Reducing NVH (Noise, Vibration, Harshness)

Yesterday I finally got a chance to apply some quality time to my Jeep (MY01).

I took the dash apart and found that the bracket behind the speedometer cluster was missing the three bolts that hold it down. There was a bolt or two missing elsewhere as well. I put it all back together properly with the correct number of bolts and the amount of noise and squeaking coming from the dash area is much reduced. It still very slightly squeaks a touch due to the tires causing a slight vibration. The treads on the Duratracs I am running cause vibration on pavement, just no way around that. It really starts to get noticeable above 80 km/h.

The glove box door was squeaking - it's probably the noisiest squeak in the cabin. I ran into Home Depot and got a roll of the friction tape referenced earlier in this thread. It appears to be basically fabric hockey tape with a little less tack to the glue. It's not expensive so I bought it anyway. I took the two clamshells that comprise the glove box door apart and applied the tape to both sides at the top edge where the lock/handle is. I applied it such that the tap is just visible where the pieces touch. That made that squeak disappear.

But, the front of the interior was quiet enough to make the squeaks in the rest of the inside more apparent. The rear hatch cover was rattling. Both of the screws at the bottom of the rear window had broken free of the plastic (broken) and were rattling so I pulled them out.

Jeep was quieter again but still some squeaks. The rear passenger side door opening moulding around the bottom was squeaking at ~100km/h. Took it apart and re-installed. Tightened down the bolts nice and tight. Gone.

The rest of the interior mouldings were still squeaking at times so I went around the whole interior tightening everything up. Around the rear hatch opening was particularly bad.

After doing all this the Jeep is really quite quiet inside. Still the occasional squeak when you hit a bump but I can live with that.

The bodies on these Jeeps are so flexible I think that the bolts/screws will all loosen up again over time, especially with off-roading. I'd like to come up with a way to keep the screws from backing out. Think a small rubber washer under the heads of the bolts/screws could allow the parts to flex but not let the screw back out? I'm going to try it.

I'm still going to take the dash apart again and apply friction tape pretty much everywhere that makes sense to see if it makes any difference to the remaining squeaks. I think where the front fascia piece meets the top of the dash is a good candidate location for more tape.

So, now my Jeep is pretty decent inside as far as noise goes, doesn't sound like the typical Chrysler POS.

The noises that remain:


  • The wind noise around the windshield - not much you can do about that with such an upright glass and weather strips. Maybe some sound deadening under the head liner could help but it's really not that bad.

  • Tire humm. Not objectionable, kinda dig it.

  • Rear diff noise from the 4.56s in the axle. It's not loud or anything, gears are installed correctly, etc., etc. It's just the nature of the beast. I'll probably add some sound deadening to the floor over the rear axle eventually. I'm the only one that notices it so it's really not a big deal.

  • The poly/ure bushings in my long arms are quite noisy when they get dry. I want to find a rubber bushing to replace them with. I'll have to re-lube every few months in the meantime.

  • My front propellor shaft "roars" when engaged (have locking hubs) but it needs a rebuild so I'm certain something can be done about that mechanically to quiet it down.

Once I do the items on the list above I'm going to guess that noise from under the body and the doors will be more apparent.

But, do the simple stuff like I did and the worst of the noise will go away and make the Jeep more enjoyable. It really doesn't cost anything either, well, $2.97 for the friction tape if you don't have any hockey tape lying around.
 
If anyone wants an OEM Lexus noise kit hit me up. It's just a Toyota labelled box with all sorts of foam, felt, and adhesive backed noise isolating goodies.
 
I'm chasing noises around the cabin now it seems. Took the dash apart again to get at the instrument cluster. Put friction tape between the clear bezel and the housing itself and now the entire dash area seems to have a very solid "impression" to it.

The shifter bezels and centre console started rattling though. Took them apart and applied lots of tape. Quiet except some times the latch on the console will buzz at certain RPMs. Cruising at ~90km/h is particularly bad. Time for some foam tape on the lid to keep the latch under tension - may fix this.

There seems to be a buzz/rattle in the driver's side B pillar moulding but I can't find it while driving the Jeep. Need to get someone else to drive while I figure it out.

Wind noise between 120-130 km/h is really noticeable now. I take back the statement that adding sound deadening to the roof isn't worth the bother. I'll do it when I get around to it.
 
For the wind noise try moving the roof rack cross bars around. This is for the WJ, but might point you in the right direction: http://www.wjjeeps.com/tsb/tsb_wj_2301303.pdf


I did not know this was an official Chrysler policy. I have been doing this for several years on my XJ and found it works wonders in reducing the wind noise at highway speeds.
 
I'll give it a try or remove them all together. My Jeep has the "short" rack so I don't think the noise I am hearing is the rails but the rails may be contributing a dull roar in the rest of the cabin.

The noise I am hearing is right at the A pillar. The weather strips are fine - just how the Jeep is shaped I guess.
 
I'll give it a try or remove them all together. My Jeep has the "short" rack so I don't think the noise I am hearing is the rails but the rails may be contributing a dull roar in the rest of the cabin.

The noise I am hearing is right at the A pillar. The weather strips are fine - just how the Jeep is shaped I guess.


There is actually quite a bit of noise around the A pillar. Try to seal it as best you can. Some people have used after market rubber strips or weather strips from different auto manufactures with varied results. I myself have not done that. Instead I turn my music louder and sing, or at least try to sing while I pretend the noise do not exsist.
 
I will replace all my window seals and weather-stripping once I repaint the Jeep.
Is there a general consensus on which ones to get? Are stock the best bet, or is there an aftermarket supplier that has a better alternative?

My '99 leaks air around the A pillar, and I really need to do something about it.
 
There is actually quite a bit of noise around the A pillar. Try to seal it as best you can. Some people have used after market rubber strips or weather strips from different auto manufactures with varied results. I myself have not done that. Instead I turn my music louder and sing, or at least try to sing while I pretend the noise do not exsist.

You mean where the door opening is? As in air leaking in/out of the cabin? I'm pretty sure I don't have that happening, can't feel any air movement with the back of my hand.
 
I took my door cards off so I can clean and lube my door lock mechanisms and linkages and found the source of a few other rattles.

All of the rivets that hold the door lock actuators on were loose the drivers door was broken by the power window regulator.
doorwithlooselock.jpg


The sweet MS paint arrows are pointing at the two rivets, I didn't see any way to tighten them so I brought the welder over.

weldeddoorlock.jpg


Small welds and not all at once, I didn't want to put too much heat into the actuator. Yes its a different door, but this one is prettier.

Drivers door:
crackeddoor.jpg


Welded door:
welddoor.jpg


With all of the lock actuators welded in place and the door welded back together the doors close with a nice solid thud and there are less rattles when I hit a bump in the road.

There were 7 cracked wires in the bundle going from the drivers door to the main chXXXis harness. If you're opening up your door for repairs you should check those wires while you're in there.

~Alex
 
I have the same crack to weld up on my door. For even more of a thud a little sound dampening on the outer shell makes a big difference.
 
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