Tremek's Tractor Collective: New to me 990 joins my 999...

Tremek · Oct 27, 2018

Front half of the PTO shaft came today:

Fit the splines on the tractor perfectly, went right into the rear half of the tiller shaft.

Fired it up: instantly bent both halves of the PTO shaft. While this is a bummer and a setback, I would like to learn what caused this so as to not repeat the same mistake...

I’m wondering if, due to needing more shaft length, using the whole length that came exerted too much rotational mass (while not being fully within the female tube) and that caused it?

The tiller side of the driveshaft (not pictured) appears to have bent right around where the bar stock side of the new shaft stopped within it.

Two before pics and one after...

Tremek · Nov 1, 2018

Folks, any thoughts around why both sides of the driveshaft instantly bent? Was the front half (steel shaft) inserted too far into the rear half (tube)? Should there be only limited engagement from the front half of the shaft into the tube? Total engagement? Need some guidance. Thanks.

VTXRider · Nov 2, 2018

I would say the shaft is too long without some kind of center support bearing. These shafts are so out of balance and spinning faster than a normal 500 rpm PTO. It just might not work running from the front pto on the 999.

Tremek · Nov 3, 2018

I see a couple posts but I'm not clear here:

What is a 990's PTO rpm/speed? I found one post indicating the rear PTO is 1:1 with the engine, so 3600 RPM, but then have found other conflicting posts... If anything I would think the 999's 2000rpm PTO would have been less rotational stress on the assembly, but I think what I unknowingly did was bend it due to too much bar stock mass too far down the rear tube.

VTXRider · Nov 3, 2018

The 990 PTO is at engine speed, 1 to 1. I think you are right. Bar stock might be too much mass.

Tremek · Nov 14, 2018

Interestingly we measured the RPM of the rear PTO pulley coming off the 990 and it looks like it's ~1000-1200 rpm at full throttle. Trying to determine the best path forward for making this work reliably.

Hammerhead007 · Nov 16, 2018

Any way you could run a solid shaft to the back with bearing support, then a short PTO shaft from there to what ever it is you want to run. The LGT165 I have has the shaft on the side of the tractor to the back, then uses a short PTO shaft from there to the attachment. This is an option for the Ford. Belt driven off the electric clutch.

Tremek · Nov 19, 2018

So the red Cenex 990 is running pretty well after some creative (new) carb modifications, swapping over the electronic ignition coil from the silver 990 to it, etc. We backyard-straightened the driveshaft tube for the tiller and found that, with the taller and narrow ag-style tires I had mounted, that suddenly there isn't a driveshaft clearance issue with the transaxle. Who would have thought, right?

Pictured below, my buddy testing the tiller:

So aside from some cleanup and paint on the red 990 it's mostly ready to be useful. Ground still hasn't frozen, so while our window for getting some garlic in the ground is shrinking every day, I think we can squeak this in.

With that said: I need some education on how to prep the ground so we're not tilling rhizomatous plants right back into the ground to create a weed hellscape for myself next spring.

Can any of you make recommendations on process of what to do to prep the ground? My general thought is spray with glyphosphate (ps also picked up a tow-behind sprayer) - wait a couple weeks or for some precip - then till the top few inches, use a rock rake or another implement to start filtering out rocks and other large debris, but then things get fuzzy from here for me. Would I next perhaps want to get a cultivator and rip into the deeper soil, then go back over it with the tiller, and then finally introduce enrichments like mulch to prep the beds?

Any advice appreciated. Thanks!

VTXRider · Nov 19, 2018

Spaying with the Roundup and wait a week works well.
I would just till it. It will be quite good as is. Hand raking is all I do after to fill in the small rows left. The less compacting after tilling, the better.
Never planted garlic before so maybe other prep is needed.

Tremek · Nov 27, 2018

So mostly bad news to share; the red tractor tilled about 100 linear feet before it decided to taco the driveshaft. So now I'm down a working tilling solution again, my buddy got a punch stuck in the roll pin channel that holds the driveshaft onto the stub shaft, and the oil coming out of the tiller has a lot of brass in it. Not good.

It's not looking good for our heroes.

We opened the case on the tiller and found what looks like a deformed thrust bearing that might be responsible for all the brass, as well as a half-missing snap ring. A few superficial gouges on other pieces... The chain looks stretched a bit and is making contact with the case. So now considering a more or less full rebuild.

Ordered a new driveshaft tube from PaulB parts, hoping we can get a working solution back together soon-ish.

VTXRider · Nov 27, 2018

That's not good. Never had the tiller apart. Hope it is repairable.

Tremek · Nov 28, 2018

VTXRider said:
That's not good. Never had the tiller apart. Hope it is repairable.

It definitely looks repairable. Just will require some muscle (I think we need a machine shop and a press to get the punch out) and some refurb.

Reading in the manual I see the chain for the sprockets listed as a #60 x 39 chain, which I take to assume it is a ANSI 60 chain, but on further inspection I think it is a 60-2 chain - double width - and having counted links including a master link, it's only 26 links long.

Anyone know enough about chains to explain why it's labeled as such in the original manual?

no2498 · Dec 1, 2018

39 should be how big the roller is
if im thinking right

john

Tremek · Dec 3, 2018

Looks like the worm wheel is worn in the unit and that's probably where most of the brass we're seeing in the oil is coming from.

I took two pics of the manual, below:

In the second picture, the worm wheel (which mates to the worm gear) is part 8 in the diagram, and part #717-0146.

I don't have any measurements of it yet (not sitting at it right now) but I believe it's a 1.25" keyed center bore and possibly 21 teeth... Does anyone know who built the tiller for MTD, and/or what company built the gear box? Trying to figure out what parts I might be able to cross-reference.

Tremek · Dec 23, 2018

Haven't made much progress on the tiller, but was able to get the (new) bent driveshaft straightened and the cross & bearing with the broken punch fixed, now need to go pick it up so that in theory can reassemble the tiller if I get a new chain and maybe a worm gear.

In the meantime, picked up a dirt scoop for a SCUT, and some cat1->cat0 pins that neck down to the cat0 lift arms, and have bodge-jobbed together a scoop for moving some compost around:

Later I adjusted it a bit for a little more clearance. It's not much, but it works for now.

VTXRider · Dec 23, 2018

That will get the job done. Can you lift it high enough to get the dump release to work?

Tremek's Tractor Collective: New to me 990 joins my 999...

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