GST use/wear question

[Jay4200]

I usually try to chop the throttle before changing gears or reversing with my L4200GST. I also make sure to stop before reversing. Lately while snowblowing, however, I've been keeping the RPMs pinned at PTO speed while shifting and reversing - just too complicated and time-consuming to run a variable throttle (Ever chop the throttle while the blower still has snow in it? It's ugly). I still stop before reversing, and I never use the foot clutch. I've heard that the GST is designed for full-power operation, and it makes sense that it is, but I was wondering about wear characteristics (wet clutches?) and if full-power operation vs. reduced-power shifting makes any kind of a substantial difference in longevity of clutches or whatever is in there that might or does wear out.

So, along those lines, is there anything inside that wears out, and if so, how often does it usually wear out, and what is a ballpark cost of doing the required maintenance when it does wear out?

 

[Baby Grand]

Jay,
My use of the GST on our L3240 sounds similar to yours.
Set the throttle based on load; select a gear based on the speed needed.
When reversing direction I leave the throttle set, shift to N while braking to a full stop, then shift to either Reverse or Forward.
The machine seems to operate very smoothly this way.
The foot clutch gets very little use:
I use it when first getting the tractor moving after starting.
Since it sleeps in a garage, I want to get it (and me) out of the garage quickly, before it fills with exhaust fumes.
At this point, the engine & tranny are full of cold oil and the foot clutch seems to smooth out engaging the drive line and the load on the engine.
After warming up, the only foot clutching I do is for very fine position adjustments -
like when backing up to hitch an implement or getting the 6' FEL bucket lined up over our 6' trailer before dumping.
I'm kind of curious what the life expectancy and wear points are, myself.
Hoping I'll find out by reading TBN, and not while in the saddle.
-Jim

 

[Jay4200]

Anybody? No Kubota mechanics or those with DIY experience on board??

 

[mike69440]

I usually try to chop the throttle before changing gears or reversing with my L4200GST. I also make sure to stop before reversing. Lately while snowblowing, however, I've been keeping the RPMs pinned at PTO speed while shifting and reversing - just too complicated and time-consuming to run a variable throttle (Ever chop the throttle while the blower still has snow in it? It's ugly). I still stop before reversing, and I never use the foot clutch. I've heard that the GST is designed for full-power operation, and it makes sense that it is, but I was wondering about wear characteristics (wet clutches?) and if full-power operation vs. reduced-power shifting makes any kind of a substantial difference in longevity of clutches or whatever is in there that might or does wear out.

So, along those lines, is there anything inside that wears out, and if so, how often does it usually wear out, and what is a ballpark cost of doing the required maintenance when it does wear out?

Kubota L39 with near 2,000 hours. Today i plowed snow all day, shifting fprward to reverse hundreds if not thousands of times at about 2,200 RPM.

I hope the wet cluch is as durable as advertized.

 

[skyhook]

Hey Jay, looks like those gst's are pretty tough, no one has had issues yet.

 

[Jay4200]

Kubota L39 with near 2,000 hours. Today i plowed snow all day, shifting fprward to reverse hundreds if not thousands of times at about 2,200 RPM.

I hope the wet cluch is as durable as advertized.

I hope the same thing. Only 2200 RPM? Rated speed is 2700 on an L39. I always run my L4200 at full blast when running a snowblower...PTO speed is around 2600 RPM, I think...and it has 2600 hours on it. I hope it lasts forever, 'cause I LOVE my creampuff L4200 and don't ever want to have to buy another.

 

[Jay4200]

Hey Jay, looks like those gst's are pretty tough, no one has had issues yet.

I guess so!

 

[HEC]

When I bought my M5700 with hyd. clutch the dealer said no need to lower rpms or even come to a complete stop if in a lower gear which would mean going slowly . I would guess the hyd. clutch would be of the same principle as gst but not sure about that. I too usually come to a stop before changing direction even if not needed . I very seldom ever run at full rpm at any task even when snow blowing. I have creeper gears so that helps when in heavy snow .

 

[Jay4200]

There is a hydraulic clutch called out in the parts manual. Both that and the hydraulic pto clutch look like wet motorcycle clutches, which are generally pretty rugged. Oddly, the GST hydraulic clutch is a 3-plate design, while the PTO clutch is a 6 plate design.

 

[Texas Fella]

The GST Transmission is designed to be shifted at operating rpm. That is the case with both shifting "gears" and forward and reverse shifting. The wet clutches that are used area designed for that purpose and similar clutch packs are used in shuttle shift and powershift transmissions in Kubota product. No worries, no significant difference in wear.

 

[blin]

I mostly bush hog with mine. I leave the lever throttle at speed for the PTO, clutch and break to a stop, then go to reverse and release the clutch. I also will down shift the gear for reverse. This way I am not traveling faster then I was in forward, due to the difference in gearing. I do not clutch when changing gears one or two notches up or down in the lower ranges, but if I'm running a high gear I will clutch on the slow down from say 12 to 9, then 9 to 4 when tuning off a dirt road and into a field.

 

[skyhook]

I would prefer to throttle down than use the clutch.

 

[kubmehc]

No worries they are built to take it. The GST valve engages and disengages the clutch smoothly and the wet clutch system produces practically no wear on the discs.

 

[rbargeron]

Clutch wear depends on how much time it spends slipping under load. If slip time is kept short, the small heat buildup dissipates, leaving the clutch nearly unaffected. Once a GST shift begins, the process is swift (short slip time) like in a car's auto trans. The design life is very long, even shifting under load.

 

[geneP]

Dick, if fast engagement lengthens wet clutch life our EverClutch metering valve should be in the fastest (#1) position for longer life? Mine was in the straight up (#2) position when I got it and I haven't changed it.

 

[tk tom]

I've heard from a local fellow running a JD in his hay business that he can just take whatever shifter that controls forward and reverse and just flip back and forth and the tractor will automatically slow down and change direction with no added user input. I would imagine that's a similar feature on the Kubotas? I'd think they're built well enough to handle such maneuvers. I've only owned/operated a HST, but the gear shift features on these things sure sound pretty durable.

 

[rbargeron]

.......whatever shifter that controls forward and reverse...just flip back and forth and the tractor will automatically slow down and change direction with no added user input.......

I don't claim to know all the variations of wet clutches - but all brands have have continued to improve, becoming more robust, positive and smoother engaging. In the early ones, abruptness of engagement depended on operator technique. Flipping the lever from Forward to Reverse could plant your face in the steering wheel. Luckily with improved design they've become much better.

 

[rbargeron]

Dick, if fast engagement lengthens wet clutch life our EverClutch metering valve should be in the fastest (#1) position for longer life? Mine was in the straight up (#2) position when I got it and I haven't changed it.

Engagement should be reasonably direct, but not so fast that it jerks the machine (or operator) around. The important idea for clutch life is not to ride the pedal. Don't slip the clutch as a means of speed control. That kills any clutch - wet or dry.

Our L3 shuttles have adjustable engagement speed to correct for climate (oil viscosity) But it's more for operator comfort. Any setting will be ok for clutch life. Your Mississippi summer shifts will be softer using the #3 orifice where my Mass winter shifts would be better on #1.

 

[tk tom]

I don't know what it's called or how it works but it sounded pretty cool. The tractor just brings itself to a stop then proceeds to go in the opposite direction. I'd think you'd have to get pretty used to the transitions so you can time it just right, there's room for a lot of oopsies in there and hopefully no running into anything!

 

[rbargeron]

Designers have a tough job. Today's operators demand more and more automation. I remember when GST's were new, they gave operators the "puckers" because tractor could roll while the clutch was disengaged between shifts. Intervention to control tractor motion during shifts was needed. Sounds like your JD hay guy may have one that handles more of that.

"Designing something to be foolproof sometime just gives rise to a new class of fools" - Warren Nelson, Northeastern Univ. 1966