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Discussion Starter · #1 ·
I am faced with a new CC ZT2 with the Hydro Gear ZT 2800 transmissions that came without the transmission fluid expansion tanks. (It is a long story involving a Big box store). I have confirmed the specific trans model numbers are indeed the ZT2800 transmissions.

My trans' have plugs in the top of the cases where it looks like the expansion tank connecting hose would be attached.

Does anyone have a clear pic, a diagram, or can describe what parts I need from Cub Cadet or Hydro Gear to install expansion tanks on these transmissions? Looks like all the mounts are already in this machine's frame, just missing the tanks.

So far I am guessing that I will need 2 each of the following:
  • Tank and tank caps
  • Tank to trans hoses and clamps
  • Hose to tank fitting.
 

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Discussion Starter · #2 ·
After a little more web time research, apparently the Hydro Gear ZT 2800 transmissions can come with both oil expansion tanks for ease of checking fluid levels, OR with what they refer to as an "internal expansion tank".

Most of the advertising of the Ultima ZT2 model refers to "oil reservoir tank" as is the case with the Home Depot, and other on line machine supplier's ads. Examples below.
  • Dual Hydro-Gear™ ZT-2800™ Hydrostatic Drive System
  • Fan cooled 10cc pumps and 16cc wheel motors on each drive wheel
  • Highly durable with an oil reservoir and internal mesh filter
  • Provides optimal torque and speeds up to 7.5 MPH
Here is the Home Depot mention on this model they sell:
  • Heavy-duty dual hydrostatic transmissions dual hydro-gear ZT-2800 with oil reservoir and filter, dual hydrostatic rear-wheel transmission for quick and effortless 7.5 MPH forward and 3.5 MPH reverse zero-turn controlled ground speeds, that quickly leaves your lawn with a professional-quality finish.
CAUTION: There are minor variances in the shipped Ultima ZT2 60 models. Unaware, my particular machine came with everything seen in the ads and Cub Cadet's specifications EXCEPT it has the ZT 2800 transmissions with "INTERNAL" oil expansion tanks.

BEWARE: This CC Ultima ZT2 is a good machine I think. The transmissions are Hydro Gear ZT 2800's among the higher residential models. HOWEVER, do not depend on the mower model ads. Visually check the actual machine you are getting to be sure the oil reservoirs are there at 11 and 2 o'clock around back of the engine, looking at the engine bay from behind the tractor. If they are not there, you have the "internal expansion reservoir" ZT 2800 models. I guess they are the same internally, but require you to remove the fill and sight plugs to check the oil levels. A routine I do before every use, now it might be a PIA but have to do it.

Forewarned is forearmed.

All the best to the MTF gang.
 

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Ooh, that does sound like a pain, sorry.

My tranny has a dipstick, which is a bit of a pain to access, at least with the sleeve hitch installed. And it makes me nervous about introducing dirt (that collects on the shelf around the opening) when using the dipstick.

I checked it when changing the fluid, of course. And maybe once or twice after that during the season.

But if the floor is dry, I'm kind of assuming the fluid is all still in there, I guess. I don't consider that being unreasonable, personally. I'm definitely not checking it every use.
 

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Discussion Starter · #4 ·
RedOctobyr,
Well I'm all calmed down now and looking forward to using this machine for a long time on my 3 acres of semi hilly land. I will probably do same as you, watch for drips and check both of them manually a few times per year. Hey at least the fill plug is directly under the 2" hole made for the tube so I can just use a long neck funnel for refilling when oil is changed!!
 
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I just received my 2021 Cub ZT2 as well, and mine didn't come with the external expansion tanks either. I actually just got off the phone with Cub and Hydro-Gear tech support and thought I'd share what I found out...
The Hydro-Gear rep told me that all new units have the internal expansion tank, which was kind of a disappointment as I like the convenience of a reservoir and the easy visual indication of the fluid level and state. The second, and most important bit of info I found out is those hex "plugs" directly under the holes in the back of the engine compartment, where the reservoir hoses used to be, are NOT fill plugs. I cannot stress this enough... These "plugs" are actually breathers for the hydro, and when I asked about filling though them the Hydro-Gear rep said to not remove them or attempt to fill through them under any circumstances! They are apparently attached to the top of the internal tanks, so if you take them out and put them back in, the tanks can become misaligned and I quote, "WREAK HAVOC" on the internals of the transmission. If you go to Hydro-Gear's website they have a full service manual that recommends filling through the larger top plug that is right next to the breather, but unfortunately not centered under the holes in the engine compartment of these mowers. In my opinion this is very misleading, and a huge oversight on Cub's part. They should have relocated the holes to center over the actual fill plug. With how tight the hydros are up against the bottom of the engine compartment, the only way to get to the "real" fill plugs would be to try to sneak a wrench in from the side. When I asked Cub's tech support whether I could fill through the side "level indicator plug" for convenience they said it was not recommended. I asked the same question of the Hydro-Gear rep and he said it doesn't matter whether you fill through the top or side plug, as long as it's not through the breather. They actually offer a fitting that comes with their service kit that threads directly into the side plugs. This fitting connects to the bottle pump in the kit, so you can fill it like a modern automotive trans.
I know that was long winded, but long story short, if you have a 2021 ZT2 and up, always fill the transmission through the plug on the inboard side of the case. Wasn't a member of this site until today, but I figured I'd make this my first post so nobody messes up their transmissions. I know I probably would have if I hadn't called them... Like you said, forewarned is forearmed.
Cheers!
 

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One last thing... here is the link to the Hydro-Gear service manual PDFs that outline the entire fluid change procedure step by step.

 

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Discussion Starter · #8 ·
Great info Alanjd93!!

I never got a reply from Hydro Gear but after thinking about it, came to roughly the same conclusion, that these are two internally different cases used on the ZT 2800 model. Maybe they are having issues with the tanks and hoses...who knows.

What I didn't know, was that filling via the breather plug hole might be a real problem. You may have saved quite a few ZT2 transmissions by posting your findings here. Thank you for posting your findings!!!

I have abandoned my initial thought of installing the expansion tanks in favor of just dealing with these newer internal expansion tank versions of the ZT 2800. I can see the larger hex head fill plug adjacent to the smaller breather plug on the starboard side, but not so much on the port side. There might be a modified, single purpose wrench in my future.

I may just order the Hydro Gear oil change/filer service kit, and utilize the fitting they provide, at least on the initial oil change. It is probably a plastic fitting but maybe I can use it as a model for a DIY brass fitting.

You get a medal for duty above and beyond...
 
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