# Tuff Torq TZT7DR Transaxle Teardown



## Bob Driver (Nov 1, 2017)

This thread is about a weak right-side transaxle unit on a JD Z525E zero turn I’m working on today. It’s a Tuff Torq TZT7DR, Tuff Torq # 787Q08247011. 187 hours on the machine…. Good opportunity to post this for guys that may have never been inside a Tuff Torq, or HydroGear reduction gear transaxle, and maybe take the fear away from tearing one down and saving some money

Machine came from the factory with 10W30 in the unit. Here’s what the pan/filter looked like when I pulled it apart, oil and filter had never been changed....









Filter is completely plugged and starting to collapse









Unit has an axial piston hydraulic pump and an axial piston drive motor. Here’s the problems with weak axial piston drive motor, spring on the right is normal…. 2 of 5 pistons with broken springs










Here’s what the “Center Section” looked like after pieces of the broken spring got into the piston pump….










Those broken spring used to be $2 each and a new center section was around $80. Tuff Torq doesn’t sell them separate any more. Two options to repair -- 1) Complete new unit $800 + shipping 2) Overhaul kit $325 with MS's cut for Sales Tax. Customer opted for the kit. 

RH Tuff Torq O/H Kit


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## BigT (Sep 15, 2014)

Thanks for sharing this Bob.

I've got an old JD 777 Z-Trac with hydraulic motors on the rear wheels. Simple setup. This mower is 16 years old and has never given me a minutes trouble with the drive system. I'm thinking I should give it a paint job and keep it running.


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## Bob Driver (Nov 1, 2017)

BigT said:


> Thanks for sharing this Bob.
> 
> I've got an old JD 777 Z-Trac with hydraulic motors on the rear wheels. Simple setup. This mower is 16 years old and has never given me a minutes trouble with the drive system. I'm thinking I should give it a paint job and keep it running.


Yep.... Huge difference in the reliability of a full-blown hydraulic drive system. Both Tuff Torq and Hydro Gear have their own set of problems with their zero turn transaxles. This is the 3rd TZT7 I've seen fail with less than 200 hours. Problem is no external filter, Tuff Torq says change the filter after the first 50 hours of operation, but nobody does that because you have to drop the unit out of the machine and split the case.

Just wanted to post something that might give a guy the courage to split the cases when they have a problem, rather than just hand Tuff Torq $800 for a new unit. Usually it's the springs that are broken, or the center section is buggered up like this one. The telltale sign of the broken springs was slowly turning the axle with it in bypass. I could hear a soft clicking noise. It was because the two piston springs were broken on the drive motor and not making constant contact with the thrust washer on the swash plate.......


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