Cobb RMM is way too soft

[fiiiesta]

Hey all. I got a 2017 Fiesta a few months ago and almost immediately knew I wanted a stiffer RMM. Haven't had time to get one yet, but today I was changing my oil for the first time and while I was under there I noticed there is already a Cobb RMM. I already knew this car was modified, just didn't know it had that. The problem is this thing is way too soft. I've had the engine slam into the firewall several times and I can just feel the softness of the RMM while driving. I can't even imagine how bad the stock one must have been.

Anyway, I've looked at a few threads and still couldn't really decide which RMM would be best for me. I believe both the Boomba and CPE are stiffer. Is the Boomba the stiffest? I want whichever is the stiffest. This car already has the least NVH of any car I've ever owned by a LARGE margin even with the Cobb one.

Also, I kept seeing people posting about the car shaking or something at low RPMs. Anyone know what that's about? The only thing I can think of is people are nearly stalling their cars and blaming it on the RMM that they can feel it happening. Or am I just not feeling it because this Cobb RMM is already broken in? I got the car with 41k miles. No idea how long the mount has been there.

 

[powermatt]

Hey all. I got a 2017 Fiesta a few months ago and almost immediately knew I wanted a stiffer RMM. Haven't had time to get one yet, but today I was changing my oil for the first time and while I was under there I noticed there is already a Cobb RMM. I already knew this car was modified, just didn't know it had that. The problem is this thing is way too soft. I've had the engine slam into the firewall several times and I can just feel the softness of the RMM while driving. I can't even imagine how bad the stock one must have been.

Anyway, I've looked at a few threads and still couldn't really decide which RMM would be best for me. I believe both the Boomba and CPE are stiffer. Is the Boomba the stiffest? I want whichever is the stiffest. This car already has the least NVH of any car I've ever owned by a LARGE margin even with the Cobb one.

Also, I kept seeing people posting about the car shaking or something at low RPMs. Anyone know what that's about? The only thing I can think of is people are nearly stalling their cars and blaming it on the RMM that they can feel it happening. Or am I just not feeling it because this Cobb RMM is already broken in? I got the car with 41k miles. No idea how long the mount has been there.

Could be old and worn out. It is one of the softer mounts, but they do wear out over time. Most of the NVH I noticed with mine was at idle when running the a/c.

 

[Sterilyze]

I have a Cobb RMM installed 1k miles ago. I was told that over time it will soften back close to a stock one, which may be the case here. The car shaking is a low frequency vibration at idle and in neutral. I can definitely hear it especially when the AC is on, even though mine is softer that the other RMM's. I don't think i could stand much more noise, so id rather just replace with another Cobb RMM or something similar when its time.

 

[Se7eN]

Anyway, I've looked at a few threads and still couldn't really decide which RMM would be best for me. I believe both the Boomba and CPE are stiffer. Is the Boomba the stiffest? I want whichever is the stiffest. This car already has the least NVH of any car I've ever owned by a LARGE margin even with the Cobb one.

Also, I kept seeing people posting about the car shaking or something at low RPMs. Anyone know what that's about? The only thing I can think of is people are nearly stalling their cars and blaming it on the RMM that they can feel it happening. Or am I just not feeling it because this Cobb RMM is already broken in? I got the car with 41k miles. No idea how long the mount has been there.

Yeah the Boomba is really stiff I had it for like a week and it drove me crazy. The vibes area real. Ocurr on idle not moving and most of the time with the AC on. I have race spec inserts in the 2 top mounts and race spec whoosh on the lower mount. Very nice and only really shakes as I said before and it's minimal.

 

[fiiiesta]

Yeah the Boomba is really stiff I had it for like a week and it drove me crazy. The vibes area real. Ocurr on idle not moving and most of the time with the AC on. I have race spec inserts in the 2 top mounts and race spec whoosh on the lower mount. Very nice and only really shakes as I said before and it's minimal.

I want to ask how bad the vibration is, but I know that's subjective and impossible to really tell through text lol. I had a car that vibrated enough to move the steering wheel nearly a full inch up and down at idle. Was the Boomba as bad or worse than that? Have you had the engine hit the firewall with your current setup at all? What about shifting? This may not be a RMM issue, but I feel like there's a lot of room to improve the shifting feel. Especially going into first, but to me it feels like it's just getting stuck on the reverse gear lockout. Like the lockout isn't completely flush, so there's a tiny little indention for the stick to get stuck on when going into first. I test drove a Focus ST before buying the Fiesta and the shifter on that thing felt insanely solid. I did see he had aftermarket shifter bushings on it though. Who knows what else he had.

 

[FiestaST27]

I have the Boomba RMM on my 2015 FiST and I love it. I’ve had it on for about 2 months, maybe about 1k miles (took a out of state trip about a month ago). It is kinda rough during cold start until warmed up and super shakey while just idling with AC on (but it’s mainly noticeable when I turn the A/C on right after warming up the car). Other than, it’s been a joy! I haven’t noticed any break-in. It feels just as stiff as the day it was installed.

 

[Se7eN]

I want to ask how bad the vibration is, but I know that's subjective and impossible to really tell through text lol. I had a car that vibrated enough to move the steering wheel nearly a full inch up and down at idle. Was the Boomba as bad or worse than that? Have you had the engine hit the firewall with your current setup at all? What about shifting? This may not be a RMM issue, but I feel like there's a lot of room to improve the shifting feel. Especially going into first, but to me it feels like it's just getting stuck on the reverse gear lockout. Like the lockout isn't completely flush, so there's a tiny little indention for the stick to get stuck on when going into first. I test drove a Focus ST before buying the Fiesta and the shifter on that thing felt insanely solid. I did see he had aftermarket shifter bushings on it though. Who knows what else he had.

I have an Fbody with a Cam and Poly Inserts all around and that thing rarely moves of vibrates as bad as the boomba rmm. Only thing I can compare it to is a Moded Honda (EG or EK) with solid mounts. It was basically a back massage on idle and A/C on. Once you got moving it wasn't that bad.

 

[Feisty Fiesta7]

I just installed AWR's stiffest mount and its stiff and you will really feel the vibration at first but now that its broken in a bit I enjoy it. it really made a difference on engine feel and wheel spin smoothness. I also came from cobb rmm which I got a lot of wheel hop with.

 

[M-Sport fan]

I have an Fbody with a Cam and Poly Inserts all around and that thing rarely moves of vibrates as bad as the boomba rmm. Only thing I can compare it to is a Moded Honda (EG or EK) with solid mounts. It was basically a back massage on idle and A/C on. Once you got moving it wasn't that bad.

I removed the Energy Suspensions poly trans mount from my '00 Z28 manual the very same day I installed it, that's how badly it shook the car (it actually made the CD player SKIP at idle, on the factory cam, and yes, that was even with the 'shaving' trick/mod done to it!).

That made me not even think about installing the poly motor mounts in that car, let alone SOLID ones!

 

[Spork1569]

I would also recommend doing the other engine mount inserts if you haven't. I had a mountune RMM which was really soft but all 3ints together was a perfect balance for me.

 

[Pablo Pistoffo]

Hey all. I got a 2017 Fiesta a few months ago and almost immediately knew I wanted a stiffer RMM. Haven't had time to get one yet, but today I was changing my oil for the first time and while I was under there I noticed there is already a Cobb RMM. I already knew this car was modified, just didn't know it had that. The problem is this thing is way too soft. I've had the engine slam into the firewall several times and I can just feel the softness of the RMM while driving. I can't even imagine how bad the stock one must have been.

Anyway, I've looked at a few threads and still couldn't really decide which RMM would be best for me. I believe both the Boomba and CPE are stiffer. Is the Boomba the stiffest? I want whichever is the stiffest. This car already has the least NVH of any car I've ever owned by a LARGE margin even with the Cobb one.

Also, I kept seeing people posting about the car shaking or something at low RPMs. Anyone know what that's about? The only thing I can think of is people are nearly stalling their cars and blaming it on the RMM that they can feel it happening. Or am I just not feeling it because this Cobb RMM is already broken in? I got the car with 41k miles. No idea how long the mount has been there.

I would be concerned about the health of your other mounts. I replaced my stock RMM with a Torque Solutions ()it died, but that's another story...) and kept having occasional engine smacking sounds. Turned out I had destroyed the passenger side mount, with about 15k on the car. I think with the upgraded RMM, the energy can be funneled into the other mounts, perhaps damaging them.

 

[DEss]

The problem is this thing is way too soft. I've had the engine slam into the firewall several times and I can just feel the softness of the RMM while driving.

I want whichever is the stiffest. .

The engine does not slam into the firewall.

If you want the stiffest, the AWR 95 duro one is for you.




DEss

 

[flbchbm]

"car shaking or something at low RPMs " It's called NVH
Vehicle noise and vibration term definitions
Noise, vibration and harshness, also known as noise and vibration, abbreviated to NVH and N&V respectively, is the name given to the field of measuring and modifying the noise and vibration characteristics of vehicles, particularly cars and trucks. Harshness is somewhat of an historical misnomer. Noise and vibration can be measured, but harshness is a more subjective assessment. There is a psychoacoustic measurement called harshness but it does not correlate very well with many harshness issues. Interior NVH is the noise and vibration experienced by the occupants of the vehicle cabin, while exterior NVH is largely concerned with the noise radiated by the vehicle, and includes drive-by noise. The noise being generated by fluid pressure fluctuation and passage through the air is called airborne noise. The noise radiated from a structure’s surface that is vibrating is called structure-borne noise. Noise is used here to describe audible sound, with particular attention paid to the frequency range from 30 to 4000 Hz. Vibration is used to describe tactile vibration, with particular attention paid to the frequency range from 30 to 200 Hz.

My 2 cents: As I mentioned in another post, TOO many choices...ugh.............. for a DD, Cobb is too soft, AWR 70a had too much NVH for my tolerances, but felt great. I bought the Whoosh Street version and am thrilled. No NVH and feels good.

Later I added the Powerflex Street Inserts to the Trans and Upper Mount. Ever-so-slight NVH, but now I forget about it and/or they have settled in. YMMV. Good luck.

 

[Ludeem1]

I was on the stock RMM and put a Cobb one a few months ago, immediately after installation I noticed more vibration especially with the A/C on. The shifts felt tighter and after about 2-3 weeks the vibration became less harsh and almost feels stock, but the shifting feel never changed. I do wanna try a different RMM for comparisons though

 

[haste]

I'm still happy with my CPE. Been on my car for 80k miles now and it STILL looks brand new. It's even had transmission fluid leak onto it and I've cleaned it off with brake clean. Whatever CPE makes the inserts out of is bulletproof. I notice some vibration when starting from a stop, even then it's not bad. I also feel a little vibes at idle with the A/C on, but only in the steering wheel.

It did break-in a little bit, but not much. I would definitely buy it again.

 

[DoomsdayMelody]

I'm still happy with my CPE. Been on my car for 80k miles now and it STILL looks brand new. It's even had transmission fluid leak onto it and I've cleaned it off with brake clean. Whatever CPE makes the inserts out of is bulletproof. I notice some vibration when starting from a stop, even then it's not bad. I also feel a little vibes at idle with the A/C on, but only in the steering wheel.

It did break-in a little bit, but not much. I would definitely buy it again.

The reason it looks new is because it was covered in oil and then cleaned, although it is surprising to see no issues after the brake cleaner... composite materials generally don’t like that stuff.


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[haste]

The reason it looks new is because it was covered in oil and then cleaned, although it is surprising to see no issues after the brake cleaner...
Sent from my iPhone using Tapatalk

Wow, you're smart. It looks new because I cleaned it? I literally put some brake clean on a rag and just wiped it off. I didn't DOUSE it in brake clean.

I should have said it still looked new even after 70k miles, before the oil leak? I look at it every time I'm under the car because I've read about some roll restrictor failures in the Fiesta community.

 

[fiiiesta]

I just installed AWR's stiffest mount and its stiff and you will really feel the vibration at first but now that its broken in a bit I enjoy it. it really made a difference on engine feel and wheel spin smoothness. I also came from cobb rmm which I got a lot of wheel hop with.

The 95a? I wasn't sure if that was too excessive. But I also have no idea what the durometer is on the Cobb. I might go for it anyway, I don't wanna end up regretting getting the 88a. How's the vibration at idle with AC? It's hot where I live so AC is on 100% of the time for most of the year. Does it feel like getting a back massage like the other guy said? Also I read this is generally fixable by just getting your idle RPM raised by about 50 in your tune. Have you done anything like that?

 

[DoomsdayMelody]

It looks new because I cleaned it?

That’s generally how cleaning works...

I didn't DOUSE it in brake clean.

You don’t need to douse anything to clean it. Just a regular amount of solvent, as you’ve clearly discovered.

I should have said it still looked new even after 70k miles, before the oil leak?

Not sure if a statement or a question, but I’ll respond to you with your own words:

Wow, you're smart.

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[M-Sport fan]

I'm still happy with my CPE. Been on my car for 80k miles now and it STILL looks brand new. It's even had transmission fluid leak onto it and I've cleaned it off with brake clean. Whatever CPE makes the inserts out of is bulletproof. I notice some vibration when starting from a stop, even then it's not bad. I also feel a little vibes at idle with the A/C on, but only in the steering wheel.

It did break-in a little bit, but not much. I would definitely buy it again.

In hindsight, my CP-E (which I still have, I purposely did NOT sell it!) was not all that bad in NVH, it's just that during the one cold snap we did get last winter (MUCH colder than it gets where you are, generally) it got REALLY rough and 'buzzy' feeling, to the point of making the exhaust system (same C-PE Nexus you have as well) have a really ratty, rattle-y sound on decel.
(But this may have been just the Cobb hangers all along. )

So I swapped it out for the VibraTechnics 'fast road' RMM which has ever so slightly less NVH than the CP-E at no air idle, and even less than that over the CP-E at idle with air.

At some point, I may try to re-install the CP-E.

BTW; BOTH of these RMMs above use an EPDM material (albeit different durometers) over a polyurethane material, like most of the others.