Cobb RMM Problems
 

UP FRONT:The intent of this thread is to attempt to find out if others are experiencing similar wear on their Cobb RMM, and their experiences. It is in no way meant as a negative take on Cobb or their RMM.

@darkstar5440 recently posted in:

http://www.mazdaspeedforum.org/forum/foru...61/index2.html

He had a problem with the outer bushing of the Cobb RMM pushing upwards, out of the mount. He posted more detailed pictures than I have, and probably a better description. He also has been in touch with @Evan@COBB, I will let him explain his experience.

After reading his post on a whim, I decided to inspect the RMM while doing an oil change today. The pictures attached show what I saw. Seemingly the same issue. It looks like the outer bushing is pushing upwards. I have noticed an increased vibration at low RPM, similar to what it felt like for the first 50 miles or so. Shifts are also a bit jerkier, but all of that is just by feel.

I drive my car hard. All the time. If I'm not, it's because I'm in bumper to bumper traffic. It also has gotten colder here recently. 30-20's daily now. The mount is only a few months old. It's seen alot of daily abuse, and I'd bet close to 100 full on pulls, as @rfinkle2 can attest to. But I don't think this is regular wear, or ideal.

According to @darkstar5440, @Evan@COBB said that this was the first he heard of it out of 850+ units sold. Apparently Evan also made it sound like this was not a failure or a problem.

Just today I sent a pm to Evan, so I do not expect to have gotten a response yet, or expect him to address it until Monday.

Here is the question to MSF. Looking at pictures from both myself and @darkstar5440, does this look like a problem or failure? Am I imagining a difference in vibrations and shift feel? And most importantly, is anyone else running this RMM seeing the same performance? Does anyone have any input or thoughts?

Thanks.

@WetzMS3; thanks for creating this thread,

My experience follows as is, i purchased my ms3 on july 27th, 2013. I received the rmm directly from cobb on august 22nd, 2013 and installed it the next day 8/23/13. When I ordered this mount it was during the chaotic v3 backorder time period which I also was involved in. I had ordered both the rmm and v3. The v3 was backordered and they held my order, I spoke with jared via email and asked if he could ship the mount out since that was in stock. He said he would ship the mount immediately separately. That did not happen and a few days later i contacted jared and asked him where my rmm was. This is why I love this company (cobb) because they have outstanding customer service and do in fact care about there customers. Jared appologized and bumped me on the v3 backorder list and shipped my rmm and v3 out that day next day air. Now when this problem arose @Evan@COBB; contacted me and has been handling the situation. That was definitely irrelevant to this topic, but I'd like to put that out there that I do like the way cobb handles themselves. This post in no way shape or form is intending on bashing them.

So I really have no idea when this mount decided to dislodge itself. Right after I installed it i obviously noticed more vibration over stock and I went on a spree of mods for the next month.
8/24 ETS TMIC
8/28 HPFP
8/29 CNT CBE
8/31 JBR SRI/TIP
9/11 UR DP/ TP
9/16 CS exhaust hangers
9/18 cobb bpv
From the beginning of september til mid october I was tuning with richtune for a 93 map and e85 map as well, so i had countless amounts of pulls on the car. Although this mount should be able to handle whatever is thrown at it.

So the mount could had dislodged itself during that time and I never picked up on a difference in performance/vibrations. Skip ahead another month and i took my car to the drag strip on october 18th and ran it 21 times LOL. On one of my launches my tmic actually smacked my hood and popped it. I had a few rough launches with wheel hop as well that night. So the next day I went over everything on the car and this is when I noticed the top bushing on the mount had worked its way out and lodged itself up against the top of the housing on the subframe. I proceeded to take the mount out and smack it flush and reinstall. It was about 40 degrees that night at the track so it was a bit nippy. I thought nothing of it and thought that maybe that happened do to the violent launches. Fast forward to about a little over a week ago. I was underneath my car and noticed the bushing dislodged itself again. This was when I posted on the sneak peak rmm thread about wether this was normal or not. That night I took it out and smacked it flush again, got underneath the car the next day and it was dislodged already. So apparently this bushing is in a hurry to get out. Now its been a lot colder here in NJ, temps fluctuating between 15-50 degrees. For the record I drive like a wreckless maniac on a daily basis and i am not nice to my car. If a Ford Festiva wants some I'm gonna give her some if you pick up what I'm putting down....I am that cocky asshole doing pulls next to a family in a mini van LOL @Evan@COBB; replied back and we've talked about this briefly and I'm waiting to hear back from him.

My worry is, will this issue lead to premature failure of this mount and why is this happening? Cobb seems to be the only one in the rmm game using this design. Below is what @Evan@COBB; had to say about the issue via PM and also pictures I have attatched. What is everyone thoughts? Has anyone else experienced this problem?

Just to be clear, you guys are experiencing the inner bushing (circled red) dislodging or shifting out of place correct?

http://i.imgur.com/7hhAlr7.png

No, the center pin which is some sort of metal fits tight in the subframe. The center pin is actually longer and sticks out past the bushings. I am experiencing the top bushing sliding out of the mount and pinning itself against the top of the subframe housing.http://img.tapatalk.com/d/13/12/01/yzupe2a9.jpg


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http://img.tapatalk.com/d/13/12/01/hy2a4e7y.jpg
Center pin by itself snug in the housing

http://img.tapatalk.com/d/13/12/01/mavygaba.jpg

Center pin installed in the bushing without mount inside the housing

http://img.tapatalk.com/d/13/12/01/3enyde7a.jpg
What the mount looked like last time I took it out


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@atvfreek; know you would be interested in this thread.

^^That is what I am seeing with it still in place too.

I also installed it around August and have added a bunch of mods since. I initially chalked up the additional vibes to that as well.

Cobb RMM Problems
 

http://img.tapatalk.com/d/13/12/01/guzu4ena.jpg
What she looked like fresh out the box, as you can see the pin sits a cunt hair higher than the bushing

http://img.tapatalk.com/d/13/12/01/arysu4u7.jpg
Also this is what the bottom of the mount looked like when I took it out



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Thanks for clarifying. So there is actually two separate bushings? A top and a bottom halve? Just trying to understand this design.

Correct


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Just spend the 100 and buy a jbr 88 and you won't have any issues

That's your issue it seems. That pin is creating just enough of a void as to allow the (possibly shrunken by cold) bushings to not sandwich snugly in the subframe and it eventually works itself out. IMO

Interested to see where this goes. Sub'd

From the man himself, this was on tuesday

So, like I said last night, this is the first I've seen of this happening. The center pin should be a little bit taller than the poly bushings because you want to tighten down on the aluminum center pin and then have the mount/poly bushings "float" around the fixed pin, so this is by design. However, your car seems to have more room in that space in the subframe than any of the cars I've installed this on in the past. Almost all of them, fitting the mount into the subframe has always resulted in a fairly snug fit.

How did you notice that this was happening? Did you notice any difference in vibrations or while driving? I ask because, if that is as far as the poly bushing can move out of the mount, then it's not really that big of deal. There is still plenty of engagement between the poly bushing and the aluminum mount to keep everything in place and do its job. However, if you have noticed an issue, then I'd love to hear about it.

As far as fixing the issue. I'm not entirely sure I have a great fix for it off the top of my head. All of our mounts are pretty much identical. If this one fits loosely, so will the rest of them. We need to come up with a way to capture that bushing in your subframe without compromising the inteded effect of of allowing the rest of the mount to "float" as the motor is moving around.

So, if you can asnwer my couple of questions, I'd love to hear from ya.

Thanks,

Evan@COBB

This was wednesday

Norm,

Thanks for the pictures. When I say "float", I mean that the mount, with the 10mm Socket Head Cap Screw, is rigidly mounted to the motor and the internal pin is rigidly mounted to the subframe. The "float" occurs when the polyurethane bushings are the only non-rigid aspect between each rigidly mounted point. Thus, the polyurethane is responsible for absorbing all of the vibrations and movement. Does that make sense? The mount is “floating” around the polyurethane bushings.

The fact that the internal pin does not move once everything is installed was by design. We do not want anything moving in the mount once installed. Obviously, that’s not happening with your car but that was the intention and that’s what we’ve seen on all of our testing, my own vehicle included.

I'm still not sure how the bushings are moving around like they are. The internal pin should only be about 0.140" longer than the width of the bushings. This was so that when you tighten the bolt, that it tightens down on the pin and not on the bushings, impeding their ability to absorb vibrations. What I don't understand is how your bushings seem to be pushing out a bit beyond that.
However, you mentioned that you haven’t noticed any degradation in performance of the mount when the bushings are moving around so, in my opinion, it's not really a huge deal. Sure, I'd prefer to not see this happen, but the fact that there is still plenty of cylindrical engagement into the mount and we know that nothing can move past where they currently are because they’re trapped in the subframe...I'd say the mount is still performing as intended.

However, if you are unhappy with the way things are working out on your car with this mount, as I would totally understand, I would be happy to figure out a way to issue you a refund. With this being the first issue I've seen like this with over 850 of these mounts sold thus far, I can't justify a design change at this point.
What are your thoughts?

Cheers,

Evan@COBB

seems like the bushing "stretched" due to the "floating". if your bushing is moving constantly and like you said before on your driving... i could see that over time the bushing stretching or warping.? first time hearing about the design of these

I posted what @Evan@COBB; had to say about the design. Apparently the pin is supposed to be longer.

I also edited my first post to share my experience now that I am not at work and could elaborate.

All,

I am currently working with the supplier of the bushings to determine the best way to fix the issue. We're currently leaning towards knurling the inside diameter of the actual mount to better grab on to the bushings when they're installed. The fit loosley by themselves but once the black pin in pushed through the middle, the bushing expands into the mount. The bushing will expand into this knurl and hopefully hold on better than what we're seeing.

I'll report back once we finish out discussions.

Cheers,

Evan

@Evan@COBB; thanks for keepin up posted!!


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Thanks for the update @Evan@COBB!

^ This is how a vendor should conduct themselves. Take note other vendors. Thank you for keeping the community updated.

i guess ill check mine

Any more updates @Evan@COBB ?

Vibrations have gotten worse, and more annoying since I know how smooth it used to run. I've got some time off for the holidays and would like to resolve the vibes one way or another.

Have there been any revisions to the RMM? Any updates on how everyones mounts are holding up? I haven't noticed any noise/signs of degradation throughout the cold weather but I haven't been down there in a while to take a look...

I returned mine months ago


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I have received a revised version of the mount. I installed it last weekend. I did not disassemble the bushings, to ensure I was not to blame for any possible future issues, so I cannot really comment on the revisions itself, as they are not visible with the bushing in place.

I plan to write a more thorough evaluation after it is more broken it. However, in the first 5 miles low rpm and idle vibrations were vastly improved over the mount with failed bushing. And that has held true for a few hundred miles so far. I intend to run the mount for a few months for a decent evaluation period before switching to something sturdier.

Apparently this issue has only happened to a handful of mounts, so I would say, just keep inspecting it every time you get under the car.

I sadly, have just noticed this thread. I too have this mount, and ive got about, 5,000 + miles on it. I have noticed that the vibrations have increased exponentially from 1k to about 1500 , after that it smooths out somewhat. I'm talking like in the seat, steering wheel, pedals , everything rattles like high hell. It seems to be more pronounced in a right or left hand turn.
After around 2k it seems to flatten out and dissapear. Is this roughly the same situation you were experiencing ?

That is the RPM range where I saw more vibrations prior to replacing the mount with this revised one.

When I first noticed the vibes I chalked it up to other mods after the mount, seems like that was not the case. There are pictures above of the bushing separating. Take a look at yours and if it looks like that, contact Cobb.

I also have additional pictures that I could send you or anyone else who would like a reference.

I wanted to break the mount in more to have a fair and complete evaluation before posting more pictures and thoughts.

At this point, the vibrations have been reduced, and as of Wed. night the bushing looked normal. I will be re-torquing and inspecting again tomorrow, as well as putting some more aggressive miles on it.

Welp....

Went to change out my oil with some fresh T6 today....And took your advice.
While i was under there, i took a quick look at my COBB RMM today, and sure as shit... The top of the mount is lifted off the surface and sitting pretty high. I didnt snap any photo's, but to give you an idea, i could probably put 2 quarters stacked on top of each other into the gap between the mount itself, and the top bushing. Maybe even 3.

Now what to do :ugh:

*Edit ... I would say ive got about close to 7,000 miles on this mount.

@x09MS3GT, contact @Evan@COBB.

That is about the size gap that I saw. Here a few pictures from the day I swapped the mounts.

As for the new mount, I checked this weekend during an oil change and the bushing was still in place. The vibrations have gotten slightly harsher than the first couple miles, but still better than the failed mount.

Roger that man, i just PM'd him and well see where it goes from there.
*Edit .. BTW , those pics of yours, looks exactly like mine.

Let us know what plays out man. I was told only 3-4 people, including @darkstar5440 and myself had experienced this issue. I'm curious if other failures are going unnoticed or if this is an anomaly and we just happened to be the unlucky ones.

changing my oil saturday, ill check mine too

@Evan@COBB; @WetzMS3;

Here are the pics as requested...

Quite dirty in there.....
4 years of Alaska will do that.

I keep meaning to get a picture under there - have all mounts Cobb currently sells been shifted to the revised design? I wonder if the Focus ST crowd noticed any of this...