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Discussion Starter #1
New tires so I got he car aligned. No drivability problems but after 25k mi on old tires the FR inside had some wear

Shop had the Hunter system. The mechanic first test drove my car. I said the steering wheel was "slightly" to the R and the RF was worn on the inside. About a hr later the Mechanic pulls car off rack and test drive. Comes in to tell me all was fine with suspension, nothing was horribly off.

But he said he did adjust the steering to take out the minor "play" with a very minor adjustment to the box.

It had been several years since last alignment and with 131k mi now I had forgotten how it felt when....well lets just say when the car was much younger. Car drives straight, steering wheel is dead center and no dead spot or slop (not that there was much at all but tighter now)

B/A on alignment
 

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this is the OEM GM alignment spec from the shop manual
GM service manual the alignment specs are 0 camber +/- 1.5 deg , caster left 3.25 right 3.75 +/- 1 deg ,, on the toe .16 deg total .

your total toe is .01 IMO too little so a wandering Impala.
Camber is OK also caster is good.

your old toe was wrong tires pointing out not in , so the tire wear will be on the inner tread .also I would suspect a lot of wandering and you working hard to keep the vehicle going straight down road. when the front springs sag the toe will do this ..the pass front spring does sag more than the driver side .. check the height see if the front is close on each side like with in 1/2 in..
 

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Discussion Starter #3
jcat

the Toe is set closer to the 0.00 +/- 0.00 per the "adjusted" alignment settings IIRC "Scribner" (? spelling) specs posted several times for the Hunter system. Basically a tighter alignment than the broader range of the published stock setting.

Car does not "wonder" on road and drives straight

Front spring height is within 1/16" with the R side being about 1/16" higher (read barely 1/16"). Not surprising since 85% of the car use is single driver occupancy

Over the course of 9 years when the last set of tires were put on and aligned the R Toe became off more than the other settings. All my tires have been "directional" so rotation was always F-B-F and the R front tread wear showed this as a result. Not much difference on inner tire wear but certainly visible after 25 k mi. I would have likely been able to get 30k mi if I had done an alignment within the 9 year tire life cycle.

Over 9 years and 25k mi obviously these changes were not felt progressing (like watching grass grow) but certainly an improved drive feel noticed once alignment was done AND the very slight tweak of the steering box screw

Of course....YMMV
 

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have the shop adjust the toe to the GM spec . you will see the difference.

with no toe the box gears will wear out since vehicle will wander .

my tires last about 35K miles and when they are replaced the tread is evenly worn . 30% left .. the last set of tires had tread separation all of the tires comp ta BFG.. side walls like new .. looked it up defective manufacturing .. then no tire replacements so I got my $$$ back .. shop put on my new Kumo tires free + balancing ..

air pressure fronts 35 psi rear 27 psi.. this is since nov 1995..

my Impala has never been to an alignment shop LOL............. I do it.. last time I did it was 10 plus years ago..

Kumo tires ride nicer but less traction, very easy to do burn outs with a little throttle .

car still has a lot of balls ..quick ..no hesitation ..

my 2016 toyota truck has the rack steering extremely tight ... the toyota spec is with a slight toe spec less than the impala. I had issues with it as it would wander on hywy roads paved not all that good so I increased the toe .. love it .. goes straight and holds steady on poor pavement .. tires look good even wear used a gauge to check .
 

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Discussion Starter #5
appreciate your comments jcat...but unless I find the car does "wonder", it does not now, I will leave alignment as is. I also defer to the tire pressure of 30 psi as stated on door label. That has worked well for the 20+ years regardless of tire brand that I have had the car.

There have been several threads on this and other Impala forums (GRAIL) posting "improved" alignment specs vs GM's published ones. They basically are "within" the same ones as published...just not as much +/- tolerance.

If I do find these particular settings pose drivability or tire wear issues I will have shop re-visit the alignment

Of the 3 tire brands I have had previous to these Nittos (BFG, Bridgestone Potenza, KUMO) the Kumo was my least favorite in terms of traction and tire wear. I have no problem spinning tires and the Kumos were more prone to that than the others. Have not driven the Nittos enough to form an opinion vs the other brands yet. With that said, just like NASCAR throwing on new tires after 20 laps, these "new" tires certainly appear to have more grip that my old worn Kumos...as any new tire should.

As far as 1/4 mi, I run a MT ET Street on a custom 15" rim....:)
 

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The adjustment to the box may not have done anything. The correct adjustment starts with the Torrington bearing at the input shaft, and then adjusting the screw on the top of the box. I believe the Torrington bearing causes more slop than the gear mesh adjustment.
 

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Diggin the rear camber ;)

Personal experience from doing WAs for a LONG time, and tearing down a lot of steering boxes , the sector adjustment seems to be out more than the input thrust bearings ,

Good to see some shops will still address adjustment as part of the job when readily accessible
 

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I like a little "push" from the camber to make the car go straight on crowned roads. I usually have around "0" on the left, and -.25 deg. on the right. Since most roads are crowned, it makes about 90% of the driving have no steering input. You can get similar results with caster if you would rather go that way. The stock caster specs give you push for crown roads, but if you have less on the right, it can make you turn left all of the time. That will cause odd tire wear (left inside, and right outside).
 

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the reason I did this tire pressure change from the door panel PSI is the rear tires would wear more in the middle of tire so 27 PSI. has worked now 20 yrs .. using a measuring of it very even. the fronts I found needed 35 PSI .. Vehicle roll much better very even wear across the complete tread , no issues ..The trunk is empty so no load ..that might be the reason I have had this problem .. If I put 200lbs of sand in the trunk my guess better traction and 30 psi would work.

the Kumo tires have a harder rubber then the BFG . the tread design does create better traction in rain , but when the rear wheels get a little extra power they will spin . If I had 30 PSI. probably spin more ...
I rotate the tires X every 10K miles approx sometimes 8K... cannot tell front from rear all the same ..my truck 2000 silverado 4X4 10-13K tire rotation 50PSI front 43psi rear .. same effect as Impala , tires all same , perfect wear ..I get 80-90K on the truck tire sets.
 

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The stock caster specs give you push for crown roads, but if you have less on the right, it can make you turn left all of the time. .
I assume this is a typo ??

Car will go towards the lower Caster

Towards the higher Camber
 
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