Cub cadet RZT 50 hydrostatic transmission

[RICKYMARK]

Cub finally came through after a great deal of argueing, flooding them with complaints, and filing a formal complaint with a consumer affairs agency. They then had the nerve to call me and tell me to "put away the pressure washer" which I've never used on it. Turns out after a lengthy discussion with their service manager (at cub itself) that their is apparently a problem if these tractors get in the rain (duh, they store them outside at the dealer) or wet in other methods i.e. washing them off. Water gets into the left tran somehow. I called it a design flaw and unabashedly offered to file a class action suit on behalf of cub owners everywhere. Next thing I knew, they had contacted the service center and told them to replace the tran. Strangely though, I still don't have the tractor back, it's in the shop goin on eight weeks now.

 

[RZT50 Rider]

Rick: Could you relate what the original problem was with your Cub RTZ50. I just purchased one in March of this year.

Thanks
Rider

 

[mokanman]

I'm having the same problem others here are having. I found this thread using Google so I joined the forum and this is my first post. I have had my RZT 50 for about three years (bought it new from a local dealer). I felt from the beginning that the left side was unresponsive and sluggish but thought that it just needed adjustment. Before I ever bought anything there my dealer has proven in the past to be less than adept at repair work so being a DIY guy who doesn't like to have my mower down for a lengthy period of time I always make adjustments and repairs myself.

Last week when I mowed, the left side lost power so badly that I could hardly finish the job (and I was only 2/3 done). Mowing downhill was fine, flat surfaces were okay but 5 to 10 degree inclines were excruciating (I didn't even attempt anything of a higher degree but in the past I've taken pretty steep hills with no problem).

Yesterday I found this link and carefully studied the repair manuals for the mower and the transmission. I'm confused as to where the actual fill port is on the transmission. Some in this thread have evidently removed the breather assembly and used that aperture as the fill port. The exploded diagram shows a 9/16-18 plug nearby (is that 18 a thread size?). A hex key (allen wrench) fits in the head of that plug but I could not get it open and did not want to apply too much force to something that maybe was not meant to be opened.

If the plug is the correct location for adding/draining oil then that might explain why some have had trouble draining it from the breather hole (especially if there are two separate chambers). You mentioned an expansion tank in an earlier thread and I'm wondering if that is under the breather assembly.

Anyway, today I drove the mower out of the garage, test drove it to find that the problem was indeed immediately still occurring. I turned it off and thirty minutes later I stuck a clean white pipe cleaner down through the breather holes in each transmission as far as they would go. The one in the right transmission (which moves just fine) had about 1/4" of very black looking oil on the end of it. I'm assuming black is not what I really want to see there but since that transmission is running okay I'm thinking I can take it off the mower, drain/replace the oil, reinstall and I'll be okay on that side.

The left side, however, is another matter as it came up completely dry. Again, if the fill port is supposed to be where the plug is located and not the breather hole then I'm checking from the wrong place. So I have two questions:
1. Can the transmission oil level be verified through the breather hole?
2. Is adding/removing oil through the breather hole a viable option and if not then does that mean the 9/16-18 plug is sealing the correct fill port?

Any guidance, support, words of wisdom, last rites would be appreciated.

 

[mokanman]

Okay, a happy update here. This is not the happy part but I was able to edit my post last night right after I created it, however, it appears I no longer can - I'm still learning how this forum works - it is very different from the only other forum I'm on.

Anyway it appears I have solved my problem and it was not related to the oil level at all. The transmission belt pulley arm pivot bolt was tightened so tight that the spring could not pull the arm to put enough tension on the belt with the pulley. I loosened that bolt (which I have never ever touched before) just a little and the problem disappeared. Now why that would have caused a problem on the left and not the right is beyond me. Another symptom of my problem was when I pushed both arms full forward the transmissions would both slow down so I would have to back them off somewhat to pick up speed.

I recently replaced both belts and both springs and the deck belt was easy peasy but the transmission belt was a b@tch! The pulley arm was very hard to deal with (the square hole was cut just inside the pulley's diameter so there was no way I could use the recommended socket wrench to pull back the arm without damaging the pulley. I had to remove the spring first! Then (because of the sticking pivot bolt) I had to beat the arm back with a handheld sledge and after replacing the belt I had to use the handle of the sledge as a fulcrum between the mower body and the pulley to push it back. Once I got the spring back on (which in itself was fun) I assumed the correct tension was being maintained. Silly me!

I still would like to know which is the proper transmission fill port. Before loosening the pivot bolt I added about 4 ounces of oil through the breather hole (after removing the fitting) and it filled that chamber about ¾ to an inch from the top. I was doing this in the dark with a flashlight and a syringe and would have quit long before getting it that full if I’d have known it was that high. I tested right after that with no results. I also purged the air this afternoon (per the procedure in the manual) prior to loosening the pivot bolt with no results. I did not check the level after loosening the bolt so maybe it will self purge with use? I’ll check that when I get time.

Anyway, though it seems unlikely, you other guys with potential transmission problems might check your pulley arm tension bolt to make sure it is allowing free movement of the pulley arm. I’m thinking that as my original belt was getting stretched the pulley arm was unable to pull it tight and that is why my problem was getting progressively worse. After I changed the belt I evidently positioned the pulley to where it was providing less tension that before and with the pivot bolt too tight it was unable to compensate. That’s my story and I’m sticking to it.

One other question (I know this is a long post so this will be it, I promise). Is there a timeout on this forum that logs you off after so many minutes of non-entry? My other forum does not have that but this one seems to. Maybe there is a setting I can change from the default for me?

 

[OldMachinist]

The mounting bolt for the idler arm should have a grease fitting in the head to grease where it rotates and it sounds like your arm has seized up on the bolt. I'd take the bolt and the arm off and get it them free'd up because if the bolt runs loose it might fall out.

 

[mokanman]

I just checked and my RZT 50 does not have a grease fitting in the idler arm bolt. My bolt does not look like yours at all. Mine does not have the tube-like structure yours appears to have and looks more like a normal bolt. The bolt is threaded into a lock nut on the top of the body and I just barely loosened it. I agree that I need to lubricate it somehow but without a grease fitting it looks like I'm limited to oiling it.

The exploded parts diagram does not indicate a grease fitting (sorry this picture doesn't look as good as it does on my PC for some reason):

 

[OldMachinist]

The picture I posted was from the RZT service manual. I went back and looked at the parts diagrams and it looks like only the early models had the grease fitting.

 

[mokanman]

Isn't that just the corporate way. Let's see... where can we cut corners to save a buck on each product so our CEO, CFO, COO, CIO, (and the one that is such a laugh to me, CDO), etc can all suck it up with their "well deserved" raises and the company and workers can all go down the tubes. I guess I'll try to oil it somehow but since I just barely loosened the lock nut (not even a sixteenth of a turn) I don't think I'll have any problems with the bolt coming loose. I'll keep an eye on it though.

As to the picture not being your mower... I'm relieved. That mower was way too sparkly clean. I haven't really had time to keep mine very clean, what with all the mowing I do. I mow about 5 acres at home and an acre each at two rental properties. I try to do mine every four days and the rental properies once a week. Once I get the other properties rented then I won't have to mow them anymore. It's a catch 22 though because the time I spend doing yard work at those properties sucks just about any time (or energy) I have left for getting them ready to rent! I'm rambling... sorry.

 

[rmarkw]

Mokanman, my story is almost identical to yours. I've had my RVT 50 for just a little over 3 years. The left side has always been weaker on hills than the right. But this year it's become a noticably worse. The mower only has 110 hours. Following some great previous post, I removed the transaxle, drained the oil, replaced oil with synthetic, and installed a new Husky 57" kevlor drive belt. Unfortunately none of the above fixed the problem.
I think there needs to be a safety recall on these before someone gets seriously hurt. Can you imagine driving a car if the brakes and steering continously went out on one side?

 

[mokanman]

It seems there are many causes for the same symptom. It sounds like you've eliminated the transmission oil being the cause. What was the condition of the oil you drained? If it was foamy looking then has your mower been out in the rain much or have you washed it much (questions that the dealers and mfg. seem to love)?

Is your drive belt getting enough tension? A sticking pulley arm prevented my belt from getting the necessary tension causing a more pronounced problem on the left side than the right. Correcting the tension completely solved my problem.