Honda Pilot - Honda Pilot Forums banner

Vibration/shimmy experiment -- MDX rear subframe brace retrofit

225K views 397 replies 121 participants last post by  20Piloteer07  
#1 ·
This is the first of a few posts I'll make about an experiment I'm doing. My Pilot definitely has a "harmonic" at 70mph that is triggered by the slightest imbalance in rotating mass. I had an old Miata ('90) that had a similar problem, and the aftermarket solved it via a chassis brace (happened to be a rear one).

I got to thinking about this, and got under a friends MDX in hopes that they had some additional bracing. In fact they do. See the photos here:
Image


Pic2:
Image


You're looking up at the rear subframe. Note the brace that is attached to the subframe bolt and runs up to attach to the unibody.

See the Pilot in comparison here w/o the brace:
Image

Note that it even has the threaded hole on the unibody for the brace.

I'm of the firm opinion that a stiffer chassis is "better", and less prone to annoying harmonics.

So, I went down and visited a confused Acura parts counter guy this morning, and ordered the 4 parts I think I'll need to make this work:
- 50360-s3v-000 -- SUB-STAY, RR
- 90168-s3v-000 -- BOLT 14x125
- 50366-s3v-003 -- NUT, FLANGE 12
- 90186-SDA-A00 -- BOLT, FLANGE 1

Circled bits in this really blurry photo:
.
Image


Total of ~$34 for one side. I'll test fit with this one side, and if it fits I'll order the other side to complete the set.

I'll keep folks "posted".

==================================

UPDATED / Directions (YMMV, do this at your own risk, I'm responsible for nothing, etc):

I've verified that the parts fit on my '05 Pilot EX/L, and I'm pleased w/the results (see notes later in the thread). YMMV.

First, check to see if you have the threaded hole in the chassis as reflected in the pics in this thread. if you don't, then you're on your own (see note on Nutserts if you're adventurous).

Here are the parts you need:
Quantity:2 - 50360-s3v-000 -- SUB-STAY, RR
Quantity:2 - 90168-s3v-000 -- BOLT 14x125
Quantity:2 - 50366-s3v-003 -- NUT, FLANGE 12
Quantity:2 - 90186-SDA-A00 -- BOLT, FLANGE 1

1) Either back the Pilot up on ramps or leave it on the ground
2) Do one side at a time -- do not loosen both subframe bolts at once.
3) Remove the subframe bolt you're going to replace w/the new one (17mm socket)
4) Install the new subframe bolt using a 17mm deep-well socket. Torque it to 69 lb-ft
5) Slip the new brace over the post on the subframe bolt, and hand-tighten the nut.
6) Hand-thread the bolt on the other end of the brace into the existing threaded hole in the chassis.
7) torque both the nut and the bolt (17mm socket). According to Tim, torque these to 47 lb-ft.

8) Repeat steps 3-7 for the other side
9) Enjoy
 
#3 ·
Here are part numbers I got from Acura of delray!

I found this in 2002-2004 MDX, rear cross-beam

25. 50360-S3V-000 SUB-STAY, $15.02 ea.

26. 50366-S3V-003 NUT, FLANGE (12MM) $1.30 ea.

27. 90186-SDA-A00 BOLT, FLANGE (12X33)$.90 ea

28. 90168-S3V-000 BOLT, SPECIAL (14X125)
$ 6.54 ea.

This is the price I got from delray acura in florida!

I hope these will help you and either members, who has problem with the vibration on the rear suspension of their PILOT. I do too have vibration on my 2003 PILOT, EX. at 65 mph.

:) :)

here a photo of the cross beam of the MDX...
 

Attachments

#4 ·
PILOT-cross beam chasis

here a photo of a 2003 PILOT:(
 

Attachments

#5 ·
Re: Here are part numbers I got from Acura of delray!

kuago said:
I found this in 2002-2004 MDX, rear cross-beam

25. 50360-S3V-000 SUB-STAY, $15.02 ea.

26. 50366-S3V-003 NUT, FLANGE (12MM) $1.30 ea.

27. 90186-SDA-A00 BOLT, FLANGE (12X33)$.90 ea

28. 90168-S3V-000 BOLT, SPECIAL (14X125)
$ 6.54 ea.

I hope these will helps you and either members, who has problem with the vibration on the rear suspension of their PILOT. I do too have vibration on my 2003 PILOT, EX. at 65 mph.

:) :)

here a photo of the cross beam of the MDX...
Thanks for posting the factory part diagrams!
Wow, I'm getting robbed, price-wise. Good to know there are other cheaper sources if this turns out to be a useful mod. If not, I'm only out a few bucks :)

You don't happen to have the part numbers for the Honda diagram, do you? I'm interested in the part number for the bushing (#4) for both the Acura and the Honda. I'm hoping they are the same, but if not that may be yet another interesting path...
 
#6 ·
rubber bushing

50230-S3V-A01 insulator A, Sub-frame mounting (lower).. Check -out hondapartsdeals.com in RI.:)

this is a part number of acura,MDX. Its is the same number as the PILOT. I just check...


Let me know the install and the outcome of the vibration of your PILOT..
 
#7 ·
Here's a part number comparison of the front and rear subframes. Bolded items are unique/different. Note that the subframes themselves are unique to the MDX which means that my brace might not even bolt up (which is why I only purchased one :) ).

I'd love to know what the differences are between the MDX and Pilot versions of the front subframe stiffener and dynamic dampers.

Image
 
#8 ·
keep us updated! :4:
 
#11 ·
Great pics, thanks. Interesting that the 03 doesn't have the pre-threaded holes.
I'll post more info on Wed hopefully, after the parts arrive.
 
#12 ·
2003 PILOT

This is not good! I have an 03 PILOT, EX. I just checked it. It doesn't have a predrilled holes with welded nuts in the sub-frame or underbody frame. I cant put that bracing bracket. Damn it! OPSS!:3: :3:
 
#13 ·
Re: 2003 PILOT

kuago said:
This is not good! I have an 03 PILOT, EX. I just checked it. It doesn't have a predrilled holes with welded nuts in the sub-frame or underbody frame. I cant put that bracing bracket. Damn it! OPSS!:3: :3:
I think its part of the screw. Its called the Early Adopter Screw. :)

Interesting though, that the 03 didn't have it, but the 04 or 05 has it. It looks like Honda experimented with the idea of the brace on the Pilot, but decided not to put it into production.

Either it didn't work; or it did, and there were political reasons not to implement.
 
#14 ·
Well, considering you're paying about $5k less than an MDX, any component that they can save a couple of dollars on and not install means more profit. If the Pilot suffers from a little more body flex than the MDX, so be it. You get what you pay for... :)

It is very possible that the lower portion of the unibody is the same for the two vehicles. It may save costs on production to simply make all the floorpans the same rather than maintain two different production stages for the floorpan for each model. It's not unusual for a production change to be made like this. On an assembly line, any efficiency that saves time and money (and time = money) will be pursued.

An example I'm familiar with is early VW Bug (and by early, I mean late '60s) Semiautos didn't have the clutch cable tube installed, as a rule, but by the end of the production run, they didn't bother to differentiate the pans and thus the '73s nearly always had a clutch tube welded in place, just like its manual counterpart. It didn't pay to have the production lines make some pans different from others.
 
#15 ·
How about the 02 MDX!

Does the 02 MDX have that bracket at all? Coz I got my 03 PILOT on July 2002... Maybe honda engineer is just determining this additional bracket to minimize the vibration issue on the rear cross beam, that was added and put to production for the 04-05 PILOT and 03-04 MDX.. Just a thought!
 
#16 ·
ctobio said:
It is very possible that the lower portion of the unibody is the same for the two vehicles.
That's what I thought. But then look at the stampings on the beams. They're look very different.

If the body/frame are different, that suggests that they share very little production time, even at the beginning.
 
#17 ·
jayjr98 said:
I've got an '05 Pilot EX with the 70mph vibration issues. This actually looks promising!! Man I hope the parts fit and I hope it fixes this freakin problem.
Just picked up the parts for one side at the dealer. I'll test-fit tonight to determine whether to order the other side. Net: I should know "fit" tonight, but won't know whether it actually makes a difference till likely this weekend (when I have both sides installed).

I can't imagine it doesn't serve some useful purpose if Acura went to the trouble of installing it on the MDX..., and Honda appeared to position themselves to use it on the Pilot post-04?
 
#18 ·
stiles_s said:


Just picked up the parts for one side at the dealer. I'll test-fit tonight to determine whether to order the other side. Net: I should know "fit" tonight, but won't know whether it actually makes a difference till likely this weekend (when I have both sides installed).

I can't imagine it doesn't serve some useful purpose if Acura went to the trouble of installing it on the MDX..., and Honda appeared to position themselves to use it on the Pilot post-04?

This was an AWESOME idea, thanks so much for experimenting and fingering this out. If the Braces Fit, you must RetroFit! Couldn't hurt... :)
 
#19 ·
This looks like a great idea and I am looking forward to seeing the results. I am in the middle of purchasing an 06 and am stressed out about the possibility of getting one with the vibration problem.
Is it a fact that MDX owners do not report the vibration problem? if so, I would put my money on the subframe stabilizer. Good luck:cool:
 
#20 ·
uns69 said:
This looks like a great idea and I am looking forward to seeing the results. I am in the middle of purchasing an 06 and am stressed out about the possibility of getting one with the vibration problem.
Is it a fact that MDX owners do not report the vibration problem? if so, I would put my money on the subframe stabilizer. Good luck:cool:
There are instances of vibration problems on MDX.org, but IMO they appear to be easier to fix on the MDX -- they don't appear to be quite as bloody sensitive as the Pilots...
 
#25 ·
stiles_s said:


Just picked up the parts for one side at the dealer. I'll test-fit tonight to determine whether to order the other side. Net: I should know "fit" tonight, but won't know whether it actually makes a difference till likely this weekend (when I have both sides installed).

I can't imagine it doesn't serve some useful purpose if Acura went to the trouble of installing it on the MDX..., and Honda appeared to position themselves to use it on the Pilot post-04?
Hola stiles_s,

Thanks for trying this out for all of us.

I took a look at my '06 and it does have the threaded holes. So, it appears that it's ready to have this attached if it'll help.

I checked out my '06 service manual and it shows that the subframe mounting bolt should be torqued to 69 ft lbs. But, do you know what the other end of the brace should be torqued to?

And, I think your parts list included a new subframe mounting bolt. They recommend replacing that it's been removed.

Thanks again!
Larry.
 

Attachments

#26 ·
I just noticed that part of this procedure involves removing 2 of the bolts attaching the subframe to the unibody. Do proceed with caution here that you don't introduce a misalignment into your rear end. Its less likely if you're doing one bolt at a time, but I would consider getting an alignment done/checked after doing this. I could just be overcautious here.

I'm not sure this bracing is designed to remove some sort of vibration at speed- I think the implication of this happening to some cars and not others is not as a result of the lack of this bracing, but that there's some sort of issue during assembly on a selection of these vehicles. I think this bracing is designed to provide extra stiffening by lessening body roll. I don't see the harm in this experiment, but I'm usually pessimistic about experiments... :)