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Bd Motor Mounts - Rubber Or Poly?


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In my quest to get this truck in tip-top shape; the next replacement is going to be motor mounts, along with a new manifold and exhaust running to the muffler.

 

Am probably going to go with some Brown Dog MMs, because I've heard nothing but good reviews from them. I'd rather pay a few more sheckles for quality products than getting cheap-o parts I'll have to replace in a year or two.

 

Question is; What's the difference between Rubber bushings and Poly bushings? The truck isn't going to be abused, and will probably remain a (mostly) street driven DD.

 

I'm assuming the stock setup is Rubber, but I've heard different arguments for both types of mounts. Can anyone school a noobie on this and give some insight on the important differences between the two? :dunno:

 

I read on BD's site that Poly mounts are better in hotter areas, and are better at resisting weather elements. FL is about as extreme as it gets for weather; not sure how much truth to this there is though.

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Poly is stiffer, which would transmit engine vibration through the body (remember, we're unibody). Weather elements shouldn't matter as they should be under the hood, on top of the frame rail.

 

Actually, my OEM motor mounts lasted 21 years, the stock replacements have been fine since. I have never seen the need to pay upwards of $80 for an unneeded upgrade.

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I agree with the above^. When you are rock crawling, you want a harder material to hold the engine in place so the fan doesn't crunch your radiator or whatever. The weight of the engine shifting all around when at extreme angles and such will destroy stock rubber mounts. Enter the aftermarket poly mounts. They hold the engine in place nicely, but there is a price to pay. Vibrations will transfer easier through the poly vs. rubber. How much vibration are we talking about? Not alot, but enough that you can notice.

 

It's your money, spend it how you like, but you asked. IMO it is a waste of money for a DD.

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Am probably going to go with some Brown Dog MMs, because I've heard nothing but good reviews from them. I'd rather pay a few more sheckles for quality products than getting cheap-o parts I'll have to replace in a year or two.

 

Good point and I agree. Why don't you get a pair of the Brown Dog rubber mounts and let me know how they work? I've read that they do transmit more vibes than the stock Mopar mounts. My first choice would be factory mounts, but they are stupid expensive.

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i got the brown dog mounts and they offered 2 different kinds of ply mounts.i got the stiffer style and really wish i hadn't.it vibrates alot,it causes everything to rattle in the jeep that didn't before.i replace the tranny mount with a new srtocker and it helped some but not enough.next time i think i'll get there softer inserts and try them.

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i got the brown dog mounts and they offered 2 different kinds of ply mounts.i got the stiffer style and really wish i hadn't.it vibrates alot,it causes everything to rattle in the jeep that didn't before.i replace the tranny mount with a new srtocker and it helped some but not enough.next time i think i'll get there softer inserts and try them.

 

I knew their poly mounts would vibrate the mirrors off the truck, but I've also read their "ultra-flex" rubber mounts vibrate pretty good too, a lot more than the stock mounts. I'd hate to spring for a pair and have it vibrate anymore than it already does. :yes:

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i just switched to the rubber inserts and they suck as much as the poly ones despite following all the instructions.i'll be switching back to rubber oem style mounts soon.i'm sure you'll never break the mounts but for an everyday truck they just plain suck.i've ran poly mounts on my 88 mustang and it doesn't shake nothing like these do.

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If the stock rubber mounts last 25+/- years, why not replace them with OEM equivalent rubber mounts? Less expensive, less vibs, and if they fail again when the next 25 years rolls around, you can throw another set in :thumbsup:

 

Yes, OEM mounts can last 20+ years, and usually do. And new OEMs cost more than the Brown Dog mounts. There really is no "OEM equivalent"; they are all off-shore junk. You might get five years out of them. Motor mounts are one of the few parts that the aftermarket can not duplicate in longevity. BD comes the closest, but who needs the vibrations?

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yeah my oem mounts lasted almost 20 years and they broke.i replace them with the anchor brand and within 3 years it pulled the stud through the driver side mount.i found the brown dog mounts and figured i would give them a try.i ran steel motor mounts on my 68 nova and they didn't vibrate like the brown dogs.i run all poly mounts on my 88 mustang and it has very minimal vibration,nothing like the brown dog mounts.i replaced the inserts with the rubber style that brown dog offers and they are only marginally better than the poly ones.for a trail rig i'm sure they're great but suck on a daily driver.very soon i'm just going back with some cheap o anchor mounts and if i have to replace them every couple years then i'll deal with it.

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Back in the old days, Did I really just say that?, We used '55-57 Chevy motor mounts when doing engine swaps. They were plentiful, cheap, could be made to work in many different types of applications and they worked. I've been looking at doing a engine swap in a '86 XJ and I see no reason they couldn't be used there. For what it's worth.

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