Front wheels stick out unevenly

[cidsamuth]

Hello,

Just installed the Pedders coilover kit and BMR 5-way adjustable front sway bar on my 2008 GT. Also did a bunch of BMR stuff in the back, but I don't think that will matter here.

As you can see, the car got aligned really well. But, it is clear to me the driver's side wheel is tucked in more than the right side. Is this going to be a tolerance stack issue with the stock A-arms, K-member, fenders, etc, or is there some adjustments that I can have the alignment shop do?

Far as I know, the car has never been wrecked. I wish it could be handled as easily as the back with the adjustable panhard.

 

[Norm Peterson]

Sheetmetal tolerances alone could probably account for that much - it really doesn't look that bad.

I do have to ask why the camber settings are set so low (-0.5°-ish), which is definitely on the low side of factory preferred (-0.75°). Unless drag racing is a high priority and you're running skinnies up front, or the car sees only gentle highway driving you'd be better off with somewhat more negative camber settings. Like -1.0° or so even if you don't drive through the corners all that hard. It might even mask the unevenness in visual "tuck" you mention at least a little. Strut suspensions typically need cambers to be set more negative than conventional short-long arm independent suspensions.


Norm

 

[biminiLX]

Can almost see the example in Norm sig pic
-J

 

[cidsamuth]

I had told them to stay around .5 on camber because I knew that was within tolerance AND I don’t like the look that comes with higher camber (ie wheel lean).

I love how the right side looks - even with the fender. I don’t like the “tucked” look of the drivers side as much .... and more camber does tend to create that tucked look.

 

[Norm Peterson]

Can almost see the example in Norm sig pic
-J

Depending on where the car is sitting in the driveway, it's at or just a tiny bit less than -2°. That's well outside the factory range of -1.5° "max negative", but the car is pretty much a dedicated corner-carver and sees road course time.

Meaning that the appearance is driven by the desired function and actually looks "right" for the way the car gets driven (engineers tend to think like that). Tread wear is closer to even than most people would guess.

Norm

 

[HISSMAN]

Why would you not want your car to handle better?

 

[cidsamuth]

Come on now .... it handles great. It’s not like -.5 and -.6 is out of spec.

Norm — regardless to camber, can you take a look at yours and see if one wheel protrudes slightly more than the other?

 

[Norm Peterson]

Quick and dirty measurement using a level and a 6" scale - the passenger side front wheel sticks out right around 1/8" more than the driver side front wheel. About 9/16" vs ~7/16" referenced to the wheel flange and the bottom of the fender.


Norm

 

[cidsamuth]

Thanks, Norm. Eye balling it, I think mine is about 3/16” difference.

 

[Norm Peterson]

Come on now .... it handles great. It’s not like -.5 and -.6 is out of spec.

But it almost certainly understeers a bit more than necessary and a tiny bit more than Ford apparently intended as their design target. Noticeably mainly if/when you start approaching the car's cornering limits like you would at autocross or an HPDE track day. Some people notice this sooner (lower cornering g's) than others.


Norm

 

[cidsamuth]

Maybe .... but with the lowering springs/shocks, huge front sway bar, and all the back end improvements (adjustable UCA, adjustable LCAs, panhard, panhard brace, BMR rear sway, and relocation brackets) .... combined with the KB supercharger, it does not understeer when trucking down my local backroads.

Instead, if I get into the throttle too soon exiting, the rear end will still break free. The front end absolutely hooks and I end up steering through the corner with the throttle a little.

As you know, there are a number of factors .... camber, front sway setting, relocation bracket setting, and tire size/quality. But, with current use, I do not feel the car understeers and I’m pleased with it.

I can always double back to camber later when I play with the other settings.

 

[cidsamuth]

I measured and confirmed tucks in about 3/16” more on the left (more flush on the right). Can anyone else measure for me and let me know if they see differences from side to side?

 

[Norm Peterson]

Maybe .... but with the lowering springs/shocks, huge front sway bar, and all the back end improvements (adjustable UCA, adjustable LCAs, panhard, panhard brace, BMR rear sway, and relocation brackets) .... combined with the KB supercharger, it does not understeer when trucking down my local backroads.

With that much power, a little more understeer than Ford built into their normal GT is probably a good thing.

At street driving levels of performance/"enthusiasm", understeer isn't always easy or even possible for most people to identify unless it's truly heavy.


Norm

 

[cidsamuth]

Nevermind, guys, I figured it out.

Measuring the difference more accurately with a string, it is 1/4". On a whim, I put a straight edge on the rims and an digital angle finder . . . the left/front, which is the one tucked more, has changed to -1% from the -.5% you see in the alignment printout. Best I can figure, the camber bolt moved after I left the shop yesterday morning. Moving the angle finder by hand back to -.5% gives me almost exactly the 1/4" difference that was bothering me.

The right side is still at the listed -.6%. Ironically, the one that moved went to something closer to what Norm was recommending, while I very much prefer the look of the right wheel.

I assume either the tech didn't get the bolt torqued to the recommended 97 ft/lbs, or perhaps 97 ain't quite enough.

 

[Norm Peterson]

That's one of the reasons I don't like aftermarket "camber bolts". You can't tighten them to full OE strut to knuckle fastener torque. This torque was originally 148 ft*lbs on coarse-thread fasteners, but following a few knuckle failures that traced back to insufficient clamp load by these fasteners a running production change was made to fine-thread bolts and (IIRC) 166 ft*lbs installation torque.

Ford has their own version of camber bolt that is full-strength, but it requires some grinding of the strut bolt holes. The procedure is in the shop manual.


Norm

 

[cidsamuth]

Yea, I gotcha. But, I can't assume the tech didn't error either in how it was torqued. I'll give it another try and look to the beefier Ford versions if it happens again.

 

[Norm Peterson]

Be careful . . .


Norm

 

[cidsamuth]

So, I took it back in today, and I’m even more confused.

They put it back on the rack and hooked the heads up. They pulled me out to the bay and showed me both sides were at -.7% — the camber bolts had not moved. That was slightly different than last week’s readings, but within normal variances.

I pointed out that very clearly the left wheel was tucked more, to which they said that was normal manufacturing variances. I then noted that I could clearly see by eye that the left was cambered more. They said the alignment rack was a $90k piece of machinery that was just calibrated Tuesday, and the lasers don’t lie.

After a bunch of back and forth, I ended up having them put the right at a slightly more camber (-.9%) to compensate for what I was seeing visually. The left, which is tucked more, was kept at -.7%. I don’t think that small a difference will matter for street driving, and it mitigated a little what I was seeing.

With weight back on the car, I can still put my level on the rims and clearly see more camber in the left than the right, despite the machine saying it should be the opposite. It’s only a small amount, but still the opposite of what it should be.

I am beginning to wonder if this is a weight bias issue, combined with some tolerance stack that has the k-member slightly to the right anyway.

Note, I have the coil overs adjusted so that each side is EXACTLY 26 5/8” ground to fender, so it’s not a height issue. Also, the preload on the springs is adjusted the same on each side (5mm).

 

[Norm Peterson]

I pointed out that very clearly the left wheel was tucked more, to which they said that was normal manufacturing variances. I then noted that I could clearly see by eye that the left was cambered more. They said the alignment rack was a $90k piece of machinery that was just calibrated Tuesday, and the lasers don’t lie.

It's also at the mercy of the tech who set the targets up on the wheels. Do not assume perfection, or even perfect repeatability to imperfect setup, here.

On the other hand "eyeballing" cambers is subject to its own sources of error - it kind of depends on what you're looking at and what you may be subliminally seeing in the background. Just this difference in "tuck" or whatever could be at play here. Keep in mind that I'm having to see all of this with a "mind's eye" because I wasn't there.

After a bunch of back and forth, I ended up having them put the right at a slightly more camber (-.9%) to compensate for what I was seeing visually. The left, which is tucked more, was kept at -.7%. I don’t think that small a difference will matter for street driving,

It shouldn't, and having the right side tire intentionally set at a slightly more negative amount of camber than the left side tire is commonly done anyway (this - it's termed "cross-camber" - helps keep the car from running downhill toward the gutter on roads that are 'crowned' for drainage reasons).

With weight back on the car, I can still put my level on the rims and clearly see more camber in the left than the right, despite the machine saying it should be the opposite. It’s only a small amount, but still the opposite of what it should be.

Are you measuring this while the car is up on the alignment rack, or later in some other location? If it's somewhere else, have you carefully measured your setup area for levelness (at least side to side)? And either made it level somehow or accounted for it with a little math?

As an example, my driveway is pretty close to level, being only about 1/16" out of level in 60" or so width (about one Mustang track width). That means if I was to measure the right and left side cambers to both be, let's say -1°, that what I've really got would be -0.94° on the "high side" wheel and -1.06° on the low side wheel. That's over a tenth of a degree on what's a very good surface for being a residential driveway.

Something like that can also happen if your front tires are not evenly worn, or are unequally inflated. What if there's a little of all three effects going on . . .

Note, I have the coil overs adjusted so that each side is EXACTLY 26 5/8” ground to fender, so it’s not a height issue. Also, the preload on the springs is adjusted the same on each side (5mm).

This is also affected by sheetmetal and overall build tolerances. I wouldn't trust this to be any closer than 1/8", not counting any tire difference-caused errors.


Mustangs are series-produced production line cars, not a small run of "one-offs" built on precision chassis jigs. My point here being that it's not worth trying to be this anal about getting these things "perfect". You'll drive yourself nuts, or at least to drink, first. Might be better off getting the fenders gently reworked to even up the "tucks" once you've decided on camber settings.


Norm

 

[cidsamuth]

Norm, so that you don't think I'm crazy, check this out.

I bought a crappy little camber gauge. Doesn't matter if it is accurate, as long as it is consistent (it is). On the first picture, I "zeroed" it out as a baseline on the right front wheel. That is the wheel they set at -.9 degrees.

The second picture shows the left wheel in relation. That left wheel, which I argued I could SEE WITH MY EYES MORE NEGATIVE CAMBER, they set at -.7 degrees. If their alignment rack was right, it should show less negative camber. Instead, it shows .5 more negative camber.

-.5 more might not be exactly accurate. Point here, there is far more negative camber in that left front wheel, and there should be less according to their machine.