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Curtis B.
Curtis B., Technician
Category: Agriculture and Farm Equipment
Satisfied Customers: 3016
Experience:  Technican turned service manager on multiple lines of equipment and rental equipment.
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Kevin we had spoke before about transmission shuddering

Customer Question

Hi kevin we had spoke before about transmission shuddering when letting out the clutch on 7230 ***** ***** deere about 5 months ago. It still does it and dealer still wants to replace it. Have not been out to check it again. Now it will do it when using left hand reverser and no clutch. Also pause between forward and reverse seems to long. Thanks again, Trevor
JA: Thanks. Can you give me any more details about your issue?
Customer: I did
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Submitted: 6 months ago.
Category: Agriculture and Farm Equipment
Expert:  Kevin replied 6 months ago.
Not good. Unfortunately with out doing some fairly in depth pressure testing I don't believe there is going to be an easy fix. My guess is that there is a problem in the reverser/traction clutch portion of the transmission. Speaking from experience we often tear down and repair the front section that contains the traction clutch and the forward/reverse module. If once the tractor is moving it operates through its entire working range smoothly both loaded an unloaded then the IVT portion is normally fine. Some dealers prefer to only install John Deere reman transmissions as they offer a Deere warranty. Are you getting any pressure warnings when the shuttle delay occurs? Thanks,Kevin
Customer: replied 6 months ago.
Transmission works fine once it shifts from forward to reverse or reverse to forward. It just seems like in between it has to wind up like a rubber band before it goes either forward or backward and gives a very slight shudder before it starts to move.
Expert:  Kevin replied 6 months ago.
Sorry about the delay, I have been in the fields myself. The delayed response and slow engagement indicates either a high fill volume (due to wear or damage), or a low pressure/modulation problem. The CR and CF clutches are responsible for forward and reverse. If the shuttle is the same delay in both directions then it may be a clutch control issue. Does the transmission respond differently when cold vs. hot? Thanks,Kevin
Customer: replied 6 months ago.
It has a longer delay when oil is cold, it is not quite as much delay if you pull the ivt stick back to about one quarter, but then there is no speed.The shuddering is worse when you are turning short and using wheel brakes.On soft ground, even at high rpm, there is a long delay between forward and reverse. Like 4-5 seconds, then it winds up and away you go.
Expert:  Kevin replied 6 months ago.
I know you mentioned in the previous post that your dealer had done some pressure tests. Do you recall if the system pressure had been within spec? If not do you have a pressure gauge and DR coupler that you could use to do some checks? Thanks,Kevin
Customer: replied 6 months ago.
No, I don't have a guage, but I know a couple guys who used to work at John Deere. I think the system pressure was within spec but he said it was fluttering 5-10 pounds on the guage. It wasn't steady. The tech just advised to replace transmission. He is the only tech they have to send out for ivt. I could get one of the former John Deere techs to put a guage on iy if we knew where and what to check. Thanks
Expert:  Kevin replied 6 months ago.
Let me do some digging to see if I can find some procedures for testing the forward/reverse clutch modulation with a simple gauge. Most of the tests ask us to us a bypass manifold to check for leaks and modulation. I believe we can do some basic checks that will verify the issue. Unfortunately I will be unavailable until Monday so I apologize in advance for not being able to get back to you more quickly. Thanks,Kevin
Customer: replied 6 months ago.
Thats no problem, its been an ongoing issue.We are gearing up for field work and this is just our loader problem. I really appreciate your helping me. I am a little reluctant to just go ahead and replace tranny.
Expert:  Kevin replied 5 months ago.
Ok so I've been doing some research to see what tests I could have you do that might help us narrow down the source of the problem. Along the way I discovered a bulletin about delayed modulation on IVT tractors of your series. The description of the problem indicates that the tractor might start off working fine when cold but the forward reverse modulation gets longer as the tractor warms up. The Bulletin also mentions that the clutch gets aggressive when the oil heats up. In this case the problem as actuially caused by software, unfortunately the fix is to replace the UIC/PLC controller. If you can provide me with your tractor serial number I can check to see if it is one of the tractors affected by this particular failure. Let me know when you get time.ThanksKevin