2004 L35 Harsh upshifts

[Mpaavola]

Good afternoon everyone. I have an 2004 L35 that when I shift gears it has a very fast and harsh engagement. The problem is most pronounced when I shift to 2nd then third then fourth. It gets better as I go up the gears. The problem seems to have come about when I changed from whatever hydraulic fluid the service company was using to the super UDT fluid. My understanding is there is an adjustment on the trans to change the speed of engagement. If so I have not found it yet. Does anyone know where on the trans this adjustment might be or can direct me to the service manual that will have this info. I don't have a problem buying the manual if I need it but I don't know which one is appropriate. Any help will be appreciated.

Thanks
Mark

 

[rbargeron]

Hi again Mark,

Of all the WSMs I've seen, none have details on actually adjusting the abruptness of the shift. After writing my reply to your post on TBN I noticed the L35 parts diagram shows four GST variations depending on serial number. The newer ones have electronic control of the clutch pack pressure rise - earlier ones had the orifice in the modulating valve body. Maybe Wolfman knows more about this.

 

[North Idaho Wolfman]

Yes that is a complicated setup, But most people over complicate the GST's and turn them into a rainbow unicorn... knome... White buffalo?

I can't tell you how may misleading, misinformation, misunderstanding posts that I've read on this transmission type.

There are several factors that can lead to it acting like that, and yes changing from a thicker fluid like UDT to a thinner fluid like SUDT2 can cause bad side effects to a GST.

First I would get the manual, there is only one for all the variations.
And Like rbargeron said there are variations per serial # so get the serial #.

Once you have The WSM in hand then jump back on and I can point you to the most common things to check and adjust.
You might also need to get a pressure Gauge and hose setup to test it.
I built my test setup off of parts from various places.
Gauge 3500 PSI
Grease gun whip hose 10,000 PSI
Adapters for 1/8 to 1/4"

P/N 97897-11642

If you don't have a local dealer:
https://www.messicks.com/part/97897-11642/l35-shop-manual

 

[Mpaavola]

Thanks gentlemen. I will get a manual ordered and go from there. The serial # is 72682. Is it possible that going back to the hydraulic fluid that was used previously solve the problem? I do not know what the shop used previously. The work order just says hydraulic fluid.
In case any one is wondering, Yes I do know how to work on the tractor. When I was working I had more money than time so I just had a local shop do any maintenance or repair. Since I retired I have more time than money. Also the closest dealer is about 45 minutes away and not much help. I order most parts thru Messicks.
My local dealer can order parts but charges me for shipping and then I have to drive to them to pick up the parts. Not an ideal setup.

 

[Russell King]

My local dealer can order parts but charges me for shipping and then I have to drive to them to pick up the parts. Not an ideal setup.

Your dealer is messing with you a bit. If you have the time just tell them to get your parts with their normal truck delivery that should come in every week or two. Then shipping is free.

Most people are impatient and ask for the fastest delivery and then the dealer will pass the cost of shipping to the buyer.



Sent from my iPad using Tapatalk

 

[Mpaavola]

Russell, I agree with you about the dealer. They generally ship parts from one of their other locations which has a much larger parts stock. The dealer closest to me (Sacramento) doesn't seem to stock much but their other store in farm country seems to always have the part.
BIA, not yet still working on a solution. I need to buy the manual to study up on the GST.

 

[North Idaho Wolfman]

Yea I'm too far from any dealer too, like 4 hours round trip too far, I order all my parts from Colemans or Messicks.

You might be able to change it back to UDT and get it to act the way it did but that is a crap shoot at best.

Your better off getting the manual and seeing what needs to be done to get it set up right.

 

[Mpaavola]

Ok, so I have the manual and gauges needed. Reading the manual I understand about check the system, relief and pilot pressures.
I have a basic understanding of the operation and it appears that the issue might be with the modulate valve or the accumulator or both. Unfortunately the manual does not discuss adjusting these items, only that I shouldn't adjust them. So having said that am I on the right track?
Any help is appreciated.
P.S. I checked on the cost of a replacement GST valve assembly. Over 3K. Not going that route.

 

[North Idaho Wolfman]

Yes, sounds like you're on the right track.

My model also says that you shouldn't "work on the valves, well the mechanic before me didn't get the memo and messed them all up, I had to go wing and a prayer into them to figure out what he messed up, turned out that he had put too large of O-ring in it.

Let me look over my manual and see what I can come up with for possible adjustments, or other things to check, it's even possible that it just needs disassembled and cleaned.

What were the pressures?

 

[Mpaavola]

Thanks for the fast response. I have not yet measured the pressures, It might be a few days before I get a chance to work on it. I don't have any problems with making adjustments even if the factory doesn't want me to. You can learn a lot about stuff sometimes by just working on stuff your not supposed to.

 

[Mpaavola]

Ok, so I checked all the pressures and here are the results.

Original Adjusted​

Relief Valve 410 425
GST Press 330 365
Pilot 360 N/A
Clutch Pack 365 N/A

The numbers above do not line up but the first number is the original and the second number is the adjusted. Pilot and clutch pack did not need adjustment.

So all of the pressures are normal but no change in operation. I did not expect any but I needed to check for a baseline. I now belief it is an issue with the Modulate valve and/or the accumulator valve. I took a look inside the modulate valve but there didn't appear to be any adjustments.
There is a graph in the manual that shows the operation of the circuits based on time but it does not provide any time values So I cannot see if the rate of engagement is correct.
So at this point of time I am going to replace the springs in the modulate valve and the accumulator unless anyone has any better ideas.

 

[Mpaavola]

Well based on the lack of responses I am going to guess that nobody is a wizard with the inner workings of the GST transmission. I will try some things and get back to everyone if I find a solution.

 

[sheepfarmer]

Thanks for keeping up the updates in spite of useful feedback on your questions. Glideshift wizards do seem to be in short supply right now, but a lot of folks learn from these threads.

 

[North Idaho Wolfman]

Sorry didn't catch your updates.

First remove the modulating valve and check for damage, debri or ??.

Pictures of the valve might help
Look on pg 3-S56 and do not remove #7 as that is the adjustment (might have to in a bit).

Also look at the adjustment on the low pass Valve Pg 3-S57 is the lock nut tight?
That will be the next valve to get into, but not yet

Do it one valve at a time and don't move to the next till all options on each step are done, and check in often, send me a PM if I miss a post.
Or send me a PM and I'll give you a Number to text me.

 

[Mpaavola]

Well Wolfman that is some more options. I pulled the plug off the bottom of the modulate valve and slide it apart but did not touch the # 7. It was in good shape and moved freely. Does that come out or adjust from the top? The lock nut is tight on the low pass valve. I have not taken the actual GST valve off of the trans. All of the work has been with it still installed. I can PM you if needed but texting is not an option. I am the only person in the world without a cell phone.

 

[North Idaho Wolfman]

Does it seem to be slow to engage then slam into gear?
does it either improve or change after running it a bit?

And it was shifting perfectly before the fluid change right?

I don't see any need to go into the guts of it as of yet.

I'm thinking pull all the valves out of the GST valve assembly one at a time and look for anything in the valves or ports.

 

[Mpaavola]

Wolfman
It is not slow to engage. Since I used to be a drag racer it engages somewhere between a trans with a shift kit and a transbrake.
It was shifting just fine before the fluid change. Regarding the fluid change I did not notice any immediate change to how it shifted. It was gradual over approx. 20 hrs run time. It seems to be a little softer shifting when it is cold and harsher when it warms up. These items are what leads me toward the different trans fluid.
I will take apart the valves and check them when I get a chance next week.