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Cherokee Motor Mounts and Transmission Mount Swap

Posted in How To: Transmission Drivetrain on July 23, 2015
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Motor mounts and transmission mounts eventually become one of those things you just can’t dodge. You usually don’t pay much attention to them, until your engine is rattling out of your Jeep or the transmission is banging against the underside of the floor pan. On our XJ, the motor and transmission mounts were shot and we could not ignore them any longer.

When the choice between polyurethane and rubber replacements came into the discussion, we finally decided to go with rubber. We used rubber because it soaks up vibration well, is a good choice for price-sensitive four-wheeling folks, and these days there are some great choices in aftermarket motor and transmission mounts that use rubber as an isolator. After much consideration and way too many nights of research, we picked up the phone and ordered motor mounts from Mountain Off-Road Enterprises (M.O.R.E.) and a transmission mount from Crown Automotive Sales.

M.O.R.E. offers a number of motor mounts for Jeeps, with applications for JK, TJ, YJ, CJ, and XJ rigs. We chose its PN JM600 “Bomb Proof” Motor Mount Kit. These are what the company calls "torsion" rubber style mounts, and the company claims these mounts will secure the engine much better than the factory units. The mounts are zinc-plated to resist corrosion too. The transmission mount from Crown is PN 52002334, and it’s a direct replacement for the XJ transmission mount.

Normally, this sort of job might be a couple of hours in the doing, but because of some peculiarities to the XJ, it took almost an entire day. We had to remove the oil filter and the oil filter housing to get to one of the bolts, and the space restrictions around the engine were such that it just seemed to be a much more difficult job than it should have been.

Before even touching the old worn-out motor mounts, we loosened all of the engine-mount hardware, and then using a floor jack to raise the engine up just a touch, we were able to wiggle the factory motor mounts out. It also made it much easier to get the new M.O.R.E. mounts into place. Compared to the motor mounts, the rear mount (or transmission mount) was a piece of cake.

This view is of the driver side motor-mount brackets from below. The stud and the nut bolt on the brackets, and the through-bolt on the motor mount itself must be loosened. For this job, we needed a ratchet with an extension, a universal extension, socket set, and open-end wrench set. Space is tight, and you’ll need a good deal of patience.
The driver side of the engine was no picnic. We had to loosen more than just the hardware on the brackets and the mount. The three bolts that attach the one bracket to the engine had to be loosened too.
Once all the motor mount hardware was loose, a floor jack was used to raise the engine/tranny up just a smidge to help make removal of the old mounts and installation of the new motor mounts easier. We know this sounds like a “duh,” but be sure to use a block of wood or patch of plywood between the jack and the point at which the jack makes contact to prevent any damage to the powertrain components.
We thought the passenger side was going to easier, but we were surprised to find out the oil filter blocked access to the through-bolt on the motor mount. This meant we had to remove the oil filter and its mount in order to get to the through-bolt. When we installed the new M.O.R.E. mount (shown), we reversed the through-bolt and then cut off the part of the bolt that protruded past the bolt before re-installing the oil filter.
The new M.O.R.E. torsion-style motor mounts for the XJ are zinc-coated to help prevent corrosion, use rubber as an isolator, and are direct bolt-in replacements. Although it may not last as long as polyurethane, rubber transfers less vibration to the chassis than polyurethane.
This is what the factory motor mounts looked like. As you can plainly see, they were not in any shape to continue doing their job well. Both were completely worn out, and one had been totally trashed, allowing the powertrain to wobble around like a whirling dervish.
Raising the engine/transmission combo a little also helped take the pressure off the hardware connecting the transmission cross member to the frame and transmission mount, making it much easier to remove the cross member.
Removing the transmission cross-member gained us access to the old and tired factory transmission mount, and boy was it ever crusty. We should have replaced this a long time ago, but as we said before, these mounts are normally the last things on your mind until the powertrain starts to bang against something and make a lot of noise.
Not only was the old factory transmission mount covered in crud, but it also was crushed and bent, and its rubber isolator had been completely destroyed. No wonder our transmission flopped around like a hooked fish on the boat deck.
The new replacement transmission mount from Crown Automotive will keep our XJ’s transmission in its proper place and tame as a kitten.
With the new motor mounts and new transmission mount firmly in place, and the transmission crossmember re-installed, our Jeep Cherokee XJ was ready for some serious four-wheeling once again.

Sources

Mountain Off-Road Enterprises (M.O.R.E.)
Delta, CO 81416
877-533-7229
www.mountainoffroad.com
Crown Automotive Sales
Marshfield, MA 02050
781-319-3100
http://www.crownautomotive.net

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