M7040 Problem

   / M7040 Problem #21  
Here is another explanation of the phenomena - this explanation pertaining to motorcycles but the same thing and probably easier to understand example with the cold oil equivalent to sticky honey on a slice of bread and trying to slide it.

I can't explain why it should move if the gears are in neutral but then again I don't have a cross section of the transmission. Yes, I have had transmissions transmit some power while in neutral but in the cases I can recall due to excessive heat and not excessive cold.

When I get home it should be below zero (F) and I will try my M135GX. Different transmission but a lot more wet clutch packs involved. It's also time I tested the block heater.

Q. Why does the Rear Wheel Turn when the bike is cold and I start in Gear, with the Clutch Pulled in.? Why is it difficult to start.?
A. The F650 has what is called a "Wet" Clutch.

Unlike many cars, where the clutch is separated from the Engine and sump, many bikes have a clutch which runs in an oil bath, the same oil that lubricates the rest of your engine.. You might ask how this works when oil is pretty slippery stuff, but if there are enough plates (The F has 7), strong enough springs there will be enough friction. Plus Oil is a very viscous liquid, so some of the transfer of the engine power across the plates is done though the oil.

A wet clutch has multiple plates running in the engine's motor oil, like the F650 engine. A dry clutch runs in its own housing and consists of one or two plates. Think BMW boxers and Moto Guzzis and most cars and trucks. They both work fine, if properly designed. A wet clutch is typically more compact and will usually engage more progressively, however as it wears, it tends to foul the engine oil with clutch material. Wet clutches are also quieter than dry clutches (think Ducati). Richard #230

Dry clutches last longer, too in most cases. Some are equally quiet, as the BMW dry clutches are noise free. Ducati has the market for noisy clutches! Don't even have to see the bike coming to know what it is. Changing a wet clutch pack is almost always easier than dry bike clutches. More labor involved in most cases, for dry ones. Costs? Wet clutch packs are much cheaper as well, when comparing the BMW clutch assemblies. Feel? Not much difference, these days, but there was a day when the early BMW dry clutches on the early boxers were snatchy! Randy748/Calif

Oil itself, until it breaks down over time or with wear, has a fairly high viscosity for a fluid. Ever dropped a piece of toast with honey on the floor and tried to pick it up sliding it across the floor a bit. Difficult isn't it.? In the same way the very small amount of oil between the plates is the same. Viscosity is temperature-related. When it is cold, oil is "thicker", i.e. has a higher viscosity.

The Clutch comprises a "Basket" Part#1 (External) & Part#2 Internal, Several Friction Disks Part #10, Several Steel Disks Part #11, and a Pressure Plate #12, which jams the whole sandwich together using the springs, 6x Part #1.

The difference between Neutral and in-gear with the Clutch in, is that in Neutral the Clutch Basket, which houses the Clutch Friction Plates and the Smooth Steel Plates against which each friction plate presses), is not driven by the Engine at all.

However In-gear with the Clutch in, DOES drive the clutch basket, BUT the pressure plate, (Large Circular Plate which jams all the individual Clutch Friction Plates against the Steel) is held AWAY from the disks, allowing them to slip past each other. Now they are NOT held away by very much and if you think back to your toast, a thick cold oil (like the honey) between the plates, will actually allow the plates to transfer some of the engines power to the Countershaft and hence to the rear wheel. That's why your rear wheel spins with the bike in gear, clutch in and the bike on the Centrestand.

So what happens is that your poor starter is meeting with resistance, albeit LESS than if you did not use the clutch at all, but quite some resistance nonetheless, and is trying to DRIVE the bike, essentially with the starter alone.! It's like starting your bike or your car in gear without the clutch in, but less severe. If you ever drove a manual car, do you remember learning to drive and forgetting to depress the clutch.? Remember how the car surged forward.? Yup just like that, poor starter motor running off the battery trying to move the ENTIRE car, or bike.
 
   / M7040 Problem
  • Thread Starter
#22  
Just thought I would give you all an update on this thread...8 years since I started this thread but I still have the m7040 and it still rocks back and forth when started in cold conditions. I just have 600 hours on the unit now so I called the dealer and asked them to come and do the service. Mechanic arrives and changes all the fluids and he starts the tractor and of course with it being cold the tractor starts rocking back and forth. Mechanic then "freaks out" and asks me how long this has been happening so i give him the whole story about previous conversations with Kubota. He doesn't agree with their explanation so he gets his service manager on the phone who also thinks this should not be happening. He then offers me to float my tractor back to their shop ( 2 hours away) so that they can further investigate the issue. This was done free of charge even though the tractor is now 10 years old and out of warranty. They had it for a week and called to tell me they couldn't find anything wrong that could be causing this issue. The service manager told me he had been to a Kubota trade show and asked other dealers if they had ever had a similar issue and none of the people there had ever experienced this issue. Sounds like I'm the lone duck with the problem. Tractor works fine so I think I'm stuck living with the rock and roll tractor.
 
   / M7040 Problem #23  
My tractor is a 2007 M5040 with 2300 hours, purchased new in 07. It occasionally has the slight forward-reverse pulsing after started. It appears to only happen when cold and not every time. My dealer said not to worry about it and at this point I don’t think of it as a problem.

If you place the High/Low range selector in the neutral position it will cease.

Allow me to praise the Orange Tractors a little. The M5040 is my 5th Kubota and has been awesome pulling 3 bottom plow, 10’ disc, 7’ tiller, snow blowing, moving dirt, chipper, mowing, haying and so much more. Could not live here without it.

It still has original battery. No breakdowns. Always starts. The front tires needed replacement after 2000 hours and I had 2 flat tires (my fault) No other problems.

I Faithfully complete the maintenance and always warm it up before use winter and summer.

Get Yourself One Now! 😊
 
   / M7040 Problem
  • Thread Starter
#24  
I'll have to try putting the high low selector in neutral to see if that takes mine jerk away as well. I didn't think that would make any difference. During warm up I always throttle back the rpm's to where the jerking stopped which was basically at idle rpm. I didn't feel comfortable not being in the seat when it was warming up with the thing rocking back and forth as I had visions of it taking off. Like you I have been basically trouble free in the 10 years I've owned this tractor. I do all the maintenance at the required interval and have used only Kubota fluids and filters. The Kubota experience has been great for me and the fact that I have a dealer that i know will be there for me makes it even better.
 
   / M7040 Problem #25  
My M7040 when very cold will do this at temps 20 F or lower. The oil is UDT
 
   / M7040 Problem #26  
I have a 7060, and run our Canadian premium UDT. When it’s cold, everything in neutral I’ll also sometimes feel an ever so slight bump/jerk, not enough for the machine to move but you can feel it in the seat. If it’s in gear, shuttle in neutral sometimes the digital speedo will flicker ever so slightly (0.04kph) or whatever. This is a ‘17 I think with 700hrs now.
Gotta love the cold.
 
   / M7040 Problem #27  
My 2009 Kubota M6040 has Kubota UDT oil in the tranny. I've fired it up down as low as -20F. Range in high - gear in neutral - shuttle shift in neutral. Never experienced any rocking motion. After proper warm up - it probably wouldn't happen anyhow.

BTW - I learned to not use the park brake on my first tractor. Too easy to forget and drive off with it still engaged. If I need absolute security against movement - angle and drive the grapple into the ground - at times I've even raised the front tires slightly - drop the rear blade and apply down pressure with the hydraulic top link. Usually just "grounding" the grapple and rear blade is enough. No need to apply added pressure. I avoid places where extreme measure would be required.
 
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   / M7040 Problem #28  
Just thought I would give you all an update on this thread...8 years since I started this thread but I still have the m7040 and it still rocks back and forth when started in cold conditions. I just have 600 hours on the unit now so I called the dealer and asked them to come and do the service. Mechanic arrives and changes all the fluids and he starts the tractor and of course with it being cold the tractor starts rocking back and forth. Mechanic then "freaks out" and asks me how long this has been happening so i give him the whole story about previous conversations with Kubota. He doesn't agree with their explanation so he gets his service manager on the phone who also thinks this should not be happening. He then offers me to float my tractor back to their shop ( 2 hours away) so that they can further investigate the issue. This was done free of charge even though the tractor is now 10 years old and out of warranty. They had it for a week and called to tell me they couldn't find anything wrong that could be causing this issue. The service manager told me he had been to a Kubota trade show and asked other dealers if they had ever had a similar issue and none of the people there had ever experienced this issue. Sounds like I'm the lone duck with the problem. Tractor works fine so I think I'm stuck living with the rock and roll tractor.

Does it still change with RPM after the oil change? I'd just set the RPM elsewhere it doesn't do it. Doesn't fix it, but at least you don't have to deal with it. I'm wondering if the actual shuttle lever is not 100% in neutral, i.e. 95% and when oil is cold and thick it's enough for the tractor to "slip" trying to go into gear and back out until the oil is warmed and thinner?

Given how many Kubota dealers are in NS you must be in the boonies to be 2 hours away from one :)
 
   / M7040 Problem
  • Thread Starter
#29  
It starts jerking at about 1100 rpm and goes away if I take it to 2000 rpm. I never liked running a cold engine at 2000 rpm so I just take it back to just above idle speed and let it warm up there. After about 5 minutes of running the jerking stops. Does the same thing after changing the fluids. Shuttle appears to be completely in neutral so I don't think that's the issue. I live in northern Cape Breton so 2 hours to the nearest Kubota dealer which is in Sydney...I'm not in the boonies but awful close.
 
   / M7040 Problem #30  
If moving the high/low selector into neutral during warm-up stops the rocking then I'd call that a win.

It's supposed to be cold enough here in NS tomorrow to give it a try.

I've got 2 friends with hydraulic shuttle shift tractors, one is a MF 3645, the other is a 60 series Deere. Neither do what you've described, cold weather or not, so it's a Kubota kinda phenomenon.
A third friend has, or had, a big Kubota, might have been a 135, and he's never mentioned it. Then again, I haven't asked the question either.

Odd that it does it with the main tranny in neutral. Thinking about it, the gears in the tranny are still spinning on their shafts, just not engaged. The viscosity of the cold oil would make it act like a torque converter, as MHarryE suggested a while back.

The high/low selector might have enough clearance between the gears that it "disconnects" the tendency to keep things spinning in close proximity.

The fact that it goes away when it's warm lends weight to that theory too.

If I'm chatting with the local dealer (Nova International outside Windsor) I'll ask if they've seen this before. They see more than a few agricultural size tractors, so the larger customer sample might have more results. I don't see them often, the 3400 has been good other than routine maintenance.

I'll ask the friend with the big Kubota if he's experienced this the next time I see him.
 
 
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