Reducing NVH (Noise, Vibration, Harshness)

[Root Moose]

I noticed a big difference in nvh reduction when I did my frame stiffeners.

Ditto

Between this and doing the straightforward stuff like cleaning up drivetrain and suspension angles and sound deadening you'd be well on your way to a quiet Jeep IMO.

Who knows what noises will appear once the easy stuff is done though. For me I don't mind gear whine that isn't too loud or tire hum. It's the squeaks, rattles, wind whistle and thunks that I'm after.

 

[Root Moose]

This stuff looks interesting - in lieu of friction tape, the anti-friction coating?

I don't know if this can be bought retail.

http://www.dowcorning.com/content/news/auto_nvh_news_release.aspx

http://www.dowcorning.com/content/auto/autointerior/noise-vibration-damping.aspx?WT.mc_id=1002601

 

[Root Moose]

Some interesting data in the linked PDFs.

http://www.squeaksandrattles.info/thesandrkit.html

 

[souske]

we used tire "fuzzy pipe cleaner" type plugs at the dealer I worked at

 

[Talyn]

we used tire "fuzzy pipe cleaner" type plugs at the dealer I worked at

for what?

 

[Super mud]

Anybody know of any coil springs softer than rusty's 3in? They say those and stock are ~150lb but I have a squished set out of a burnt tj that measure much thicker. Stock are .500" Rusty's are .565".

They should be much better than what I have now, which are .625" and aren't even flat on the bottom so the drivers side hits the frame rail and sway bar. Don't know the brand since they came on the jeep.

I have a saggy stock pack in the rear. I got a bargain on these nice leaves off craigslist. Mine were mismatched. I added a main flipped around for a "military wrap." Before that they road awesome. Now they ride ok. They sagged bad. Might try to go back softer somehow. Also flipped the little "overload" upside down which did nothing for ride quality. Plus medium length shackle and ~1.5" taller u bolt eliminators I made. (4") If I go down to 3 inches, I should be able to get some more shackle angle out but it's decent now.

 

[souske]

For stopping squeaky old dash plastic BS

 

[Talyn]

For stopping squeaky old dash plastic BS

I'm not familar with what you are talking of, have a URL?

What about some kind of treatment for the weather stripping to lessen the squeaks from that? Armoral doesn't work.

 

[souske]

The sticky rope type tire plugs. If your dash has a squeaky plastic rubbing on plastic sound, insert the string and trim to fit. Just cushions the pieces, aNd reduces noise.

For the weatherstripping, a little silicone works wonders. Clean the old stuff off, then rub a little silicone in to swell and soften the weatherstripping

 

[Talyn]

Ok.. now I know what you are talking about

 

[Adrian96XJ]

The 3 best things I have done to improve the ride of my (About 4" lifted) XJ were installing standard (load rating C) tires, R/C drop brackets & installing WJ lower control arms. The WJ control arms were a big improvement.
Google “wj control arms on an xj" & a bunch of articles will come up, I got the Idea from Go Jeeps site.

I'll post a big X2 on the WJ arms. Apart from narrowing them I also notched them (welded the area back) to clear the shock mount on downtravel

 

[dieselenthusiast]

This thread describes one element that I always consider when building a Jeep. I build my Jeeps to handle moderate off-roading, but most of the time I am towing, commuting, or getting to and from my property (mountain driving, dealing with snow, mud, etc). I’m building my 2000 XJ as we speak, and I have been careful to select modifications that keep NVH in mind. I run OE wheels and a “P” rated tire on both of my Jeeps. A “P” rated tire does a tremendous job of reducing road noise. It’s like a suspension for you suspension. Vibrations are greatly reduced and I have never gotten a flat tire by running a quality “P” rated tire. If you run a Jeep Liberty 17” X 7” rim, then you can have a P rated tire that is 32” tall. I haven’t tried to find a taller “P” rated tire, but they may exist.
I also went with the DPG 4” hybrid lift kit. OME springs/shocks allows you to select the right springs for your desired load. I have front and rear JCR bumpers with the tire carrier. I also added RE drop down brackets to keep my suspension near OE specifications.

My next plan is to start laying down sound dampening material such as dynamat. I will replace all my window seals and weather-stripping once I repaint the Jeep.

Great thread!

 

[kdailey4315]

I have Brown Dog rubber engine mounts and they seem to vibrate a whole lot more than stock mounts.

 

[Talyn]

The brown dog mounts will vibrate more, even their non-poly ones. I have then and like them. You feel the engine a lot more and reduces the chance of the manifold cracking from engine movement. Not for someone that wants no vibrations.

 

[dieselenthusiast]

The brown dog mounts will vibrate more, even their non-poly ones. I have then and like them. You feel the engine a lot more and reduces the chance of the manifold cracking from engine movement. Not for someone that wants no vibrations.

Talyn, what motor mounts would you recommend for those who are looking to minimize vibration?

 

[Talyn]

Stock mounts.

 

[yossarian19]

While putting a clutch into a Volvo 240 series, I noticed that the transmission cross member uses rubber bushings between the unibody and the member. Looked it up on Mcmaster-Carr and there are, of course, lots of options.

Anyone thought about adding bushings to further isolate the drivetrain from the body?

Also, the older volvos used bushings to mount the accessories like the alt / ps pump / ac compressor, etc. I wonder if something similar could be adapted onto the 4.0 - but haven't looked under the hood to consider it.

 

[Root Moose]

The transfer case mount is already a big rubber thingy so isolating the cross member probably wouldn't be needed.

 

[Talyn]

While putting a clutch into a Volvo 240 series, I noticed that the transmission cross member uses rubber bushings between the unibody and the member. Looked it up on Mcmaster-Carr and there are, of course, lots of options.

A Toyota 4 runner i was working on had a damper on the transfer case itself. Bushings between the tc cross member and the body would you give you a TC drop.

Also, the older volvos used bushings to mount the accessories like the alt / ps pump / ac compressor, etc.

How and why? The accessories are attached to the engine which are isolated by the engine mounts. Plus the bushings would cause play in the accessory belt drive.

 

[N8N_99xj]

How does this foam stuff not promote rust? Other than that it sounds great.

I wouldn't use it anywhere that could get wet. Porsche foamed the pillars of the 914 and that's the first place they rust. I'm sure processes and products have improved over the years but in the DIY realm i always worry about rust... Foaming the "frame" seems like a bad idea to me