TC35 Shuttle Shift, Won't Engage When Hot

[Wild Bill the 2nd]

Got a chance to run the tractor tonight after work. After 45 minutes of driving and shifting my issue was back.

I-Parked the tractor, turned it off, tried to shift, made no difference. Still would not shift.

II-Took the seat and cover off of the tractor and the transmission was at 110 degrees. Not too hot.

III-Took a video of the view into the transmission

IV-Clutch pedal free play did not measure any different from when it was cold. I have not adjusted it back to the prior setting. After looking inside the beast and watching it try to shift I think it has to be something in there.



The collar that the fork slides (assembly 13) just does not want to move. Sometimes the syncros look like they are out of alignment preventing movement and sometimes they look like they are perfectly lined up and still nothing wants to move.

It's all getting too real... I still had a bit of hope before tonight.

 

[Wild Bill the 2nd]

Had a mechanic (who's outfit used to sell New Holland tractors) stop by the house yesterday. We got the tractor up to temp to where I started having some shifting issues and we looked around inside the trany. Unfortunately I am no closer to a definite solution. We all but ruled out the linkage binding.

If you ask me it is looking like it might be a bearing issue. Perhaps making the shaft hard to turn at a certain point in the rotation. When it is in this hard spot the shaft will not rotate freely in order to allow alignment for the shift. Or maybe it is in that collar that slides in order to engage fwd/rev.

What ever it is it will not be known for sure unless the tractor is split. My biggest fear is, that since the problem does not show up until things are hot, the cause could be overlooked when tearing it down when cold...

 

[Harry in Ky]

With two synchronizers on the same shaft, why would a bad bearing affect only one of them? These are ball bearings, so a problem there would most likely create a noise, vibration or both before it would affect the shifting. You will see your problem once you get the synchronizer out on the table.

 

[RickB]

With two synchronizers on the same shaft, why would a bad bearing affect only one of them? These are ball bearings, so a problem there would most likely create a noise, vibration or both before it would affect the shifting. You will see your problem once you get the synchronizer out on the table.

Not quite a month later, same advise. Synchronizer isn't shifting. The shaft has no radial or axial movement, hint: it isn't a bearing problem. It's the synchro.

 

[Wild Bill the 2nd]

This transmission stuff is all new to me and I was / still am in denial. I was thinking that an issue with the synchro would be visible from the top side. Like ground teeth or lack of movement.

We will find out what is going on fairly soon. Started the disassembly last night.

 

[Wild Bill the 2nd]

Thank you by the way for all of your input, I may be a little dense but it just wasn't / isn't making sense to me. I'm sure it will once things are opened up and I see how the internals work.

 

[RickB]

This transmission stuff is all new to me and I was / still am in denial. I was thinking that an issue with the synchro would be visible from the top side. Like ground teeth or lack of movement.

We will find out what is going on fairly soon. Started the disassembly last night.

When it won't shift? That's a lack of movement.

 

[Wild Bill the 2nd]

What I meant is that the syncro freely rotates when you touch it with a screwdriver. It does not appear to be bound up at all.

Funny thing, this afternoon my New Holland mechanic called and he had a response to his New Holland "Assist" inquiry about this issue. Supposedly these exact symptoms have been seen at least one time before. They said it was a tractor with only 80 some hours and it turned out to be the pilot bearing in the flywheel. Not exactly sure how that would ever manifest itself with those symptoms but I will certainly check it out on my way to the trany.

 

[Harry in Ky]

Your problem is NOT the pilot bearing.

 

[Wild Bill the 2nd]

Split the tractor and torn down the transmission tonight with the New Holland mechanic. There is nothing that jumped out at us as excessively worn. The 3 keys that run in between the inner and outer splined gears look slightly worn but not too bad. Not sure if that would do it. The syncros looked good. They were well outside the wear tolerance.

Here are some pics, though I don't know if they can show enough to be of any help. If anyone wants pics of any specific parts or combinations of parts just let me know. FYI, as expected, the pilot bearing looks just fine.

 

[Wild Bill the 2nd]

[URL=http://s200.photobucket.com/user/biRe: TC35 Shuttle Shift, Won't Engage When Hot

Took the parts to work today and we definitely think the issue is in the splined gear / collar assembly. There are virtually no signs of wear on any parts except for the three keys. If you assemble the gear pack without installing the 3 keys in the inner gear everything slides butter and aligns like perfectly. Put those keys in and things get real tough.

The one/two and three/four gear packs slid much easier. The fwd/rev pack has a much heavier spring clip but I think it is mostly due to the keys.


We hit the keys with some 280 grit and then I tried polishing them with a diamond stone. They are much smoother (there were some slight ridges in them) but they still have some deeper marks in them.


Reverse gear and synchro


Inner and outer splined gears


Forward gear and synchro


The shift fork shows some light wear. The other side has an equivalent amount of wear but on the opposite side, possibly indicating a misaligned fork. Miss-alignment could be due to a bent fork, bent linkage , or out of tolerance machining in the transmission casting. Nothing is readily apparent.

I just tossed the assembled fwd/rev gear pack (with polished keys) in the oven and checked its operation at 150*. It does not seem to be any different than at room temp. Unfortunately I did not have a baseline with the unpolished keys.

At this point my thought is to purchase 3 new keys and re-assemble the tractor. Anyone think of or see anything else?

Harry or Rick, see any issues with the synchronizes?

 

[Harry in Ky]

From what I see in your photos, the keys look to be right up there as an issue. They look pretty hammered. No interference to speak of between the shift collar and the inner hub? Only one photo(the bottom one) shows a synchro ring installed on it's respective gear. That looks about right, position wise, but hard to tell from that distance. Looks to me that the keys may well be the biggest problem. As for replacing just the keys --- your money, your call. They always come apart faster the second time.

 

[Wild Bill the 2nd]

The book states a .031" minimum clearance between the synchro and ring gear. I have over .050 on the forward gear and over .060" for the reverse.
There is no interference sliding the collar over the hub without the keys. For the price of the keys and the time it took to get here, they are getting replaced.

 

[Wild Bill the 2nd]

So, an update. I filed/stoned some light burrs on the gears of the sliding collar and replaced the three keys 2 weekends ago.
Everything worked fine after that. I've mowed 20 acres in the last 2 weeks with no issue. I got the transmission up to 160 degrees with use.

I've since sold the tractor and am now waiting for a hydrostatic model to be delivered.

My take on the whole thing... It was definitely not a syncro issue. I did nothing with them. I don't see how shifting while moving slightly would affect those keys that I replaced at all. They are simply a detent between the inner and outer sleeve and are never moving at different speeds. I do agree that shifting while stopped will extend the life of the syncros but mine had a LOT of shifts on them and still looked pretty good. I did not come to a full stop for the majority of those shifts either.

The tractor was picked up last night and I did one last quick mowing of what can be seen from the road. I shifted 85 times in maybe 20 minutes. That is just a small fraction of what I typically mow. I just think what I was doing with the tractor was not suited for the transmission type. In 2 hours of typical mowing I would likely have 400-500 shifts if I were to guess.

Thanks for all of your help with this. I hope this info can serve someone else if they should run into a similar situation.
FYI, splitting the tractor isn't super difficult, just tedious and time consuming.

 

[bones1]

I have the same issue with my 300DTC Farmtrac. I have to split it without a manual. Do you have any tips on where to begin?. What did you remove first?. ThankYou.

 

[Wild Bill the 2nd]

Send me a PM with your email address and I will get you some additional pictures and info.

The manual that I borrowed from the dealer was invaluable but it was the first time I tried doing anything near this involved.

Things needed to be taken apart, pins removed, bearings hammered out, etc in a specific order.

Again, send me a PM and I will get you whatever info I can.