Tef20 wont select fwd gears

Mark stevens · Nov 18, 2023

Thank you for allowing.me to join the forum. I have a tef20 that wont select any fwd gears. Tractor not used for 6months and gear selectors were seized. I took gearbox lid off and freed off selector rails with wd40 and a light tap - all free. Rebuilt it all and it now won't select any fwd gears. Start and reverse are fine. Detent springs/plungers are free on selector rods ( i took them out and cleaned them). Doesn't look to be any damage to the gears or excessive wear on gear faces where they select.
I am baffled.
Any help or advice is greatly appreciated, regards, Mark.[/b]

BarnyardEngineering · Nov 18, 2023

Can you be more specific? How won't it select any fwd gears? Does the lever not move into the positions? Does the lever flop around? Does the lever click into place like normal but the tractor won't move?

rustred · Nov 18, 2023

Seams like u have one fork out of place. Make sure all
gears are in neutral. Make sure forks are in neutral
position and care fully make sure they go where they go.

Janicholson · Nov 18, 2023

The link shows an Endoscope for a smart phone. using the device taped to a piece of stiff wire, it can look inside your transmission to see precisely what is wrong.
through a fill hole of other port. Knowledge is priceless. Jim
one option

Janicholson · Nov 18, 2023

You are sure welcome to be here, hope we can help. Jim

Mark stevens · Nov 19, 2023

All forks are in neutral. With gearbox lid removed the only selector shaft that moves correctly is start/reverse. 1/2 and 3/4 only move about 3mm either way and hit a hard stop. I have checked the back end and there are no obstructions etc in the rear diff/axle casing where the selector shaft retaining plate is. All Detent springs/ pins have been removed from front to ensure they ate not causing the issue.
It feels like the two selectors can't move because something is misaligned.
All locking wire and locating bolts are intact and in place.

Duner Wi · Nov 19, 2023

You say you the plungers and springs are free. How about the 2, 1/2 inch balls at opposite end on the 3 shift rail/ shafts, very well may not be the balls but it is the only thing I can think of unless the forks to gears are indexed incorrectly.

Mark stevens · Nov 19, 2023

Which 2, 1/2" balls? The only things I can see are the 3 plungers and springs that locate the selected gear by dropping under spring pressure into a notch in the selector shaft, and hold the shaft from moving out of gear. Are there 2 more balls somewhere I am missing? If so where are they please and I will locate them and check them. Many thanks.

Duner Wi · Nov 19, 2023

Opposite end of the detent springs and pins. Two balls moving horizontally separately between 3rail shafts. Purpose is to keep you from selecting 2 gears at the same time. That is what I think their purpose is. They are clearly showing in parts book.

fdt860 · Nov 19, 2023

If your tractor is not running, Make sure you roll the tractor back and forth as you try to engage gears.

Mark stevens · Nov 20, 2023

Thank you for explaining where they are etc. Could I ask you to post a picture of the parts page please so i can visualize exactly how to get to them and check, Many thanks, Mark.

Bruce(OR) · Nov 20, 2023

WD40.
Water Displacement Formula number 40. The first 39 didn't work to displace water, but the 40th attempt to do
so proved successful.
Oh wait.
Your not displacing water, are you? I suspect rust and varnish might be more so your problem than water.
Hmmm.
Me?
I like Kroil when the pockets are deep or I have a real problem, PB Blaster is on the cheap side and works
most of the time, just not always. Seafoam Deep Creep, Hopwes Penetrating oil is good also and INHO, better
than PB But maybe not quite up to the level of Kroil. There are a few others, not to mention the ever so
popular 50/50 mix of Acetone and ATF.
You believe WD-40 got things free and life is good.
Have you tried starting the tractor in neutral and releasing the clutch?
Does the machine stall out?
Your stuck between gear ranges. Two of those shifters are not laying nice with each other.
Did you verify that the shift forks are still connected to the shift rails?
What about that one that doesn't move? It is borken?

Mark stevens · Nov 20, 2023

All 3 move, but only S/R will select. 1/2 and 3/4 only move about 3mm each way - when they stop it is a hard mechanical stop, not a gummed up stop. They are not seized in the casing as is often the case.

caterpillar guy · Nov 20, 2023

I would jack one wheel up then you can turn the transmission gears with that as they turn you could have some help with either the turning or the shifting to see if the gears are aligned to shift or if they are just hitting the other gear misaligned so they hit an abrupt stop like you describe. With the lid off do the gears slide freely on the shaft they set on, and can you slide them with your fingers, or do you need a pry bar to slide them? The balls they speak of ar the ones that some set in the shift tower or plate in the middle of the shift rail and contain only one per rail and some have them in the transmsiion case and one at each end of the rail with a spring on top visible when the lid is off the top. The springs will stick up out of the holes slightly so as to hold the rails from slipping out of place during operation or to hold them in a particular position. Sometimes they get rusty and rough to move when setting over time.

Duner Wi · Nov 20, 2023

Hope this helps

Mark stevens · Nov 20, 2023

Thank you for the picture.
I have 25/26 on the diagram - would/Could I also have 23/24 in the back end. My top cover is larger than shown and covers both gearbox and clutch gallery/chamber.
My shift rods move freally by fingers as do the gears at the bottom of the selector forks, but hit a hard stop. I can't tell if it's gear misalignment or selector rod/shaft. I have turned wheels and engine by hand to align everything by eye and still nothing. I have put cover on and run the tractor and once in 500 plus tries i got 3rd/4th! Reverse is slick as anything.
I might measure accurately the location of the selectors on the shafts and then undo the wire/lock nuts/bolts and try and engage gears with fingers- if this works I know it is a selector rod/ball/spring (23/24 above) issue and not a gear misalignment.
The gears don't appear to have dropped at all, and I have checked for lateral play with sa pry bar (gently). Please keep the advice coming - it is very helpful thank you, Mark.

Duner Wi · Nov 21, 2023

Mark stevens, When you said this

"S/R will select. 1/2 and 3/4 only move about 3mm each way - when they stop it is a hard mechanical stop".

your saying hard mechanical stop made me think it might be the balls won't shift so you can select gears other then Reverse and Start.
Here is correct picture of you shift forks etc.

Mark stevens · Nov 21, 2023

Thank you, that looks like mine.
The balls (10) on the diagram look to be in the housing that the start interlock plunger (11) is in. I'm not sure how to access these to be honest.

Mark stevens · Nov 22, 2023

Any idea how i access the balls marked up on the diagram at the back of the gear selector shafts please, kind regards, Mark.

Duner Wi · Nov 22, 2023

The Dealer Shop Manual for TEF20 should address the balls.
My TO20 manual says you need a double split. You need access to the front and rear of the transmission to remove the shift shafts and balls. There is a sequence of events you must follow for the TO20. I have never had my transmission completely apart and never had to deal with the balls.

Tef20 wont select fwd gears

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