Turned rotors and not the problem. I believe it is driveshaft u-joint. Vibrates when accelerating. Stops when coasting and vibrates when using engine to slow down. Just have to figure which one and how hard to change.

Just wondering if anyone thinks my major front end vibration may be due to bad engine mounts.
Refresh:
92 montero rs
wheels balanced
rotors turned
bad vibration on acceleration
stops when coasting
happens when using engine to slow down.

How hard are they to change?
Thanks

I'm always in trouble. And it doesn't look like it's gonna stop now.
I'll have my wife spank me later for posting the same question twice. This may actually work to my advantage.
Anyway anyone got any ideas on the engine mount question?

Not sure I'm following your repair process... you think its the ujoints, but you still suspect the engine mounts? Or are you trying to figure out other possible options?

Also, you'll get more results on your questions if you try to make your questions and subsequent followups as specific as possible. For example, when did you balance the wheels? Was it lately? I've had wheels balanced, and chuck a weight on the way home...

In any event, I've seen instances of a vibe that feels like its in the front, but turns out to be a result of something wrong in the back: rear ujoints could manifest a problem this way...

I am thinking out all options. in the last 2 weeks had the tires balanced. Did not fix the problem. Then I took the back wheels off and put them on the front. Did not fix the problem. Then I turned the front rotors now it stops nice but still vibrates.
So now I am wondering if it either engine mounts or rear axle u-joints. It does not vibrate when I am coasting only when accelerating or using the engine as a brake to slow down.
Also know the wheels did not chuck a weight because they came home in my pickup. This thing still vibrates too badly to drive anywhere.

Put it in N and lock up the ebrake. Crawl under and wiggle the rear DS and look for slop in the ujoints.

Others can correct me if I'm wrong, but with the Gen 2 4-wheel system, your front driveshaft is not turning if you're still in 2 wheel drive with the factory system. The front axle disconnect system [CAD as posted by others]allows this to happen. So, only your rear driveshaft u-joints would be a cause for concern if you're getting vibration while driving, front's should be ruled out if you're still in 2 wheel drive.
That being said, check ALL the drivetrain mounts, I've had strange vibration issues due to wear in some of them. I've replaced the T-box mounts, and one at the front diff.
Also check the front crankshaft pulley bolt at the engine, I too have had vibration -on-acceleration issues from the engine when my "second issue recall bolt loosened up" and once I replaced the crankshaft pulley bolt and pulley with the latest stuff from Mitsu, that too went away[seriously, 3 mods to one crankshaft bolt <img src="/forums/images/graemlins/angry.gif" alt="" />, I mean <img src="/forums/images/graemlins/rolleyes.gif" alt="" />]
Anyway, there's a few more things for you to check. Let us know what you find

I just checked the u-joints on driveshaft and they are toast.

Toja so...

I have replaced all the bearings. the main driveshaft u-joints had the tires mounted and balanced and still have a vibration at 20 in 4wd and 2 wd.