hydro-gear question about motor and pump blocks

[jcassity]

ZT 2200 EZT transaxle is the whole assembly

within is the center section as well as the motor block and pump block.

the blocks have pistons / springs and thrust washers.

Need the piston **** (brand new) SPRING LENGTH**** for either the pump or motor block. asssuming the springs are interchangeable for either block. Again,, this request is only for ***NEW*** springs.

So,, if anyone has a new puimp or motor block,, can you please measure with a caliper and reply? most calipers dont go to the 10'thousanth but if you calibrate and jot down teh spring length go ahead and estimate the 10 thousanth.

Bonus to anyone who can state the spring height at "x" value ft/lbs. example,, you tell me you set up a spring and applied 10 ft/lbs compressive force and the total spring length or better known as "spring height" is "X" value.

willing to pay for both answers.. jcassity AT frontier DOT com / 304 772 4082,, ask for scott

these two answers do not reside currently in:
-service manual
-Tech Support (states the info i want is proprietary

My purpose is to narrow down to the gnats ass what exactly is the failing part now.
what my issue *WAS*> zero turn mower equpped wtih 2) ZT-2200 transmissions , left trans became unresponsive after warm up,, repsonse gradually went away up to the point the mower was unsafe to operate. I took the left apart and using several grit stages of wet sanding ,, i cleaned the minor record player gooves prodominantly out of the *motor block* and very mnior ones on the pump block as well as the center section.

What my issue is *NOW* > left & right are both equal performers when cold,, Both transmissions equally loose about 10% after hot (which according to tech support this characteristic is expected with units having high hours. Therin afterwards,, the left unit continues to loose about 10% more response.
this means my left trans is at 80% when hot,, and my right is at 90% when hot.

link here to one of a few vids i am doing to *solve* this issue. its my belief that this particular facet of these motor/pump blocks have not been addressed yet by anyone. What i mean is there is "some" info on cleaning / facing the surfaces of the motor/pump block to center section,, yet if your problem is partly still there,, then the only items that remain are the springs becoming weak or becoming "shorter" by just a smidge. Once i know a "spring height" value,, i will reopen mine and if i am short,, this means i can * shim * behind the thrust washer on all springs to take up that difference. My thoughs are not only did i have center section surface damage but over use, i have also lost piston surface presures due to the springs themselves becoming more worn. Springs alone are not for sale according to tech support and this is telling in my honest opinion. there is nothing at all wrong with my wanting to troubleshoot this deep. if this is not your cup of tea, then keep it to yourself. There are still people who want to find out what all the probable faults are when doing a repair.

i did complement hydro-gear on their buisness modle. Us men have noticed these transaxles piled up at shops and to me,, the first time i saw that it was clear message to me that "i better not even think about opening those puppies up" or "those must be hard as heck to work on",,, when in reality they are not. What hydro-gear has done is perfected the balance of customer use vs customer repair ratio's. If a repair shop tries to repair,,, then the center section,, pump block, motor block , seal kit,, oil change and labor to do said repairs are cost prohibative because your now just a few more dollars away from buying a new one.

Also i am just facinated with the human mind that this hydro/mechanical unit performs such huge amounts of work and like magic,, they completely reinvented piston stroke and virtually eliminated "reciprocation" by keeping one block tipped at a 30 or so degree angle. just like the kiddy ride at the local state fair,, i think its called the "tea cup" ride,, that concept is applied within this magical performer.

 

[EFSM]

I took the left apart and using several grit stages of wet sanding ,, i cleaned the minor record player gooves prodominantly out of the *motor block* and very mnior ones on the pump block as well as the center section.

How did you make sure your sanded surface is perfectly flat? That is more than important. I have sanded grooves out of the motor block using a head sanding machine, but that leaves the surfaces accurate to 0.0005 or so (less than a thousands). I don't know how you'd get the center section flat enough.

I can just about guarantee that your springs are not the problem. There is a shim in each piston that the spring rides against. These don't normally fall out on their own, but they are absolutely critical, not because of spring tension, but because the spring will wear through the piston. The shim is softer than the spring or piston.

 

[jcassity]

thanks EFSM, i supplied answers to that already and i agree with you.

 

[jcassity]

EFSM- also i forgot to expand,,
I do disagree on one aspect you mentioned,,, I do find it possible that the springs could become weak and this is universally accepted as normal and a probable fault. if this were not the case then there would not be a market for spring shims in the first place such as when valve seat presures are low and such. when this particular transmission is parked for the winter, the springs are seated at different depths and remain there until moved. The only set of spring a user could be able to reduce this effect would be the block that is tied to "neutral" where bypass is wide open. thi would relieve spring pressures on this full set because the block is pushed away from the center section.

my request to ask someone if they can give me the spring height seems reasonable considering the age of (11 years) and unknown hours. All i am after for this threads purpose is to obtain "new spring" information................
A- new in the box spring length of the motor and pump block
B- new in the box spring length of the motor and pump block with X value of ft/lbs applied.

both parts i mentioned earlier i am willing to pay for this information.

the reasons are that i went from zero operation to perfect operations but after hot conditions, my left is a little bit less than the right.

 

[EFSM]

the reasons are that i went from zero operation to perfect operations but after hot conditions, my left is a little bit less than the right.

We have found that this is because of the oil getting thinner and more bypassing through imperfections in the pump faces. We have had many of these transmissions apart and repaired, and have never seen a spring loose strength. They may break, but a spring overheats badly, they don't usually loose their tensile strength. I measured a good used spring here and it is 1.880".

 

[jcassity]

thanks, that value i can comare with mine. are you able to confirm the motor and pump block springs are the same length?

your making a point that i can get on board with because i dont see a tremendous amount of heat imposed on the springs as compared to an automotive head where the exhaust chambers run underneath. I am attempting to find out if the remaining missing 10% of perfomance after warm up is spring presure loss or not. I know you didnt watch my vids i posted on this but i did already replace the oil and as well create a drain port. Tech support said that "hustler" did not use from the factory 20w50 oil.. back then ( over a decade ago), they were using a synthetic unknown viscosity oil,, again this is from Hydro-gear support wheni was asked "who" is the name on the mower.

I am hoping to find someone who has a new motor or pump block.
Maybe i will go on ebay and poke around there to see if a seller can measure this for me.

 

[EFSM]

are you able to confirm the motor and pump block springs are the same length?

Not now. I don't have one apart right now.

 

[jcassity]

no worries, thank you. i have an ebay seller looking at the 7p10cc (pump block) spring length.

lets see if he replies. if he comes back with 1.880 then confirmed and +1 you win!

again, much appreciated.

 

[jcassity]

Team,
A nice ebay;er sent me the "NEW" spring length for the oil pump block.
the attached picture shows the new length to be .047" longer than the "used" condition stated above at 1.880.
New length is 1.927.
this is a digital caliper so since im for the most part skeptical and partial to analog calipers,, i will however trust it.

.047'' longer is very significant i would think.


note to self
Hydro-Gear ZT-2200 EZT- Center Section Repair Pt 1
7p10cc - oil pump block 70723
5p10cc - motor pump block 70331

 

[jcassity]

can anyone here tell me if the springs from the pump or motor blocks are interchangeable?
if yes thenthe answer to my question just needs confirmed by a couple more people saying thier "NEW" springs are longer than 1.880'', this value which ESFM was kind enough to share !

much appreciated, Scott

 

[jcassity]

anyone>?

 

[Woodpecker]

anyone>?

While there is some good general ope knowledge here it’s primarily a chainsaw forum. Have you tried any of the landscaping forums? You might be more likely to get answers there since those folks use and repair hydro motors more.

 

[jcassity]

thank you very much, i was not clear i guess when somone over at foxthunderbirdcougar forums suggest here.
much appreciated,, i will move on and continue the saga. i have filled in a few gaps with even more new info and dive in for another repair on the left side. if what i do works, then all that info will translate over to the right

you can go ahead and delete my account please

 

[r7000]

i watched some of your linked video, clean your bench haha

you are over complicating things

- the hydro trans they fit into zero turns and tractors are hack jobs not intended for durability and longevity. don't kid yourself. look at heavy equipment like a dozer with a hydro trans that moves tons. They last. why - because they're big, huge oil quantity and oil coolers, neither of which your hydro trans has. and filters. The physics and the consequences are the same between the two.
- you messed with yours, and seem to have gotten respectable performance when cold, but it loses that when hot. what's that tell you - there's a clearance [wear] problem as the oil heats and leaks from where it's not supposed to and you lose power.
- solutions are to reduce oil heating, not likely in your setup; increase oil viscosity and/or use a viscosity improver additive like that old stp jiz or lucas... might help. There's a reason why they use 50wt oil in hydro's.
- replace the worn parts in the hydro, which will be the two pumps. I suspect the driving pump/block on the axle might get the most wear as it sees the load/weight of the coming from the axle... i'd have to look at the parts diagram to refresh my memory.
- the springs inside the pistons are not the problem. There is no way they would be too weak to not push hard enough to be a cause of the problem resulting in leakage between the sliding face of the rotating block; if you expected those pistons to be so forceful to prevent leakage at that interface you would not be strong enough to assemble the thing by hand. it would be like thinking piston rings in the typical gas engine needed to be so tight to give compression - the piston then wouldn't be able to slide, and then that would be such a parasitic power loss. you simply need new block/piston assemblies. They wear! more so in units like this with minimal oil, no cooling, no filtration.
- can u reface your block where it's worn, i don't have enough experience doing that to say. but from what little i saw in your vid, use good sandpaper intended for metal. start with 220, then move to 300, then 400, then 600, then wet 1000; don't expect hitting it with some *s-word 200-400 for 10 seconds is going to be a solution, and get a nice piece of clean glass that you can best assure a flat surface. Otherwise spend a couple hundred and get all new block/piston assemblies.