Third times the charm, or so they say. I've been down this road many times. The first time was with JKS/Currie 1" Motor mounts. I had to do some modifications to get these to work correctly on my YJ. Of course, the 2.5L YJ has to be the black sheep making aftermarket parts scarce for them. (The 4.0L YJ, TJ and 2.5L TJ use the same mounts.) I never really talked to anyone about the second pair I acquired. These were from a company called Trans-Dapt Performance (TD Performance). They mainly sell to places like Summit Racing and JCW to name a few. They contacted me out of the blue, wanting to create a 1 and 2 inch engine lifts for the 2.5L YJ. I think they must have read my article on 4x4wire.com when I did the modifications to the Currie set.
After several emails back and forth, they sent me a prototype set to try out. With a little more tweaking, they were perfect and so TD Performance started selling them. Although last I saw, they had dumped the mount idea and went with a spacer instead. This is what JKS has done. The biggest advantage to the spacer is that you retain the stock mounts which are soft and keep the engine vibrations down. This is really important with a 2.5L since they tend to vibrate more then the 4.0L's. The polyurethane mounts aren't bad but they do transmit more vibrations then the stock. The vibrations are most noticeable when idling but are also felt at higher RPM's. So, after 5 years with the poly mounts, I raised the white flag. With suspension seats like MasterCraft, Beard &Premium Racing Products (PRP), there is no foam to absorb small vibrations. So every vibration from the engine goes straight to you. Don't plan on having a soda stay carbonated for long either. So it was out with the old and in with the...well, older and new.
The original engine mounts were sold off long ago. Even so, rubber degrades over time and they would have needed replacing anyway. Contacting a friend at
Willys Off-Road Supply Company and a new set of engine mounts were on their way. I should mention that
Crown Automotive Sales Company Inc. has picked most of the replacement manufactured parts for the most Jeeps. The package includes the passenger and driver side mounts along with the transmission mount. At the same time the
JKS Budget Motor Mounts were on their way, too.
Most if not all of you will just be adding the spacers to your existing mounts. This makes things easier as I've managed to lose some metric nuts that are required for the install. So instead of slapping these babies in, I had to run to the hardware store. On a YJ, the belt tensioner is built into the power steering (p/s) pump (on a TJ, the belt tensioner is a bit different, refer to Factory Service Manual for details). This requires removing the air box then loosening three 13mm bolts. There is one bolt on the front and two on the backside. One of the bolts in the back is under the intake runner. Use the same 13mm socket or wrench to loosen the lock nut at the bottom of the p/s pump. There will be a bolt that runs perpendicular to the engine which will move the p/s pump and ultimately adjust the belt tension.
Once the belt is removed the Alternator can be removed. There are two 15mm bolts holding it in place. The top-most has a nut on the backside. Be sure to disconnect the oil pressure sending unit wire before moving the alternator. It's the wire that goes to the small canister attached to the side of the engine block, just behind the alternator. Lift the alternator forward and place it on the fender so it's out of the way. This will expose the passenger-side engine mount.
Next, you will want to support the engine. Use a floor jack to lift the engine and take the weight off the engine mounts. Once the weight is off the mounts, work on once side at a time and remove the bolts. The passenger-side will have one large bolt running though the mount. The mount sits on a small spacer that raises the mount up an inch. This will be removed with the mount still attached. On the underside, there is one large bolt that holds the spacer to the frame. Once that's removed the mount should come out.
Be aware that this spacer is only on 2.5L YJ's and many times is missing. A stronger replacement can be bought at the Dealership if it is cracked and/or missing. The spacer will have a stud welded in the center and on the other side a hold and another stud. To use the JSK Budget mounts, the outer stud must be removed. This is easily accomplished by drilling out the stud. The head of the stud will remain but that's ok.
The only other modification that will be required on all Jeeps is with the mount stud. This will need to be trimmed 1/4" to allow enough room for the supplied thread adapter to fit. Once that is done the adapter can be installed. Make sure you tighten this down as much as you can now. Once the spacer is on, you can not tighten it. Also if it is loose, it will spin off the stud if you try to move the mount later. (This isn't really a problem if you're removing the engine mount anyway.)
Here's a trick that will save you time. Too bad for me, since I forgot it this time and had to relearn it the hard way (wasting several hours fumbling with it). With the engine jacked up. Put the mount in place on the engine side and slide the bolt through so the engine mount is hanging off the engine. Then lower the engine and finish bolting it to the frame. If you don't do this, it will be very difficult to align the engine with the mount later. The driver-side can be a real pain with the limited space and two bolts to align with the frame but it's a lot easier then trying to align the mount to the engine. I should also mention this is really a two-person job, one person to man the jack while the other person tries to align the holes. It can be done by one person but takes three times as long.
Once both mounts are in, the only other thing to do is put it all back together. Make sure you adjust the belt to the right tension or else it will squeal. Also make sure you reconnect the oil pressure sender wire.
Conclusion:First thoughts; after years with poly mounts, going back to rubber mounts was interesting. Hopped in, turned the key and the engines starts up. You heard the noises but nothing else. No shaking, no rattling, everything was stagnant for once. I’d gotten used to the polyurethane vibrator. The polyurethane mounts do feel firmer off the line though. The engine doesn’t torque as much which allows the power to reach the wheels quicker. Feathering the clutch differently was required.
For long road trips the rubber mounts are really nice. No more vibrating rear view mirror and sodas will stay fizzy even after a few stops. For those who are doing this for the first time though, nothing will change. The rubber mounts will give you better driveline angles. Instead of having to install a 1-1.5 inch transfer case lowering kit, the 1 inch motor mounts will do the same without sacrificing ground clearance. So, if you want to get rid of your transfer case lowering kit and don't want to feel like your driving a vibrator (although some might like that feature) then check out the JKS Budget Motor Mounts.
