Sound Insulation

Topic: Sound Insulation (Read 1342 times) previous topic - next topic

Sound Insulation

August 22, 2018, 04:19:00 pm

Has anyone found a successful way to insulate the drivetrain noise while driving? I would say most of the noise is the whine of the transmission. The other day I placed several sections of 3/4" rubber mat in the bathroom and kitchen area. That did muffle the noise a fair amount but not enough and the rubber mats on top of the ceramic tile are not a viable option.

I have considered some spray foam insulation on the underside. Some expensive other brands have a type of spray foam on the underside.

Thank you for your thoughts.

Re: Sound Insulation

Reply #1 – August 22, 2018, 04:56:39 pm

Look on Ebay at the "Noico" products,it's heavey foil backed by butyl rubber designed for heat and noise,have used the products
with good results.It's sticky,just follow the directions.

Re: Sound Insulation

Reply #2 – August 23, 2018, 01:57:41 pm

Whine is usually from the differential. If it's very loud it may need adjusting or new bearings. Not a job for anyone less than a shop that knows what they are doing.

Keith

Re: Sound Insulation

Reply #3 – August 23, 2018, 02:12:25 pm

Agree with Keith,we have road noise but no whine or anything like that from that area,try greasing the u-joints and the drive shaft
zerts and see if it effects the noise any,if it sounds different you know it's in that area.

Re: Sound Insulation

Reply #4 – August 23, 2018, 02:53:15 pm

I have considered the differential, and it may well be the differential. I have checked the temperature with an IR gun and it runs about 140 degrees F. The driveshaft was lubricated in May. What makes me think it is not the differential is that the pitch changes as the transmission shifts. The differential gears change speed gradually as your vehicle speed changes.

What kind of adjustment is there in the gears?

Thank you

Re: Sound Insulation

Reply #5 – August 23, 2018, 04:01:37 pm

I only notice engine noise and road surface dependent tire noise.

Re: Sound Insulation

Reply #6 – August 23, 2018, 08:19:29 pm

Quote from: Ed W – August 23, 2018, 02:53:15 pm

I have considered the differential, and it may well be the differential. I have checked the temperature with an IR gun and it runs about 140 degrees F. The driveshaft was lubricated in May. What makes me think it is not the differential is that the pitch changes as the transmission shifts. The differential gears change speed gradually as your vehicle speed changes.

What kind of adjustment is there in the gears?

Thank you

May be turbo whine, or just engine noise. Adjusting a differential can be quite labor intensive as it usually involves disassembly, adding shims, reassembly and rechecking, and maybe doing it again. Shady used car dealers we're known to just add sawdust to get rid of a whine.

Re: Sound Insulation

Reply #7 – August 24, 2018, 12:08:34 am

There is a bearing on the front of the transmission behind the harmonic balancer where the shaft leaves the transmission. If this bearing develops play or comes loose, it will make noise and vibrate. The only solution is to take it to an allison shop and have it inspected. It requires a special tool to tighten. I had mine checked at stewart & spencer in Dallas last week. got a clean bill of health and no charge.

Re: Sound Insulation

Reply #8 – August 24, 2018, 11:07:02 am

Ed,thought about the problem,check the fluid just to make sure it's full,can check from the keypad and the dipstick.

Re: Sound Insulation

Reply #9 – August 29, 2018, 11:41:29 pm

Ok, after driving the coach a few hundred miles over the last few days and listening to the noise and looking at the Silverleaf display, I would say the most prevalent noise is NOT coming from the transmission as I had thought. I checked the differential fluid level and checked the axle temperatures at all the bearing points. Temps and level are good. Trans level is also good. So maybe the noise is at "normal" levels. It changes directly with engine load. I will have someone in NAC listen to it in November. In the meantime maybe I will drive a different coach to hear what their "normal" is, or I might find someone to drive mine that has a point of comparison.

I did drive with both doors (bathroom and bedroom) closed today and that helps.

Thank you

Re: Sound Insulation

Reply #10 – August 30, 2018, 11:21:02 am

Probably from the Rockwell rear end. Some of them like to "whine"

Re: Sound Insulation

Reply #11 – August 31, 2018, 12:37:10 pm

I have read this thread with interest wanting to know what could cause such a noise. Today, I had a crazy idea to ask about. Could it be the fan kicking up to high? I know with our coach, when I use the high idle, the fan noise is much greater inside the coach. It too has a slight whine and is very noticeable. Is the noise present when you use the high idle?
Like I said, it's a crazy thought.
glen

Re: Sound Insulation

Reply #12 – September 01, 2018, 11:37:02 am

If by high idle you mean turning the cruise control "on" and then hitting the "set" button and the idle kicks up to about 1000 rims, the answer is no. Not sure how I control the fan speed or what the fan sounds like.

My noise is likely the differential and a "normal" noise. Within the next few weeks I hope to add some insulation on the underside above the rear axles and see what that does for the noise. Part of my problem is I drove a Prevost a few weeks ago and could not hear much of any noise. So the challenge is to make the FT quieter.

Re: Sound Insulation

Reply #13 – September 01, 2018, 02:26:29 pm

My coach developed a significant amount of driveline noise in very short period of time. I'm guessing the noise was there but not really noticed until it got pretty bad. It turned out to be a very worn pinion bearing and once that was replaced there is no noticeable driveline noise in the cockpit area. I think if you isolate and fix the problem you probably won't need any additional sound deadening material. As a matter of fact if you did add the sound deadener you may just be covering up a potentially more serious mechanical issue.
Once again my 2003 U320 has no noticeable driveline noise so I would suggest that yours shouldn't either if all of the mechanical parts are working properly. My $0.02 worth.

Steve

Re: Sound Insulation

Reply #14 – September 01, 2018, 03:50:04 pm

Ed, we have a 38 ft U320 and I have never heard any driveline noise.
I agree with Steve B. You should try and find the cause of the noise as opposed to just adding insulation to mask the noise.

Re: Sound Insulation

Reply #15 – September 01, 2018, 04:49:57 pm

Thank you for the comments. Now to find someone who would be qualified to diagnose and repair, unless I wait until I am down in NAC in November.

Re: Sound Insulation

Reply #16 – September 01, 2018, 05:08:08 pm

It could just be your tires some brands run quieter than others.

Re: Sound Insulation

Reply #17 – September 12, 2018, 07:07:25 pm

Picked the coach up from Inland Truck Service in Des Moines today. They replaced the u-joints and installed a re manufactured carrier bearing assembly. Much quieter on the way home. Likely quieter than when we bought it 20K miles ago. Now I just hear a bit of tire noise and a little bit of wind noise.

I think I will spray some insulation in the front tire wells and see if that absorbs the bit of tire noise there is.

$3400 at Inland if anyone is wondering. Glad to have it quiet now.

Have a good day.

Re: Sound Insulation

Reply #18 – September 12, 2018, 07:23:47 pm

Wow, $3400? Did they do a lot more repairs?

Jim

2002U320

Re: Sound Insulation

Reply #19 – September 12, 2018, 07:29:21 pm

No, just u-joints and the differential assembly.

Re: Sound Insulation

Reply #20 – September 12, 2018, 08:47:52 pm

What do you think was/caused the problem?

Re: Sound Insulation

Reply #21 – September 12, 2018, 08:54:42 pm

Do not know what caused the problem. I think they were a bit surprised at only 170K miles and how clean the fluid was. The fluid (Amsoil synthetic) was changed at 50, 100, and 150 K miles.

Re: Sound Insulation

Reply #22 – September 12, 2018, 09:06:13 pm

Quote from: AncloteJoe – August 24, 2018, 12:08:34 am

There is a bearing on the front of the transmission behind the harmonic balancer where the shaft leaves the transmission. If this bearing develops play or comes loose, it will make noise and vibrate. The only solution is to take it to an allison shop and have it inspected. It requires a special tool to tighten. I had mine checked at stewart & spencer in Dallas last week. got a clean bill of health and no charge.

That issue is for the md3060 transmission. The u320 has the HD4060

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