TC35 Shuttle Shift, Won't Engage When Hot

[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.