OK, today I did put up the front of the car and pulled off a wheel, and take lots of big, full-page, high-resolution pictures of the Azera's front suspension. I'll share observations inline with the pics.

First observation: the lug nuts.




When I took off both wheels, the lug nuts were all completely different torques. And by different, I mean VERY different. Some were seriously overtorqued and some were little more than finger-tight. Thor has had ever-so-slight a balance problem at highway speed since new. After re-installing the wheels I took him out on the highway and he's sound as a pound, smooth as silk at all speeds (up to 90... *ahem*). Uneven torque on the lug nuts can lead to very bad things, especially on alloys, where they can lead to warped wheels, and in all cases, warped brake rotors. The important lesson is, go out, loosen the lug nuts a quarter-turn, then re-tighten to at least close torque. I have torque wrenches and tightened the lugs to exactly 100 ft-lbs. Based on the force required to loosen, I'd guess 2 or 3 on each wheel were tightened to around 130-150 and others were around 50-60. This is WELL worth doing for those of you who, like me, still have effectively brand-new cars and have not replaced brakes or tires yet. (It may be worth checking for the rest of you - even well-meaning mechanics can be somewhat sloppy with an air impact wrench.)

Next observation is that there IS an anti-sway bar, pictured in these:




It's a very heavy one, I'd guess somewhere around of 30mm (I did not bring out my calipers for this). It runs under the car, behind the transmission housing, but the size of this anti-sway bar indicates that Hyundai saw the need to rein in some serious lateral lean.

The next observation regards the steering knuckle, control arms, etc., and this has to do with the "wallow" and POSSIBLY (but not necessarily) the clatter over bad road:



My car DOES apparently have the 040s.





So here's a bunch of shots of the suspension, and I suspect at the end of the day, this is the enemy for lateral lean:



That long, goofy, swan-necked steering knuckle attached to a flimsy upper control arm.

The lower control arm, pictured well in these:




Is a solid wishbone with two-point connection at the inside edge, the lower ball joint for the steering knuckle at the outer edge, standard stuff. The upper control arm, pictured here:



Is a flimsy horseshoe-shaped thing with the upper ball joint mounted off-center.

I am not an engineer or an expert, but the distance between the upper and lower ball joint is incredible, something on the order of 18". The problem is, the wheel bearings and CV joint are housed in the steering knuckle, as well as the brakes. So effectively the wheel, and the entire frame, has an extremely easy time "wallowing" and nothing resists it because the upper and lower ball joints are so far apart; the control arms do nothing to keep the wheel geometry consistent with the body. They just bend without resistance and that far-away, goofy upper control arm does next to nothing to prevent the frame of the car from leaning along a lateral axis relative to the geometry of the steering knuckle (and wheel).

The springs are VERY skinny. Heavier springs alone may make a serious difference in the car's nosedive and other "too soft" suspension characteristics.

This also may be insignificant, but the anti-sway bar tie rod on the Jags is fixed directly to the lower wishbone. The bushings between the "lifter" and the lower control arm may serve to dampen some of the potency of the anti-sway bar.

On the Jags, there is a similar (though larger & heavier) lower wishbone control arm and upper independent dog bone arms that connect to the upper ball joint via pass-through bolts. These are much heavier than the Azera's upper control arm and have much heavier bushings. Additionally, the upper and lower ball joints on the Jags are maybe 10" apart (vertically). I know there has to be some extra clearance for the CV joint on a front-wheel drive car but this is ridiculous.

I'm still not sure about the rattle but I'll hear it soon enough, I'm sure. I only drove Thor 91 miles in May, and 30 of those were the highway-speed balance test I ran out today, so it may be a bit before I hear what you guys hear. The only thing I'd be suspicious of is how well the bottom of the shock seats in that wishbone spacer over the prop shaft and CV joint. Like cheap desk chairs, if the barrel isn't INCREDIBLY closely-matched, any lateral motion or jar while the thing is under pressure and it'll "pop", while the barrel of the shock re-seats itself. If that wishbone lifter is bored out even a half of a MM wider than the barrel of the shock it would probably make some noise. On the Jags, the shocks AND springs are seated directly on the lower control arm, which is not possible on a FWD car. I assume Hyundai engineers meant for this setup to be pretty tight and noiseless.

Now I'd be interested to hear from snaglepus or somebody else who actually knows what they're talking about... what do you think of this suspension setup?

Cheers all!

-Andy

This post has been edited by andyman32: May 31 2008, 07:46 PM

This post has been edited by andyman32: May 31 2008, 07:58 PM

Great stuff Andy!!! :clap:

Thanks for taking the time. I wish I knew enough about how these things work to make more sense of it all.

Il n'est rien... there's a good chance that all of my conclusions are absolute nonsense. At least the photographs are accurate. I have SUPER high-res (8MP) pics if anyone wants them. I'm guessing the dampened work of the sway bar via the "lifter" bushings in the lower control arm are partially to blame - on the Jags, the sway bar tie rod is bolted directly on to the lower control arm.

When the wheels lean, they "twist" the sway bar. One wheel tugs down on the tie rod and the other pushes up. So the torsional (twisting) strength of the sway bar applies counterforce to keep the wheels righted - actually, to keep the control arms level. The thickness of the sway bar directly impacts how much counterforce is applied. Since this effect is softened via the "lifter" (I wish I knew what that thing is actually called) bushings in the lower control arms on both sides, and since the upper & lower control arms are so far apart, the design seems to allow for almost no resistance to leaning.

I wish I had paid more attention to the Regal, Taurus and S70 when I was doing brakes - what I really don't know is how much of this is just standard front-wheel-drive stuff. It makes sense that the "lifter" on the bottom of the shock should be dead-center with the axis of the wheel but I don't think it should be that tall... unless I'm completely off base comprehending the suspension (high probability). Most of the severely limited comprehension of suspension geometry I have gained in the last 9 years has been on rear-wheel-drive cars. I'm going entirely on intuition here.


This post has been edited by andyman32: Jun 1 2008, 07:43 AM

Thanks for the great dissertation. Jaguar has had many problems through the years, but suspension has not been one of them. May I suggest trying at a really great engineering school........at,of course, IOWA STATE,AMES? You may, or may not ,be right in your conclusions on Azera's suspension, but it's food for thought.

Great job Andy and thank you :excl:

This front wheel drive is not like any I've seen. All struts on my FWDs are connected from the top fender directly to the axle hub… no rubber bushings to wear. Also there are NO upper control arms. The bottom part of the strut which is connected to the axle hub has a plate where the spring sits. As the axle rises it pushes on the spring. The struts in these cars have to be strong because they are essentially the ONLY connection from the wheels to the body (suspension wise). The sway bars are connected directly to the lower part of the strut.

Hyundai’s approach of connecting the axle to the car is thru the “lifter”, strut, upper control arm and that ridiculous “goose neck” thingy. To compound the situation the “lifter” is connected to the lower control arm thru bushings and ball joints, introducing flexing into a system that should be rigid.

It is self evident as the bushings wear so will the suspensions performance, ride, stability and wallowing. The sway bar is connected thru the “lifter” and not connected directly to the strut. Because of all the bushing and ball joints and extra control arm people in the north in snow and salt areas will be affected the most… like me!

All these “extra” parts with no direct solidly bolted connection from the axle to the car explains why this suspension wallows and hard riding on rough roads. It can also be seen why there is so much lateral and front to rear swaying. There are so many parts involved there’s no way you can expect much compliance on rough roads.

I can understand why they went this route to an extent? It's stong point is a soft ride over smooth to moderate roads because of the aforementioned bushings and the "extra" interconnecting flexing components which help absorb the bumps... and we all know the weak spots.

The only savings I see is you can have cheaper struts because they are not the main and only support structure as in most FWD cars with McPherson suspension. The “engineering” (if you want to call it that) appears to have been done right after they came back from their New Years Eve Party. What's really confusing it's probably more expensive also?

I'd take a deep breath before going out and install aftermarket struts if and when they become available... and why nobody has come out with aftermarket improvements. The design of this suspension handycaps the ability to improve on it... like putting lipstick on a pig. Perhaps, I say perhaps the newer struts maybe the best you can ever get to improve the system and why there is nothing more Hyundai can do... their locked into the design. This is my first Hyundai, I wonder if they use this in any other car in the line?

I'd stay with the existing OEM struts from Hyundai and replace them and the rubber bushings if and when they wear out.

Again great job with the pix… sheds a lot of light on the issue.

This post has been edited by raw6464: Jun 1 2008, 06:10 AM

Another few minor points now that I'm reading over the hmaservice shop manuals:

1)

Another "cost" of the dual-wishbone suspension layout (even an awkward one like this) is that the camber is not adjustable on this suspension. Same as the Jags. My Vanden Plas does have negative camber on the front driver's side wheel that is just BARELY out of spec. Probably a cumulative effect of a few hard potholes and sagging bushings on a heavy car. The only solution is to start renewing bushings all around, particularly upper control arm bushings (with negative camber). It is also probably due for new ball joints.

When, as Russ said, the strut tower connects directly from the lower control arm to the frame, installing a "camber kit" that shifts the position of the assembly relative to the frame will adjust the camber. In this case, there is nothing that can adjust the vertical alignment of the hub / steering knuckle. hmaservice.com says: "Camber is pre-set at the factory and doesn't need to be adjusted. If the camber is not within the standard value, replace the bent or damaged parts." Good for the first 10 years... not as good after that. :(

2)

The lug nut torque spec is 65.1 - 79.5 ft-lbs (90 - 110 Nm). So I overtorqued them upon re-installation (100 ft-lbs), but this also means that the few on both wheels were EXTREMELY over-tightened from the factory. I re-iterate that it's worth it to go loosen the lugs and even just "rough" it if you don't have a torque wrench, make them close by hand. Obviously my lugs were put on by a guy (or gal!) who was at the end of his shift and not paying a whole lot of attention to what he was doing. :whistling: I expect to find the same on my wife's car.

Cheers all! :beer:

Follow-up: Both cars had lugs way, way out of spec. Mine was worse. I just evened out the torque on the lugs on the rear wheels. On both sides of the rear wheels, 4 out of 5 lugs were so tight I had some trouble loosening them with a 24" breaker bar. I'd guess all of 150 ft-lbs, possibly more. The overtorqued lugs on my wife's car (3-4 on each wheel) were not quite that tight, felt like in the low-100s. They did pop the torque wrench at 80ft-lbs (setting for re-tightening) and still required quite a bit of extra force to loosen.

Andyman32. Like others, very nice job. This may explain a couple of things, 1) Why replacing the struts did not ultimately resolve the problem if it is a design issue. 2) Why, if other parts are worn and are not replaced, that after a while the problem comes back sooner for those who have the TSB performed. 3) Why, depending on our road conditions, some do not see nearly the problem that others see. 4)Why Hyundai says it is operating with in design specs. 5) Why there will probably be no fix for current models, too extensive of a repair/replacement unless it becomes a safety issue. I am sure there are more. Others feel free to chime in. A course, if those with huge amount of knowledge about this subject come back and give us their thoughts and tell us that all of that you mentioned in design is not unusual then my suppositions would be false.
It would be interesting to see what made the '08 different, since Hyundai made a point in their ads to mention a suspension change. It would be interesting for those with '06 and '07 models built during the TSB time frame to see what is different with their's since the TSB only addresssed the Struts and if memory serves the -040 were the cause and you and probably me have the -040 since mine was also built in April '07. Are there other makes/models that use a similiar suspension setup? Hard to think that Hyundai just came up with something so unique and only on the Azera. Doesn't the Veracruz use the same frame/chassis or however it is identified as, as the Azera? Just curious. Again thanks for going through this effort.

The 041 strut was the standard and the TSB called for replacing it with the 040. On my 07, it did improve for a while, but the wallowing has returned. Will be interesting to see what the Regional Service Manager says after he drives it sometime late this month.
I excerpted the relevant text from above and will give it to the RSM. He can take his own pictures!
I drove an 08 and could not tell the difference.
Even if it is a design problem, it seems Hyundai could bite the bullet and replace the components with something that works, especially as they are now trying to sell themselves as a "quality" manufacturer.

This post has been edited by Carolina Bob: Jun 1 2008, 12:55 PM

Mahout has a lot of experience with the Azera suspension and in this thread (posts #s 7 & 9) Iwork4Hyundai alluded to the shocks being the problem but he doesn't elaborate and he hasn't posted since 9/06. It would be really cool to have a practicing Hyundai tech chime in.

I would venture to say the shocks contribute to the wallowing... the inability to dampen the spring rebounding. However the wallowing I believe is "built into" the design of the suspension. The shocks have nothing to do with the lateral and axial swaying that can be induced with the car standing still.

There are just too many "flexible" UNSPRUNG parts from the top of the fender to the axle hub as integral part of the system. The strut is connected to the lower control arm with a rubber bushing. This means the play in the bushing has to be taken up before the shock even knows what's happening... in both directions.

The bushings are probably there as a compromise to the hard riding characteristics of the system… again partly from design and party from unsprung weight… a strong argument can be made placing the hard ride hard on all that unsprung weight. All that mass below the spring gets driven up hard and the shock can’t handle it. “Conventional” McPherson systems don’t have: the strut to control arm wishbone, the upper control arm, and the long bar connecting the lower to the upper control arm with all the connecting hardware. And they all add flex to the system.

I don’t see Hyundai redesigning this system to fix the existing complaints... it is what it is. To engineer and manufacture a redesigned replacement suspension is WAYYYY to costly.


EDIT: FYI browsing thru they Hyundai service site, Hyundai uses same Azera design type of suspension on some cars but not all. The Sonata is one, but the Tuscon and the Elantra are not.




This post has been edited by raw6464: Jun 1 2008, 04:35 PM

Thanks for the break down.
What about after market coilover sets. Are they worth considering?

They will help with the suspension compression characteristics, but the only ones we know about so far lower the car, and I would not wish all of those alignment issues on anyone, especially on a car like this with a voided 5-year warranty that may yet include a solution to the lateral leaning, which would probably not be covered with aftermarket shocks. (Wait until 5 year + 1 day to put them in, at least!)

Aftermarket shocks & springs will NOT help this setup with the leaning ("wallowing").

The only thing I could imagine that might help would be to put an even thicker anti-sway bar in; attach its tie rods directly to the lower control arm; and since the entire assembly is so tall, maybe install a second one that attaches to the UPPER control arms.

Now actually I'm really curious to see the suspension of a tall, plush-riding, high-quality, front-wheel-drive luxury car that DOESN'T have nose-dive, rattling or swaying... you got it, an ES. I think I will hunt on the web for pics tonight.

Andy,
I agree whole heartily to your recommendation to campoly. Making after market alterations to the suspension (or anything else you can't take off) is a "get out of jail, free pass" to the dealers to deny and void your warranty. How far a dealer will invoke this claim is mutually inclusive to their business ethics.

Making aftermarket changes to the suspension on this very contentious issue can and will be used against you when going back to the dealer.

I have an 06 ES with 25K miles... it does nose dive on hard braking and lean in hard turns, done so from delivery and has not gotten any worse... but it is significantly less than the Azera. It is a soft riding car made for the demographic market for most luxury cars buyers. To be honest it is bland driving (but comfortable) experience. It is not for the G force junkies.

I've went the BMW route twice... great handling cars with junk hardware and switches... every car has it's strong and weak points, they where the MOST troubling cars I've every owned.

I have to say as a new Azera owner this forum and threads like this has been very informative in understanding the suspension issue… your pix shed a lot of light on it. Although I would have preferred a Lexus type ride, the Azera is what it is... a very good car for the money. All things being equal and it doesn’t turn out to be a lemon I’ll keep it for 5 years. And I’ll think of the $10K I saved every time it wallows.

Ciao,
Russ

Yep. I also have a better understanding now thanks to you and Andy and Bazzel's link to the Hyundai video interview which was very insightful and really to all who have engaged here. I feel like we've come to the bottom of this.

When I bought this car I was looking for a quiet comfortable car that I and my family could take short trips in. I didn't expect a BMW or Audi like curve carving driving experience for the price that I paid but I did get a quiet comfortable car with very nice extras for not so much money (and a great sound system, btw). Yes, the suspension could have been much better but I really do like everything else about the car.

I now think:

A. The Azera suspension "is what it is" and was apparently designed with the Korean market in mind where they seem to like the sensation of floating in a boat on choppy water while riding around the streets of Seoul and not trying to drink anything out of an open cup. :D

B. It would not be prudent to modify it due to the warranty issues.

C. I will just have to make sure my driving habits are appropriate for the suspension such as it is.

D. I will continue to enjoy the car for it's many other merits for at least 4 more years and I will stop whining and complaining about the suspension because I now know "what" and "why" and my mind is now at ease with it.

Thanks all! :beer:

Now, is anybody up for a chorus of "Kumbaya" :gitara:

Thanks CarolinaBob for the correction regarding the strut number. I wonder if that was the "improvement" in suspension that Hyundai was referring to when they said the '08s got improved suspension and those of us with late '07 builds got that added. Right now the suspension is still tight with 6k miles on it, bounce test is good, so will monitor, and as I said before the roads we travel on we don't see any of the problems for now. And considering everything else we got with the car, and no car being perfect, and the price we paid we will deal with it as long as no major mechanical problems pop up.

Good luck with your Azera and lets hope t