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 | jbarrett
Join Date: Jan 2004 Posts: 5 oklahoma 
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2004-06-15 88575
The 4700 hydro that I use creeps forward after the pedal is released.The tractor only has 700 hours on it, but JD can not stop the creeping they said the transmission would be the cheapest way to repair this problem, does any one out there have a similar problem and a simpler soultion.
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 | yooperpete
Join Date: Jan 2004 Posts: 1413 Northern Michigan 
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2004-06-15 88576
I have a Cub-Cadet CUT with hydro that also creeps. I'm told that most hydro's do this. My garden tractors do it too. I've learned to live with it, by putting on the brake or put the range selector in neutral. ....
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada 
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2004-06-15 88581
Let me take a different tack, jbarrett what type of transmission fluid are you using? ....
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| jbarrett
Join Date: Jan 2004 Posts: 5 oklahoma
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2004-06-15 88589
Not low vescosity, regular HY Guard. ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2004-06-15 88599
I have been studying the viscosity numbers and comments on this board.
Some folks have reported their HST's are sluggish in the stop and start phases. Dealers have told some that use of UDT in their HST equipped Kubota's instead of Super UDT (which has a very thin viscosity) will result in poor transmission performance.
Deere pushes very hard for us to use Low-Vis despite temp charts that seem to indicate otherwise.
From my own experience, I bought a BX22 that had Super UDT installed at the dealer. It worked just fine. At the 50 hour mark I changed to Chevron All Weather... which although it is a full synthetic has a higher viscosity than Super UDT.
Two things happened after the change. The tractor started to "creep" and I noticed that the top speed felt slower.
Recently, I bought a Kubota RTV from a local dealer who does not carry any Kubota fluids. I took delivery of the RTV with Case fluids in the sump. All was well at first, but now I notice at the 30 hour mark that the transmission is starting to act a little sluggish. When I take my foot off the pedal there is a one second or so delay before the pedal retracts and I feel the HST brake. I get same delay when I start. I suspect that at 30 hours, the fluids have started to change viscosity due to normal wear.
So..... here is the question I pose: Maybe hydrostatic transmissions are designed/machined to function best with thinner viscosity oils.
We wouldn't consider pouring gear lube in the automatic transmissions in our cars even though we know that it is the fluid of choice in a manual transmission.
We also know that pouring automotive 10w-30 in an aircraft engine instead of the straight 90 wt will ruin it.
Is it possible that UDT and Hy-Gard are best used in manual transmissions while Super UDT and Low-Vis are designed to function best in HST's?
Maybe the clearances in an HST are too close for the higher viscosity fluids.
....
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| jbarrett
Join Date: Jan 2004 Posts: 5 oklahoma
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2004-06-15 88604
I may go back to Low VIS, however JD told me to put the HY Guard in a couple years ago to reduce leak down. The service rep thinks I have internal wear inside the transmission. ....
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 | kwschumm
Join Date: Feb 2003 Posts: 5764 NW Oregon
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2004-06-15 88608
I may well be wrong here, but if wear is the problem it seems that Low Vis fluid may make the problem worse. Before replacing the tranny it may be worth taking it to another dealer for a second opinion. ....
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 | Chief
Join Date: Jul 2003 Posts: 4297 Southwest MiddleTennessee
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2004-06-15 88618
The above discussion on oils may well be the issue or have some degree of influence on the problem but I would think that if a hydro is creeping like that; perhaps either an adjustment to the linkages may be in order or there may be a problem with a directional proportioning valve. ....
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| tk_csa
Join Date: Nov 2003 Posts: 28 western New York
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2004-06-18 88815
My 4700 is the same way, since ~300 hours (now has 550) I use the reverse pedal as the brake and doing that stops it from creping on the flats or gentle slopes. (BTW same type Hyd fluid since it was new) ....
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