csmeance

hi,
My older brother is looking into an RL. He loves the car, but wants to mod it. He likes the CMBS feature, but the PAX is ok for him. He wanted to know weather doing any of the following mods could affect the two systems or cause unwanted alerts:
Suspension (coilovers)
Suspension (swaybar)
Exhaust
Cold Air Intake
Rims: will this trigger an alert on the MID with aftermarket rims or will the system be quiet about it. (TPMS Sensors will be mounted)
Mugen Bodykit
Underdrive pulley

Thanks for the help, I hope he appreciates as much as I do.

Chas2

I am kind of in the same situation, owning an ACC CMBS PAX car, and being foiled by the dealer on mods on suspension, because of unsaid issues, which I gather to be liability type issues. These are my conclusions only, and they change as I get more info. They do not have a technician's know how behind them.

Here is the deal as far as I can tell.

PAX
The PAX wheel tire assembly, which is much heavier than a standard wheel tire assembly, perhaps almost 1.5 times. As a result, Honda tuned the rear suspension differently than the stock car. As far as I can tell from looking at the parts list and working with a dealer parts department, the front springs and dampers are the same part. The rear springs are the same part. The rear damper is a different part number.

My conclusion is that the rear damper has been tuned with different rates to handle the heavier wheel tire combo. As far as the parts department can tell, A-Spec suspension parts will fit on the CMBS equipped car.

The PAX tires are really OK for a stock ride. The car actually handles and rides better with the PAX than the standard tires, probably due in part to the 18" (approx) wheel diameter, the lower profile and inherently stiffer sidewall. The PAX are probably a tiny step toward the A-Spec ride and handling, definitely better than stock.

I have no complaints with PAX other than I don't know what to do when they wear out. That being said, it would be nice to have high performance tires available to use, like the Pilot A/S

RIMS
While you will unlikely find any wheel with the OEM +55 mm offset, other than Honda A-Spec wheels, especially if you are maintaining the OEM 8 inch width, there do seem to be more than a few wheels out there, especially ones from Japan, that will fit. The wheels should be hubcentric, so the weight of the car is borne on the hub, and not the lugs. The wheels should be compatible with TPMS as you noted, or you will be driven crazy by the error messages. You need to pay attention that the wheels will clear the large 4 piston front brake calipers. See the RonJon threads on his Legend wheels. Even though he selected a 45 mm offset while keeping the stock 8 inch width, he had to go down to 41 mm so the brake calipers would not interfere.

Finally, of paramount importance, you must maintain the same rolling diameter, because all the computer parameters are set assuming the nominal diameter of the 245/50-17 tires. So 245/45-18 tires (whether standard or PAX) run virtually identical rolling diameters nominally 1 mm larger, and the recommended 245/40-19 are a little farther off, 2 mm, insignificant differences in both cases.

Suspension (A-Spec, sway bars, other coil over type (realizing that the rear suspension is not set up for a coil over by design), etc.

The dealers say that Honda not only does not recommend the A-Spec being fitted to a CMBS car, they say it must not be fitted. My conclusion is that the drop of 3/4" changes the view of the radar enough to require some realignment, and that factory alignment is hard to do in the field, by a dealer, and may come up with unintended results that will put both Honda and the dealer in a liability situation in our litigious society. Since the same radar is used for ACC, it may also change the way that works, either with more falses or with too close a following distance, etc.

This would apply to all other suspension mods. It changes the angle of view on the radar. Look at all threads detailing the trouble Spicy Mikey has with even trying to figure out if his CMBS is working correctly, and if the dealer can adjust it.

Other Mods
Other mods, like cold air intake, exhaust, underdrive pulley have all been done by several on the board, well may be not the pulley so much, and no problems have been reported. I do not see how they would interfere with the CMBS because you are not really altering the stance of the car.

So that’s my two cents.

VOdoc

Great info. Thanks from a fellow CMBS/PAX owner for taking the time to compile and post it.

csmeance

wow, thank you for the information. If anything, My brother will end up getting the legends in 18's for the RL since he likes them. Also I doubt that lowering the car about an inch, I think touge did 2 inches, but it should not effect cmbs that much, and if it does, i can alway try and redo the grille sensor a little higher to it points a littler higher to accommodate it, but doubt it will change to much as it should have been designed with an error compensation incase some guy decides to tow something with the RL. With PAX< what is the rim size and tire size? Also are PAX tires availabe in different sizes from online retailers such as tirerack? I will search in the mean time, but its good to get an answer from here to incase i don't search well. Thanks for the help so far, and my brother does appreciate it. BTW, I read up on mikey's case and it just sounds like the the control has the wrong parameters located in it and a new one should fix it.

csmeance

BTW, if my brother decides to get the elgends, and cannot find PAX tires that fit the legends, can he just throw some run-flats on them or will there eb an alert message on the MID or a lamp lit up?

lland

He won't find PAX tires to find the legends. The PAX wheel is different and the PAX tirer mounts differently than a standard wheel. I'm not sure about other brands of run-flats.

As long as he has working TPMS sensors on the wheels, he should get pressure warnings on the MID.

LL

jftjr

I'm sorry, I just have to say this thread amuses me...

Let me summarize...

"Can I do X, Y, and Z?"

"Maybe you can do Z, and you definitely shouldn't do X or Y"

"Cool, thanks for the info... and when I do X and Y it shouldn't be any big deal!"

.....

Chas2

I do not know what lowereing will do to the CMBS. Acura specifically warns against modifying the car suspension for CMBS in the manual. The bold emphasis for page 327 is mine.

The way Honda does this, burying the warning in the middle of the manual, is why I believe it to be a liability issue Honda wants to avoid. Other clues for me are Honda saying A-Spec is not available for the CMBS cars, and NOT giving the dealer parts people any other info except "it will not fit, do not install" (at least in my experience with both the dealer and Tim at HondaAcuraWorld.com), when we have independently researched the parts and it appears that there are no differences to the interfaces at the front coil over attachment points, the rear springs, and the rear dampers.

Technically, I do believe the ride height issue due to a suspension change could be overcome with adjusting the radar unit, but it seems to be a difficult thing to do in the field, and looking at it from both the Honda corporate and the dealer point of view, an avoidable liability issue by strategically inserting warnings and instituting policies on mods.

2006 RL Manual, page 327

The radar sensor may not scan as
intended under these conditions;
Your vehicle is tilted because of a
heavy load in the rear or from
modifications to the suspension.
Do not overload your vehicle (see
Carrying Cargo on page 305), and
do not make any modifications to
the suspension (see Accessories
and Modifications on page 303).

And from page 303

WARNING!
Improper accessories or
modifications can affect your
vehicle’s handling, stability, and
performance, and cause a
crash in which you can be hurt
or killed.

Follow all instructions in this
owner’s manual regarding
accessories and modifications.

Although non-Acura accessories may
fit on your vehicle, they may not
meet factory specifications, and
could adversely affect your vehicle’s
handling and stability (see page 306).

And the other referred to pages 305 and 306 speak to load limitations, and how to calculate, etc.

Touge does not have CMBS or PAX, by the way, so it was never a problem for him, although he does report at least one in Japan who does have CMBS, and installed the Tein Comfort Sport coilovers.

The Teins would seem to be the package to install since there are 16 steps of adjustability in the dampers, so you could tune the rear dampers accordingly to compensate for the PAX wheel tire assembly weight.

The PAX rim is asymmetric, on side being about one inch smaller than the other side, which aids in keeping the tire on the rim when flat. Bottom line is that the rim size, designated as 235mm x 460mm, (approx 18" x 9") is unique, as is the PAX tire size, designated as, 245-680R460A (equivalent to 245/45-18). There are only two tires in the correct size made for the RL, the Michelin Pilot HX MXM4, and the Michelin X Ice.

Technically, there are two other tires that would fit (the all season and the winter tires), you could get the Honda Odyssey Touring minivan tires to fit on the RL 235 x 460 rim, but why would you want to?

Tire Rack does not currently support the PAX system.

As lland notes, you are not able to fit other run flat systems onto the PAX wheel. While compatible with standard wheels, those systems depend on an extremely stiff sidewall, different bead structure, etc., to support the car with no air in it.

However, if you decide to get another type of run flat, with a standard wheel, as the RJ Legends, you could.

If you decide to get standard tires, you will probably want to retro fit the spare into the trunk, which someone else on the forum already researched, see below:

* Trunk Spacer Assembly (Part number: 84542-SJA-A00)
* Adapter - Spare Tire (74651-S2x-003)
* Bolt - Spare Tire (74652-SDA-003
* Label - Spare Tire Adapter - Not really needed but cheap (74653-SJA-003)
* Nut - Wheel (90304-SJH-A91) - Need 20 of them or 16 and a set of wheel locks
* Disk Aluminum Wheel (this is the spare) - 17x4T (42700-SJA-J51)
* Valve - Rim (42753-SBB-661) - Need 4 unless you car reuse the valve stems from the PAX wheels. I don't know but at less than $1.00 each, might as well get new ones.
* You will also need TPM sensors if you can't or don't reuse the ones in the PAX assembly.

Chas2

You are so right! I have to laugh when I saw this comment, even though I wrote a lot of material for it!

lland

That was me and the cost of the above (at discount) came to just over $500 and doesn't include the spare tire itself...just the wheel. For $500+ and the cost of four tires and four wheels, I now figure it's probably the same cost just to replace the PAX with PAX when the time comes (althought I have seen some OEM wheels and tires pretty cheap on eBay) and not have to worry about any suspension/CMBS/ACC issues either.

LL

Chas2

Thanks, lland! I will have to put that reference in my notes I maintain on the RL!

csmeance

hankis for the info guys, I will relay it to him. Also just one last queston, besides the attena change and no onstar option, was anything changed on the 07 RL? Lastly, in the 07 rl's with ebony interior, is the headliner and pillars black upholstry or is it still a gray color

Chas2

You need to check with the dealer on all of these items.

It is not clear to me that whether the antenna is omitted on just the base model, or all models, pictures in the website for 07 and 08 show some cars with shark fin antenna. I think it is just sloppy photo editing on their part.

Changes that I know of off the top of my head
07 Base has no prior equivalent
06 Base = 07 Tech Package
06 Tech = 07 Tech+ACC/CMBS/PAX

06 XM Radio and OnStar are free for one year, 07 XM is three months, OnStar is omitted
06 rearview camera is an optional accessory, 07 camera is standard
06 has no mp3 port, 07 mp3 port is standard
06 all models have wood interior pieces, 07 base has plastic wood simulant
06 all models have Active Front Lighting System (AFS), 07 base has no AFS

headliner and pillars are gray in the 06, don't know about the 07