road gear noise

[arl242]

I have a 492 MF and just began noticing that when I am going down the road in only my highest gear the tractor becomes extremely noisey. It sounds like it may be from the rear end. It's so loud I cannot open the windows and people turn their heads when I come by. If I had to say what it sounds like it would be vibrations. Any help is very appreciated.

 

[5030]

Is it FWA? if it is it needs to be in 2wd.

 

[JWR]

It is hard to guess whether you have a mechanical problem of some sort (such as rear axle bearings, a transmission problem, etc.) You said "Just began...?" Are you sure this was not around previously? Certainly it ought to be in 2wd on pavement as the other person said. Does the nasty noise go away in 2wd ?

I have seen (on both a JD 4700 and a MF2660) that running in the highest gear on hard smooth surfaces can become VERY noisy. There might not be anything wrong mechanically. Keep in mind none of this stuff is intended for high speeds. What happens is that the large rear tire tread bars produce both an audible sound and a vibration at the frequency of the rotation of the tire times the number of lugs. That is normally benign and not all that loud -- sort of as expected. However, resonance comes into play big time. When you get the rotational speed up to a point where the frequency matches the natural frequency of other parts of the tractor there is a huge multiplier in both sound and vibration. Does your noise go away if you slow down by say 10%? Does it also smooth out some above some speed ? My bet is that in the highest gear of farm tractors there is a road speed where the tire lug pounding the pavement resonates with the "slop" or clearances in the transmission or rear end as the gears mesh. When you reach that point of resonance, the noise will be horrendous compared to other speeds. If you can affect the noise a lot by slight changes in speed that's what is going on. If you CANNOT affect the noise much by varying the speed then you probably do have some mechanical problem such as bearings.

 

[Citydude]

JWR is correct. My L3400 sounds like it's going to scatter parts all over the road when I'm in high gear going at high speed. When I let off the throttle and gear down, the noise goes away. It just doesn't like getting in a rush.

 

[redman135]

Make sure you are in 2wd like 5030 says. Some tractors in4x4 at road speed get very noisy.

 

[arl242]

I purchased this tractor a yr ago and have had it on the road 7 or 8 times due to a farm I rent a mile away. I didn't notice the noise the first few times. I do make sure it is out of 4WD. One additional thing I noticed after the last time was when I unhooked the attachment from the rear it seemed hot in the back. If I operate around 1300 RPM's there isn't much noise, but when I throttle up it really takes off. If I go down to my next lowest gear there is no noise.

 

[Citydude]

I purchased this tractor a yr ago and have had it on the road 7 or 8 times due to a farm I rent a mile away. I didn't notice the noise the first few times. I do make sure it is out of 4WD. One additional thing I noticed after the last time was when I unhooked the attachment from the rear it seemed hot in the back. If I operate around 1300 RPM's there isn't much noise, but when I throttle up it really takes off. If I go down to my next lowest gear there is no noise.

Time to slow down and smell the roses? If it isn't making noise while working in lower gears, it's fine.

 

[Smokepole62]

Does it have wet brakes and planetary hubs? If so, make sure the brakes are disengaging. Planetary hubs have separate fill and drain plugs on each side. Could be the hubs are dry.

 

[Smokepole62]

Yep, just looked up on tractor house. Get the manual out and check all your fluids in the driveline. Do a dip test on each and take to dealer for analysis if needed.