X500 - K72B Transmission (slow in forward drive when hot)

[Jackson53]

+1 on the question of Trans Oil Replacement on schedule?
The dealer doesn't have to do that. It's acceptable for you to DIY as long as you use the Lo-Viz Hygard and keep the receipt and record the event in your Owners Manual, Service Record section. (Which I'm sure you did.)

The dealer is probably unwilling to commit a staff member for an hour to run the machine up to temperature so as to replicate the fault as JD won't cover that time under the warranty.
Their test will be what is called a "Slope Test" where the machine should hold it's position on a 30-40 degree slope with light pedal pressure. Since they normally do this test when the unit is cold it usually fails to fail the test. (i.e. It passes). Then the disputes begin...

IF not too far from the dealer, can you ask for a Field Service Tech to call at a pre-arranged time so you can run it for an hour beforehand so they can experience the loss of power? Then they will file a DTAC report. Then you get a new Trans.

Also ask if your dealer has a Tech called Aaron and if so, let me know.

Also, check the tension spring on the belt idler tension plate and that the plate is moving freely to ensure correct tension. (I know you say they're taut. Just double check) I found the X500 Trans Belt Idlers to be a weak point. They are a warranty replacement if rough/noisy.

The remedy for a weak transmission is full warranty replacement.

This warranty support is one good reason why you bought a JD!

I do all the regular maintenance on the X500 including oil changes, etc and have service record and receipts.
The dealer was perplexed because never had a problem with the K72 transmission however they are a big outfit (Chesterfield Australia) so have all the resources. The dealer is 1.5 hours away. Will mention your suggestion that they send someone down to look at X500 while transmission hot.
The pulley/idler on the traction belt was checked by the dealer and one was replaced because leaking grease from sealed bearing. Assume they checked tension - will recheck.
I have been through the process of transmission diagnosis in the Technical Manual and the bottom line is that the transmission has to be replaced. I have advised dealer.

When looking at the drawings of the transmission the only thing I can think of is there is a problem with the centre cases, hydro motors and pistons not functioning when hot. What do you think?

 

[Spanner]

Likely to be some scoring on the plates allowing bypass,As the oil thins it bypasses more. Bypassing oil gets hot. Hot oil gets thinner. Thin oil bypasses more easily. Bypassing oil gets hot... :confused2:

Usually the scoring on the plates is obvious when opened-up.
Sometimes the plates can be 'polished' if the marks aren't too deep.

Labour time ($) plus parts ($) is usually more expensive than to Remove/Replace the trans as a unit.

Plus the new Trans comes with a 3-month warranty. The "rebuilt-by-dealer" Trans has no warranty other than Consumer Legislation.

Dealer claims warranty off JD for you. JD claims warranty off Kanzaki. The dealer will be required to hold the trans for 3 months pending possible recall to the factory. In practice, outside USA, the unit is scrapped after 3 months.

I would strip them down and save diffs and shafts for out-of-warranty help to hard-up customers. Never needed them on the K72.

Better scrap value if the steel and aluminium are seperated = more Beer Vouchers for the workshop. :drink:

 

[Jackson53]

Likely to be some scoring on the plates allowing bypass,As the oil thins it bypasses more. Bypassing oil gets hot. Hot oil gets thinner. Thin oil bypasses more easily. Bypassing oil gets hot... :confused2:

Usually the scoring on the plates is obvious when opened-up.
Sometimes the plates can be 'polished' if the marks aren't too deep.

Labour time ($) plus parts ($) is usually more expensive than to Remove/Replace the trans as a unit.

Plus the new Trans comes with a 3-month warranty. The "rebuilt-by-dealer" Trans has no warranty other than Consumer Legislation.

Dealer claims warranty off JD for you. JD claims warranty off Kanzaki. The dealer will be required to hold the trans for 3 months pending possible recall to the factory. In practice, outside USA, the unit is scrapped after 3 months.

I would strip them down and save diffs and shafts for out-of-warranty help to hard-up customers. Never needed them on the K72.

Better scrap value if the steel and aluminium are seperated = more Beer Vouchers for the workshop. :drink:

Thanks - I will keep you updated on final outcome so if it happens to someone else then all are aware.

 

[Spanner]

Standing-by...

 

[crazyal]

One thing you might be able to do is take it to the dealer then spend an hour or so mowing their yard. Once it acts up then have a tech look at it. I would still measure the oil/ case temp. If it's getting above what Tuff Torq recommends then I would want it replaced. At 200 hours and no external signs of why it's overheating (if it is) then chances are something is wrong inside and has gotten to the point where either it needs rebuilding or, because it's under warranty, replaced. Keep us informed as to how things are coming along and the end result.

 

[jimtur]

Greetings all,

My X500 has the Kanzaki K72B transmission and when the transmission oil gets hot after approx one hour of lawn mowing there is a noticeable loss of power in forward drive. The X500 has done 200 hours and is still under warranty but would like to know if anyone has had similar problem.
The engine is running smoothly, no unusual noises from any of the rotating equipment (gearbox, idlers, pulleys, etc), traction and mower deck drive belts are taut and not slipping, gearbox and engine oil all at correct levels (no signs of any leaks).
Removed the mower deck and inspected the mower drive belt and traction drive belt - both belts in excellent condition (no cracks) and no slackness.
Suspect centre case and hydro motor in transmission might be the problem. Appreciate any feedback.

Internal pump/motor/base need to be replaced or rebuilted.