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Hydro Gear G730 trans shudder

Posted By: Fastzntn

Hydro Gear G730 trans shudder - 05/22/19 02:22 PM

Checking to see if anyone ran into a similar problem as I’m having.

Last weekend I mowed with my Craftsman Garden Tractor (G5000 series with 24 hp Briggs, hydro gear g730 trans). Very hilly yard, about 215 hours on the tractor.

Problem I’m noticing- full power, blades engaged, going up steep hills, the tractor will vibrate/shudder and lose forward speed. If I nurse the pedal slowly it happens less but still happens. Engine pitch/speed stay the same, so I believe it’s something after that.

Anyone have something similar happen? I’m on the road but want to start diagnosing as soon as I get home. The grass is growing fast in TN!
Posted By: CT8

Re: Hydro Gear G730 trans shudder - 05/22/19 03:21 PM

Is there enough oil in the trans?
Posted By: Fastzntn

Re: Hydro Gear G730 trans shudder - 05/22/19 03:26 PM

Originally Posted by CT8
Is there enough oil in the trans?


It’s one of those sealed “never needs maintenance” deals (not that I agree with never needs maintenance). I can attempt to check via the plate that I assume the factory uses to fill through. Have not noticed oil drips or evidence of seepage on the trans case.
Posted By: jeepman3071

Re: Hydro Gear G730 trans shudder - 05/22/19 03:46 PM

I would try changing the oil. Seems like the G730 is serviceable:

https://www.youtube.com/watch?v=3u97bb-GKFA
Posted By: JTK

Re: Hydro Gear G730 trans shudder - 05/22/19 06:19 PM

Originally Posted by Fastzntn
Originally Posted by CT8
Is there enough oil in the trans?


It’s one of those sealed “never needs maintenance” deals (not that I agree with never needs maintenance). I can attempt to check via the plate that I assume the factory uses to fill through. Have not noticed oil drips or evidence of seepage on the trans case.


Could it be the drive belt slipping? Cooling fan intact? The G730 is the Cadillac of HydroGear's lineup for garden tractors. Like said, it should have a spin on filter and a relatively easy means to drain/fill the oil. I'd check the belt, tensioner/idler first, then make sure the transaxle isn't caked with debris and the fan is good. The oil shouldn't be horrible at ~200hrs, but this would be a good time to change it and the filter.
Posted By: spk2000

Re: Hydro Gear G730 trans shudder - 05/22/19 08:22 PM

Just changed mine out in my Snapper GT300 which is a 22HP Briggs and has a K57 transmission. Most say not serviceable but you can pop top vent cap off and vacuum fluid out. I was replacing with Mobil 1 15W50. Works great for a while but if you have a steep hill will likely break down. My hill is really too steep for the mower but it works so I use it. Had a guy with commercial mower tell me he would not try it on his zero turn. Main issue is not getting it out but getting the new fluid back in. I would ride it around a little bit to mix and heat fluid up a little maybe 5-10 minutes. I can always tell when the Mobil 1 breaks down because my mower starts climbing slower and eventually will not go up the hill. I can then back up and go other direction which is a much gentler slope. I am trying the Amsoil Hyrdostatic 20W50 fluid and have heard great things about it. Just mowed today for the first time and so far could not tell a difference which may not be a bad thing. At some point I will post something on BITOG about the durability vs Mobil1 but not enough time on it yet.
Posted By: Fastzntn

Re: Hydro Gear G730 trans shudder - 05/24/19 09:34 PM

Not great news on the mower......

Changed fluid and filter (GTX 20w50/OEM filter). Added 3 quarts per spec. Started mowing and it seemed to be doing ok. Hit the hills again and now it’s worse. Lots of jerking and shudder, vibration, and it sounds like rattling coming from the trans. Barely made it back up the driveway and it’s pretty much unusable for mowing.

I did check the belt tension, linkages, etc while I was changing fluid. Pretty sure the trans is toast at this point.
Posted By: JTK

Re: Hydro Gear G730 trans shudder - 05/25/19 06:16 PM

Sorry to hear that! When you changed the oil, how did the drained oil look? I've not heard of one of these G730s failing. 215hrs is nothing. Just for reference, I looked up replacement units online. $1000. I'd email hydrogear just to see if they could help or have suggestions. I know there's various youtube videos on rebuilding hydro transaxles. Doesn't look too bad.
Posted By: Fastzntn

Re: Hydro Gear G730 trans shudder - 05/26/19 12:06 AM

Originally Posted by JTK
Sorry to hear that! When you changed the oil, how did the drained oil look? I've not heard of one of these G730s failing. 215hrs is nothing. Just for reference, I looked up replacement units online. $1000. I'd email hydrogear just to see if they could help or have suggestions. I know there's various youtube videos on rebuilding hydro transaxles. Doesn't look too bad.


The oil was brown when it came out, didn’t appear sparkly and didn’t smell burned.

I just did the same thing on a replacement and saw $1k as well. If it came down to that I’d lean towards buying a replacement mower. Simply because this one has been marginal for my hilly yard. But if I missed something or there’s an easier fix I’d be ok with keeping this one going.

Good call on contacting hydro-gear, I’ll do that and see what they say.
Posted By: anthonym6

Re: Hydro Gear G730 trans shudder - 05/31/19 12:10 PM

Check to make sure none of the mounting bolts are broken. Might not be the issue, but my zero turn had broken a bolt allowing one of the Hydro Gears to move excessively which made it shudder and cause the mower to buck under the right conditions. Normal mowing it wasn't an issue.
Posted By: Fastzntn

Re: Hydro Gear G730 trans shudder - 06/03/19 05:20 PM

Everything led back to an internal transaxle problem unfortunately. Could not justify putting more money into a tractor that’s not designed to tackle my yard (6 acres, half of it cleared, slopes, ruts, etc). While it had enough power, the frame flexed a lot, it got stuck several times due to being traction limited even in seemingly easy to navigate sections of the yard. A small portion of exposed root was enough to cause a problem if there was any slope.

So I bought a John Deere 1023E grin

Spent about 4 hours working with it over the weekend, and I should have had something like this from the start.
Posted By: JTK

Re: Hydro Gear G730 trans shudder - 06/03/19 06:23 PM

JD 1023E!!!

Talk about movin' on up in the world! Congrats on that. I'd be looking forward to using it.

Sounds like the right move if you toasted about the best transaxle HG makes in that short of time, you needed a machine built entirely better.
Posted By: bobdoo

Re: Hydro Gear G730 trans shudder - 06/03/19 11:11 PM

For everyone who owns a hydrostatic transmission, here's some tips.

Go SLOW up steeper hills. There's a LOT more heat and wear generated when the swash plate is at a high angle (giving high ground speed).

Keep the transmission CLEAN. Grass, straw, dust and dirt insulate the tranny. High heat breaks down the oil

Change the oil (as much as you can). In non-servicable trannies, you can remove the whole rear axle, and turn it upside down to drain it. Make sure you get an accurate measure of what came out. There are videos out there to help. The small tractor forums are a fount of knowledge. Drain from the top if you can, using a small diameter tube. Check diagrams online to find out how to snake the tube lower in the tranny, if that's possible. (Along those lines, I wonder if it would be useful to overfill, operate at low ground speed to mix old and new, then drain more out?)

I have put Liqui Moly in my transmisson, in the hopes that there's some added protection from all the sliding parts.
Posted By: meep

Re: Hydro Gear G730 trans shudder - 06/04/19 08:33 PM

^^^ an oil extractor made easy work removing used fluid from my entry level Ariens ZTR. IIRC is was around a quart each?
Posted By: JTK

Re: Hydro Gear G730 trans shudder - 06/04/19 10:01 PM

That's the thing with this G730 drive. It's easy to do a D/F on and has a spin on filter.
Posted By: Fastzntn

Re: Hydro Gear G730 trans shudder - 06/05/19 11:36 AM

Originally Posted by JTK
That's the thing with this G730 drive. It's easy to do a D/F on and has a spin on filter.


Agreed. In this case, I removed the left rear wheel for better filter access (filter was on really tight). Removed it and let the case drain. Lowered that side a bit to try and drain as much oil as possible. Installed new filter and refilled the case through the top vent hole with a hand pump (the vent fitting and plug were easy to remove).

The tractor manual never recommended service for the transaxle. After talking to hydrogear they recommend 100 hour initial service, then every 400 after. That would have been nice to see in the manual, but mine experienced issues starting at only 215 hours. Guess we’ll never know if a service at 100 would have made a difference or not. Seems like with all the rave reviews about the G730 I may have just gotten unlucky here.
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