coast valve

bczoom · Mar 18, 2008

I rely heavily on my engine braking, especially when hauling wood (or something else that's heavy) down a hill.
I can let off the pedal and the RTV will stop.
With this coast valve, will the RTV stop like it used to or will it coast/roll down a hill?

Guest · Mar 18, 2008

[quote user="bczoom"]I rely heavily on my engine braking, especially when hauling wood (or something else that's heavy) down a hill. I can let off the pedal and the RTV will stop. With this coast valve, will the RTV stop like it used to or will it coast/roll down a hill?[/quote]

The cost valve will eliminate almost all the engine braking. It would be for those people who simply don't like that. Its probably the machines biggest strength, but I guess there are those who just don't care for it.

doggman · Mar 18, 2008

In H the engine braking is minimal but it's not like putting it in neutral either. In the other gears there's more braking effect. You probably would not stop coming down a hill without using the brakes. However, Kubota didn't forget to put big brakes on the RTV - they're very predictable and capable. 
With the coast valve it's a lot like heading downhill withyour ATV where you wouldleave it in gear, let off the gas, and use the brakes, too. 
The stops are just a lot smoother when you let off the fuel. The abruptness is eliminated.

mardyn · Mar 19, 2008

Can someone post a link to the ebay site which offerws the coast valve... I can't seem to find it.



mardyn

doggman · Mar 19, 2008

Type or cut and pastethe following into the eBay search box. Kubota RTV 900 1100 coast valve

doggman · Mar 19, 2008

Type or cut and pastethe following into the eBay search box. Kubota RTV 900 1100 coast valve

mardyn · Mar 19, 2008

Found it & ordered one today.

That automatic braking function is the most annoying aspect of an otherwise great vehicle. 

wtf would they design something like that in the system with no easy way to adjust it or disable it is beyond me. 

I'm looking forward to getting it installed.



mardyn

doggman · Mar 19, 2008

mardyn, You'll need a 10mm allen wrench or hex socket and a small cylindrical magnet, like the type used to retrieve dropped nuts and bolts, to change the valve. I had to use a real long nosedpair of needle nose pliers to get mine out since it was a close tolerance piece. You'll also need to elevate the hydraulic oil tank so that you access the valve port - but it's easy to do. I also uncoupled the quick disconnect hydraulic hoses to the bed cylinder and that made it even easier. The instructions are pretty clear. Let us know what you think when it's done. We were really pleased with the results. 
Now, if somebody can come up with a one handed non-finger smashing latch for the bed we'll really be smiling...

bczoom · Mar 19, 2008

[quote user="doggman"]Now, if somebody can come up with a one handed non-finger smashing latch for the bed we'll really be smiling...[/quote]

To tilt the bed? If so, I (and others) have one... Reach down next to the emergency brake. Lift or lower lever. Done.

DieselHound · Mar 19, 2008

doggman,
Thanks for the coast value feedback. I would like to hear from more people that have installed the valve and hear what they have to say about the results. I am looking at getting one myself so that the wife can enjoy a smoother ride when she is taking the RTV for a spin. P.S. I am currently in Trieste, Italy for business and it is amazing how many small utility vehicles they use here for every day work. You can see all kinds of small diesel utility trucks ( similar to Kubota ) driving around downtown. Also, ATV are allowed to drive on normal roads with vechicles. I like the setup they have here.

doggman · Mar 19, 2008

DieselHound, 
My girlfriend loves the way that the RTV drives now. She usuallydrives withacollieor twoon the seat and now she doesn't have to worry too much about catapulting the pooches into the dash. 
Since the highway shoulders are considered as lanes in heavy traffic you almost need an ATV/UTV sometimes in Italy. They're not shy about driving a big 200 hp ag tractor down thehighway, either. I followed a Lamborghini vineyard/orchard tractor for 50 miles in Piedmonte one time. It hauled ass! BTW - How much is diesel over there now? I usually go twice year but with the euro so high Ihaven't been there this year yet.

DieselHound · Mar 20, 2008

Diesel 1.404 Euro for one liter.. which is about $2.17. So a gallon = 3.7 liter.. so $2.17 X 3.7 = $8.029 dollars per gallon! Outch!

Guest · Mar 20, 2008

[quote user="DieselHound"] P.S. I am currently in Trieste, Italy for business and it is amazing how many small utility vehicles they use here for every day work.[/quote]
I vacationed in Italy about two years ago, my wife now wants to move there [

] Its a very nice place to tour.

ddttweeks · Mar 20, 2008

solitude
I read your post the other night and ordered one for my 1100. Same price and excellent delivery. Had the part in 2 days. Only takes 5 minutes to install on the 1100. Can easy be changed back and forth for different tasks. Also got a kubota high air kit. Installed that tonightTakes about 20 minutes and works great with rear screen. Top part is a cleanable dirt trap still uses factory air box changes inlet only. Dirt trap is plastic well have to see how it last. I cut 1 inch off the top section to get it below the roof. Only tried the coast valve for 100 yards. Don't have to work on friday's so I'll play tomorrow.

solitude · Mar 21, 2008

ddttweeks

 I think you will like that coast valve.I never got used of that braking on the rtv just like driving a standard shift truck in low gear all the time!
I never really got used to it.And thanx for info on 1100 air cleaner e mailed my dealer this AM and told him to cut it off an inch like you said.
I ordered 1100 a couple days. thanxfor tip 
 Solitude .

ddttweeks · Mar 22, 2008

solitude
Got a chance to play with the coast valve friday and this morning. The reason i bought one was last friday night i got sucked off the trail in deep snow and had to let off quickly not to hit a tree. In the process my wife kinda got thrown into the windshield. I't happened so quick that i couln't control the deceleration. I think the coast valve will be great for the type of riding i do. So far i like it alot and on the 1100 it's less than a 5 minute job to change so i can easily have the best of both worlds.

doggman · Mar 23, 2008

I had a chance to load up the bed quite a few times with a yard of damp soil and test the transmission brakingwith the coast valve. With that much weight there's virtually no braking in H. A very minimal amount with M and a little bitin L. If you regularly rely on the trans for braking with heavy loads then the coast valve probably won't make you happy. I will say that the juice brakes handled the chore without a problem.It'll be interesting to see how they wear.

RTV_Greg · Mar 25, 2008

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>I've had one of these "coast valves" for about one year now, and I couldn't be happier. Right after I bought my RTV, I had both my side and my wife's side of the family over at our house, and I was of course proud of my new RTV, so I was letting some of them drive it, even after explaining to all of them about "how to drive it" all of them complained about how they didn't like the braking. I was of course disappointed of not having their approval. Not long after that, I had heard of this valve throughmy dealer, so I got one and installed it. I was very pleased with the operation, and now, almost one year later, I couldn't be happier. I can now let anyone drive it, or let someone borrow it, without the need to explain "how" to drive it. <o

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For the people wanting the technical information…..I was of course interested in how this valve worked as I am somewhat of a gear head (or at least I think I am). I originally got an email address (sfsspecialties@gmail.com) for these guys and that is how I got my valve, but I did end up talking to the guy (tim) that designed and machines these valves. He was explaining to me that the coast valve is quite a bit different than the original valve. He told me that the coast valve is based off of a "balanced spool" principal which unloads the oil pressure created during braking, which is different than how the original relief valve works. He was telling me that he has received a few messages on ebay from people that said they just adjusted their relief valve so the machine would coast and they didn't think buying this valve was necessary, but he explained to me that if you just adjust the original relief valve to a pressure that allows it to coast, that the pressure can fluctuate to pressures lower than the charge pressure, and that can cause the hydrostatic motor to "cavitate" and after that happens for awhile, you can ruin your hydro motor. If I understand him correctly, it is like getting air into the system. But by using the unload valve in a balanced spool system, the pressure is constant throughout the flow range (low to high wheel speed). The coast valve also has an orphased hole machined in it to allow a metered amount of oil to leak by so that it is easier to change gears (like when you want to shift down for more power, but the gear shift is "stuck") This guy seems pretty smart, and he wasn't even giving me a sales pitch, I had already bought the valve, I was just wondering how it worked. 

He has an RTV that he has done multiple things to (increased horsepower, aluminum wheels with oversized tires, full cab w/ stereo, etc) but he was telling me that he is currently working on a kit to increase travel speed. 

Alright, hopefully that answers some of your questions about how the valve works. I highly recommend the valve. He was going to send me an email when he gets something going on this kit to increase the speed. I’ll keep you posted if I hear from them.

Greg

TWO GUNS · Mar 25, 2008

First Greg, 
 I would like to welcome you to the forum ...... !!!!!! Glad you jumped on in ~~~~
 Also, I would like to thank you for the post you made on the " coast valve" , that is interesting !!!! And yes, please keep us on to date what you learn about the increased speed kit, I myself, would not need one, for I don't run mine very fast anyway, I'm a snail-trailer,but there are some folks out there in RTV land, that states they would like to go just a little faster ~~~~~~~

doggman · Mar 25, 2008

Hi Greg,
Thanks for the explanation - it makes a lot of sense.I figured thosetiny machine cut notches on each end of the spool were theretobleed a little fluid and equalize the pressure. I think the guy is right aboutunbalancing the circuitwith a mis-adjusted relief valve. It probably could cause cavitation (like water in a blender) thus making foamy hydraulic fluid, and harm the hydraulic motor. However, it might be possible to drill a tinyhole in each end of the stock relief valve and mitigate some of the unbalanced condition. However, it could be an expensive experiment. 
It'll be interesting to see what he comes up with to make the hydraulic motor turn faster. 
If you email him sometime maybe you could encourage him to introduce himself on this site.

coast valve

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