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Broken Transmission Mount

BIGSLVRXJ

NAXJA Forum User
Location
Des Moines, Iowa
Hey guys my tranny mount between the crossmember and transmission is broken. I had my tranny rebuilt like 4k ago and somehow they missed the fact that it must have been falling apart. Anyway how big of a PITA is this to replace? Also, I'm wondering if this is causing the following problems.
1. There is a hard jerk back when engaged into reverse.
2. There is a rattling noise when in gear like an exhaust clamp that is broken, but none are broken.
I assume a tranny mount might be causing these but I don't know. If anyone can help me with any of this stuff that'd be great.
TIA,
Collin
 
Hey. The tranny mount isn't too bad to replace. On my 84 it's four bolts through the crossmember and two through another part of the mount. The upper ones through the other part are a bolt and nut combo, so it's kind of a pain to get those in and out, but it's very doable with a floor jack and some basic hand tools.

I think the first time I pulled that mount I left the crossmember in and just worked around it.

Edit:

Oh yeah this did fix some exhaust rattles I had too, though I didn't have them before I took it to Midas for a new muffler, so I contend that it wasn't right to start with. It was the tail pipe knocking on the gas tank shield.

Bill
 
Thanks for the reply, ya wanna drive 40 miles to help me do it. Actually it doesn't sound like too hard of a project especially if all those bolts were just moved 4k ago. Does anyone else have input?
 
Did mine on my '90 not too long ago. Easy job, just a bit messy with all of the crap that was on the cross member. Just be sure to have good jack stands to keep the tranny up a bit and your fine. This is been covered a lot here, so search a bit and you'll find lots of information.

It's often recommened that if you replace the tranny mount you also replace the motor mounts. I didn't on mine, but I will get to it. If you don't you hasten the demise of the motor mounts.
 
I have gone through 3 trans mounts because of hammering it hard with the stick shift. If the trans mount goes it is most likely time to change the engine mounts also or you'll be changing the trans mount again, trust me ;)

If you aren't too hard on it go with stock style ounts as the poly and bomb proof transmit vibrations to them frame and become very annoying.
 
I don't do any offroading really so I'll just go stock I think. I wasn't going to replace the engine mounts but if you guys think it is a good idea I will give it some thought. Thanks for all the suggestions so far.
 
Collin

You can always have a friend help you check them. Easiest way is to put it in gear with a foot on the break and apply some gas. The engine shouldn't have too much lateral movement at all. Do this in reverse also.

If the trans mount goes bad chances are its bad motor mounts that helped cause it.
 
Sparky said:
Collin

You can always have a friend help you check them. Easiest way is to put it in gear with a foot on the break and apply some gas. The engine shouldn't have too much lateral movement at all. Do this in reverse also.

If the trans mount goes bad chances are its bad motor mounts that helped cause it.


Sounds like a dumb and dangerous idea to me. Better way it to stick a bottle jack under the tranny or t-case and see if they move up when jacking. If it does then you've got a bad mount.
 
Weasel Thank you for bringing up a potientally dangerous situation.

IF you do as I suggested above. First apply you emergency brakes.Open the hood of the jeep and install the hold up bar. The engine movement should be observed while standing to the side of the vehicle. I would hate to think anyone would try to see this by crawling underneath or standing in front of the vehicle while it is running. Start the engine apply the foot brake and put in in gear. Apply the gas slowly with the other foot still on the brake. Full throttle won't need to be applied, just enough to bog the motor and cause it to torque a bit. If the mounts are bad the motor will have excessive movement.

Remember accidents are caused by unsafe acts and unsafe conditions. By all means if you feel anthing is unsafe don't do it.

I feel if you jack the transmission or transfer case I am not sure you will see the lateral movement of the engine but instead the trans moving. With good mounts the engine will still move jacking it up. But I am sure you can put the jack someplace else to check the engin mounts
 
Last edited:
Yep, tranny mount is piece of cake and that noise is most likely coming from the bracket that holds the exhaust pipe. It mounts into the rubber on the tranny mount and when that goes it makes a noise that is annoying as hell.
 
First off to everyone who has replied thanks for the help. Well, I know for a fact the mount is broken, I was just trying to see how easy it was to replace, but it sounds pretty easy. I'm almost positive the broken mount is causing the rattling because as it rattles, the floor right above the tranny vibrates pretty bad. I think it is what is causing the jerkback too, but I'm not quite sure. Any other comments?
 
Got the tranny mount done. It helped the jerk back slightly and fixed the exhaust rattle. Thanks for the info guys, really appreciate it.
 
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