Alignment question, pulls left
 

I have just completed new torsion bars, set my corner balance (hopefully correctly), turbo tie rods, and some other little stuff. Anyway, I took the car in for an alignment, not a Porsche place, but they do them from time to time, but a very reputable and quality shop, all they do is suspension work. Got the car back and it drives awesome, corners great, feels good, except......pulls left, not bad, but does pull left.

I initially thought it was the road, but pulls left on any road, more noticeable above say 45 mph. It will pull up the road crown in the right lane, and even faster in the left lane. Doesn't jerk the wheel but constant pressure is needed to maintain straight path. For example, if I'm in the right lane, on the interstate, driving 75, if I let go of the wheel, it take about 4 seconds to drift completely into the left lane. Not bad, but annoying.

The car drove straight as an arrow before, I've checked tire pressure, ride height again, etc.
I also repacked the front wheel bearing before the alignment, could I have gotten the nut too tight causing drag???? Never had this happen on any other car but I don't know anymore.

Here's the alignment specs, not sure what some of it means but maybe someone more knowledgeable can look at it and find something. I spoke the the shop about it, they insist it is not the alignment and must be another problem with the car.

LF (degrees)
camber -1.00
caster +5.93
toe +0.02
sai +11.06
incl ang +9.92

RF
camber -1.10
caster +6.08
toe +0.02
sai +11.80
incl ang +10.54

LR
camber -1.48
toe +0.01

RR
camber -1.50
toe +0.01


Front totals
total toe +0.04
cross camber +0.10
cross caster -0.15

Rear totals
total toe +0.02
cross camber +0.02

Fr setback -0.12
Rr setback +0.01
Thrust angle +0.01


Anyone.......help??

Mine pulls to the right after a recent alignment. I will be interested to see what settings need to be adjusted to "recenter" our cars.

do any of you guys know if the toe was set with the wheels pressed?.. and I say that a bad corner balance will cause a drift, some guys don't............Ron

Pressed? What do you mean? The car was sitting on the alignment rack, was never lifted, and had ballast in the drivers side to compensate for my weight. Other than that, not sure.

I am with Ron all the way. It is a bad corner-balance that is causing the pull

I could picture a bad corner balance causing a pull while on the brakes, but just in straight ahead driving...? Especially since the alignment seems to be pretty much straight ahead. Something is introducing a yawing force into the car. Does the "pull" actually turn the steering wheel to the left or do you just need to turn the steering wheel to the right to keep it straight?

Have you confirmed that your brakes aren't pulling. Although it wouldn't technically cause "pulling", did the shop have your steering wheel centered when they did the alignment?

BTW; Is your car lowered? How much? Have you ever adjusted the bump steer?

Didn't we go over corner balance on a related thread and found that you were within 20 or so lbs? If so, my vote would be to check brakes for pulling, not so much chassis alignment. Also, check for thrust angle, although those number look decent ...have an alignment shop go over thrust angle one more time.
--Wil Ferch

Clay: Mine did the same thing-if it pull to the left you have too much weight pressing on the r frt wheel. The castor setting on the right is pushing you left. Unscrew the r frt torsion bar adjuster 1/2 turn-go for a ride. I suspect each time you do this you will notice less of a pull. You can also lessen the ride height on the l rear wheel to compensate for a visual imbalance.

Actually pulls the wheel to the left, braking is fine and doesn't seem to pull more or less when braking. And yes, corner balances were around +/- 4lbs when we discussed this last time. I haven't checked the corner balance since getting the car back, should I? I don't think they messed with the ride height, I hope not anyway. Would this have an effect on straight ahead driving though? If it's that sensitive, wouldn't this affect any 911 with just a driver or a heavier driver vs passenger (assuming car was balanced empty)??? I wouldn't think it would make that much of a difference just driving on a straight road. Plus, the car had not been corner balanced when I got it, and it never pulled with my arse weighting down the drivers side, so why would it now
:confused: :confused:

maybe I should have said "very bad corner balance".. but it also depends on the other variables on how sensitive it is, IMO.....Ron

the 911 has a tendency to move the toe settings out when being driven.. so a bar is pressed on the inside of the front wheels to "press" them out to compensate.. all 911 book alignment settings are figured with the wheels "pressed", otherwise a "0" toe set without pressing will = toe out, which can be a PIA on the street. I also do my alignment with 3/4 tank of gas.............Ron

RoninLB:
Small correction...
The earlier specs said to aim for zero ( 0) toe "pressed"...meaning a spring-loaded broomstick device to impart a 15-45 lb load between the wheels...just as you suggest.
Later specs...said to be retro'd to the earlier cars, too...would have you set a slight toe-in ( Approx 1/16-1/8")...without pressing, as this accomplishes the same thing under a more conventional basis...

--Wil Ferch

yeah Will.. I knew about that.. when I saw .02 I saw a zero.. I figure 1/8in = 7.5 deg..

I had new tires and an alignement on my 66 and it pulls to the right And I also thought about ajusting the T bars but it would change the ride highth wouldn't it, From the front it would look lopsided, It has improved since I have gotten some ware on the tires, But still pulls some, The car has taken a Hit on the left front but doesn't look all that bad could this be a reason??

John, we had a car with alignment dead on, ride height was perfect, yet this car pulled right, to drive it on the highway you always had to correct left to go straight.

Turned out the corner balance was WAY off... the corner balance was corrected, the alignment rechecked now the car tracks straight as an arrow "no hands"

We double checked the car and there was no apparent collision damage causing the corner to be off, so its still a mystery why tha cars corners were so screwed yup.

Hmmm. Thanks Tim!

ummm.... maybe its time for me to re-check corner balance too.
Had mine done last year, but upgraded the entire suspension & didn't re-do it. Now the car pulls to the right :( I have to keep pulling the steering wheel a bit to the left to compensate.
But then, as a few others ahve asked - if a 200lb passenger doesn't affect the car, then the corner balance must have to be WAY WAY off for a car to pull? Off by >200lb seems very unlikely... any comments / thoughts?

Guys..I had many alignments on my 69 and it always pulled to the right.
I tried everything I could think of.Finally I installed larger torsion bars in the rear and replaced spring plate bushings...now drives perfect and I couldn't be happier about it.

Mine was off by 100lbs and the car pulled a lot. I got it within 7 lbs now it goes dead straight

Close to the end of the brake pads life....one side will tend to pull. Check pad wear.....btdt.

Took the car to DE today, obviously still pulls left, instructor commented on it as well. Also noticed the car would turn a lot better to the right than the left, I drove it and agreed, feels really weird turning left, like it wants to dive in at first, but then understeers, kinda strange and unstable feeling. Turning right is really good, maybe a little oversteer at speed, but maybe normal.
Braking doesn't have any more effect on the pulling left syndrome, does it all the time. If it was a corner balance, and if i balanced the car with ballast for me in it (230), then the instructer (125?) drove it with me in pass side, wouldn't that change things? Does the EXACT same thing.

I'm completely confused on this, I've got an appt (after much arguement) at the alignment shop to have it checked again on weds, I guess we'll see what that brings.

Is there some way I can check it too, or does it really need to be on the rack?

Other than that DE was great, cold miserable misty rain all afternoon, so got some good slipping and sliding in, kinda spooky :eek: :eek:

Clay, you just described a textbook case of corner imbalance. I suspect you'll need to raise the LF and RR to load these corners more. Or drop the RF and LR to achive the same.

Good luck!

Even though moving weight (drivers) around the car doesn't have any effect? and just going straight, no brakes?

Raise as in ride height, or raise the wheel into the wheelwell (lower ride height)?

Raise as in trying to raise that corner of the car.

It doesn't matter what you load into the car. It's like a bar stool that has one leg that's too short. Doesn't matter where you sit on it, the leg is still too short. Same goes for corner balancing.

Listen to Tyson. He is correct, an other alignment without a cornerbalance first will do nothing except lighten your wallet

What do you mean by pull left? Does it pull left while its under braking, or does it pull (drift) to the left when it in a straight line and you remove your hands from the steering wheel? If it pull left under braking it probably the brake, if it drift while it's in a staright line it's probably an alignment. I see that the caster on the left and right are not the same. Caster is critical for a car to track in a stright motion.

Think of a shopping cart with with the front caster for wheels. How many time have you gotten a shopping cart that doesn't go straight? Most of the time one of the wheel isn't any good, or the cart been bang up so much that one of the wheel is out of alignment.

I'd sharpen the focus strongly on two things..
- verify CB is correct , as you suspect.
- verify that caster is indeed the same for both sides...more important than getting it maxed out.

Wil Ferch

Given the caster specs that I listed, is the difference enough to cause the problem?? Assuming CB is correct or within a reasonable amount.

I guess I'm saying double-check the caster and CB that was listed to you earlier. May be cheap insurance to go to another ( or same) alignment shop just to verify the results handed to you earlier, by going on the rack again. This sort of thing happened to me before and drove me nuts until I double-checked at a different alignment shop. Result? The readings *were* different and all of a sudden...explainable as to what was wrong.
--Wil Ferch

Corner Balance
 

The Factory Tollerance is 20 lb. difference from side to side
without drivers weight. Since the car did not pull prior to you
doing the work, I would guess it is the Corner Balance. If you
also replaced tires at the same time the work was done you
could have a radial tire pull. This can be checked by rotating the
tires side to side, on just the front tires. The car sould pull the
other direction or even track straight. Are the tires directional?
Try this anyway to prove it is the Corner Balance. No Alignment
on the planet can correct a bad corner balance.
I don't think I would mess with the ride height adjusment
yourself, any change in ride height will effect the toe adjustment
which will cause rapid tire wear. Check the tires first and if it isn't
a radial tire pull, take it back to your tech and have him recheck
the Corner Balance.
Hope this Helps,
Steve Alarcon

Ahhhh. ..the famous Steve Alarcan....Todd Serota's favorite alignment guy ( Todd..of TrackQuest school..DE... fame..on Rennlist).

I'd listen to Steve....

--Wil Ferch

well - I'm having my CB checked this weekend... Hpefully that would get rid of my right drift problem.

A question for the experts - if I am doing CB myself, I need to get my alignment re-done/checked at the end. Is that correct?

thanks...

Well, as stated before, I replaced the torsion bars, did the corner balance myself, with drivers weight, got within 4 lbs according to my Ruggles scales (accuracy?) and then had it aligned (with drivers weight). Now I've got the pull and strange handling, not just on braking, all the time. It did not pull before the torsion bar change, or alignment even. No new tires, and they are directional. I'll put it on the scales again to double check, I'm still planning on getting it on the rack again, just to make sure.... Should I insist that the camber numbers are exact?? How much is too much off?

Anyone know of a good alignement/corner balance shop in the Lincoln/Omaha area????

Corner Balance
 

When the Corner Balance is done with the drivers weight in the
car the weight will not be within the factory tolarance of 20 lb.
The corner balance should be done on a ratio of the weight.
A good book on this is HOW TO MAKE YOUR CAR HANDLE by
Fred Phun. This book will explain what is commonly done by
the computer on digial corner balance scales. You need to find
someone in your area to put your car on this type of scales. They
will push the cross-weight button and the number you want to
see is 50% with the drivers weight and the car perfectly level.

Good luck!
Steve Alarcon

Did anyone happen to notice how far out of spec his alignment numbers were or are they totally meaningless? According to my spec book, an 80 SC is normally set at +0.5* camber in front and 0.0* camber rear.

If I took my car in to have aligned, I would insist on having it done as close to factory spec as possible or else accept whatever dubious handling that may result.

Why not have it aligned all over again and this time have it done by the book?

Joe

I asked for some common street track alignment specs here. The majority of the responses I got was -1.0 front and -1.5 rear, max but equal caster.

I used the corner balance calculator here http://vintagebus.com/cgi-bin/balance.cgi to figure my corner balances. However, when playing with my older Ruggles scales tonight, I noticed a fairly serious discrepancy in the accuracy. If I would stand on one scale, it would read 240, then to another 218, then another 223, and another at 238. Hmmmm, using 4x multiplier for the rear....makes accuracy out the window. Anyone ever tried using different scales other than the Ruggles ones? Looks like an ordinary bathroom scale to me.

Even so, I still have a really hard time believing the corner balance is causing all of my problems....the car was lowered by the PO, when I spoke to him about it, he said he just crawled under the car and adjusted the fronts down, and lowered the rear spring plates as low as they'd go, didn't balance the car at all, only had a basic alignment done, cost him 50 bucks. Car drove perfectly straight. Even when I got done with the torsion bars and test drove it un-aligned, unbalanced, it drove straight, didn't pull. Only thing I did was take it to the alignment shop and now it pulls.......????

Once again, how important is that caster number, how close is close enough?

It takes a large difference in caster to cause a pull. When aligning a car, we were taught in Tech school to build in a slight pull to the left to compensate for road crown. You'd make the left camber .2 degrees more positive than the right, or, the left caste .4 degrees less positive than the right to achive the road crown compensation.

It takes about .5 to 1.0 degrees caster difference left to right to cause a noticeable pull, but depends greatly on car, tires and other variables.

Clay,
You or the shop should have road tested it before giving them the thumbs up. It's probably been too long since you had it done to go back and say do it again (gratis). I'd suggest talking to them and see what they can do for you. If they're reputable, they should work with you on this.

However, if your corner balance equipment is off, this could explain the car's abnormal handling symptoms.

Sherwood Lee
http://members.rennlist.org/911pcars

Yeah, I called them the same day I had it aligned, I noticed it on the way home. They road tested it, but just around the block, in traffic?!?! I called them immediately and that's when they argued with me that it wasn't the alignment, maybe it's not, but after another call I finally convinced them to at least put it on the rack again and double check it. Got to have it there by 8am tomorrow, we'll see what that turns up, if anything. I'd at least like to know for sure, I know I'll have to have it redone if my CB is off too. Oh well.