Changed bad transmission mount, now have vibrations in drive or reverse while parked

89grand

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Today I changed the transmission pan and gasket because it was leaking, and while doing it, I noticed the mount was shot. I didn't have time to order one, so I bought one at a local parts store. It's supposed to be rubber. I tightened the mount to the tranny since you can't get to it later, got the skid plate up enough to finger tighten the 4 nuts, then had trouble getting the skid plate to line up, so I used a pointed pry bar to get the skid plate in place to get the bolts started. I tightened passenger side first, then managed to get the drivers side in using the same pry bar, then I tightened down the 4 tranny mount nuts in the skid.

I started the Jeep and have massive in cabin vibration in gear. Should I loosen the 4 tranny mount nuts, and the 6 skid plate bolts, put it in gear to let things settle in, then tighten down all of the above? Or should I have not tightened the mount to the tranny? It doesn't seem like you can tighten the mount to the tranny after the skid plate is in place.

I feel like it is tightened down, but not in it's neutral happy place.
 
Today I changed the transmission pan and gasket because it was leaking, and while doing it, I noticed the mount was shot. I didn't have time to order one, so I bought one at a local parts store. It's supposed to be rubber. I tightened the mount to the tranny since you can't get to it later, got the skid plate up enough to finger tighten the 4 nuts, then had trouble getting the skid plate to line up, so I used a pointed pry bar to get the skid plate in place to get the bolts started. I tightened passenger side first, then managed to get the drivers side in using the same pry bar, then I tightened down the 4 tranny mount nuts in the skid.

I started the Jeep and have massive in cabin vibration in gear. Should I loosen the 4 tranny mount nuts, and the 6 skid plate bolts, put it in gear to let things settle in, then tighten down all of the above? Or should I have not tightened the mount to the tranny? It doesn't seem like you can tighten the mount to the tranny after the skid plate is in place.

I feel like it is tightened down, but not in it's neutral happy place.

I doubt it has anything to do with tightening bolts, what they call rubber on aftermarket trans mounts is as stiff as the poly mounts and transmit a lot of vibrations, the Mopar mount is pricey but works wonders.
 
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I guess what I meant was the fact that I had to pry the skid plate into position to start the bolts on each side, that made everything not in a neutral, relaxed state, like it's torqed in one area or another, and that might be transfering the vibrations.
 
I too doubt it has anything to do with tightening bolts.

I suspect it's a cheap, low quality transmission mount that may actually not be made out of rubber, but something much stiffer.

There's also a possibility you need to drive it around for a while and see if it "breaks in".
 
I guess what I meant was the fact that I had to pry the skid plate into position to start the bolts on each side, that made everything not in a neutral, relaxed state, like it's torqed in one area or another, and that might be transfering the vibrations.
I follow your thought process .

I'd at least loosen it all up , rock the Jeep back and forward , and see what happens.
 
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Curently in search of a mount, and while searching i came across few reviews of people complaining about vibrations while parked and drive. Stiffer mounts will produce that vibe
 
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if you had any pressure on the 4 center nuts and then cranked the skid it could be holding cocked.

loose the skid down but don't take the bolts out just let it hang off the frame some. then loose those 4 mount nuts. jack the drive-train up just a little to let the pressure off the mount just so it'll settle.
then bolt the skid back up tight, and last your 4 nuts.

for that mount, if you cannot pull it out of the box and flex it in your hands it's prob to stiff.
 
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A new mount gave me vibes too. (6 speed). Crappy mount with crappy rubber. You can try and loosen everything and let it try to center itself. Or try flipping the mount front to back. That shouldn't matter, but the mount could be slightly out of wack.
 
Coincidentally the same happened to me yesterday, I feel more vibration, but nothing too bad. (It helped me find a couple of loose wires in the cab :) ) The ride is definitely tighter. I did some research beforehand and this increase of vibes is common on polyurethane mounts.

By the way, while cleaning the skid fasteners I noticed some traces of what looked like threadlock. Is this right?, do these bolts need to use threadlock?
 
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Today I changed the transmission pan and gasket because it was leaking, and while doing it, I noticed the mount was shot. I didn't have time to order one, so I bought one at a local parts store. It's supposed to be rubber. I tightened the mount to the tranny since you can't get to it later, got the skid plate up enough to finger tighten the 4 nuts, then had trouble getting the skid plate to line up, so I used a pointed pry bar to get the skid plate in place to get the bolts started. I tightened passenger side first, then managed to get the drivers side in using the same pry bar, then I tightened down the 4 tranny mount nuts in the skid.

I started the Jeep and have massive in cabin vibration in gear. Should I loosen the 4 tranny mount nuts, and the 6 skid plate bolts, put it in gear to let things settle in, then tighten down all of the above? Or should I have not tightened the mount to the tranny? It doesn't seem like you can tighten the mount to the tranny after the skid plate is in place.

I feel like it is tightened down, but not in it's neutral happy place.

Do you have a link to the mount you purchased, so when that day comes, I don't buy the same one?
 
Tip. Always make sure you run the same material in your mounts. Don’t mix rubber and urethane such as urethane motor mounts and rubber transmission mounts.

That said if the vibration continues you may have to loosen your motor mounts and transmission mount, wiggle it all around so it centers then tighten back up. Although it should theoretically do this automatically u less something is different in the new/old mounts or your motor mounts are rusty or worn too.
 
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Do you have a link to the mount you purchased, so when that day comes, I don't buy the same one?
Before I condemn the mount, I'm going to drop the skid again, loosen the tranny mount at the transmission, to allow it some movement, then see if things line up, if they do, then I'll tighten the mount where it's at, then reinstall everything. I feel like everything is not centered, and I'm torquing on the mount when I had to pry the skid over to get the frame mounting holes to line up.
 
I feel like everything is not centered, and I'm torquing on the mount when I had to pry the skid over to get the frame mounting holes to line up.

I like this approach. Whenever I removed my skid, I only put the transmission nuts on finger tight, until the skid was in place. Then I tightened the transmission mount.
 
When I installed a new trans mount (rubber) I had no problem getting all the holes lined up but still got vibrations at idle with my 6 speed manual.
 
I loosened everything up, then retightened it, and still have vibes in reverse and drive although maybe not quite as bad as last night. I'm going to drive it around and see if it settles down. If not, I guess I'll be looking for a Mopar mount.
 
I took it for a drive and realized my old tranny mount has been fucked for years. Whenever I took off kind hard from a stop, I'd get a clunk in the floor. I assumed it was because of my pinion angle and not having a SYE, but it doesn't do it now, so it was the wasted mount. I think I may take a close look at the motor mounts because maybe they are trashed from driving with a trashed tranny mount so long, and that might be contributing to the vibration in gear.

It's also very possible that this new mount just sucks. The rubber seems very hard you can't move it at all.
 
I just replaced the transmission mount on ours this weekend. I didn't have to pry anything in place. I lined up the 4 bolt holes with the mount first. Then I started one corner of the skid plate and went to the other side and put all three in loosely. Went back to the first side and put in the last two and snugged them down before going to the other side and snugging them down. It was a bit of back and forth to tighten them down but it made a noticeable improvement in the vibes I was feeling. Motor mounts are next!
 
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Just want to check in here with another update. Before anyone goes and blows 100 bucks on the Mopar mount, I just went through the same issue. Used a mount from NAPA because, it didn't seem like a big deal at the time, and had the nasty vibrations at idle that everyone has been describing here. Crown is an OEM supplier for Jeep, so I decided to try them. Ordered the mount from Summit for around 30 bucks and it works like a champ. No more vibes. Feels just like stock again. Happy days!
 
I grabbed a couple pictures while I had the mounts on the bench yesterday, to try to get an idea of what might be contributing to the vibrations from the NAPA mount, because one did not seem noticeably softer than the other.

A couple of things I noticed:
The steel bar that goes across the rubber mount - On the NAPA unit (the dirty mount) it is flat stamped steel that looks like it actually clamps down on the rubber part of the mount, whereas, the Crown mount looks like an OEM unit. It is a steel bar that goes over the rubber part of the mount without actually touching it. I believe this bar is only supposed to act as a secondary holder for the engine, should the rubber fail.

The rubber portion of the NAPA mount looks a bit wider, which could make it more rigid as well?

Finally, in the close ups, you'll notice a gap in the rubber mount, where it attaches to the base, creating a bit of an up-side-down 'U' On the Crown mount, this gap is decidedly larger than the NAPA mount, which likely gives it bit of cushion, or way of absorbing vibrations, rather than passing them into the cab.

So, in reality, I don't think the NAPA mount is necessarily bad. If it came down to running that mount and saving a hundred bucks over the Mopar unit, but having some vibrations in a trail rig? That doesn't seem like the worst thing you could do. But knowing the Crown mount works, appears to be the same as OEM, and is maybe 10 bucks more than the NAPA piece? You'll likely just need to wait to have it delivered. So, if it isn't an emergency, I don't think you can go wrong with the Crown piece.

NAPA vs Crown MM 04.jpg

NAPA vs Crown MM 02.jpg


NAPA vs Crown MM 03.jpg
 
All the mounts you get from parts stores are junk. Believe me ive been there. Broke down and bought the pricy mount from the dealer..Ahhhh what a pleasure to have a smooth idle no vibes..