Considering a B7100 HST - Thoughts?

[InJustice]

Hey y’all,

Recently became a proud hobby farmer and came to the realization that we need a compact tractor for mowing, landscaping, and gardening.

looking around we found a 1982 B7100HST with a Woods 145 Du Al FEL, 2400 hrs on it. There is an issue with the High end of the HST being weak, and a small hydraulic leak on the rear end.

So, thoughts? I want to make sure that the High end power issue won’t promulgate down to the lower end, or that it is a fixable issue. I’m thinking the hydraulic leak has something to do with it, but I don’t have that much experience with Kubota’s.

Thanks in advance,
InJustice

 

[Roadworthy]

I don't know what you mean by the high end being weak. I hope for your sake that doesn't mean the clutch is slipping as that would involve major disassembly of the tractor. Yes, an HST tractor does have a clutch. The hydraulic leak is not likely part of the problem unless fluid is quite low.

 

[PaulL]

If you mean the drive is weak when in hi gear, then yeah, that's a sign the HST needs work. Although yes, that can also happen if the fluid is low (which a leak could cause). Before you buy it, take a pail of fluid, fill it up. See if the problem goes away. If it doesn't, then pay quite a bit less for it. Fixing HSTs can be expensive.

 

[InJustice]

I don't know what you mean by the high end being weak. I hope for your sake that doesn't mean the clutch is slipping as that would involve major disassembly of the tractor. Yes, an HST tractor does have a clutch. The hydraulic leak is not likely part of the problem unless fluid is quite low.

I'm not entirely sure, as I haven’t had the chance to test drive it yet. I’ll let you know when I get the chance.
My assumption is that something is slipping in the high gear (it’s a two speed), because the low gear runs fine and it starts up great.

I’ll see what I can do on the price. In regards to the HST, would it be better to buy a new transmission for it or try an overhaul? Trying to get an idea of what my best course of action is. (New trans + tractor <$ new tractor.) Most other tractors in class are a bit out of our price range right now.

 

[TheOldHokie]

I'm not entirely sure, as I haven’t had the chance to test drive it yet. I’ll let you know when I get the chance.
My assumption is that something is slipping in the high gear (it’s a two speed), because the low gear runs fine and it starts up great.

I’ll see what I can do on the price. In regards to the HST, would it be better to buy a new transmission for it or try an overhaul? Trying to get an idea of what my best course of action is. (New trans + tractor <$ new tractor.) Most other tractors in class are a bit out of our price range right now.

Be careful. The engine drives the HST hydraulic pump. Loss of engine horsepower will result in a corresponding loss of high speed HST pulling power. Does the engine maintain RPM?

Dan

 

[InJustice]

Be careful. The engine drives the HST hydraulic pump. Loss of engine horsepower will result in a corresponding loss of high speed HST pulling power. Does the engine maintain RPM?

Dan

I’ll be figuring that out when I go in. What are the cases in which the engine rpm would rise/fall? (Rise if load/efficiency drops off? When would it fall?). And what would be the cause?

 

[TheOldHokie]

I’ll be figuring that out when I go in. What are the cases in which the engine rpm would rise/fall? (Rise if load/efficiency drops off? When would it fall?). And what would be the cause?

The HST is just like any transmission - it multiplies engine power before transmitting it to the drive wheels.

I dont know the specific behavior of the B7100 but the transmission should be able to transmit full engine power to the wheels. If you put it in high range and head up a steep hill you should be able to drag engine RPM down by "flooring" the HST pedal. If the load is high enough and the HST is transmitting "full" input power you will stall the engine just like you would with a gear transmission.

If the engine maintains RPM but ground speed slows or stops the transmission is "slipping". The HST actually has a mechanical clutch so thats a real possibility and relatively easy to fix. If the clutch is holding then the pump/motor system is not making full pressure and that is an involved and expensive fix.

Dan

 

[InJustice]

The HST is just like any transmission - it multiplies engine power before transmitting it to the drive wheels.

I dont know the specific behavior of the B7100 but the transmission should be able to transmit full engine power to the wheels. If you put it in high range and head up a steep hill you should be able to drag engine RPM down by "flooring" the HST pedal. If the load is high enough and the HST is transmitting "full" input power you will stall the engine just like you would with a gear transmission.

If the engine maintains RPM but ground speed slows or stops the transmission is "slipping". The HST actually has a mechanical clutch so thats a real possibility and relatively easy to fix. If the clutch is holding then the pump/motor system is not making full pressure and that is an involved and expensive fix.

Dan

Awesome, that gives me a good idea of what to look for. Thanks for the info.

 

[JimmyJazz]

I would start the adventure (hobby farming) with purchasing a tractor with no known problems. If you enjoy wrenching and have the time that's a different story. Good luck.

 

[PaulL]

If you're seeing it as a cost saving measure (i.e. buying a tractor that needs some repair, as you cannot afford a tractor that doesn't), then make sure the discount is enough to actually fix it.

HSTs are repairable for someone who knows what they're doing. But it's not popular with many places - so you'll find there are some guys who'll do it cheaply and well because they know what they're doing. And other places that just pull it apart and randomly replace parts until it works, charging you for all that.

With my ride on there was a local guy who was happy to reface it (not really sure what that means, but there's some sort of wear that they can basically grind back). He knew exactly what he was doing, and it was really just his time it cost me. Whereas replacing stuff would have been time + parts.

Everything is repairable, the real question is at what cost and whether you'd be better off (financially) buying one that already works.

My experience is that in L gear the tractor and the transmission aren't working hard - it's low gear. So it'll go fine. When you put it in H gear then it exposes any weakness. That could be the engine (as someone else noted), the HST, or the clutch. You'd probably also find that if you put it in L but with load on it (pulling something perhaps) that it will also show "weakness".

My thoughts on diagnostics.....I think running a PTO implement would tell you something - if the PTO is weak under load that would point to something in common between the PTO and the drive. However, I can't recall whether the PTO also runs through the HST on those. I do still think checking fluid is an easy and quick solution - if it's got a leak and hasn't been used for a while it may just be low on fluid. Mine was "weak" in H gear when the fluid was low, put fluid in and magically fixed. It basically just didn't have enough fluid to pump, and in H it's moving a lot of fluid.

 

[TheOldHokie]

If you're seeing it as a cost saving measure (i.e. buying a tractor that needs some repair, as you cannot afford a tractor that doesn't), then make sure the discount is enough to actually fix it.

HSTs are repairable for someone who knows what they're doing. But it's not popular with many places - so you'll find there are some guys who'll do it cheaply and well because they know what they're doing. And other places that just pull it apart and randomly replace parts until it works, charging you for all that.

With my ride on there was a local guy who was happy to reface it (not really sure what that means, but there's some sort of wear that they can basically grind back). He knew exactly what he was doing, and it was really just his time it cost me. Whereas replacing stuff would have been time + parts.

Everything is repairable, the real question is at what cost and whether you'd be better off (financially) buying one that already works.

My experience is that in L gear the tractor and the transmission aren't working hard - it's low gear. So it'll go fine. When you put it in H gear then it exposes any weakness. That could be the engine (as someone else noted), the HST, or the clutch. You'd probably also find that if you put it in L but with load on it (pulling something perhaps) that it will also show "weakness".

My thoughts on diagnostics.....I think running a PTO implement would tell you something - if the PTO is weak under load that would point to something in common between the PTO and the drive. However, I can't recall whether the PTO also runs through the HST on those. I do still think checking fluid is an easy and quick solution - if it's got a leak and hasn't been used for a while it may just be low on fluid. Mine was "weak" in H gear when the fluid was low, put fluid in and magically fixed. It basically just didn't have enough fluid to pump, and in H it's moving a lot of fluid.

Good advice. These models are getting very long in the tooth. Fixing the HST is just one issue - follow on problems are inevitable. Sinking thousands of dollars into major repairs is not cost effective compared to a newer machine with fewer hours and problems.

Dan

 

[mikester]

Have you been listening to the New Wave radio station? I hear 1980 calling you.

I asked my daughter what she was watching on Netflix. She said "old movies from the year 2000"

On the more serious side if I inherited that SCUT I'd take it, I wouldn't consider paying money for a mystery used one. If I buy a tool it's because I want to get a job done. I have no interest in perpetually fixing things and constantly finding new problems to spend time on.

 

[nave.lb]

If you're seeing it as a cost saving measure (i.e. buying a tractor that needs some repair, as you cannot afford a tractor that doesn't), then make sure the discount is enough to actually fix it.

HSTs are repairable for someone who knows what they're doing. But it's not popular with many places - so you'll find there are some guys who'll do it cheaply and well because they know what they're doing. And other places that just pull it apart and randomly replace parts until it works, charging you for all that.

With my ride on there was a local guy who was happy to reface it (not really sure what that means, but there's some sort of wear that they can basically grind back). He knew exactly what he was doing, and it was really just his time it cost me. Whereas replacing stuff would have been time + parts.

Everything is repairable, the real question is at what cost and whether you'd be better off (financially) buying one that already works.

My experience is that in L gear the tractor and the transmission aren't working hard - it's low gear. So it'll go fine. When you put it in H gear then it exposes any weakness. That could be the engine (as someone else noted), the HST, or the clutch. You'd probably also find that if you put it in L but with load on it (pulling something perhaps) that it will also show "weakness".

My thoughts on diagnostics.....I think running a PTO implement would tell you something - if the PTO is weak under load that would point to something in common between the PTO and the drive. However, I can't recall whether the PTO also runs through the HST on those. I do still think checking fluid is an easy and quick solution - if it's got a leak and hasn't been used for a while it may just be low on fluid. Mine was "weak" in H gear when the fluid was low, put fluid in and magically fixed. It basically just didn't have enough fluid to pump, and in H it's moving a lot of fluid.

A fun

The HST is just like any transmission - it multiplies engine power before transmitting it to the drive wheels.

I dont know the specific behavior of the B7100 but the transmission should be able to transmit full engine power to the wheels. If you put it in high range and head up a steep hill you should be able to drag engine RPM down by "flooring" the HST pedal. If the load is high enough and the HST is transmitting "full" input power you will stall the engine just like you would with a gear transmission.

If the engine maintains RPM but ground speed slows or stops the transmission is "slipping". The HST actually has a mechanical clutch so thats a real possibility and relatively easy to fix. If the clutch is holding then the pump/motor system is not making full pressure and that is an involved and expensive fix.

Dan

Im new to Kubotas and

If you're seeing it as a cost saving measure (i.e. buying a tractor that needs some repair, as you cannot afford a tractor that doesn't), then make sure the discount is enough to actually fix it.

HSTs are repairable for someone who knows what they're doing. But it's not popular with many places - so you'll find there are some guys who'll do it cheaply and well because they know what they're doing. And other places that just pull it apart and randomly replace parts until it works, charging you for all that.

With my ride on there was a local guy who was happy to reface it (not really sure what that means, but there's some sort of wear that they can basically grind back). He knew exactly what he was doing, and it was really just his time it cost me. Whereas replacing stuff would have been time + parts.

Everything is repairable, the real question is at what cost and whether you'd be better off (financially) buying one that already works.

My experience is that in L gear the tractor and the transmission aren't working hard - it's low gear. So it'll go fine. When you put it in H gear then it exposes any weakness. That could be the engine (as someone else noted), the HST, or the clutch. You'd probably also find that if you put it in L but with load on it (pulling something perhaps) that it will also show "weakness".

My thoughts on diagnostics.....I think running a PTO implement would tell you something - if the PTO is weak under load that would point to something in common between the PTO and the drive. However, I can't recall whether the PTO also runs through the HST on those. I do still think checking fluid is an easy and quick solution - if it's got a leak and hasn't been used for a while it may just be low on fluid. Mine was "weak" in H gear when the fluid was low, put fluid in and magically fixed. It basically just didn't have enough fluid to pump, and in H it's moving a lot of fluid.

Im new to Kubots and HST’s. I bought my first 7100 about 4 months ago and somehow now have 3 tractors (1 is gear drive) a loader, backhoe, tiller and box blade…apparently i like them…Or i have a problem. also likely.
Your right about buying tractors in need of repair. Ive done well with it but its a slippery slope. The cost of parts and a mechanic if you have to pay one can quickly turn a “great deal” into an expensive repair. The Kubota WSM has some very good info for diagnosing the hydro transmission to pinpoint an issue. Ive read quite a bit of technical data about them and have come to one conclusion. I like the gear drive.