Rtv1100

[SpudHauler]

On the RTV's there is a servo valve adjustment screw that you can turn in or out to make the transmission more aggressive. I've been playing with mine as it seems lazy getting away from a dead stop, or on a hill trying to take off from a dead stop. Unless in 1st, it just bogs out.

Can someone give me an idea of what to look for and what way to turn the screw to get the more aggressive take off? Out, would be less spring pressure so more aggressive?

How are they adjusted from the factory? Can you check a pressure point and adjust until a certain pressure is reached or is it just driver feel?

Stupid me I didn't record the factory setting. I think about 4 turns out.

 

[eserv]

The servo spring you adjusted is designed as servo centering spring. to get it back to factory remove the hst control rod off the servo lever then jack the rear of the machine up, put it in gear (in TWO wheel drive!!) and adjust the screw you turned until the wheels are both stopped. You turn it out to increase the stall engine speed and in to reduce it. this valve wasn't designed for this purpose but it DOES work and will give you a noticable increase in launch torque. ( because it allows the engine to rev higher at stall thus producing more power. This valve seems to have a greater effect on the 900 than the 1100.
Ed

 

[SpudHauler]

Okay, so the hst rod and this servo centering spring do interact.

I've adjusted the rod by jacking the machine up, putting it in H, 2 wd and hold the throttle wide open using the Throttle Control Knob, not the pedal, and then adjusting the rod until I got the wheels stopped so there was no more creep and it does shift better.

But obviously the HST rod adjustment is meant to be done after your suggestion for the servo centering spring, so then the aggression will be set to my preference and the HST would be in Netural.

Thanks, I'll give it a go tomorrow.

 

[SpudHauler]

Ed,
Here is what I did. Removed bolt from the HST control rod, pictured here with my red wire tie as a marker for adjusting, and with tires off the ground, throttle (hand throttle) clamped wide open, trans in H 2wd, we adjusted the servo screw, second pic, in and out all the way with no change what so ever.

Then, bolted the rod back together and fine tuned it until the wheels had stopped turning. Same scenario, H 2WD, full throttle, etc... We did this previously but with the fluid changed to Premium UDT at 51 hrs, now has 58, has made a slight change and we corrected the HST neutral once again. Shifts better too.

So I'm back to 5 turns out from bottom on the screw and not getting the extra punch I was looking for.

Are we on the same page with this one?

Pictures tell a thousand words.

 

[SpudHauler]

My pictures to go with what I'm looking at on the RTV1100 2009.

Sorry about the size, had trouble getting them resized. Learning, always learning.

 

[SpudHauler]

Finally got the pictures sized.

 

[eserv]

You won't get a lot of extra punch by adjusting the servo valve on the rtv1000. It'll help some but that is a heavy rig for a 25 hp engine! I have gotten some results by adjusting the high pressure relief valve upwards but you are doing it at your own risk! ( I have 2 machines running at 3500 psi with no problems so far) and, yes, they are both well off warranty!! Make sure your throttle is going to full open and you can increase the full speed up on the engine a bit. Just remember, these adjustments are outside of the design perimeters so don't be surprised if something breaks! ( but then, the competition is breaking down all the time so a little down time with the Bota we could probably live with huh?) It isn't hard to increase the fuel on those engines too but in my experience you'll make more smoke than additional horsepower, remember, there is no turbo to give it more air!
You COULD put a nitrous kit on it but the transmission won't allow you to use much more power. Some people turbo them. Kubota have a turbo version of that engine that puts out 32 hp! that would wake it up!!
Ed

 

[SpudHauler]

Ed,
I think I've found my problem, but must do some more testing to be sure. I'll fill in the details this weekend with the results. It may be very helpful to more people.
Later

 

[SpudHauler]

Ed,
Here is what I found.

 

[SpudHauler]

And more pictures.

 

[SpudHauler]

Third round of pictures.

 

[SpudHauler]

And last picture for fun.

 

[SpudHauler]

Forgot this one picture. Again for fun

 

[SpudHauler]

Ed,
It's been a while but I'm back at my RTV again and looking over your information about the servo and reading the manual.

We've adjusted the 'servo regulator screw' the one pictured here in my post, but never touched the 'servo screw' the one you mentioned. After reading the manual for the 10th time, just realizing there are two servos mentioned and one is actually called the servo regulator. I never noticed.

Perhaps that is why my 1100 has always been difficult to shift. I've been concentrating on the wrong servo screw.

The manual says I should have two pressure gauges and set the pressure the same on P1/P2 to get a good neutral. But you are suggesting just do this by watching for tire rotation. Sounds like your method is simpler and just as accurate. Is this what you found and is the reason I don't need the gauges to get the same results.

And what about the one I've been playing with. After doing the neutral adjustment on the 'servo screw', what do I use as a guide to adjusting the 'servo regulator screw'.

I've made sure I have full throttle and have checked and adjusted the brake operated hst pressure release lever to be sure it is not partially activated by setting the spring tension so it is just loose on the lever and that's all. So no problems there.

You didn't notice but I have a turbo installed. See the funny ex pipe in one of my pictures. Big difference in power. And the instructions that came with it said to add 2 washers behind the 27mm cap back at the pump to increase working pressures but don't have a gauge yet and not sure what the pressures actually are. The other trick was to remove the orifice, 2mm allen wrench, in behind the servo screw you are talking about, which must
be the biggest reason for lazy take offs because after drilling that out, because it was so tight the wrench rounded the hex in two tries and couldn't be removed, it rolls twice a freely. Really noticed that difference right away. And when the boost builds away she goes.

So you see I'm still trying to learn about this hst stuff and will not give up.

Have a EGT gauge coming so I can monitor the turbo results and fine tune that part. Of the three settings for the High speed they gave me, I'm at the middle and find in colder weather I've lost some top speed, the rest seems okay, but hoping the gauge will tell me what's going on. I have the high air intake kit and that may affect air flow to the turbo so adjusts might be required for my setup. Also would like to get some fuel economy back as it seems too thirsty for the gain, but if the EGT numbers are good I'm also fine with that. The other adjustment was for mid-range and they only had one setting, which I used, but again, hope the EGT will help me fine tune.

I let you know the results for sure.

Interested in hearing what you think and the adjustment on the servo reg. screw.

 

[SpudHauler]

Well it has been a while but I did make some great progress. Or at least someone did.
I talked with my dealer and had them adjust the neutral pressure, hex bolt with 17mm lock nut on right side. The dealer tech said the neutral pressure was off by quite a bit. Not sure exactly how much but the check was obviously worth the effort. And I understand they had quite a time getting the port plugs out. When I got it back it was still creeping so I immediately turned the HST adjustment out one complete turn and that made a big difference. And I then checked my pressure release lever to make sure there was just the right amount of tension on the spring so it engaged fully when the brakes are applied but not too much so that it releases completely when not in use.
So with the servo regulator screw, slotted screw with 14mm lock nut, out 2 turns from bottom, I set about to adjust the hst lever. Manual says 1mm less than full travel on HST arm, so I rigged up a dial gauge and set about to have exactly that measure with the throttle wide open, pedal to the floor, actuator arm against it's limiter stop and the HST arm 1mm less than full travel.
Wow, what a difference. Sorry I didn't measure first to see how much I changed the HST rod adjuster, but this change made the bigger difference after having the neutral pressures checked. It now shifts very well. Still requires some brake at times and a little patience, but always shifts. And when it doesn't quite go, a little blip of the throttle while holding a little pressure on the lever and it goes every time. This with about 90 hrs so it is still a really new machine and I sure things will only get better. Matter of fact you do notice the difference when the trany gets up to temperature as the shifts do get easier. And the brake pedal/pressure release also must have helped as applying the brakes definitely releases pressure and makes it shift better. Very happy.
Now if they would just put a solenoid like the fuel cut off on the pressure release and hook that to the brake light switch so any application of the brake would applied full pressure release I think that would be great. Kubota are you listening?
I know most don't notice the shifting as bad as some of us do, but this is because you don't plow snow with your RTV's. Anyone who does knows the shifting problems all too well.
Then this weekend I did one other thing that annoyed me to no end. Why have a special gate on the reverse-slot for the shifter. These machines don't shift unless you are stopped and it's not like you are going to speed shift from low range to medium range and hit reverse. So I ground out the little extra metal jutting out into the slot. Works great and does make it easier to shift. One hacksaw and a little filing, problem solved.

 

[eserv]

If I owned one of those and was using it as you are to plow snow I would fabricate another pedal in there to use as reverse. The hydrostat in that machine HAS reverse, Kubota just haven't made use of it! You would not have the torque sensing when operating in reverse but, plowing snow you wouldn't really need it anyway. I don't think it would be too hard to figure out.
Ed

 

[SpudHauler]

I thought of the reverse pedal, but I want to trade mine for the new door/slide window setup, and this one is my test bed to see what works best!
And you're right it would not be hard to gear up. Not sure how it would work in H and in reverse. Could be a speed demon.
Anyway, do you know which way to adjust the servo regulator screw, slotted/14mm lock nut, for more aggressive down shift?
And if 1/2 turns is considered allot?
I was going to experiment with it and try some different settings as I don't feel it downshift when going up hills. And when plowing I don't notice it down shift in L, and maybe it will not, but L is the only gear I use for plowing.
And because the HST lever is linked to this adjustment, I suppose I'll have to check the travel of this as well to make sure I don't loose the 1mm of free play at the end of it's travel range.

 

[eserv]

The servo adjustment will have no effect on what you are calling downshift, it is totally dependant on the high side pressure. I doubt you would "feel" it anyway, because it is not really a shift but a gradual change in the swash plate angle of the servo motor effectively increasing the displacement of the motor combination. you could alter it by changing the spring rate on the servo motor, I have never tried changing that but it would be easy to do. With the extra power you have I'd suggest that you need more spring pressure to keep it from "shifting" down so early.
Ed

 

[SpudHauler]

Part of the upgrade to turbo was to put 2 thick washers behind the big spring at the rear under the 17mm hex nut.
I wanted to have the pressure checked when the dealer had it in their shop for the neutral adjustment, but they never got to that part, so I'm left not knowing what I now have.
But it definitely has some great pushing power.
The only part that is still puzzling is that at times it will just sit there and moan. If you can get it moving 2" you are free. But in high traction situations when you are stuck, it has a hard time spinning the tires. Reverse is the worse as the ratio is higher than L. Stupid move on Kubota part, L and R should have been the same ratio. So you are forced to push forward to get that little rocking motion you need to get her free. So far I haven't been stuck this winter, YET!
I know, I should not have said that!

 

[eserv]

Did you increase the forward high side pressure? If you put washers behind the big spring on the back, you may have increased it's pressure to above the high side pressure. then you won't have any torque sensing ( shiftdown) I don't know how far you can go with the high side pressure before something breaks but I have one machine here that I set to 4000 psi ( stock is 3700-3840). unit must be warmed up to check pressure. With stock settings the transmission is only capable of approx. 20 HP, that is why it just sits and hums over relief! ( and why a turbo isn't all that effective without seriously increasing the pressures and/or flow. The flow is hard to change but the pressure is not. Like everything else though!You modify it, you break it, it's not Kubota's or my fault!