F3680 4wd Engagement advice please

[Mike Hamilton]

Hi all, I purchased 3 F3680 machines out of an auction figuring to sell 2 of them. So they all run perfectly with full operation on everything EXCEPT, all of them seem to not engage in 4wd mode, nor does the AWD assist seem to work. I say this because i test them all through regular cutting and through circumstance in tricky situations. My suspicions/evidence is that when I am going up a hill or stuck in the mud, in any drive mode, I NEVER see the rear wheels spin only the front wheels so I would assume that if I am in 4WD that I "should" get at least Both front and Rear spinning. Most of my other 4WD equipment has a mechanical 4WD Shift but these machines dont seem to operate that way.

I cant find ANY posts anywhere of anyone having difficulty, I cant find anywhere a description of the "theory of operation" on the shifting and "how" it works, and I cant find any prints so I can see how the cabling or Linkage is laid out or connected.

I also can not see through or around the body shrouds to view the linkage and Can not even figure out how to take the covers off simply to have a view for inspection. I seem to have been stumped on all angles.

I am not used to being this stumped, I even paid one of those "ask a technician" which was completely useless who just double talked and didn't really clarify anything.

I would appreciate ANY hints or advice on any aspects of the above points, theory of operation, how it "should" work (normal operation), prints on how the linkage looks, just anything would be better than being absolutely stonewalled here. It cant be that complicated unless some clutch is burnt out or something, like I said, I am used to a Mechanical shift that has an absolute engagement, this doesnt seem to be the same. Also there is tons of torque to the machine in both high and low ranges, I just cant seem to get any drive to the rear (small wheels)...... Any advice would be greatly appreciated, Mike

 

[wgator]

Mike, welcome to OTT. Can't really help you with problem as I don't own a F3680. What I can help you with is a link to the online/downloadable workshop manual for it. I see you are in Canada but hope you can get to the link to the F2880,F3680 WSM BY CLICKING HERE.

 

[MOOTS]

The 4wd lever is on your left while sitting on machine. You can see it is the only lever on the far side in picture. The floor pan is easily removed with only a handful of bolts. After removing all pedals and roll bar.

 

[Mike Hamilton]

Mike, welcome to OTT. Can't really help you with problem as I don't own a F3680. What I can help you with is a link to the online/downloadable workshop manual for it. I see you are in Canada but hope you can get to the link to the F2880,F3680 WSM BY CLICKING HERE.

Thank you, that was at least more information than I had already, I am looking at it carefully to see what I can deduce. Much appreciated.

 

[Mike Hamilton]

The 4wd lever is on your left while sitting on machine. You can see it is the only lever on the far side in picture. The floor pan is easily removed with only a handful of bolts. After removing all pedals and roll bar.
View attachment 49323

Thanks Matt, I knew where the shifter lever is located, it is what it is linked up to through linkage that I was interested in... any chance of getting a picture of what the lever actuates?

 

[MOOTS]

Thanks Matt, I knew where the shifter lever is located, it is what it is linked up to through linkage that I was interested in... any chance of getting a picture of what the lever actuates?

Ahh I misunderstood. I don’t think there is much linkage, I believe the lever goes straight into the transmission case.

I can’t get a better picture, as I’ve since gotten this unit back together and out the door.

Have you pulled up the breakdown on kubota site? Most of the pictures on there are very good. I use it and the Toro site just about daily at work.

 

[Mike Hamilton]

Hi Matt, well I did look already since you mentioned it, I thought I would look again more carefully, it was under an obscure description "clutch lock" which kind of makes sense. I hope I am not dealing with 3 burnt out clutches here. Not sure how familiar you are with these, but I notice when I do shift into 4WD and back, there is really no mechanical resistance of "feeling" of any kind of positive mechanical shift, it is just soft when going back and fourth. Does that sound normal or should I "feel" it shift somehow. I suppose the smooth shift would be normal if it is just shifting a valve or something. I need to learn more about the theory of operation on this, I am a bit ticked off, all my other 4WD machines I have zero issues, and here I have 3 Kubota 3680's and none of them work in 4WD.

 

[MOOTS]

Our 2 3680’s and 2 2690’s are easy to shift, no real resistance other than maybe a detent type feel.
I’m not 100% sure, but I don’t think there is a clutch pack, the breakdown looks like #10 moves a splined washer onto the shaft in transmission that is spinning with treddle input. Which makes the rear wheels have motion.

Have you jacked machine up and verify the rear wheels are not pulling, driveshaft spinning? Or is it a seat of pants feel? When I mowed with ours, I really couldn’t tell I was in 4wd on flat turf, you could feel a bit while turning hard though. All of that could be working and the problem is in the rear axle. Just tossing ideas around.

 

[MOOTS]

Any luck with this Mike?

 

[Mike Hamilton]

Any luck with this Mike?

Hi Matt, I got hung up with my Backhoe yesterday, the next step will be to get the machine up on stands and test the driving wheels. All I know is in 4WD mode, I see the front wheels spinning and no spinning on the rear wheels, thats whats driving me nuts, I cant see why when Im stuck and in 4wd full mode, why the small rear wheels dont spin.... I will be trying it jacked up and let you know.

Thanks so much, Mike

 

[MOOTS]

Just happened to toss a 2690 on the lift. Maybe the linkage arm has popped out? That would be a very easy repair!
This is 2wd

This is 4wd. The lever doesn’t move much.

 

[Mike Hamilton]

Hi Matt, WOW thats EXACTLY what I wanted to see, ... its been raining here a bit, but now I can look for the mechanical shifting. My guess is that the linkage is ok, then I will get it up on stands and test it. You know it may be just a basic limitation of the design, since this is not a "GEARED" engagement, it "may be a simple functional limitation of the Hydraulic engagement to the rear wheels, My initial concerns came from observing that the rear wheels would not spin when stuck, my experience with 4WD when stuck or going up a hill in 4WD is that when stuck both front AND rear wheels should spin, so when the rear wheels didn't spin I assumed that there was NO Drive going to the rear wheels, this could be a false assumption and it may be that the transmission simply can not transfer the full power/torque to the rear drive wheels in the same what as a direct mechanical geared 4WD engagement. What do you think about that theory?

Thanks, Mike

 

[MOOTS]

Hi Matt, WOW thats EXACTLY what I wanted to see, ... its been raining here a bit, but now I can look for the mechanical shifting. My guess is that the linkage is ok, then I will get it up on stands and test it. You know it may be just a basic limitation of the design, since this is not a "GEARED" engagement, it "may be a simple functional limitation of the Hydraulic engagement to the rear wheels, My initial concerns came from observing that the rear wheels would not spin when stuck, my experience with 4WD when stuck or going up a hill in 4WD is that when stuck both front AND rear wheels should spin, so when the rear wheels didn't spin I assumed that there was NO Drive going to the rear wheels, this could be a false assumption and it may be that the transmission simply can not transfer the full power/torque to the rear drive wheels in the same what as a direct mechanical geared 4WD engagement. What do you think about that theory?

Thanks, Mike

I don't believe that theory is correct. Part #10 moves a coupling in the housing onto a shaft in transmission, that spins with treddle movement. Shaft inside transmission is always spinning if mower is moving. The coupling takes that rotation and sends it down the drive shaft to rear wheels.
They are calling it a one way clutch. Part #140.

Something could be going on with it. It has a breakdown too, lots of replaceable stuff in there.
But hopefully it is just the linkage....

 

[Mike Hamilton]

I don't believe that theory is correct. Part #10 moves a coupling in the housing onto a shaft in transmission, that spins with treddle movement. Shaft inside transmission is always spinning if mower is moving. The coupling takes that rotation and sends it down the drive shaft to rear wheels.
They are calling it a one way clutch. Part #140. View attachment 49443
Something could be going on with it. It has a breakdown too, lots of replaceable stuff in there.
But hopefully it is just the linkage....

Well you do agree then that if/when I am stuck/spinning front wheels, when in 4WD the rear wheel(s) should also spin OR move the machine if not spinning?

 

[MOOTS]

Well you do agree then that if/when I am stuck/spinning front wheels, when in 4WD the rear wheel(s) should also spin OR move the machine if not spinning?

Yes, I agree with that. If front wheels are turning, while in 4wd, one or both rear wheels should be spinning.

 

[Mike Hamilton]

Hi Matt, sorry to drop off the radar, well I feel a bit dumb, I traced the issue with the rear NO Drive, seems like I am getting power to the drive shaft, but it is spinning in the rear axel, so there must be a spline or bevel gear stripped, any idea what the simplest way to get at the gears to see which one is stripped?

 

[Mike Hamilton]

Well pulled the Drive shaft, nproblem, all splines look good now just trying to figure out the best way to get to the internals to see what part is stripped, let me know if there is an easier way, in the meantime I will try to figure it out, I think I may just start by pulling the axels out, this is on the rear (small tires at back)...

 

[Mike Hamilton]

Well pulled the Drive shaft, nproblem, all splines look good now just trying to figure out the best way to get to the internals to see what part is stripped, let me know if there is an easier way, in the meantime I will try to figure it out, I think I may just start by pulling the axels out, this is on the rear (small tires at back)...

SO need advice on the easiest way to enter this assembly to determine what gear(s) are stripped, I assume they must be... pull the axels or get to it through the driveshaft spline item A. Which direction to attack it from would be appreciated. Although I may wind up taking it from all sides in the end correct?

 

[eserv]

Well pulled the Drive shaft, nproblem, all splines look good now just trying to figure out the best way to get to the internals to see what part is stripped, let me know if there is an easier way, in the meantime I will try to figure it out, I think I may just start by pulling the axels out, this is on the rear (small tires at back)...

I wonder if someone has removed a gear or something to disable the 4wd? It seems odd that all 3 machines would have failed internally! We have had very little trouble with those axles.

 

[MOOTS]

Mike, have you checked the coupler that connects pinion (A) to the drive shaft? Jacked it up and spun the wheels? Is anything moving?