95Z28M6

Could anyone confirm for me the reason the car is pulling to the right after I had my alignment set to PFADT's dual purpose specs? The tech said that he couldn't put anymore camber into it cause he started loosing caster. I do remember the washers are still behind the upper arms, and I meant to pull them but forgot. I'm guessing it's pulling right because of the caster being split to the right side. If anyone could confirm, I'll change it. Before is on the left, final is on the right. Thanks in advance.

MongoZ06

Without knowing just how much it's pulling to right the 2 things I would consider being the cause are
-The imbalance in Caster, more caster on 1 side can cause the car to pull in that direction
- Did the alignment tech have the wheel centered and use a steering wheel lock?
(I had a tech fail to properly secure the steering wheel and had this type of issue)

BEZ06

Yes - that caster split is probably a big cause of the pulling. Split caster is the way street cars are commonly set up to compensate for road crowns.

And - I recommend you get that toe checked!! Take a look at the note at the top of this Pfadt alignment sheet:

http://pfadtracing.com/pdfs/Corvette...09.12.2011.pdf


You can see in there that it says: "Negative toe measurements indicate toe-in".

The +/- signs used for toe aren't universal, but in about 99% of cases negative toe means toe-OUT, i.e., opposite of Pfadt's use.

Your alignment sheet shows that your toe front and rear are negative, with the rear actually quite a lot.

Check with your alignment shop on what their negative toe means - toe-out or toe-in. Find out if they read the note at the top of the sheet.

I bet you have quite a lot of toe out when the Pfadt sheet actually calls for toe-in.

.

SunnydayDILYSI

I'm not an engineer, but a couple of ideas. Your front end toe was way out of wack before the alignment (.7 on left side and .05 on right), so I would expect the car to feel very different after. Generally, roads slope to the right to help displace rain, so you will get a gentle pull to the right going down the road with a good alignment. Your caster is now fairly different from left to right. I don't know if that would cause a pull, but seems unnecessary. I would balance it out next time even if you have to give up a small amount of camber.

95Z28M6

Thanks guys, I asked him more than once if the negative toe meant in or out, and he said it meant toe in, I'll double check it with toe plates. I could always pull the washers in the upper arms for the camber and get the caster back in it and evened up. The steering wheel is slightly cocked to the left, which I was gonna straighten out by bringing the RF tire in a flat or two to give it a hair of toe in and straighten the wheel.

SunnydayDILYSI

For the back, a little toe in helps to straiten the car on corner exit. For the front, you either want to be neutral or have a very small amount of toe out to help with turn in. If you have toe in on the front end, I would fix that too.

UstaB-GS549

Check your camber. If the bolts were not torqued to spec they will slip.

Nowanker

Caster will cause a pull to the side with the lower value, theoretically your readings would have a pull to the left. With that amount of caster, it's generally invisible anyway below ~1/2 degree split... I'd look elsewhere for the pull.
By 'pull' do you mean A) the car wanders to one side when you take your hands off the wheel, or B) the car drives off to one side when you hold the wheel straight?
A: How bad is the pull? typical road crown might cause a pull to the right. Extra neg camber makes the car wander anyway. Otherwise, with the angles you show, I'd suspect the tires first. Try swapping the F side to side. Dragging brakes can also cause it. Assuming there isn't anything loose or worn that will allow the suspension to move around and find a new location 'while-you-drive'!
B: Completely different situation. It's easy and common to have the toe set correctly, but to a steering wheel position that isn't straight ahead. Easy readjustment...
I'm in the business, and have NEVER personally seen or even heard of an alignment machine that reads toe in as a negative value. Not to say that they don't exist...

95Z28M6

Ok, so when I say pull, I mean a freshly paved road, less than a year old. On pavement that angled in both directions (part of the road has drains in the center). If I let go of the wheel at 35+ it creeps it's way to the right and keeps going. Even if I hook the crown, even if I pull the wheel left first and then let go...the car gradually pulls off to the right. Like I said, I'll grab our race cars toe plates and make sure the rear is toe'd in, but for the front shooting to the right, the caster split is the only explication...since it tracked straight before the alignment, and those settings were a mess.

rfn026

I like caster as close to equal on both sides. You've got a pretty significant caster split.

I generally like to get as much caster as possible and still have it equal on both sides. That's because I like straight line stability.

I think you need to have this alignment done over.

Richard Newton
The C5 Box Car

Racer86

My 2 cents,, caster split will cause the pull. On short track roundly pounders, we use caster split to help with the turnin. Car wants to turn left all by itself,,, big time.

Nowanker

Again, after doing literally >1,000 alignments:
All other things being equal, a car will pull to the side with the least positive caster.

froggy47

Your final caster is crap, that's the pull.

Have him do it over.

Bill Dearborn

When I look at his spec sheet it indicates to me the car should pull to the left not the right. Everywhere I look on the net for the definition of Caster Pull I see that caster differences will always cause the steering to pull toward the side that has the least amount of caster. Having it pull to the left on a crowned road would be the right setup but he is talking about roads with the drainage in the center not the sides so the middle of the road is the low point. The car is still pulling to the right when the caster says it should pull to the left and the road surface says it should pull to the left. There is something else going on. Maybe the LCA cams weren't tightened enough and they slipped which would cause an alignment change that could have happened when the car was pulled off the rack or drove out of the driveway.

Bill

froggy47

IMO everyone on the thread is assuming that the alignment tech and resultant spec sheet are correct.

I call BS flag.

Everyone here should know that even WITHOUT camber plates a tech can get way more than -1.0 negative, closer to 2-2.2 easy without plates.

These super duper high tech alignment racks are only as good as the data base specs they pull (often using the vin) AND the TRAINING OF THE TECH.

I think the whole mess is a botched alignment.

my 2 cents.

sccaGT1racer

If these are your true alignment specs your car should be pulling left. Caster pull will always go to the side with less caster. Is your steering wheel off center or is it drifting right?

rfn026

At one point in my career I taught people how to align cars. You can cheat the machines. Froggy may have hit the real problem.

I used to be able to get any sort of print out I wanted without touching a single bolt on the car. I never did it to a customer's car but we discovered that it was pretty easy to do.

It may be that you need a new shop more than you need a new alignment.

While we're on the subject of alignment … Before I take my car to the alignment shop I paint yellow stripes on very nut and bolt. I then check to see if anything has actually moved during the alignment process. Paranoia is not all bad.



Richard Newton

Nowanker

...or find a shop that you can trust instead.
They do exist.

froggy47

Or do your own, it's not that hard.

Solofast

Froggy's right.

I once had a tech that was doing the alignment and got it to where it was supposed to be, but all the jam nuts weren't tight yet and he wanted to turn off the machine and then finish tightening it all up.. He started to "finish the job" with the machine off and I told him to turn it back on and give me a "finished" sheet.. He hemmed and hawed but final turned it on an the toe had changed a bunch in the tightening process.. Moral of the story is to make sure you get your finished print out with everything tight and done and not before...