Adding a 2nd muffler on a JD 790

kebo · Nov 14, 2008

Hey all, been away from here for a long, long while. Just sort of lost in interest in reading here but just got it back since I just picked up a sweet 2001 4x4 790 with Model 70 FEL and bar tires. Loaded it up and drove away for a cool $9500 exactly a week ago today, not bad huh? Clock shows a mere 388 hours and really looks a lot newer than its age.

To tell you about me some, ten years ago I bought an '81 JD 750 that was two wheel drive aand included a 4ft disc harrow for $4500. So, I came here and started asking a lot of questions since that was my first tractor. After using it for about 4 years, I traded that one and $1000 cash for an '84 750 that was 4x4. At that point I had about $5500 in the '84 model. Anyway, that one whet my appetite for about 6 years in which time I built up an even bigger appetite for more power and a FEL. Came across the JD 790 on craigslist a week and half ago and jumped on it like flies on a dog t**d. Couldn't be any happier about that purchase!

Anyway, as you all know the 790's have the muffler under the hood with side covers on it to help muffle the sound a little bit. These engines are also direct injection which usually doesn't have as loud of a diesel pinging like the indirect injection motors (on the 750's) have. To get to my point, I'm now 51 and like many folks our age have accrued some hearing nerve damage over the years. This has resulted in a condition known as hyperacusis, which basically means I'm hypersensitive to most sounds that wouldn't bother someone with no hearing nerve damage. I also have "distortion" which means that when I do hear sounds above a certain sound level it sounds like a I'm listening to a busted speaker cause it makes a "rattling" sound. So yeah, I've been wearing ear plugs and hearing protecters for several years now (around loud stuff) to protect what hearing I do have.

So my question is: I would like to quieten down the 790 just a little bit more if I can so I'm wondering if adding a 2nd muffler inline with the straight vertical exhaust pipe would quieten it down anymore? Or do you think it would be a waste of money and have little or no desired effect?? I still wear plugs with it, especially when I'll be running a bush hog, I just want to make it quiet as I can cause it really helps make riding it more comfortable and enjoyable for me. What do you all think about adding a 2nd muffler????

Oh yeah, I sold the little '84 4x4 750 through tractorhouse.com in just two days for a cool $5800! That included the 4ft Landpride bushhog I was pulling behind it because I'm planning to get me a 5ft bushhog for the 790. So, I basically got my purchase price back out of it and I'm quite happy about that too. Now I can go shopping for new bush hog!! Thanks in advance for any comments you folks can provide.

I'll have more questions to ask about the 790 but I'll bring them up later on. I did get the manual with it and have read it from cover to cover already (well, except for the spanish half of it) but it doesn't cover everything. Nothing in there about removing the FEL!!!
That will be another thread I guess....

john_bud · Nov 14, 2008

Dang Kebo, you perfectly described my ears!

I wear top notch shooting muffs around any thing loud. I also have trouble hearing in loud areas like bar, crowded room etc. It's wierd as I can make out conversations across the room, but not next to me.

ANyway, I would get a top notch Donaldson muffler. One of the coated models. You may have to do some farmerization to get it to fit and mate up. You don't want a straight thru design. You want one that has a blockage, but will need to upsize to keep the flow good. Probably have 1 1/2" pipe now and would be good to go to a 2" or 2.5" ID design. It should drop the sound volume and the tone down lower - deeper. The coated mufflers have an external coating that also makes them quieter. If you want it to be pretty, a stainless sleeve could be cheaply made and fitted to the outside.

jb

SPYDERLK · Nov 14, 2008

Isnt most of the noise from the engine itself and not the exhaust. Assuming your muffler is intact...
larry

patrick_g · Nov 14, 2008

Likewise the ear thing guys...

A second muffler will make it quieter but maybe not as much as you would expect. Lots of the noise is not in the exhaust note. Having the exit hole of the exhaust system farther from you and aimed away from you will help noticeably.

Mufflers emit noise directly from their walls as the acoustic pressure waves inside the muffler bang away on the outer walls of the muffler (like beating a drum.) It will be better if you can get the body of the second muffler away from you.

Pat

Hooked_on_HP · Nov 15, 2008

Insted of adding a second muffler I would replce what you have with a good quality automotive muffler. I did this on my tractor and made quite a difference.

kebo · Nov 15, 2008

Hooked_on_HP said:
Insted of adding a second muffler I would replce what you have with a good quality automotive muffler. I did this on my tractor and made quite a difference.

Now that's something I hadn't thought of! I will have to look at that pretty hard when I get back up to my parents house, that's where I keep my tractor at. Thanks!

Mech · Nov 15, 2008

I thought about a second muffler on mine but I just put an extension on instead to get the exhaust away from the loader arm. I decided most of the noise comes from the engine and echos off my canopy.

dynasim · Nov 15, 2008

Apparently(I don't have first hand knowledge), there are active sound deadening ear muffs available that are quite effective. There have been a couple of threads about them.

They work by actually cancelling the sound out. I am pretty sure the technology and concepts are valid.

Anyway, they would also help with the bushhog noise.

Chris

kebo · Nov 15, 2008

dynasim said:
Apparently(I don't have first hand knowledge), there are active sound deadening ear muffs available that are quite effective. There have been a couple of threads about them.

They work by actually cancelling the sound out. I am pretty sure the technology and concepts are valid.

Anyway, they would also help with the bushhog noise.

Chris

Chris, I already have a pair of Philips noise cancelling headphones that I use when I travel by plane. They really aren't that effective at deading noise imho. I also have a pair of Howard Leightner electronic sound amplifing/noise limiting headphones that I use when I deerhunt to protect me from the rifle muzzle blast. They shut off momentarily when the sound pressure level exceeds a preset decibel level. Now these headphones will REALLY deaden the sound, but they get pretty uncomfortable after a couple hours use or when it's really hot weather. That's why I want to put more focus on reducing the noise at its source. Thanks for everyone's comments though.