Hydro-Gear ZT-2800 Transaxle: Specs, Oil, Filter & Replacement

Short version: the ZT-2800 is Hydro-Gear's estate-grade transaxle, "our most rugged residential transaxle for machines up to 1000lbs": a 10 cc pump and 16 cc motor, up to 300 lb-ft of output torque and 8 mph, on a 1.0 in axle. It's serviceable, with an external 52114 spin-on filter and 20W-50 engine oil; change both at 75–100 hours, then every 400 hours. Kit 72750 has the oil and filters. To replace one, order by the full model number on its label and tell us which side it's on.

ZT-2800 specifications

Spec	ZT-2800
Application	Residential (estate grade)
Model number prefixes	ZH through ZM, shared with the ZT-3100 and ZT-3200
Pump / motor	10 cc/rev (0.61 in³) pump, 16 cc/rev (0.97 in³) motor
Input speed	3000 rpm maximum (non-charged) or 3600 rpm (charged), no load; 1800 rpm minimum. The product page lists 3000 rpm.
Output torque	Up to 300 lb-ft (406 Nm)
Speed	Up to 8 mph (12 kph)
Machine weight (gross)	Up to 1000 lb (453 kg)
Axle	1.0 in (25.4 mm); tapered, 4-bolt or 5-bolt flange
Reductions	ZH/ZJ 20.69:1 · ZK/ZL 24.74:1 · ZM 27.23:1
Brake	Debris-free internal brake standard (the manual describes an internal cog-style parking brake); external friction brake optional
Options	Shock valves, charge pump, internal expansion tank. Built in charged and uncharged versions.
Oil filter	Hydro-Gear 52114 external spin-on, 25 micron nominal / 40 micron absolute
Oil	20W-50 engine oil
Unit weight	32 lb (14.5 kg)

Torque, speed and weight are Hydro-Gear's product-page "up to" figures. The 2013 manual rated the ZT-2800/ZT-3100 at 300 lb-ft intermittent and 160 lb-ft continuous.

Model number and prefix

A ZT-2800 label carries a model number like ZH-JPBB-SF7B-2XLX. Hydro-Gear's Cross Reference Guide assigns prefixes ZH through ZM to the ZT-2800, ZT-3100 and ZT-3200 together, so the prefix alone doesn't separate them; the full number does. The prefix also tracks the reduction: ZH and ZJ are 20.69:1, ZK and ZL 24.74:1, ZM 27.23:1. See how to find your Hydro-Gear part number.

ZT-2800 service: oil, filter and capacity

Item	ZT-2800
Oil	20W-50 engine oil (minimum 9.0 cSt at 230 F, API SL)
Filter	Hydro-Gear 52114 spin-on
First change	75–100 hours
After that	Every 400 hours
Capacity per transaxle	70.3 oz (2079 ml) or 71.9 oz (2126 ml), depending on model characters 7 and 13; 56.6 oz (1674 ml) when character 13 is T (internal expansion tank). Excludes the expansion tank and hose.
Practical fill	About 2 qt per transaxle, 4 qt for a pair
Service kit	Hydro-Gear 72750: 5 qt Hydro-Gear Commercial Transaxle Oil, 2 filters, fitting and pump

• Filter install: hand-tighten, then 3/4 to 1 full turn after the gasket contacts the base. Remove with a socket-style wrench, not a strap wrench.
• Draining: Hydro-Gear's procedure drains through the filter port; the manual describes no separate drain plug. Let units with an internal expansion tank cool below 100 F, and use a drain pan 12 in or larger (8 qt is optimal).
• Filling: fill until oil appears at the top port, then top up through the expansion tank to the "Full Cold" line.

Filter cross-references and oil details: Hydro-Gear oil & filter guide.

ZT-2800 problems: what to check first

Hydro-Gear names three symptoms of air in a transaxle's hydraulic system: noisy operation, lack of power after a short time running and high operating temperature. Their fix is to check the oil level and purge:

1. Check the oil level and release the parking brake. Ideally, raise the drive wheels off the ground.
2. With the bypass open and the engine running, slowly move the control forward and reverse 5–6 times. The oil level will drop as air comes out.
3. With the bypass closed and the engine running, do it again 5–6 times. Stop the engine, check the level and top up.
4. Repeat until the unit runs at normal noise and moves smoothly forward and reverse at normal speed, then repeat under normal operating conditions.

Purge after any time the system is opened, oil is added or changed, or a replacement transaxle goes in. Full procedure and how the cam-style bypass works (push the mower no faster than 2 mph, parking brake released, no hydrostatic braking while open): how to purge a Hydro-Gear transaxle.

RFQQQ's practical advice, not Hydro-Gear's: before replacing a ZT-2800, check the oil level, that the bypass is fully closed and the drive belt, then purge properly. If it's still noisy, weak or running hot after that, the problem is likely internal.

ZT-2800 vs ZT-3100

Both have a 10 cc pump, 16 cc motor, 1.0 in axle and the 52114 filter. The ZT-3100 is rated for up to 350 lb-ft, 9 mph and 1200 lb against the ZT-2800's 300 lb-ft, 8 mph and 1000 lb, and Hydro-Gear classes it as entry-level commercial rather than residential. Hydro-Gear strongly discourages fitting any model the mower maker didn't specify, so treat the comparison as background, not an upgrade path. More: ZT-3100 guide · ZT-2800 vs ZT-3100 vs ZT-3200 vs ZT-3400.

Parts, seal kits and rebuilds

Hydro-Gear's BLN-52441 service and repair manual covers the ZT-2800 with exploded views and parts lists, and Hydro-Gear's support page has ZT videos for trunnion seal, input seal and bypass seal replacement. We stock Hydro-Gear repair and seal kits and replacement parts; send us your model number and we'll confirm which fit.

Ordering a replacement ZT-2800

1. Read the full model number on the label, e.g. ZH-JPBB-SF7B-2XLX.
2. Note the side: left or right as you sit in the seat. Left and right units can carry different model numbers.
3. Add the mower maker's part number if the label shows one, plus your mower's brand, model and serial.
4. Fill and purge the new unit before putting it to work.

Shop ZT-2800 transaxles or send us your numbers through the Hydro-Gear part finder.

Frequently asked questions

Sources: Hydro-Gear ZT-2800 product page, ZT-3100 product page, Cross Reference Guide, Oil, FAQ, Support; service manual BLN-52441 (Apr 2023) and BLN-52441 (Jan 2023); Toro-hosted copies of BLN-52441 (2021) and BLN-52441 (2013).

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