• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


The dreaded "Clunk" sound and feel.

Messages
34
Likes
13
Location
Lake Elsinore
#1
Well I'm starting to drive my car more aggressively now taking it to 6000+ RPM, driving more spirited and I hear and feel this clunk sound.
From my reading it must be the dreaded rear motor mount issue.
There seem to be many choices in aftermarket rear motor mounts.
My question is, is one aftermarket engine mount any better than another?
The Cobb looks to me to be the most popular Stateside.
From driving aggressively I also noticed wheel hop, does changing the rear engine mount solve the wheel hop issue, or is there another solution?
Are there any negatives to changing the rear engine mount, I don't think anything can be as disconcerting as that clunk sound. Feels like something is breaking under the car.
 


Messages
255
Likes
29
Location
Cleveland
#2
Clunk on hard shifts? Could be the mount. The only down side is added vibrations. It also helps get rid of the wheel hop.
 


frankiefiesta

1000 Post Club
Messages
1,852
Likes
509
Location
forked river
#3
It's all preference. If you want something as smooth as stock, but with the benefits of a stiffer mount go with Cobb.

If you want race car mount go with boomba. There are other options as well, but these are the only two I have experience with
 


Messages
346
Likes
61
Location
Gainesville
#4
Modbargains compared the Mountune and Cobb on the same car, and concluded that the Mountune is the softer of the two. It's what I have, and it is fairly soft especially after break in. Be warned though, that there is a very good chance that the Mountune unit will groan and creak after a while I'm not the only one to experience this and it seems that Mountune doesn't care much to solve the problem.

If I could do it again I'd go with the Cobb.
 


westcoaST

1000 Post Club
Messages
1,157
Likes
290
Location
Corona
#5
Eventually the cobb unit will make squeaking noises upon acceleration. A little lithium grease applied with a syringe will stop the squeaks.

Sent from my SM-G935V using Tapatalk
 


dyn085

2000 Post Club
Messages
2,434
Likes
820
Location
Vancouver
#6
I haven't had any noise out of my Cobb RMM. It definitely seems like the majority go with it for the daily-driver comfort along with decreased engine movement.
 


Messages
164
Likes
36
Location
Albuquerque
#7
I really haven't had clunking issues in my 2016.

The issue I have is when shifting into 2nd and 4th on hard acceleration.

My guess is a RMM will help with that
 


Rhinopolis

Active member
Messages
665
Likes
180
Location
Houston
#10
To help reduce wheel hop, also replace the motor and transmission mounts along with your RMM. Upgrading all three and you will definitely transfer more vibrations in to the cabin, but shift feel and overall driveline smoothness under acceleration will definitely be enhanced.
 


Messages
184
Likes
46
Location
clermont
#11
look at the material that the rmm is made from.some of these motor mounts will decompose under heat and time.if you live in a state that is warm most of the year stay away from poly.do some research on the subject before you buy.
 


westcoaST

1000 Post Club
Messages
1,157
Likes
290
Location
Corona
#12
Polyurethane bushings swell less and degrade less than rubber elastomer bushings. Not the other way around. Heat resistance is 70 to 120 degrees C (158 to 248F) depending upon formulation. Rubber heat resistance is 70C.

Sent from my SM-G935V using Tapatalk
 


Messages
184
Likes
46
Location
clermont
#13
westcoaST, i did not talk about rubber, what i am referring to is EDPM vs polyurethene which is ethylene propylene diene.edpm has outstanding heat,ozone and weather resistance. polyurethene can fail at 200 degrees f and edpm at 320 degrees f. there is one company that i know of that produces a rmm out of this material.my mistake for not being more specific with materials.
 


westcoaST

1000 Post Club
Messages
1,157
Likes
290
Location
Corona
#14
EDPM has very poor compatibility with gasoline or oil, and typically has a working temp of 150C, depending on the monomer formulation. Shore hardness is lower than PE.

Sent from my SM-G935V using Tapatalk
 


Messages
184
Likes
46
Location
clermont
#15
working temp is 150 to 160 degrees c and hardness is manipulated with chemicals.i guess it all depends on what web info you are looking at.
 


Similar threads



Top