Who Has Used Poly Engine Mounts ? - JeepForum.com
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post #1 of 19 Old 12-21-2013, 04:33 PM Thread Starter
jsawduste
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Who Has Used Poly Engine Mounts ?

Curious as to what you felt or heard in noise and vibration over a factory or aftermarket rubber mount vs a Poly mount.

The long story.

Finally getting around to installing the StnkyFab engine brackets.
http://www.stinkyfab.com/heavy-duty-...or-mounts.html

Have these engine mounts with the rubber isolators. Nice beefy mount but a poor execution on the bottom plate for the bolt to go through.
http://www.mountainoffroad.com/_e/Je...r_YJ_TJ_LJ.htm

See the lip where the elongated hole is ? My drivers side mount bent at that location. The frame horn is flat for the mount to set on. Strange bend but true. I can only assume the mount was flexing on the stud.

Looking at the Currie Mounts
http://www.currieenterprises.com/ces...t.aspx?id=1063

The base on these mounts are fully boxed in. A much stronger design.

The MORE had rubber while the Curries have the more ridged poly bushing.

What can I expect in any changes in vibration or noise ?

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post #2 of 19 Old 12-21-2013, 04:39 PM
JBTJ
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With poly mounts you WILL feel more vibrations. I use only rubber motor and transmission mounts.
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post #3 of 19 Old 12-21-2013, 04:43 PM
AmbuGrl
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We have brown dog mm. We originally went with poly to replace the OEM mounts. The vibes were annoying and we ended up switching back to rubber. Problem resolved.

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post #4 of 19 Old 12-21-2013, 04:53 PM
superj
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Yup. Just say no to poly engine mounts

I don't feel like working on anything, at this time.
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post #5 of 19 Old 12-21-2013, 05:30 PM Thread Starter
jsawduste
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Quote:
Originally Posted by AmbuGrl View Post
We have brown dog mm. We originally went with poly to replace the OEM mounts. The vibes were annoying and we ended up switching back to rubber. Problem resolved.
Brown Dog`s mounts have an even longer unsppourted flat bottom plate then the Mountains. Those would not be my first choice poly or rubber.

The engine itself has been fully balanced and sports the heavy 12 cwt crank.

Be interesting to feel/hear the differences. More I think about it, hell it`s a Jeep not a Caddy. Worse case I go back to rubber and weld in some triangular braces.
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post #6 of 19 Old 12-21-2013, 05:44 PM
StanF
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I think the poly is okay for the 4.0L and horrible for the 2.5L. I would still recommend the rubber first.

This is based on first hand experience with the 2.5L Brown Dog poly and rubber mounts.
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post #7 of 19 Old 12-21-2013, 05:48 PM
Norcal_chris
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I run poly motor and trans mounts.

It is slightly rediculous.

Ruined a perfectly good jeep.


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post #8 of 19 Old 12-21-2013, 06:18 PM
kjg26
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I need to replace my trans mount. Is it ok to run rubber motor and poly trans. Local parts store has energy suspension trans mount

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post #9 of 19 Old 12-21-2013, 06:28 PM
Day215
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I have brown dog poly MM and energy poly trans mount, if the vibration I feel is caused by the material, then it the least of my worries. I would do poly again without hesitation.
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post #10 of 19 Old 12-21-2013, 06:30 PM
JBTJ
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Quote:
Originally Posted by kjg26 View Post
I need to replace my trans mount. Is it ok to run rubber motor and poly trans. Local parts store has energy suspension trans mount
Sure, no problems doing so. But, you may feel a little more. No big deal though.
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post #11 of 19 Old 12-21-2013, 06:40 PM
Norcal_chris
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Quote:
Originally Posted by kjg26 View Post
I need to replace my trans mount. Is it ok to run rubber motor and poly trans. Local parts store has energy suspension trans mount
Its best to keep poly/poly or rubber/rubber.


The drivetrain twists under load, and if one twists significantly more or less it can cause issues.

Ruined a perfectly good jeep.


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post #12 of 19 Old 12-21-2013, 07:17 PM Thread Starter
jsawduste
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Well setting in my Lazy Boy Chair pondering todays big question. Have decided to cancel the poly and go with rubber. That matches the trans/TC eliminates any potential fights between them.

I am going to triangulate the bottom plate to stiffen to up a bit though.

Or I could take some power out of the stroker and torque multiplication out of the gearing.

Nah.......
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post #13 of 19 Old 12-21-2013, 10:07 PM
lincolnmatthews
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I had vibes with what thought was worn out OEM mnts after a AX15 conversion etc, so I had Browndog rubber engine mnts installed & I put in a aftermarkt trans mnt in, had the same vibes! The installers had torqued the "dog crap" out of the dog mnts, so after I loosened them to specs it helped but still have vibes. I'm thinking about going to the "stealer" & buying OEM mnts but don't know what they will cost & not 100% sure that they will help.
The mnt for the trans came from Autozone & seemed quite hard (made in China) where as the original was somewhat soft. Of course it was 25 yrs old, who knows? Anybody know where you can get mnts like the originals?
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post #14 of 19 Old 12-21-2013, 10:15 PM
linusb
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I like my poly motor mounts. If your motor runs like crap maybe it's an issue having poly but I like the small bit of extra feedback in the steering wheel with the poly. I do not get vibes.

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post #15 of 19 Old 12-22-2013, 07:17 AM
fishadventure
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Poly is for stuff where stiffness counts. Like in an autocross car's suspension. IMHO rubber is best for motor mounts.

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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