greetings all. I have a case 420CT that i recently purchased that seems to have an annoying and buzzy muffler vibration at about 2/3 of full throttle. If you place your hand on it while its vibrating its really apparent. It only does it in a certain RPM range. lower rpm and high rpm it smooths out. I am wondering if anyone here has had this happen? Is it familiar to anybody? where does one even start looking? Regards Tony
Sounds like the baffles are busted inside of it and you need a muffler or ear mufflers.
thats a real possibility...resonating at certain rpm's, i will take a look
Sounds like you’re probably chasing an exhaust resonance issue. The fact that it only happens at one RPM range and goes away above and below that is pretty typical. I’d start by checking the simple stuff first — make sure the muffler brackets, clamps, and bolts are tight, and look for any spot where the exhaust might be touching the frame or a heat shield. Also, check the muffler itself. Sometimes the inside baffles can come loose and only rattle at certain RPMs. Since you can feel it by putting your hand on the muffler, try holding different parts of the exhaust while it’s doing it and see if the vibration changes. That usually helps narrow down where it’s coming from.
The baffle issue was pretty common and a lot of people spend money on a new muffler. Mufflers got real expensive over the year and I started the cut the end off the muffler with a cut offf wheel on a disk grinder and look inside first. Usually I would just take out the broken stuff and weld the end back onto the muffle and all was fine. This only works if there are no holes in the body of the muffler.
Been there and done that myself to donate some of my own time to save a few bucks and not just on equipment.