jimna 254 4wd binding up

You may want to look at the transfer case to see if teeth are missing on those gears, we had a similar problem in the shop and that was the issue.

Trevor Nystrom

Keno Tractors

Parts Department

Trevor@kenotractors.com

541-850-8193

866-363-8193

I would be tempted to remove the front drive driveshaft as a quick test that would isolate the front end but the drive line to it would still be active. But if it is magnified to the point you can feel it only under load this might not tell you much., but it might too.

Take the 4 x 4 shaft off, jack up the front end, turn the front wheels see if they turn free , they should turn in opposite directions.The problem could be in the center 4 x 4 pumpkin or in one of the front driving shafts.You will just have to isolate them one at a time.We have all the parts in stock, we also have a complete center pumpkin ready to bolt in as well as complete drive assemblies depending on your mechanical abilities we can help with just parts or the assembly

Tommy

Affordable Tractor Sales

“Your Jinma Parts Superstore”

http://www.affordabletractorsalesco.com

Jetster-

This may be far-fetched, but did you look at the 'claws' that need to connect for 4-wheel drive to see if there are any problems? (see picture below)

I would be tempted to use something like assembly lube on critical mating surfaces just in case you end up running it a little longer than you would have wanted to.

so when you took the propeller shaft out to front axle did the problem still exist?

Inquiring minds want to know.

Jetster,

There was a statement in your first post that is still bothering me. It said:

“If a push the clutch in when moving the tractor comes to an abrupt stop from the front wheels”

If you still have the energy to pursue the problem, I have a couple of thoughts.  (tractor reassembled if required)

Can you put the tractor on a downward incline, engine off, in 4-wheel drive, clutch out and brakes off.

Does it roll?

Now push clutch in.

Does it roll?

Now try those same two actions with the engine running.

What were the results?

That one had/has me scratching my head

do you have a loader on the tractor? If so there has been problems with the front axles assm. with overloading the buckets and running on real ruff terrain or getting them stuck with the front wheels turned on angle . A friend of mine just went threw this with a older Kubota.

Are you a new owner? Has it done this since you bought it? This is faarr out there but, . . . I bought a parts truck that did this after I got it running, it had different gear ratios between front and rear diffs. Are you positive the right size tires are on it?

So the tractor would roll downhill with the clutch in or out.

Please clarify what was meant in your first post by:
“If a push the clutch in when moving the tractor comes to an abrupt stop from the front wheels”

Then this:
“If a push the clutch in when moving the tractor comes to an abrupt stop from the front wheels”
is no longer happening?

ok I will get that info. but I believe it was a gear with some missing teeth and bad bearings, but I will get a confirmation on that

Jester,
Let me try my question a different way-

When you are moving along in 4-wheel drive and you depress the clutch – what happens?

ok I got a verification on went wrong with his tractor it was the spindle bearings which fell apart and wiped out the gears. I do not believe that is your problem. But what you are saying that with the tractor in 2 wheel drive the tractor operates normally. Only when in 4 wheel you feel the problem. Is this correct?

Jetster,
Let me summarize since the info is now spread over several messages.

1. When driving in 4-wheel drive at a steady speed, the tractor starts to hobby horse due to the front drive binding up.

2. When driving in 4-wheel drive, if the clutch is depressed, the tractor is stopped by the front wheels with no actual tractor brakes applied.

3. When sitting on a downward incline with tractor in 4-wheel drive, the tractor will roll down the hill whether the clutch is In or Out and whether the engine is running or not. It does not stop or slow down unless the actual tractor brakes are applied.

Are these all correct? If not, please clarify.

I have some thoughts but it will take me some time to describe them properly.
Also I would not use 4-wheel drive until the problem has been resolved

I think there is something about gear ratios or tire sizes being wrong ,the reason I say that is if in 2 wheel drive everything is turning just not connected under power, when 4 wheel is engaged then you have 2 things turning on the same ground speed but powered at different speeds , so it binds .everything must match within factory plus and minus windows. I have heard of new back tires and bald fronts giving issues. I guess you could mark the rear and front tires roll the tractor one revolution one the rear and the front should turn more than once but the marks should be in the same place once the one turn has been made. well I think anyway.

Jetster,

Your problem presented a challenge. I have thought about it for some time and spent time with all of the exploded parts pictures I have. There may be nothing new here that you have not considered, but I have now gotten the thoughts out of my head.

Situation:
1. When driving in 4-wheel drive at a steady speed, the tractor starts to hobby horse due to the front drive binding up.
2. When driving in 4-wheel drive, if the clutch is depressed, the tractor is stopped by the front wheels with no actual tractor brakes applied.
3. When sitting on a downward incline with tractor in 4-wheel drive, the tractor will roll down the hill whether the clutch is In or Out and whether the engine is running or not. There is a feeling of ‘binding’ with each rotation of wheels, but tractor does not stop or slow down unless the actual tractor brakes are applied.

Normal 4-wheel Drive Operation – forward motion

Clutch engaged:
Engine is driving the transmission and through the ‘claws’ the front drive shaft is engaged. The engine is forcing the forward gears of the transmission and therefore the front and rear axles to move the tractor in a forward direction.

Clutch dis-engaged:
Engine is disconnected from transmission. Transmission is now potentially free-wheeling, but the tractor wheels are still in motion. The tractor wheels are now driving the transmission gears, allowing tractor to continue in direction it was traveling prior to clutch dis-engagement.

Jetster’s 4-wheel Drive Operation

Clutch engaged:
Engine is driving the transmission and through the ‘claws’ the front drive shaft is engaged. The engine is forcing the forward gears of the transmission and therefore the front and rear axles to move the tractor in a forward direction. There is a ‘binding’ indicating that the front wheels do not want to do what the engine/transmission is forcing it to do.

Clutch dis-engaged:
Engine is disconnected from transmission. Transmission is now potentially free-wheeling. The rear wheels are trying to drive the transmission gears in a forward direction. The front wheels do not want to move in a forward direction and cause the tractor to stop.

RonJ opinion (prior to results of Situation 3 above):
There is something forward of the ‘claw’ on the front drive shaft that is binding. I recommend that the tractor not be driven since this must put significant strain on those 2 claws.

I do not understand why when Jetster was coasting down the grade in 4-wheel drive, the tractor did not stop whenever the clutch was dis-engaged on the downhill run. Unless there was too much inertia from the rear wheels that over-rode the front axle resistance resulting in the feeling of binding rather than stopping.

What I would do:
Remove the front tires (to reduce the weight) and raise the front end.
Determine the rotation of the front drive shaft to move wheels for a forward motion.
Verify that the shaft coming out of the front of the Transfer Case is turning the right direction.
Rotate the front drive shaft in that direction to try to locate the ‘resisting’ parts.

this is so weird like with load you have a shaft that gets torqued and flexes and binds, I am going to be quite interested on what finally shows up as the problem. Have you tried jacking it up and letting it run in gear using a mechanics stethoscope ? Talk about a grasp at straws.

Can this problem be caused by a cracked, bent or broken axle? I’m just wondering if when there’s weight on the front end that a cracked, bent or broken axle would cause the gears to bind as they are not aligned properly.

Jetster,

Sometimes when there have been some strange noises, etc on the transmission, there have been recommendations to overfill and run them for a period of time.

Do you think that might be worth trying on you front axle?

I’ll be interested in the outcome of this. It sure has all the earmarks of a missing tooth on the ring or pinion.

Jester,

After going back and reading the entire thread from the start, I think that David was on the right track with his remarks about the tires.  You said that you have had the tractor since new, everything is original and that the problem has been getting worse over the last year.

Somewhere in the past I have read that you can not mix tire types. That is to say you can not put ag tires on the back and turf tires on the front for example.  This is because the tires are sized to roll together for the gear ratio involved.

I think it is entirely quite possible that the front tires have worn down faster than the rear tires and now as David pointed out they are not within the working limits of each other.

Here is an experiment that won’t involve any dis-assembly.

Jack up one front wheel and the same side rear wheel just enough to get ground clearance. Mark the “bottom” of each tire and with 4WD engaged, rotate the rear tire one complete revolution. I would do this by hand with the engine off and the transmission in neutral. Watch and count the revolutions of the front tire. This will give you the ratio of front to rear.

Now, measure the circumference of each tire. the ratio between the two should be really close to the gear ratio between the axles.

Do the lugs on the front and rear appear to be worn at at the same rate? It is quite common for the fronts to wear faster especially if you do a lot of tight turns on hard surfaces.

Another experiment would be to drive on some smooth sand or soft soil in 4WD and watch the tracks. More than likely the lugs on the front tires will be “pushing” the soil and leaving deformed tracks as the front tires are not rolling at the same rate as the rears. In really soft conditions, I would bet you won’t feel the binding as the fronts will be sliding instead.

You could put it in 1st/low/creeper and get off and watch as the tractor runs under power. You should be able to see the front tires “load up” and then slide forward to release the tension. Sort of “skipping” as they try to catch up to the rear tire travel.

I am not sure if I have explained these thoughts very well. Please let me know if something is confusing.

Stuart

If the tire size is correct, what about the actual TIRE PRESSURE ?  Maybe its as simple as that?

Here is a old reprint post from another forum by Kelvin back in 2000 on TractoByNet on how to check for proper tire size:

 When correct 4wd tractor front-rear tire size pairings are unknown or unavailable, I have come up with a simple test to determine if questionable substitute tire sizes are acceptable AFTER they are installed on the tractor. While I have an engineering degree, my statement is far from scientific or educated so please feel free to debate this issue.

Kelvin’s Questionable Test: To determine if your tractor’s 4wd gearing is compatible with the installed wheels & tires, do the following test with the tractor engine shut off and transmission in neutral (this is easiest on smaller tractors):

(1) Put the tractor in 2wd mode and see how easy the tractor is to push straight forward or backward.
(2) Put the tractor in 4wd mode and then see how easy the tractor is to push straight forward or backward.
(3) If there is resistance in 4wd mode that was not encountered in 2wd mode then the tires size may be a problem.

In my specific case, the Kubota B6100/B7100 tractors call for 20.5×8.00-10 front turf tires which are no longer available (there are golf car and trailer tires available in that size, but they (1) don’t have the correct tread and (2) supposedly are not the same size as a tractor turf tire bearing the same numbers).

With my AG tires, my improvised test was successful. With turf tires mounted (correct rear tires with 20.0×8.00-10) the test failed (I had a lot of difficulty pushing the tractor in 4wd).

While comparing the B7100 to the B7100’s replacement (B7300) I noticed that all of the recommended Ag and Turf tire sizes were the same except for the front turf tires; instead of 20.5×8.00-10 the B7300 recommended a 21.0×8.00×10 which is a tire that is available. I bought a pair, mounted them and performed the above test. The tractor rolled equally easy in 2wd and 4wd mode.

So is the above mentioned simple test valid? If so, whomever reads this may want to pass the tire size information to anyone with “turf tire-equipped 4wd B6100s or B7100s” that the 21.0×8.00-10 is an acceptable substitute front turf tire.

I know it has been suggested before but I would make sure the front tires are the correct size. Several years we had one of 4 Jinma 254’s in the same shipment come in with smaller tires and wheels we had to swap them out with a set purchased from Northern.

Ah Ha! There is your answer. That works out to a 12% difference, which is quite a lot.

When the rear tire travels 127″ the front tire must also travel 127″ or “something has to give” In your case the rear tires probably have more traction and are making the front tires slide (or hop) those other 14″ in every revolution.

The gear ratio itself is not really important until you try to figure out what circumference the front tire needs to be to match the rear tire.

Maybe someone else with turf tires can measure for comparison. I have AG tires on mine.

It doesn’t hop the 14″ all at once but rather hops a little each time it “binds up”. It also may be sliding some before it gets enough pressure built up to cause it to break loose. This is probably contributing significantly to the wear of the front tires which in turn makes the problem even worse.

There are a couple of different ways to calculate the gear ratio and tire sizes but they all boil down to exactly what you did. However far the rear tire travels, the front one must travel the same distance or something has to give. By jacking up just one side you kept the opposite tire from rotating which effectively took the differential out of play

If I remember correctly, when doing ground work (plowing, planting, cultivating) it is proper to have something like 6 to 8 percent tire slippage. This allows the soil to build up into the lugs of the tires give the best traction. The tracks left by the tires make this really obvious. That is why I had suggested finding some soft ground. Your idea of waiting for some snow or ice would do the same thing.

You may be able to duplicate the effect on dry pavement. Get lined up for a straight run on a consistent surface such as a paved driveway. Put it in 4WD and first gear, in low range and in creeper gear. Put a chalk mark on the bottom of all 4 tires, and a corresponding mark on the pavement.  If you have a helper one person can drive while one watches and marks the pavement where the mark on the tire comes back around to the ground. You can do this yourself if you have to as at idle the tractor is moving slow enough to get off and back on. If you are uncomfortable with getting back on, you can at least grab the fuel cut off and stop the engine.

Having a helper is best because the person on the tractor can yell you “HOP” when he feels the tractor bind up and release. You can make a mark on the pavement when this happens. After 2 or 3 revolutions of the rear tires you will have enough “tracks” on the ground to get a visualization of what is happening.

I will try to get out and measure the circumference of my AG tires today. Then we will at least have something for comparison.

In 2WD the front and rear wheels won’t be connected to each other and the problem should not show itself as the front wheels are free to turn at whatever rate is needed.

I measured my tires this afternoon. I have a 2006 284 with AG tires. Rear are 9.5 X 24 Front are 6.00 X 16

Circumference of Rear is 129″ and the front is 91″. One side jacked up and locked in 4WD the front tire travels 126.5″ per revolution of the rear tire. This is only a 2% difference which is probably within the allowable tolerance. The backlash of all the gears in the system probably adds up to more than that.

These are the original factory tires and have less than 20% of the tread worn off. They appear to be wearing evenly between front and rear. Also the 2% difference could probably be removed by altering the PSI in the tires. I did not check the tire pressure and only measured the one side.

It would be interesting if you could find some tires and rims from another unit to swap onto yours to see if that cures the problem.

Let us know what you find.

Stuart

Awesome to hear that you got your issue resolved, sure took some figuring though.  I do have tires in stock if you need to order some.