GTX 2100 Hydrostatic Transmission (Transaxle) Slipping
 

Hi everyone. As they say on the radio — I’m a long time listener, first time caller. Thanks for all the guidance you give to us.

My 2012 GTX 2100 started to “pop” while turning sharply last week. Then it quit moving entirely and made a noise like it was slipping. I swapped the hydro fluid for 15w40 as I’ve seen suggested on here, and it worked ok for about 27 seconds afterwards. Now it’s sitting in the yard in the place where it decided to stop again. The grass is getting long and my SO’s patience is running short.

I started looking at the Google for replacement Hydro Gear transaxle so I could play around in the garage for a weekend. But I’m a little confused about which to get. Do I need just the Hydrostatic Pump Assembly (pn 918-3243) or do I need the whole Hydro Transmission Kit (pn 759-04322)? The pump assembly is $700-800 depending on where I buy it, and the kit is $1050-1100.

I’ve got 460 hours on it (the PO put 420 of those on it). The engine is strong and the 54” fabricated deck is solid. I don’t think I could replace what I’ve got for $1000 so I’m leaning toward forking out the cash for the parts rather than buying a new one. (But if anyone has a low hour 82 series available I could change my mind).

Thanks for your help!

Tim, you may have a failed gerotor assembly.

Part #27 here.
https://www.partstree.com/parts/cub-...rostatic-pump/

I would check that first.

You better do some more digging. Hydro's have no gears in them to make noise. I don't have any idea what kind of noise you would be hearing that sounds like "slipping" but I am a long time tech. Rebuild hydrostatic transmissions, automatic transmission and gear drives from lawn mowers to cars to heavy equipment and farm tractors. When something "slips", unless there is a belt, or a dry disk clutch involved, it's usually quiet. If the rear end was making a popping noise while turning sharply, I'd say something happened in the differential. I'd start by checking that out. Better pull it out of that high grass and into the garage.

I'll toss out a couple other possibilities 1st check and see if you have stripped splines on the axle or hub(items circled in red) 2nd you may have a problem with the 4 bolts that hold the diff together (items circled in green)

I was thinking the splines on the hub too but the parts look up shows that they use a different hub then the 3k's do.

http://assets.partstree.com/web4/pho...e998d/full.png

It could be the other side of the axle may have stripped splines but I have not seen that issue yet.

The gerotor was/is a common issue on these newer HG hydro's. The oil was probably hot when it failed and when you changed it, the cool oil worked until it failed completely. That is my guess.

Wow. You guys are great. I’m pushing it into the garage this afternoon and pulling the rear wheels. Yesterday after I changed the fluid I noticed the left rear wheel was “wobbling” when I pushed the forward pedal to try to get it to go. So It makes sense that it could be something other than the transmission itself. The gerator seems logical.

Pardon the dumb question, but if it is in fact the gerator on the left rear, why wouldn’t the right rear tire move the tractor?

It won't move the right tire because it has a differential gear.

So I pulled the wheels and I think it’s safe to say the problem is something related to the axle or differential connection as opposed to the hydrostatic component itself. There’s a lot of play in the left axle - can pull it in and out too far and I can recreate the “slip” when I turn it by hand. But there are way too many bolts down there for me to tackle this project without help. So off to the repair shop we go. At least I know the parts should’nt cost $1000!

Thanks for the good advice, y’all.

The gerotor is in the hydro pump.

Pull the rear wheel off and see if the hub has splines. The 2000 series service manual shows splines but it doesn't include the GTX series so they may have changed them. The parts look up shows it not to have splines but maybe it is wrong. Here is what the 3000 series splined hub & axle look like.
Attachment 95354 Attachment 95355

If it is not splined and in good shape it sounds like something let loose in the rear and that doesn't sound good. I would call the shop you are taking it to and see if they ever split a Cub Cadet cast iron rear. I'm betting in my area that 99.999% of the shops wouldn't even know where to start. I'm thinking that is going to be a big labor job if they have to open it up. Can you post some pics of it or better yet put up a Youtube vid?

No splines to be found when I pulled the wheel, unfortunately. I should have snapped a photo... if I get a few minutes this week I’ll post a YouTube video of the problem noises as well as what I see when I pull the wheel.

Thank you again