Model 734778 Drive Units Troubleshooting

bartles

Well-Known Member
Joined
Jun 28, 2016
Threads
70
Messages
226
Working on a Model 934778 60".

The mower had a broken drive belt. I replaced the "broken" drive belt and the idler pulley. The belt, cogged, look hardly used, and the idler pulley bearing was tight. I put a new belt(cogged) on along with a new idler. I started the mower up, warmed it up a little and drove it out of my shop for about 15' and the drive belt broke. When I first started it up to drive it out of my shop I noticed both drives were a little jerky but not unusually noisy..
When I was replacing the drive belt I did not turn the drives at the fan(s) very much.

What do I start looking for that would break a belt? A failed pump in one of the drives?

Thanks in advance,

bartles
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
104
Messages
11,954
Two possible causes.
  • Transaxle mounting brackets broken.
  • Hydro fan(s) curled up into belt path. If a fan problem it is usually the left hand one.
Fan PN 607729 (HG 52576).
 

bartles

Well-Known Member
Joined
Jun 28, 2016
Threads
70
Messages
226
Thanks! I'll start there...wish I had paid more attention when I replaced the belt...simple stuff gets one every time!!
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
104
Messages
11,954
The problem I see with the fans is heat related. They are softening during running and as a cool down is done they set a bit curled up which each time gets a little bit more. Many time you will the fan tips being damaged as they start hitting the frame then later the tips starts getting into the belt path causing belts to break. It is common enough I keep a couple sets of fans in stock.

The last few years it also been the trans mounts being broken. That why I have a couple set of frame mounts in stock too. BTW Red Dog (Big Dog) in the same size has the same problems except their mounts are painted Red instead of Hustler Yellow. These kits are upgrades as they are using heavier gauge metal.
 

bartles

Well-Known Member
Joined
Jun 28, 2016
Threads
70
Messages
226
The problem I see with the fans is heat related. They are softening during running and as a cool down is done they set a bit curled up which each time gets a little bit more. Many time you will the fan tips being damaged as they start hitting the frame then later the tips starts getting into the belt path causing belts to break. It is common enough I keep a couple sets of fans in stock.

The last few years it also been the trans mounts being broken. That why I have a couple set of frame mounts in stock too. BTW Red Dog (Big Dog) in the same size has the same problems except their mounts are painted Red instead of Hustler Yellow. These kits are upgrades as they are using heavier gauge metal.
Well my "power of observation" truly failed me on this one!! Hopefully I can attach a photo of a missing bolt from the rear mount!!!

Thanks again for helping me focus!!

bartles
 

Attachments

  • IMG_20250324_081629331.jpg
    IMG_20250324_081629331.jpg
    61.2 KB · Views: 28

kbowley

Well-Known Member
Joined
Jun 8, 2011
Threads
3
Messages
186
Is your unit a CVT (two belts, one from the engine and one on the transmission)? Also, I need a wider screen shot to put that part into perspective in relation to the transmission.
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
104
Messages
11,954
Is your unit a CVT (two belts, one from the engine and one on the transmission)? Also, I need a wider screen shot to put that part into perspective in relation to the transmission.
Maybe if you get off the lazies and actually look up the mower then you would know is it not a CVT system. Don't be so lazy not to do your research you as would know they are HG ZT2800 units. And BTW it is the rear mount and appears to be the LH drive unit.

Well my "power of observation" truly failed me on this one!! Hopefully I can attach a photo of a missing bolt from the rear mount!!!

Thanks again for helping me focus!!

bartles
Very common with the Raptors as when they first came out they only used plain nuts when lock nuts were needed. They didn't even use lock washers. Actually using lock washers too under the bolt head doesn't hurt.

There are actual torque specs but I have yet to copy the upgrade kit instructions and convert them to a PDF. So use the standard torque for the bolt size used.
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
104
Messages
11,954
Is your unit a CVT (two belts, one from the engine and one on the transmission)? Also, I need a wider screen shot to put that part into perspective in relation to the transmission.
Maybe if you get off the lazies and actually look up the mower then you would know is it not a CVT system. Don't be so lazy not to do your research you as would know they are HG ZT2800 units. And BTW it is the rear mount and appears to be the LH drive unit.

Well my "power of observation" truly failed me on this one!! Hopefully I can attach a photo of a missing bolt from the rear mount!!!

Thanks again for helping me focus!!

bartles
Very common with the Raptors as when they first came out they only used plain nuts when lock nuts were needed. They didn't even use lock washers. Actually using lock washers too under the bolt head doesn't hurt.

There are actual torque specs but I have yet to copy the upgrade kit instructions and convert them to a PDF. So use the standard torque for the bolt size used.
 

kbowley

Well-Known Member
Joined
Jun 8, 2011
Threads
3
Messages
186
Maybe if you get off the lazies and actually look up the mower then you would know is it not a CVT system. Don't be so lazy not to do your research you as would know they are HG ZT2800 units. And BTW it is the rear mount and appears to be the LH drive unit.


Very common with the Raptors as when they first came out they only used plain nuts when lock nuts were needed. They didn't even use lock washers. Actually using lock washers too under the bolt head doesn't hurt.

There are actual torque specs but I have yet to copy the upgrade kit instructions and convert them to a PDF. So use the standard torque for the bolt size used.
You are a real ass; all you do is demean people. Nuisance to the whole community. I would love to see you work in my shop for a couple weeks just to see how stupid you are. Probably takes you a full day to diag a spark plug. Go away; Blocked and reported. You must be one lonely person.
 
Last edited:

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
104
Messages
11,954
You are a real ass; all you do is demean people. Nuisance to the whole community. I would love to see you work in my shop for a couple weeks just to see how stupid you are. Probably takes you a full day to diag a spark plug. Go away; Blocked and reported.
Apparently you are overly sensitive to serious criticism about how lazy you are.

You have no idea what I am capable of. Let see you do as many four bypasses on the Z800 and Z900 ECUs and still have all the safeties function as intended. Just complete doing a triple bypass on a Z925A yesterday.

Or figure out what causing an engine to idle fine when first started and start surging like mad when throttled up and continue doing so even at idle speed until the engine is shut down. Yes that took a several hours to figure out as I never had one in 15 yrs to do it. Of course I had get pass the bad camshaft, destroyed starter, and the fried stator first to get to root cause.
 
Top