936031 Hydro-Gear issue

[bertsmobile1]

You get a pump/motor kit that is complete apart from the axel seals & oil.
It is about 1/2 to 2/3 the discount price of a new tranny depending upon where you get them from.
While they are simple in construction they are high precision machining and high precision cost a lot of money.
I have access to polishing wheels from a previous life as a metallurgist so I can polish the surfaces down to 2000 grit with wet & dry then pop them on the plate and take them down to 4 micron.
Sometimes this works, and sometimes it dosent , it all depends where the wear is.
If it is just the valve chest & manifold plate then they can be lapped if the wear grooves are not too deep but if the wear is in the cylinders then it is scrap metal.

 

[paulbot]

I looked over the Hydro-Gear service manual and got a few part #'s, seal kit, 70331 10cc Cylinder Block Kit $67 (2) Hydro Gear 70477 KIT, CENTER SECTION and 50551 Thrush Ball Bearing (2) shipped for $275. Might try and pull it tomorrow, break it open and see if anything else looks bad before ordering. I don't mind dropping a bit for new pumps. But I didn't see the " pump/motor kit that is complete apart from the axle seals & oil." you mention. But didn't search any deeper than the above mentioned parts.

edit- fresh look at service manual today, didn't take hydro apart, but guessing this can be done with 2 sets of cylinder block kit, seal kit and mill down of the Center Section Assembly. Something like US160 unless other parts are damaged.

 

[paulbot]

Finally tore it down just to look at it, see if it's worth putting any money in it. Looks like a new center section at the least. Still pondering what to do with it. They are $145 online, considering milling it down but it looks too far gone.

 

[BlazNT]

Way too far gone in my opinion.

 

[bertsmobile1]

Holey Hell Batman how did that one get past Quality Control will all that porosity in the castings.
How old are those units ?
If not too old send those photos to Hydro Gear and see if they will come good with either free replacements or new parts at cost.
All those holes you can see were at one time a little bubble in the metal.
he ones that were ruptured by the machining would act as little oil reseviours which would be fine, but the ones that were just below the surface so wore through during service would yield little flakes of alloy which would grind into the working faces and drastically reduce the working life of the pump or motor.
Those really deep scores would have been caused by that happening.
In other words they are defective in materials quality.
So ask nicely and see how you go.

You might like to use a line like
" I think I need to replace these items on my ???????? transmission which failed last year and left me stranded
A friend looked at them and said the castings were defective due to excessive porosity and should never have been allowed to leave the factory
I would appreciate you opinion on replacements"
Good luck.

And don't even consider machining those as the castings are defective and can not be repaired.

 

[paulbot]

Nice thought but it's a 2000 model, not likely they would step up and cover it. Might try, though!

 

[bertsmobile1]

When you start with an enquirey and not a demand it is amazing what some companies will do.
If it embarasses them enough to at lest give you wholesale on the new parts you are 40% ahead.
Or they might go overboard with technical help or send you a full rebuild kit at a discount or just laugh.
I have found Hydro Gear to be very helpful to me and quite supportive so it won't hurt.
The castings are definately defective I can tell you that having been a foundry metallurgist in a previous life.
They did not even need to be machined, you can see the defects on the outside of the raw sections.
So Hydro gear will also recognise that at the first glance.

 

[paulbot]

Thanks for your insight this whole thread. I'm going to do just that, start it as an inquiry like you mention. Because I'm in the position of needing the mower and not having much funds right now. It's at least worth a try. Will keep you posted. I might even wait a day or two so it won't be in the pileup off the weekend.

 

[paulbot]

Please find below a link to the service and repair manual for your transaxle. Replacing the center section will be needed. Attached is a schematic with part numbers. You will want to check the lower part of the cylinder blocks for scratches or scoring as well. The second link below is to our service center locator. We do not sell anything directly from our manufacturing facility so it will be necessary to work through a service center.

Man I was kinda proud of the effort I put in the email all for a canned response.

 

[bertsmobile1]

Well, it cost you nothing but time.
Worth a try.

When you do the work please remember that these unit are mad in a sterile dust free factory so you , your working area and the box itself can not be clean enough.
FWIW I work out of a disused house.
When I split a hydro box, I degrease, pressure wash, soda blast then pressure wash the box again before taking it up to the bathroom.
They get worked on in the bath, after I have wetted down the room with a fine spray hose.
The box gets covered with a damp cloth ( old curtains ) every second that I am not working on it.
After adopting this method all my box repairs have been good.
Just bear this in mind.
A vry small amount of dust you can not see will do a lot of damage inside the box.

You see a lot of videos of people "fixing" them in open grubby workshops & "mums" dirty garage.
What you don't see is that 2 years later the box is trash again cause dust got in.