holografique

Is it possible for a new suspension system to take some time to "settle" in? Particularly in the case of the RLX suspension TSB?

RLX-Sport Hybrid

I would guess not.

I did experience something I did not expect today. I was attempting to merge into traffic going up hill on a salt covered by dry surface. I gunned it hard and around 30 mph the front wheels lost traction and there was wheel hop in the front suspension! I backed off immediately, but wow! To lose traction on dry pavement going up hill? That is serious power. Now I wonder if that was a road angle, surface issue, tire issue (new tires), or just simple massive torque delivery.

What do you think?

mgalbr22

"Settling in" meaning you had your front struts replaced and you still have the same clunk and rattle? If so, that is precisely my experience.

George Knighton

Not really, not in this day and age.

You want a damper to feel basically the same way out of the box and up to the point you would think about replacing it.

I'm afraid to ask why you're asking this.

George Knighton

When they perform the TSB, are they replacing top hats or just the dampers?

KenRLX

I recollect that the TSB includes a spring/damper assembly.


I would actually expect a very slight 'settling in' as the damper piston seals tend to conform to the cylinder and the friction drops a bit. But I would not think the damper piston or body valves popping open and closed would get any quieter.


(Then, at the other end of the life curve, the piston seals fail, the oil leaks, and they 'settle in' to a very non-damping mode- ;-)


So ride 'stiffness' might, might get a bit less with some break in miles.


Regarding rattles, as I posted before, the damper TSB helped a lot, but still did not fully stop the rattles on all surfaces. So, I am currently trying some non-invasive shade tree ideas to tame some of the noise induced by the damper piston rod - which is attached to the car at the top of the shock towers. (The SAE technical paper I referenced in one of my other posts claimed essentially all shock noise came from that mounting point.) If I have any luck, I will post my observations.


And as an overall note, the RLX meets all my expectations given the price of the car... except for that bonus rattle they tossed in.

mgalbr22

Entire strut assembly

Comfy

<br />
One of the reasons for the slip may be the upward incline itself. The weight of body and engine tends to shift backwards on an up incline and it may cause less pressure on the front tire causing it to slip. You are right in assuming that high power and torque combined with decreased friction between road and tire (salted surface) can cause the slip as well.

holografique

This is exactly why I'm asking. I'll report more in detail later, but the good news is, not only has the rattle/noise issue remained resolved, but the overall ride feel and "confidence" in the suspension seems to have improved some more since the front suspension TSB was performed.

George Knighton

Expensive! 0_o

I wonder if they took the opportunity to change both the valving in the damper and the spring rate, in order to help with the harshness problem people have talked about, aside from the rattle.

RLX-Sport Hybrid

While pulling into a office parking lot this morning, the entrance was a little steep and it felt as if the inside rear wheel actually left the contact of the pavement for a moment. If that is the case, our suspensions are quite a bit stiffer than I thought. Next time I will see if I can repeat that experience and see if indeed that is what happened.

mgalbr22

Whatever it was, it didn't correct the problem.
As I've noted previously, recall notices and tsbs surprisingly do not require the statement of the root cause of the defect nor the corrective action, e.g. design, material, process change.

RLX-Sport Hybrid

As a follow up to my comment: I entered the same parking area again today and since no traffic was around I got out to look to see if indeed the right rear wheel was not touching the ground, and it wasn't. It was off the pavement by about an inch. The driver side front was barely touching and the passenger front & driver rear suspensions were compressed significantly. It reminded me of a friend's Golf GTI that did the same thing. Nothing to complain about. Just commenting on the tautness of the suspension. Interesting.

holografique

^ very interesting. More proof of how "stiff" the general suspension design is.

So to elaborate a bit more on my OP...since having the car now for over 30+ days since the suspension TSB was performed, I have noticed that the general "feel" and "confidence" in the suspension has improved when dealing with large bumps or other significant changes in road elevation. The car recovers better than it did before and while it is is still much stiffer than other vehicles, there is an improved muted softeness or padded response to it that has become increasingly noticeble over time.

Another way to explain it is: it seems to have moved closer to the same ride suspension quality I experienced in the TLX. Where the TLX for me was a 100% score (great ride suspension and overall quality), I'd say my RLX is now more like a 60-70% score, coming from a 30-40% score previously.

Where there have been no changes or improvements in behavior after the suspension TSB is with smaller bumps or "choppy" road conditions where you have long areas of unconsistent or "unsmooth" road pavement (breakup from weathering, wear and tear, etc). Under these conditions the car is still very jittery and harsh. I consider this a very different condition that hitting a pothole, large bump, etc.

So while I know Chris (mgalbr22) has not had the same experience after having the TSB done, I'm hear to say that it has provided some significant improvements to my RLX to the point where it's really allowing me to enjoy driving the car again and feeling excited about getting behind the wheel every time I step inside. It's allowed me to regain a level of confidence in the suspension where I am no longer necessarily having to be distracted or negatively impact my driving experiencing because Im having to spend soo much mental energy paying attention to road conditions to avoid them. I hit bumps now with a confidence I only remember having when I owned my old 06 TL.

holografique

I was put in another loaner TLX (White V6 Tech) on Monday after bringing in my RLX for the headlight TSB. This is my fourth time experiencing the "suspension" system of the TLX, only further confirming my findings above.

Man, if only the RLX suspension ride feel was like the TLX...

TampaRLX-SH

I agree the rides are very different. But the RLX retains Honda's double wishbone suspension which in my opinion, is more stable at high speed but characteristically harsher than strut type front suspensions. This may be a reason Acura is moving all the models to this type of suspension configuration? The TLX is strut style suspension now.

George Knighton

There's basically two reasons why Honda started moving to McPherson struts.

In the first place, installing struts in a car is inherently much cheaper. The way that assembly lines work, and the way that the strut assembly is put together in the first place, it's just all easier and cheaper.

But in the second place, something that Honda learned early on in the safety game is that cars needed to be a certain size (big) in order to be able to have double wishbones or other complicated multi-composition designs and meet crash standards.

Because the old fashioned double wishbone suspension needs rooms for the arms to move, you can take up less space with McPherson designs. Then you can use the space that you're saving for more trunk (if rear engine) or engine bay room or, more importantly, the engineers and designers have a lot more latitude with how to design the crush zones to get the maximum safety.

Now....having said all that....

Engineers and concept designers are still going to want to use the double wishbones wherever the idea fits the cost and retail models, and where the vehicle is of a size or performance to justify it.

The biggest reasons you want double wishbones where you can get them is because they adapt better to power-on, power-off radical changes in vehicle attitude, and because it is easier to handle things like bump steer and other geometry weirdness.

When I had a FWD RLX on the track, I was very impressed at how well it handled bouncing over gaters without upsetting itself. An independent rear suspension, whether or not it is powered, is also an important part of being able to do this and it is why the old fashioned P71 that American police departments loved so much could be out run by an FWD underpowered Impala. :-)

I would not agree that the double wishbone suspension is characteristically harsher [sic].

It is inherently and characteristically the opposite because you have so many more angles to work with. You have to be much, much more clever with McPhersons to get good handling vehicles once you're used to how double wishbones work.

The only reason we went with McPherson has to do with cost and an ability to be able to design safety more easily.

The first Honda McPherson designs were the EP3 and DC5. Honda learned the hard way how horrible (inherently) was the basic design and they had to get very clever with the 2006 cars that replaced the 2002 cars.

Compared to these first McPherson designs, Honda learned to move the steering racks down almost to the ground, and to attach the tie rods to the hub instead of the strut.

They also learned to lengthen the stroke of a McPherson strut to the maximum by leaning the strut backwards toward the passenger compartment. The first design, nobody thought of that. So you had a low engine lid over a very low, wide spring strut with little compression, and that make for both a harsh ride when people tried to "improve" on their Civic and RSX handling, and it would also cause people to run the risk of blowing a strut even with a mild improvement like the cooperative Showa/Mugen bolt-in design.

Believe me...if people could afford it, they'd always want double wishbones.

Porsche: McPherson works because there's no weight on the nose.

Audi: McPherson does *not* work as well as Honda designs.

:-p

TampaRLX-SH

The purpose of my post was not to define which was the better suspension design but to point out the difference between the RLX and the rest of the Acura line up.

And regardless of which is better (and I believe double wishbone is) it appears that Acura (and Honda) are switching to strut configs. I agree it is likely driven by cost savings but it appears it has also afforded suspension tuning that the mass buying public favors....softer, if less precise.

Every model that Honda and Acura has switched to a strut type config has been carped on by the enthusiasts and track experienced. Yet the buying public has spoken as sales of such models have generally soared. I think the RDX is the most acute example from the 'sporty' gen 1 to the 'refined' gen 2.

It appears Acura applied this logic to the TLX and I read similar praise on the 'refined' ride, even from RLX owners.

If I had a choice, I would pick the double wishbone, but I would still expect a more compliant ride from a PAWS RLX.

mgalbr22

Totally agree. See my post under other suspension thread.

mgalbr22

The key to the effective implementation of any design is execution, which derives from a meticulous design process, including design and process FMEAs, thorough design and product validation testing to destruction, etc. there are always pros and cons to design alternatives that involve performance, cost, durability and other factors. Whichever design concept is chosen after weighing these considerations must be properly executed-assuming it is not flawed, in principle, and is theoretically suited to the application.
All of this is a long-winded way of stating that acura's primary problem seems to lie in the execution of the design, not in the selection. That is a valid marketing and competitiveness question, but doesn't lead to failures, defects and recalls.