I have a b7800 that has 39 hours on it. And it has started to make a noise underneath the seat area in the drivetrain or slightly more forward.It only does it in 4wd and when the tractors cold. when it warms it goes away. The Dealer is baffled and has changed front bearings in the frontend of the driveshaft area.(said they were overtightened from factory). this did not solve the noise. its getting worse with more hours. So now the dealer has changed the mid bearing in that front shaft and still nothing. The pump pressure was 500pounds low in forward speed so they put a new valve in it bringing the pressure where it is supposed to be (4500psi?) .Now kubota has been involved and they said to quite that noise,fill that hollow Front driveshaft totally full of grease. The dealer has drilled a hole in this and has used a needle on a grease gun and filled it.Also the back plastic cover has a weep hole for moisture to seep out and they have filled that with grease also making one big mess do to slinging. The Grease has fixed the syptoms but not the problem. It still growls and chatters high pitch in 4wd. Its just muzzled with the grease. I have googled this and seems to be a problem with kubota. Of course they are playing dumb. I Feel this has something to do with the gears in the 4wd as they feel like they are not meshing correctly and i am getting a slight vibration in the fenders from it in 4wd. when i shift out of 4wd it is quite, and smooth traveling.Can anybody touch this one?
Kubota B7800 Driveline Noise in 4WD
- Thread starter walleye883
- Start date
Are the tires on it the correct size? Does it bind up when driving in 4WD (more than normal, like when you are turning)? Perhaps the front and rear tires aren't correctly matched, and the bind is damaging the driveline?
I would check the owners manual against the tires that are on it, to see if they are correct. Then again, maybe the factory sizes aren't correctly ratioed to begin with.
Have you checked your gear oil, to see if you have any metal in it?
I would check the owners manual against the tires that are on it, to see if they are correct. Then again, maybe the factory sizes aren't correctly ratioed to begin with.
Have you checked your gear oil, to see if you have any metal in it?
Hodge, that's the first thing that came to my mind as well. Miss matched tires on a 4wd can be a real mess. I even ran into having different brands being a problem. My old B 7100 needed tires and I could only find different brands to go on the front and rear. They were the correct size but the tread depth was so different that it caused the ratio to be out of whack.
Yep, and the tractor is more sensitive to the size difference than I thought they would be. I replaced the front tires on my 7100, which went up a 1/2" in diameter, and I had to monkey with the tire pressure to get it to operate in 4WD without binding while driving straight.
The tread depth was so different on mine that even tire pressure didn't help out enough. I ended up having to shop around and found rear tires that had deeper tread and even then it was still in a slight bind. It was usable but I never tried to use 4wd on hard ground after that.
The noise you are describing may not be the same as this http://www.orangetractortalks.com/forums/showthread.php?t=694&highlight=b7800+whine
It is worth a look though!
Ed
It is worth a look though!
Ed
The tires have been checked and according to tractor data.com the industrial tire of that model should be fronts@ 23x8.50x14R and the rears @12.4x16R .They are correct! The noise when in 4wd is coming from the driveshaft area. Something is spinning on the shaft that comes when its cold and goes when its warm (like expand and contract). Every bearing in that shaft has been replaced. The shaft is hollow and it amplifies the sound. What all is spinning and rotating when the forward pedal is pressed? It sounds like the bearings going out of a electric drill or a circular saw? Whatever is spinning or rotating when Im going forward is responsible. It does not do it in reverse?
Guys this is a brand new tractor, that been to the dealer three times. All fluids are full and looks good. The problem started at around 35 hours and it has 42 hours now. How do I investigate this plastic shield they are talking about cutting off with the plastic bushing? From what I read it solves the noise problem?
Hope you solved the problem. I had what I think is the same noise. Removing the plastic bushing did the trick. No dealer intervention needed.
If you have a parts manual, it's page 108 - FRONT DRIVE SHAFT - G135 - Ref. #1000 - Part Ref.# 6C040-5755-0. At the narrow end a white plastic bushing is in there (not pictured), apparently for strength? Anyway, cut it out and my problem went away.
Hope this helps. Ed (OTT "eserv") gets the credit for this one.
David