Noisiest PT Ever

[BobRip]

When comparing my PT422 to Clint Blake's, we noticed that his was much quieter. The only real differences are that I have the ROP and I have cut holes in the sides of the cover where the exhaust pipes end. I also have plastic tool boxes, one mounted in front of the fan and one mounted behind the fan. The machines were made within a few months of each other. I always wear ear protection and Clint never does, there is a definite difference. My 422 has been loud since new and is now 5 years old.
Has anybody got suggestions on why this could be happening and what I could do about it.

Bob Rip

 

[J_J]

This a principle of acoustic dynamics, which I learned in my Navy training many years ago. You are probably hearing the sound of the exhaust from two directions. One path direct, and the other path redirected. If you remove the rops, you will notice a difference, but the rops is there for protection. You should line the bottom of your rops with sound absorbing material. A layer of foam might be enough to dampen the noise. You might try two different types of foam, a low density foam which has lots more air space , or a high density foam which would be more dense and not easily compressed. Even a piece of carpet with a foam backing would help. I would make a temporary jig to try out different types of material. Ear protection is always good. I hope this little bit of knowledge helps in some small way.

 

[Barryh]

Another thought might be to take a very light piece of plywood paneling. Cut it to within a few inches of the Rops on each side width wise, and run it down from the top of the Rops to the bottom of the seat in the back. Attach it near the bottom somewhere.

You could attach it top side to the back of the Rops with extended brackets so it stayed angled with your engine cover. You could also put it on hinges so it could move when not secured to the bottom of the seat for checking tank oil and so on. Maybe paint it black and put black molding around the edges. If done right I am sure it would just look like part of the PT. I would think it would deflect engine sound away from you. If this were my machine and the sound bothered me that much I would give this a try. If you don't like the end result you could always take it back off later. /forums/images/graemlins/shocked.gif

 

[Barryh]

You could also cut a window slot and put in a light weight piece of Lexan to see when backing up. /forums/images/graemlins/shocked.gif

 

[BobRip]

J.J., that seems like a good idea. It confirms what Clint Blake was suggesting. I will try this first.

Thanks
Bob Rip

 

[BobRip]

Barryh, thanks for the suggestion. If J.J.'s suggestion does not do enough noise reductions, I will give this a shot. It sounds like something I could design to take on and off easily.

Bob Rip

 

[Barryh]

Bob,

I can't tell you how much I am really liking my cab on the PT.
Not only does it quiet it down inside, but I was moving a small rotted tree the other day about 6 inch thick, it fell back and hit the thick Lexan glass in front where my head was and bounced off onto the ground. Did not even scratch the glass.
I am thinking about improving it making it more stream line, and so the side windows can open during the summer time. I may just keep it on all year with some improvements not sure just yet. It was not hard to build and it would filter out most of your noise. Just a thought. /forums/images/graemlins/shocked.gif

 

[BobRip]

Good thought. Thanks. I bet the windshield also stops chips from the stump grinder. Mine is an old version and cannot be reversed. I did make a windshield once to help in cold weather. It helped, but I broke it. I may make another.

Bob Rip

 

[BillCroasmun]

Barry,
Nice feedback on the cab. I was wondering how you liked it. I never gave noise reduction a thought with regards to a cab. I also never thought about leaving it on year round I imagined it would be hot but with removavble or opening windows that may not be bad either... With our lack of snow so far this year my soft cab conversion hasn't been a priority (althogh I did look at a Craftsman walkbehind snowthrower cab which just has the three sides that may be a quick conversion. /forums/images/graemlins/wink.gif)

 

[Barryh]

Yes it would be great for blocking wood chips, also nice if you want to work in the woods during a rain storm. I already tested that out. Mine was a hurry up job knowing winter was coming, it turned out much better than I thought.

This summer I plan to take it back off and improve on it. So far haven't had the need to install a heater. I'll make a frame for the side windows so they come off or open. May still end up being to hot. We will see. /forums/images/graemlins/ooo.gif

 

[Barryh]

Hey there Bill,

If I decide to leave the cab on year round. I plan to put in a small console with 12 volt plug in's and some extra toggle switches for extra lighting. The 12 volt adaptors could be used for a plug in fan during the summer and a heater during the winter among other things. /forums/images/graemlins/ooo.gif

The soft cab idea is a good one as long as you don't turn your baby over. I would worry that it would keep me from jumping clear in that situation. I read somewhere someone had a JD or Kubota and bought a golf cart soft cab and rigged up some tubing to drape it over and it worked great. You might want to check into that also.

 

[BobRip]

</font><font color="blue" class="small">( This a principle of acoustic dynamics, which I learned in my Navy training many years ago. You are probably hearing the sound of the exhaust from two directions. One path direct, and the other path redirected. If you remove the rops, you will notice a difference, but the rops is there for protection. You should line the bottom of your rops with sound absorbing material. A layer of foam might be enough to dampen the noise. )</font>

J_J, I went out a bought some foam from an acoustic engineering firm. Don't ask me what it is, but it seems to help. The sound is very different now and muffled. While wearing my ear protection/radio I can hear the radio much better and at a lower volume. I also got some Dynamat and put it on inside the engine compartment on the solid sections. It is supposed to dampen the vibrations in the metal. I actually did this first, and put some under the ROPs. I could not actually see a difference from it. I then covered most of the under ROPS with the foam. I have attached a picture.

One word of caution, the foam had some dust in it. I seem to have caught a cold from the dust, unless it's just a coincidence. I have since blow off the dust. I hope I got it all.

So the under ROPS foam was a good suggestion. My thanks to Clint Blake and J_J.

Bob Rip