John Deere 4300 Shaking When Engaging HST (forward or reverse)

   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #11  
Then (according to what super55 writes) sounds like the hydraulic charge pump is a (or the) problem.

Have never experienced the HST chatter on my 4300 at low RPM and usually 1500 rpm's is where I operate.. except when rotary cutting or other PTO attachments (save for the turboSaw that is cutting stumps low at low rpm).
At low rpm and cold tranny oil, low rpm will sometimes cause a hydraulic whine (sing) that a few rpm boost up will cause to go away.

The chatter sound on the video sounds like something locked up.. parking brake holding, reverse pedal in wrong position, internal tranny fail, ??

So far, not a good description of the problem from the OP. Hoping to get more, maybe in the form of another video, from chasing down several of the proposed suggestions.
Naturally interested because I also have the 4300 and like it a lot. None of the computer/electronic "improvements" made to the models that followed.
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #12  
On my 4400 I can reproduce what the OP was describing but only when it is in C range at low RPMs . B range only if I am dealing with temps in the teens.

On my JD 1420 commercial mower its a different story. On a cold start with cool temps and if I mash the pedal it will do that bucking for about 10 seconds until i either throttle up or the fluid warms up.

As you said Beenthere, this shouldn't be overly difficult to diagnose compared to the 4310. When the went to the electronic hydro things got vastly more complex
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #13  
I get the same reaction and sound, if i forget to release the parking brake. Check that?
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #14  
The shudder should go away if your run the tractor at a higher RPM. This is because right now at a low RPM your hydraulic charge pump isn't pumping enough fluid to the transmission. When you press it rapidly all the way down the squash plates are opening fully and there's not enough fluid going through. The lack of charge pressure will cause bucking as you mentioned.

Also as Footer said check the linkage and make sure return the pedals are returning properly.

Hydro transmissions and low rpms typically don't play well together. I typically just keep my 4400 hydro at PTO rpms.
I have the same issue with a tractor I just bought. I’ve done a complete fluid change including cleaning the screen. Is their a fix for this, or is it just a part of this tractor?
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #15  
check to make sure you don't have a stuck brake. it will do the same thing.
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #16  
check to make sure you don't have a stuck brake. it will do the same thing.
I checked that today. It isn’t the problem. Are their any valves that need cleaned???
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #17  
Sorry about the delayed reply.. Been away from the computer. Is it still shuddering when running at PTO rpms even after warmed up? If you did filter swap and cleaned the screen then once the oil is warm you should not experience shudder if the RPMs are up.

Just out of curiosity did you end up using JD hy-gard or hygard lo-viscosity. If you use generic tractor hydraulic fluid it has too much viscosity for the for pump especially if you are in a area that gets winter temps.
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #18  
The noise you are hearing is caused by high system pressure. There is something that is loading the hydraulic motor in the transmission. It is either the motor itself, something mechanical in the gear transmission/final drive or the brakes.

The next question is why is there high system pressure?
Does the tractor ever move?
Does it act the same way in fwd and rev?
Is it the same regardless of what gear range you are in?
Have you tried it with the tractor off the ground?

You mentioned that you did some work on your brakes. Have you verified that those aren’t engaged?
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #19  
My 4300 cuts the engine when forward or reverse pedals are pushed, also if I activate PtO for midmower. This all goes away after 30 to 40 minutes of warm up. So, hydraulic fluid change?
 
   / John Deere 4300 Shaking When Engaging HST (forward or reverse) #20  
Years ago on my JD 4400 the dealers installed a loader with a 4 in 1 bucket , they delivered the tractor to me I started driving the tractor and the hydraulics were strained trying to over work , long story short the control leaver installed to open and close the 4 in 1 was sticking .
 
 
Top