Coast Valve removed from RTV today and OEM one adjusted and put back in

[DelfinoTX]

The design is cleary for that purpose; to have controlled downhill engine braking. And the damper is there to smooth out that deceleration.. Using the stock coast valve setting without the throttle damper makes the RTV drivetrain come to a stop very quickly.. I know, i tried it.. In 2wd it would lock up the rear wheels and skid everytime i released the throttle.

With the coast valve (technically its the reverse check/high pressure relief valve) adjusted out, there is no need to have the throttle damper... Although I belive Kubota could re-engineer that valve to have a cable attached through the cap or plug that would hold the valve open to allow free-wheeling and release it via cable to enable engine braking.. The best of both worlds... Too easy if you ask me... Kubota are you listening? How bout an assesory item to do just that?

DelfinoTX

 

[coobie]

My dealer told me that he wouldn't adjust the factory valve like discussed because it caused cavitation and accelerated transmission wear and heat with tiny air bubbles all throughout the transmission. He told me that is why the purchased "coast valve" does not have a spring, and is just a solid valve. There is no spring to give allowing cavitation, thus a market for that design over just making adjustments to the factory valve. To me, not being any expert by any means in hydro transmissions, this made sense. Why would the factory make dampening rigs etc. if they could just adjust the spring rate of the valve without causing damage?

Again, I am not a hydro transmission expert. I'm just going by what I was told along with the fact that Kubota made other changes to try to alleviate the abrupt stopping rather than change the spring settings on the existing valve. So I obviously have no definitive proof that adjusting your own valve will do damage, how fast it will do damage, or exactly what damage it will do. I'm just going by what my dealer told me and applying that information to the fact that Kubota made other changes to help the sudden stop rather than just turning a screw on the existing valve.

I was also told adjusting the factory valve would cause cavitation,that is why installed the coast valve.coobie

 

[slowzuki]

Usually a throttle return damper is installed for emissions reasons but who knows for sure in this case.

 

[bobm737]

I got the coast valve also, and it is great, I am just wondering why you would change back, is there a potential problem with the transmission using the coast valve? I put my old valve back in to see if it would help me get my transmission out of reverse, but no help there of course, still stuck. Bob

 

[joeshmoe_44883]

Do you still have the coast valve for sale? And what are you asking for it?

 

[bobm737]

Yeah Joe,I do still have the coast valve, I am going to try it with the factory valve for a while and see if I can stand it, but will admit that the solid coast valve made letting off the throttle a lot more pleasant. I wonder if anyone has sued Kubota because they stuck someones head through the windshield because their foot slipped off the throttle?

 

[wswoode]

Nobody on the other forums really talked about adjusting the OEM valve, but I have "heard" that some dealers would do it. After looking at it for a few minutes, it was clear that the allen screw locks in the spring tension, so all you have to do is loosen that, and then unscrew the flat head screw, which in turn relieves tension on the spring.

The plug which covers this is removed with a 10 mm allen wrench. The pictures I took are looking down. If you have a 10 mm allen that works with a 3/8" socket, life will be easier. But after you take the plug out, use a magnetic pick up too to remove a spring, and then use the magnetic pick up tool to take the valve out. I can do it now in less than five minutes, for me the hardest part was locating the 10 mm plug. But, there is only one 10 mm plug on the back half of the transmission, and it is very close to the hydraulic oil tank on my 900. I hope these pictures work!

Wayne

The Pic's are great. The pic's sent with the valve were impossible to locate the plug. Thanks again. Woode

 

[litenyaup]

Was wondering about adjusting the factory valve....any long term issues? Need to do something with this machine to get rid of that harsh deceleration.

 

[litenyaup]

Well super fast shipping. Arrived yesterday and put it in today. Works flawless. Took me all of 5 minutes to install. I can be at full throttle and completely take my foot off the accelerator and it's a very smooth easy slow almost coast to stop. No more getting thrown threw the windshield.

Highly recommended for anyone who had no use for breaking assist.