Yesterday I replaced the motor mounts with Brown Dog brackets & mounts and replaced the OEM transmission mount. That fixed a lot of problems as the driver side engine mount and the transmission mount were much worse than I thought.

Now, I have a new noise. Sometimes when I go over a particularly bad pothole or hit a washboarded patch of dirt road, I get a rhythmic knocking noise in the engine compartment for a second or two afterwards. It seems to be worse when I am going up or down hill.

Any ideas? I can't seem to replicate the problem in my driveway, and I got no problems in about four hours of driving on the highway. I also did not have an issue on a bad stretch of forest service road.

 

First thing to check. Exhaust pipe clearance over the passenger side of the cross member. Especially when the engine is under load/torque.

 

There's about an inch and a half of clearance now between the hanger and the crossmember (it was definitely hitting before in reverse, which is one of the problems that the new mount solved). I will check the actual pipe tonight.

Is the trans mount flexible enough that it can move that far? I suppose I'll try to find some chalk or something to see if it leaves a mark.

 

I just put a trans mount in as well. It was after-market, and immediately gave me clearance issues between the exhaust pipe and cross member. Someone on the forums alerted me, right after I did the job, that it would probably be clanking the next morning. I thought, no way, I just test drove it and it was fine. Sure enough, the next morning, after it had a chance to settle, it was a clanky, thumpy, mess.

So I just thought it should be the first thing you check. The clearance between the pipe and the crossmember is what ultimately matters. Regardless of how high the hanger is. So I have a mopar mount coming tomorrow, and I'm hopeful its just that the after-market mount is too short and too soft. I'll be able to compare them visually once I get the new mount, and perhaps take a few comparison pictures.

What brand trans mount did you go with?

 

Mopar mount.

The rubber in my hanger is sagging and I was thinking yesterday as I was putting on the new mount that I should have replaced it too. Unless the bushing is sold separately this is another $75 down the jeep hole:

http://www.moparpartsoverstock.com/p.../52058882.html

 

UPDATE: It is my transfer case hitting my factory skid plate. I must have slightly changed the angles with the lift or the new mount is quite a bit softer than the old one. I also have a 242 case which I believe is a bit bigger than the 231.

For now I put some washers on the skid but I think the ultimate answer is to get an aftermarket skid like the JCR.

 

I have a 242 and factory skid. I used a NAPA transmission mount to fix clunking between the transfer case and skid.