b7800 locker problems

[Verticaltrx]

I haven't looked at the diff lock on my B3200 closely to see what/if there is any linkage, but that is the first place I would look. There were a couple of linkages on my tractor that were not set up properly when I got it (the 4wd was almost impossible to engage/disengage), but once adjusted they are all working good. The diff lock pedal may not be fully engaging the locker which of course would shear off the mechanism under a heavy load. I only have 120hrs on mine, but I use it for a lot of heavy work including a lot of excavating and dirt work with the loader and pushing out brush, so far no trouble.

 

[bstrom]

I actually don't use the the darn thing much anymore because the front wheel assist is so effective. I was coming uphill out of the woods in fairly deep snow in 2 -wheel drive and started slipping even with chains. I stepped on the diff lock - a little better but not great. Shift into front wheel assist and without the diff lock it takes right off through the snow.

It seems to be more effective in reverse for me, if I am stuck backing up a hill or through snow, it seems to really pull me out if I step on that thing. Maybe I don't know what I'm doing or maybe -just maybe - mine is busted too! Now I'm worried - I'd better check it tomorrow.

 

[Verticaltrx]

I looked at my shop manual last night and there really aren't any adjustments on how the locker engages. The only thing that could affect its engagement would be a bent foot pedal or engagement fork.

The way it work is there is circular plate on the carrier that is pretty thick with a big notch (about 3/8 of the circle.) On the right hand axle shaft there is another plate with the matching tooth that locks into the cut out when slid into place by the engagement fork. When they lock together it locks the right hand axle shaft to the carrier, which therefore locks the right hand side gear and spider gears which makes the other side turn. Its nothing like any of the automotive based lockers I've seen before, but it does look pretty stout, especially since its upstream of the final gear reduction. If you don't mind post up some pics of the failed parts when you get them, I would be interested to see exactly how they failed.

 

[captin_insano]

Thanks for the input. I looked at the linkage and had seen there was no adjustment. Its kind of a poor design IMO and I can see from looking at it that the linkage is at least part of the reason its hard to press compared to the older b2150. Once its fixed and the warranty is out I'll definatly upgrade the linkage to at least have some sort of bushings where it piviots. I'll put a little leverage on it too to make it easier to operate.

You wouldnt have an exploded view of the locker by chance would you? If not, no biggie dont go out of your way because I'll just pester my dealer to get me one. Where is there a gear reduction past it, if there is a gear reduction after the locker it should in theory be pretty strong under torque. I think the L series looks like it has the reduction after the locker but looking at mine together I cant see any obvious place where there would be one.

My pedal isnt bent, it has plenty of room to travel but the fork I cant comment on yet. Again, thanks.

 

[herringchoker]

1. You wouldnt have an exploded view of the locker by chance would you?
2. Where is there a gear reduction past it, if there is a gear reduction after the locker it should in theory be pretty strong under torque.

1.You can get a pdf parts manual for your tractor at :

TractorSmart.com is your online source for Kubota online parts.

I have one for the B7800, but being a computer dummy, I can't figure how to pull out specific pages for you. If you get a pdf file, the exploded view of the locker is in the REAR DIFFERENTIAL and DIFFERENTIAL LOCK PEDAL sections. It's pretty much as Verticaltrx describes.

2. The REAR AXLE section shows the gear reduction outboard of the differential case.

Hope this helps.

 

[captin_insano]

I looked at the other B tractors on the lot at the dealer when I droped mine off today. They had b3030's, 3200's, 29xx, 7510, etc. All the tractors there had a very different linkage and a MUCH better feel to the locker. I'll get some pictures of my linkage, its a pretty crappy set up compared to the others I looked at. I would assume this is a b7800 thing or is it possibly a model year difference? If I would of actually seen this (its hidden pretty good) before I bought I would of went with a different tractor. Its like something you would expect on a lawn tractor from the walmart. I hope theres an upgrade by now. There was a 7510 there sitting outside with the rear torn apart. The diff was covered with plastic and I assume it to have been a customers so I didnt mess with it but I really wanted to get a look at its guts.

 

[crbr]

I looked at the other B tractors on the lot at the dealer when I droped mine off today. They had b3030's, 3200's, 29xx, 7510, etc. All the tractors there had a very different linkage and a MUCH better feel to the locker. I'll get some pictures of my linkage, its a pretty crappy set up compared to the others I looked at. I would assume this is a b7800 thing or is it possibly a model year difference? If I would of actually seen this (its hidden pretty good) before I bought I would of went with a different tractor. Its like something you would expect on a lawn tractor from the walmart. I hope theres an upgrade by now. There was a 7510 there sitting outside with the rear torn apart. The diff was covered with plastic and I assume it to have been a customers so I didnt mess with it but I really wanted to get a look at its guts.

PM sent to you. I can send you a parts manual in PDF or click here (below on the thumbnail picture).

.

 

[captin_insano]

Thanks crbr. I'll save you the time on the manual, the pic you posted gives me a good idea what I need to look at. I do appreciate the offer though, I just hate to take up anyones extra time on this. I Imagine it would take a little effort for you to attach and send it and the pic gives me a good idea of what I'm looking at. The locker itself should be self explanatory when I see it. Again thanks for the offer, mighty fine of ya.

 

[whistlepig]

My B7800 has over 400 hours on it. I rarely used the differential lock until this past week. Over 40 hours of moving snow with the loader and used the differential lock countless times with no problems. I do know that the differential lock can't be engaged with the rear tires spinning. That's a guaranteed way to destroy it. Doesn't necessarily make the B7800 a bad tractor. I owned a 1964 MF135 (which was a tank) and it was the same way. The owners manual said not to engage the differential lock while the tires were spinning or it would shear the differential locking pin. It may only take once.

 

[captin_insano]

I'm not saying the 7800 is a bad tractor. Mine obviously has some issues I need to figure out though and based on my experience with it and now comparing it with others I wouldnt make it my first choice again. I'm not happy to say that but it is what it is. So far just looking at it I can see the linkage is not on par with the other b series I've put my eyeballs on. I WILL upgrade this linkage once the warranty is out. The problem i see with it is for starters where the linkage goes through the figure c420 in the picture. if you look under the seat you'll see this is just a notch in the metal with a bent chunk of metal "pinching" the linkage in there. It looks like it will pinch in tighter the harder you have to push it. The foot lever section is long with no real gussets or mounts to support it before that pinched spot. The final lever near number 110 is short and offers little leverage. I think I can improve on this linkage set up for starters. My locker has never worked or felt like the aforementioned b2150, nor does it feel like any of the other b tractors I checked out today and I think this linkage is at least part of the problem. I think theres more to it but i really do think this can be improved for starters.