Front Camber 1.75-2*neg, Caster All possible, Toe 1/8" out
Rear Camber 1.5-2* neg, Toe 1/16"in

Quite a range huh? Only agreement is Rear Toe at 1/16
Which one do you think would work best for me? Along with autocrossing, this is my daily summer driver (about 35 mi/d), and I take an couple 300 to 600 mi road trips/yr.

Sidney004

Here is my pick:
Front: Max Neg Camber possible(You will be lucky if you get -1 1/4)
Castor: 4-5 Pos
Toe out: 1/8 - 3/16 out

Rear -(Max Front Camber value - 1/2)
Toe in: 1/8

Don't forget: Full fuel tank or the amount of fuel you use at the event
Tires inflated to track pressures
Sit in the drivers seat
Disconnect sway bars

In my case, I CAN'T achieve a front neg camber of greater than 1 deg, I don't know how these other people are doing it.

jwt1603

Depending on which front spring you have you can pull out the steel shims between the spring mounting pad and the attaching point. The color of the paint dot on it tells you how high the spring sits and how many shims there are. Of course you can't see the dot until you pull the spring out so you can't tell if it will work or not until it's out.

Or, if you can do it legally in the class you run in, you can grind down the pads at the ends of the front spring. Eckler's, Mid America, etc, all of them sell a front lowering kit for C4s.

Either way it's pretty cheap but not real easy to do unless you have access to a lift. Getting to the bolts holding the spring in place is a lot of fun even with a lift.

VBP also makes a kit that's more expensive and gets more negative camber in the front but a lot of classes don't allow it.

Jacki&GeneZ16

Thanks Sidney, I did not think to sit in the car during the Caster sweep. I been "practicing" aligning at the Base Auto Hobbie Shop where I stood on a ladder, reached in to turn the steering wheel. I'll get behind the wheel Saturday. Is there another time I need to get in the driver's seat?

My front swaybar is a bear to connect, what do I lose if I don't disconnect them?

Jacki&GeneZ16

Thanks jwt1603, I appreciate your comments I did have the rear spring off last winter and know those spacers. During the winter I'm limited to working on my jack stands. Can I get the front spring out when only 18" off the ground? I am still on the soft stock standard springs for a non-Z51. I'll try to close to Sidney's Camber and Caster, but expect to fall short without the added spring work. Changing the springs will be on my list for next winter's projects. I hope to get the springs out of a 1984. Is that a fair way to go?

jwt1603

Well anything is possible I suppose but the bolts that hold the front spring in place are a real bear to get lined up again when you put it back together. Actually just the front bolts are difficult, the rear ones are easy. Plus you have to drop the lower A-arms to slide the spring out.

It's really not difficult but then again it isn't easy either. I don't think it would be advisable to try and do it on jack stands. Just MHO of course.

As far as the spring, just remember that spring ride height and spring strength are not the same thing. A Z07 spring typically makes the car sit up in the air more than a base spring but it's stiffer than a base spring. And there is also some variation between same spec springs. That's why GM used the paint dots on the assembly line. The color of the dot told them how many shims to use to get the desired ride height.

So the result is that just because you use a different spring, with all else being equal, it doesn't necessarily mean the car will sit lower. By having the car sit a little lower you gain a little more negative camber because you have changed the geometry. Nothing radical of course but it does get you a little more negative in the front on a C4 without actually changing the suspension set up.

Slalom4me

I suspect that there is a typo in the Guldstrand values.
My vote is that the front toe should read 1/16-1/8" 'out'
instead of 'in'. For an '89, the OEM spec is 0 (+/- 0.10º)

Either way, the three recommendations can be seen as three
levels of response/tire wear aggressiveness. I would order
them from mild to wild as follows:
I agree with Sidney004 that a limiting factor for a stock vehicle
is how little front negative camber is available. Offset lower
control arm bushings and ground upper control arm spacers are
methods to attain more negative adjustment (but these may not
be allowed.)

Under the circumstances, my vote is that you settle for the milder
settings. My view is that toe has a greater impact than camber or
caster on tire wear and driveability. Settings of 1/8-3/16 at the
front may be great for turn-in at Solo II, but the car will 'tramline'
in the ruts and the tires will wear on the street.

Alternatively, if you are comfortable with making your own settings,
consider dialing in more aggressive camber values and then alternate
between track and street toe settings. Unlike toe, my feeling is that
camber has relatively little impact on tire wear. To assist with toe
adjustment, make or buy some toe plates.



Consider adding standoffs (bolts or ?) to the toe plates so that you
can register off the wheel instead of the tire sidewall.

I vote against swapping to the '84 springs, even if they fit (when was
the front susp design altered - 87 or 88?).

Also, as you increase corner grip, consider the consequences for
engine lubrication.

.

larryfs

don't go crazy with the rear camber. it just doesn't work well. -1.0 is perfect. anything beyond that the car will oversteer like crazy. cost me $100 to re-align it.

Jacki&GeneZ16

Thanks Slalom4Me, I typically make typos but not this time. I checked Guldstrand Motorsports Preparation Manual & Parts Catalog (1991) they mailed it to me in May 2004. Maybe they corrected this in a later edition.

I'll try to get as much Camber as I can, but keep it in A Stock this year. that is a great suggestion to get Toe Plates. I would like to go for an alignment that is more for autocrossing, but I have experienced the "tramline" effects and sound line a home toe adjustment before and after with do it. The Base's Alignment machine costs $50 for me to do all 4 wheel and $25 to do just the front. That is eating into my tire money.

That suspension change was in 88, so I am told via other CF threads. Once the Hoosiers A6 are mounted that should give me the grip. I heard of one C4 pilot had a "plate" welded into his oil pan (with a hole to accomodate the oil pump). Any other ways to protect the engine lubrication with the added grip or if one is doing high speed on extremely banks turns?

Jacki&GeneZ16

Thanks larryfs, sounds reasonable. At the stock settings I have way too much oversteer already. I don't want to add more. Maybe I should put the skinny original equipment swaybar back on?

Jacki&GeneZ16

Thanks again jwt1603, I'll heed your cautions and research more on the springs and height before I change. Given my C4 is a Vert and they have the extra X frame (lossing 1" clearence), clearence is already a challenge on speed bumps for my daily driving duties.

STEVEN13

Hi,

I would think the opposite, the more - neg camber the more chance of understeering.

Last time at Pocono my C4 (1992) had -1.25 front and -.5 rear camber and the car was loose (oversteering). Toe is zero in the front and the back is 3/16 toe in.

Next time out I will increase the neg camber in the rear. Also tire size has a lot to do with these settings-larger rear tire may require less neg camber in the rear.

Steven

Slalom4me

WNDOPDLR has recently converted to a drysump and others have posted
in his thread about their setups. A costly route, but deemed necessary for
durability once cornering passes a certain threshold for accelerometer
'G' readings and duration.

Before this threshold, modified pans and accumulators can provide
protection over stock. IMO, changing the pan is easier than plumbing
an accumulator - BUT!! I suspect that an OEM pan with an accumulator
would have been a better initial combo for my particular needs.

Look at the demands placed by the events. I don't believe I was
generating high enough loads long enough for concern in low speed
events. I began to be concerned when I was recording 1 G +/- for
5+ seconds.

BrianCunningham

Since everyone drives different, the best way is to learn how to align the car yourself, actually not that hard, and experiement.

This page shows how: http://www.vettenet.org/align.html

If you drive to events, watch your toe setting, camber won't kill your tires are much as too much toe out. But that's easy to set at the event and then reset once your done for the drive back.

Jacki&GeneZ16

As I did my final preparations I noticed that VBP had a note "...these specs are symmetrical. For example, when we recommend 1/8" toe in, that indicates on 1/16" each front wheel..." thus they don't look too aggresive dividing all VBP specs by 2. They look like this:

Front for each side
Camber -0.75*to -1.5*, Castor 2.0*to 2.5*, Toe 3/32" out (.09")
Rear for each side
Camber -0.375*to -1.25*, Toe 1/16" in (-0.125")

Okay folks!! This is what I got:
Front
Camber Left -0.98* & Right -0.94*
Castor Left -2.17*& Right -2.71*
Toe Left 0.8" & 0.10"

Rear
Camber Left -0.46* & Right -0.44*
Toe Left 0.16" & 0.16"

Not bad, huh? I was surprised I could have gotten more than the near -1.0 camber on each front wheels. Hey Sidney004, you may be able to get the more than -1* if on the unpercontrol arm front bolts you also switched the 18mm black spacer (between the frame and control arm) with the 9mm black space (between the locking nut and the control arm), and leave the black spacers alone on the back control arm bolts.

As I review my notes, I see that I goofed. I should have did a negative Toe on the rear. Well tomorrow at Anchorage PCA autocross I'll find out if this alignment helps. Same parking lot used by Arctic Region SCCA Autocross a few weeks ago that I did so poorly on.

Hey Brian, thanks for the link to the vettenet.org/align info. However, this helps me ID another possible goof. I did not drive my Vette around the block (I did not want to lose the bay with the Auto Hobbie Shop only Alignment machine) after making adjustments.

MY COSTS: I spent $50 to align 4 wheels on thier machine on 7/20, $25 to redo the front on 7/21, then $25 after I took the 18mm black space from the front bolts and put it between the frame and the control arm on the back bolts on 7/27, and today $50 more to to the above. Well that is not bad ($150 total) and I still don't think I got it right, but I am still learning. However, if I would have taken my specs and my earlier switching ideas to someone else that many times, I bet I would have spent 2 to 4 times more.

Maybe I should get the equipment vettenet.org/align suggests and do it at home. But this old AF civilian would miss BSing with the GIs and shop staff. They especially enjoyed it when Jacki brought in her ZO6Z16 for me to change the oil and filter. A few of them will be out tomorrow to see their 1st Autocross, one may run his Jetta.

Some much for now, thank you all

Slalom4me

Do you mean that the rear was set to toe out?

If so and if you happen to see this reply before you leave for your
AutoX, then be prepared to feel the rear end break loose and attempt
to swing around under heavy braking in a turn.

Should this kind of behavior occur, you can compensate by braking
hard while the car is traveling straight and slowing it down before
turning in.

Rear geometry of the C4 causes the toe to change in the toe-out
direction when the rear lifts as it does under braking. With static
toe out, plus whatever additional toe out gained under braking, my
vote is that you will notice some instability.

.

Jacki&GeneZ16

Yes, I goofed and did a slight Toe Out on the rear. Maybe I should try it, a few weeks ago I could not get the back end to oversteer when Ineeded. I have not left yet, it is raining.

Jacki&GeneZ16

I survived! Had fun and learned more about my car the the "feel" of it. Though a bit "unwheeldee" with more oversteer than I expected. On one early run I rounded up 7 cones, but only 4 were standing for 2 second penalties. Before the next AutoX in 3 weeks I get that rear toe to the Negative side.

The important thing was that I steadily progressed and got shorter times. After 5 runs of crushing cones, I did the last run that count cone free and my fastest time. Much better than last AutoX where all my times were with in 1 second each other. Today I was only 5 second slower than the fast drivers (all on racing tires, me on 5 year BFG that I should trash). I cut another second off during the dollar fun runs. I am happy, ignoring the cone penalties had a spread of improvement 3 seconds difference between my early runs and my fastest at the end of today's event.

I'll be ordering 275/45x16 Hoosier A6 (for 9.5x16 wheels) or 265/45x16 Kumho V710 (for 8.5x16 wheels) to stay stock. That will keep me in AS, right? Hope they help me get closer to the fastest times of the day cars by 2 or 3 more seconds.

Sidney004

Does anyone have a pic depicting the location of the 18mm and 9mm black spacers. I don't think I am getting it. By the way, I had taken this car to a "race alignment EGGSPURT" who confidently told me he got the most neg camber possible.

Slalom4me

I don't know about black spacers, but here is a photo by Andy Bolig
that shows the silver Position #1 (thick) and Position #2 (thin)
spacers for the UCA shaft. of an '85



On an '89, the thick spacer is one piece (looks like 2 pcs in the '85 image)

In the image, shims are visible between the spacers and the frame.
Removing spacers tips the wheel in at the top and moves it in the
direction of negative camber. When the spacers are all gone, the
remaining option is to reduce the thickness of the Position #1/#2 spacers.

If one or both of the spacers on your car has no shims behind it,
then your alignment person is correct - he has maxed out the
camber using conventional means.

From The Bottom Up by Andrew Bolig

The article says the washers are different in the later
cars - they changed up to the newer ones for more
caster. I don't have the p/n close at hand for the thick
late model one, but the thin one is p/n #10268932. A good
parts person should be able to use this number to
zero in on the p/n for the other. Expect to pay around
$4 ea.

.