How To: Changing Your 4x4's Transmission Mount Bushing
It would seem that it’s gotten to the point in my off-roading career that I’ve developed tone deafness. This can happen easily. See, your mind starts to associate certain uncommon sounds with needed maintenance/repairs for your 4x4/Off-Road vehicle, and refuses to acknowledge that they exist.
Ok, so I’m joking a bit. But just a bit mind you. Fact is, sometimes, we can become accustomed to subtle sounds that build up over time. That is, until finally, only others hear the sounds. These “others” are most likely going to be your friends. These, “friends” point out the maintenance need that you have, and then all of the sudden, you finally hear it…the horrible sound of needed maintenance.
In all honesty, many times the sounds are less noticeable due to your being inside the vehicle, where as if you had heard the vehicle run, turn off, crank, or the like from outside, you would have noticed it instantly.
This actually happened to me the other day. My friend told me that my transmission bushing was bad. I was like, no way… He told me "yeah, it’s going bad". It just so happens that my wife came home the next day while I was outside. Sure enough, I heard the dreaded clunk of a bad transmission bushing. Well…I guess “dreaded” is a bit strong for the emotion felt. Still, it’s never nice to have to add to the ongoing maintenance list. So, any problem is technically “dreaded”. One good thing about transmission bushings replacement is that it’s fairly easy to do.
Let’s go over what it takes to change this important bushing assembly on a typical 4x4. It should be noted though, that each 4x4 manufacturer is a bit different. So, 4x4 transmission bushing and mounting systems may change 4x4 to 4x4. For our purposes of illustrating, we will be changing the transmission bushing on a 1992 Isuzu Trooper/Holden Jackaroo. However, most 4x4 transmission mount bushings are similarly oriented and can be replaced using the concepts found in this article.
First Things First
Before you do anything, you’ll want to make sure that your 4x4 vehicle is parked safely for doing maintenance work. You will be working under the vehicle, so working on flat ground it your best option. Performing this repair on a cement pad, or in a garage, is even better.
Here are few things to check out before you crawl under the 4x4:
- Make sure the emergency brake is applied
- Make sure that there is space for you to move comfortably (relatively speaking) under 4x4
- Make sure you have sufficient light under the 4x4. This will help you see what your doing.
- Make sure you have all the tools that you need before getting started.
- Make sure that the family, or your spouse knows that you will be working on this particular vehicle.
- Make sure that the transmission and transmission mount cross member are clean before starting any work
- Make sure to pay close attention to all jacks and tools, how they are placed, what they are holding up, and what potential hazards could be involved before continuing.
Setting Up And Required Tools
After making sure that everyone knows you’ll be doing work under the vehicle (This is so they don’t try and drive off with you under it), and that the other preparations have been taken care of, now you can get all your tools out and get to work.
You will only need a few basic tools to do this job. Having a few power tools will help make the job even faster. Here’s a short list of what you’ll need:
- Jack to lift/support your transmission. Just make sure that it has enough reach to actually pick the tail of the transmission up a couple/few inches.
- A wooden board Strap piece of 1”x4” or 2”x4”
- Socket set and Ratchet: You will probably only need two or three different socket sizes for this project. Having the whole kit is best though. Incase someone has changed out or adapted a different bolt/nut in the past.
- Breaker bar/Impact gun
- Transmission Bushing
Reviewing the new transmission bushing is a good idea. You’ll want to make sure that it includes the needed nuts for installation. If, for some reason, these nuts are missing, you will need to purchase them before you start the replacement process.
There are a various ways to remove your transmission cross member. My preferred method only requires one jack, and there is no need to reposition the jack until the very end of the process. Here’s how it works.
Make sure and remove all transmission and transfer case "protectors"/"bash guards".
Using your ratchet (or your impact gun and socket), undo the two nuts that attach the transmission mount bushing of your 4x4 to the cross member.
Place the jack toward the rear of the transmission. Using good judgment, place the jack on a portion of the transmission/transfer case that will withstand the pressure of the jack pushing up on the casing. Now jack up the transmission and transfer case until relieves pressure off of the transmission cross member.
Supporting the transmission support cross member, remove the bolts that attach it to the chassis rails on each side of the 4x4.
|Transmission mount cross member bolts are exposed to extreme conditions. Because of this, they may be extremely rusted or deformed. Under such conditions, you may find that a breaker bar or impact gun is needed. Photo Credit: Eric McGrew|
After removing the transmission support cross member, using a wrench (or ratchet and socket) remove the transmission mount bushing nuts that fix the bushing to the transmission casing/housing.
Once the old transmission mount bushing has been removed, attach the new transmission mount bushing to the transmission casing/housing.
|When installing the new Transmission mount bushing, you just have to reverse the removal process. Photo Credit: Eric McGrew|
Now lower the transmission assembly so that it's a bit lower than the 4x4 chassis rails.
|Lowering the Transmission assembly below the chassis rails will make re-installation of the transmission mount cross member even easier. Photo Credit: Eric McGrew|
Loosely attach the transmission mount bushing to the transmission mount bushing.
Raise the combined assembly until the transmission cross member lightly touches the chassis rails. Line up the bolt holes in the transmission mount cross member, with the corresponding holes in the chassis, then install and tighten the bolts appropriately.
|It's always a good idea to go back and re-check all the bolts on the cross member and transmission mount bushing to make sure that everything is tightly buttoned down. Photo Credit: Eric McGrew|
Now tighten up the nuts on the lower portion of the transmission mount bushing. Making sure to fix it firmly to the transmission mount cross member.
|Always remember to tighten all of the transmission mount bushing stud nuts. Tightening the firmly is a good idea, but be careful not to strip the stud or over tighten it, causing it to shear off. Photo Credit: Eric McGrew|
Re-install the transmission and transfer case protection plates, reaffirm that all the bolts are installed correctly and tightened appropriately, remove the jack, store your tools, and go have some fun in your 4x4.
If after having replaced the transmission mount bushing, you still hear excessive movement in your drive train under load or during start up and turn off, then you will want to inspect the 4x4 motor mount bushings as well. Having someone stand outside of the vehicle during circumstances that produce the undesirable sounds, is a good way to determine where the sound is actually coming from too.
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