WiKDMoNKY

Time for new motor mounts. I would like to go with aftermarket mounts like Brown Dog, but I don't want to deal with any new vibrations. I see on BD's website they have the Ultra Flex rubber mounts (instead of the polyurethane). Would the rubber versions have less potential for vibration?

I am not a rock crawler and only cruise fire roads. I don't need the best ones made, but don't mind spending a few extra bucks on better parts.

Thanks in advance!

extrashaky

The rubber in their mounts is not like the rubber in OEM mounts. It's quite a bit stiffer. So you can't expect them to feel like stock.

I have those exact rubber mounts. They vibrated like a **** at first, but a) I have a stroker rather than a stock motor and b) they calmed down considerably after everything broke in. I suspect that if you're putting them under a stock motor and you install them correctly, you will either have no vibration issues or any issues you have will be minimal.

I bought the whole kit, including the engine brackets. Once I saw how well they're made, I don't think I would put anything else in there.

Be sure to check to see if Brown Dog is still doing the 10% forum discount.

WiKDMoNKY

Would you consider the BD brackets as necessary for a stock motor for minimal cruising on fire roads? Spending $350 on motor mounts and brackets is 10% of what I paid for the darn Jeep.

extrashaky

Well, that depends.

I would buy the motor mounts either way. OEM mounts are fine, but they eventually fail and have to be replaced. The way the BD mounts are made, even if the rubber or poly failed, they would still work. And if the rubber or poly bushing wears out, you just replace it rather than replacing the entire mount. Even if BD went out of business, you would still be able to get rubber bushings for those mounts. But I don't think they've ever actually had a set fail, so chances are pretty good I'll never have to replace them.

As for the brackets, back in the 90s there was a quality control issue with the 4.0L engines where the holes for the mounting bracket on the passenger side were not drilled to the correct depth. As a result, when the motor mount brackets were mounted to the engine, the bolts were torqued down against the bottom of the hole rather than the bracket. That allowed vibrations that over time weaken the bolts and can break them off, causing the engine to suddenly tilt and send your fan into the radiator.

Chrysler fixed the problem on later years, so I don't know if yours was affected by that issue. If I had one of the years that was affected, I would most definitely spend the money on the BD brackets. What they do is make use of several extra mounting holes that were drilled into the block but not used. That spreads out the load and more securely mounts the engine to the uniframe.

If your year is not affected by the problem, they are not really necessary. Mine should not have been affected by that problem, but I went ahead and bought the brackets anyway to make the entire setup bulletproof. I like knowing that I could beat the crap out of this Jeep and not worry in the slightest about the mounts. And if it were ever scrapped, I could take these off this Jeep and put them right on the next one. Or I could sell them to someone else. Either way, they're so solid that they would perform just like new ones.

WiKDMoNKY

Which is the best OE brand mounts if I did not want to go with Brown Dog?

Petvet92

I broke 2 sets of stock motor mounts just driving on regular and fire roads (before my lift). I've had Daystars on since and with a lift no issues.

WiKDMoNKY

Any vibrations on the Daystars?

Petvet92

No vibrations in the Daystars that I've noticed

WiKDMoNKY

I've gone ahead and ordered the Brown Dog Ultra-Flex Rubber mounts with new bolts and nuts. The kit with the new brackets, is too rich for my blood right now. Hope it does not rattle my teeth out!

Any recommendations for new transmission mount? I might as well do them all while I in there.

extrashaky

Yeah, you have to loosen the transmission mount to install the motor mounts, so it's a no-brainer to go ahead an replace it. I just went with an OEM style rubber mount. The only "performance" transmission mount is the Daystar poly mount, and from all I read it just didn't seem like it was worth the money.

Metmknice

What? I did absolutely nothing with the trans/corresponding mount/crossmember when replacing engine mounts, brown dog's included.
Your local Carquest/Adavance, Napa etc should have a stock replacement trans mount in stock.
Since the mount is slightly different on later models, not sure of the OFA is in the way. But you may want to replace those o-rings while you are there. Pretty much all you need to do is use a jack with some wood or something similar to support/slightly lift the engine to remove the through-bolts, remove the old mounts, reverse order for install. IIRC, BD recommends to tighten the through bolts snug, then back off 1/2 (180 deg.) turn.
I will be putting a poly trans mount in my MJ, but that is only because I have it in a box of parts I picked up a while back. When I replaced my trans mount in my XJ I used the stock replacement from carquest.
I would recommend replacing the engine mounts first, as they are stronger than the factory ones and will help keep the engine/trans more in place when you swap the trans mount.

extrashaky

Pretty sure you're supposed to.

WiKDMoNKY

Sorry, I am a noob, which o rings are you referring too?

WiKDMoNKY

O-rings????

DFlintstone

He's talking about the oil filter adapter O rings. They are known to harden and leak...at some point. Doable without messing with the engine mount though.