I have a 502.255070 10hp rear engine mower for my mother's cottage. A years back it got a little water logged when the river came up, but it only got into the transaxle and not the engine. I pulled the trans, cleaned the mud out and filled it with 00 grease. Since then it has had a "hiccup" when moving forward or reverse and it's slowly getting worse. While moving the trans feels like it slips out of gear and then lurch forward and continue to drive, but it does not do this in regular intervals. Its a SPICER 3975 transaxle, I've pulled it back out of the tractor and everything appears to mesh correctly, the brass bushings all appear to be in good shape, and the gear selector appears to be aligned and working correctly. Any suggestions?
Transmission "hiccuping"
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Have you checked the "KEY" between the Input Pulley & The Input Shaft?
It may be worn, or the Saft, or Pulley may be getting "HOGGED-OUT" (worn out)...
I'm not familiar with that Transaxle, but it makes sense to me.
Good Luck!
-Thomas (12)
Western Washington State
Sent from my SM-J337V using Tapatalk
It may be worn, or the Saft, or Pulley may be getting "HOGGED-OUT" (worn out)...
I'm not familiar with that Transaxle, but it makes sense to me.
Good Luck!
-Thomas (12)Western Washington State
Sent from my SM-J337V using Tapatalk
Yup, the keyway & key on the input shaft are still sharp edged with good engagement.
We purchased the tractor in almost new condition a few years back when the husband passed away and he only used it sparingly on a small suburban yard. There is very little wear anywhere on the tractor and why I'm spending the time and effort to keep it running.
We purchased the tractor in almost new condition a few years back when the husband passed away and he only used it sparingly on a small suburban yard. There is very little wear anywhere on the tractor and why I'm spending the time and effort to keep it running.
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It likely has a belt drive for both blade and motion. The drive(motion) belt would also have a clutch mechanism, likely a pulley that provides tension so the PTO drives the pulley on the transmission. If the tension pulley had bad ball bearings, it could jam up and cause the belt to slide over a non-rotating pulley, which could make the drive seem intermmittent. The belt itself could be damaged, or the vee of the pulleys contaminated, possibly causing slippage. I would be checking the belt, tension mechanism, clutch apply/release mechanism, and the pulleys.
One other thing is the keys in the output shaft could be deteriorated, allowing the wheel to turn on the drive axle and then catch at random intervals.
tom
One other thing is the keys in the output shaft could be deteriorated, allowing the wheel to turn on the drive axle and then catch at random intervals.
tom
Its a new belt as of this spring but that didn't solve the issue. I didn't think about a jammed tensioner pulley. The axle keyways & key, like the input shaft, are very sharp edged with good engagement. I've been looking over the obvious mechanical issues but been focusing on the transmission and not the power delivery from the motor.
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Different transaxle, but my Craftsman LT (with a Peerless 6-speed unit) started to develop lurching and jerking.
After taking it apart twice, and checking gear meshing, gear selector keys, etc, I finally figured out it was gears in the differential wearing out, and starting to slip. One hint for me was that it was more pronounced while turning (which forces the diff gears to rotate against each other). And that it would also sometimes happen while hitting the brake. That meant, for my tranny, that the issue was happening somewhere within the tranny (rather than being related to a belt/pulley), as the brake is basically near the input of the tranny, so it loads up the gears when you hit the brakes.
I bought a used transaxle for basically the same price as the worn parts. The new one is filled with gear oil, rather than grease. That seems better to me, since the oil will flow around and stay on all the rotating surfaces, vs the thick grease that got pushed away into the corners of the housing.
After taking it apart twice, and checking gear meshing, gear selector keys, etc, I finally figured out it was gears in the differential wearing out, and starting to slip. One hint for me was that it was more pronounced while turning (which forces the diff gears to rotate against each other). And that it would also sometimes happen while hitting the brake. That meant, for my tranny, that the issue was happening somewhere within the tranny (rather than being related to a belt/pulley), as the brake is basically near the input of the tranny, so it loads up the gears when you hit the brakes.
I bought a used transaxle for basically the same price as the worn parts. The new one is filled with gear oil, rather than grease. That seems better to me, since the oil will flow around and stay on all the rotating surfaces, vs the thick grease that got pushed away into the corners of the housing.
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I have what might be a similar issue with my Peerless 801 transaxle on my JD 160. I'll be cruising along in first, second or third and it will lurch briefly (kinda like a stutter, almost) then keep going. I've been told that's an issue with the shift keys inside the transaxle wearing out... Haven't had the nerve to try to pull the thing and find out, because my rims are seized onto my axles....
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I have a feeling that the transmission/transaxle will be the final nail in the coffin of these old AYP products. It may be they will last, and then again, maybe not. There's no scheduled maintenance for any of the 5-speed gearboxes that I know of. The grease is supposed to last the lifetime per the manual.
If I knew any preventive maintenance to prolong their usable lifetime, I'd likely do it unless it was too difficult. I don't know a lot about Bentonite grease.
tom
If I knew any preventive maintenance to prolong their usable lifetime, I'd likely do it unless it was too difficult. I don't know a lot about Bentonite grease.
tom
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I add some gear lube to the grease if I have to take one apart..(and its not fubared inside and worth re-assembling!)..
I have used Drydene "red" high temp wheel bearing grease in many manuals that had Bentonite and it seemed to work as good ,the gear lube keeps everything wet and well oiled--that bentonite grease often migrates away from important parts and lets them rust & wear out...
I have not seen bentonite grease for sale anywhere locally so I used what I could get at local parts stores...my theory is any grease is better than none!..
I have used Drydene "red" high temp wheel bearing grease in many manuals that had Bentonite and it seemed to work as good ,the gear lube keeps everything wet and well oiled--that bentonite grease often migrates away from important parts and lets them rust & wear out...
I have not seen bentonite grease for sale anywhere locally so I used what I could get at local parts stores...my theory is any grease is better than none!..
New idler pulley installed and the mower still lags & hick-ups. Took the trans back out and opened the cases and nothing seems out of place. The gear faces have very minimal surface wear, the bronze bearings are all clean with minimal wear, the differential seems to "lock" when you try to hand rotate both axles. I'm at a loss now...
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What does 'lag' mean? If the engine is at operating rpm, and you ease up on the clutch/brake pedal, most will lurch forward if you are not gentle, especially in higher gears. It will not jump so much in the lower gears. If it does not engage when you release the pedal, then the pedal linkage may possibly be gummed up or difficult to move, or the belt is slipping on the input pulley or the engine PTO pulley.
I would check that you did not get the linkage all rusted up when it got the 'bath' and is now becoming stiffer to operate. In the 'release' direction, the only thing moving it is a spring. If the bushings and rotation spots are getting rusty, that can cause the linkage to be barely letting the belt get good 'grab' on the pulleys. IOW, make sure the clutch linkage is all freed up and moves readily. The only opposition force you should feel is spring tension when you push on the pedal. With the engine off, if you release the pedal, it should spring back freely, AND the tensioner pulley should snap against the outer belt surface. SNAP. Okay, maybe just push back quickly. Check for that as a linkage that does not move freely could be keeping the pedal partly 'pushed' even though it is at the top of its travel.
tom
I would check that you did not get the linkage all rusted up when it got the 'bath' and is now becoming stiffer to operate. In the 'release' direction, the only thing moving it is a spring. If the bushings and rotation spots are getting rusty, that can cause the linkage to be barely letting the belt get good 'grab' on the pulleys. IOW, make sure the clutch linkage is all freed up and moves readily. The only opposition force you should feel is spring tension when you push on the pedal. With the engine off, if you release the pedal, it should spring back freely, AND the tensioner pulley should snap against the outer belt surface. SNAP. Okay, maybe just push back quickly. Check for that as a linkage that does not move freely could be keeping the pedal partly 'pushed' even though it is at the top of its travel.
tom
Clutch operation and belt engagement are perfectly fine. I'm 90% sure its something internal and maybe a gear lash / shimming issues and not external to the trans axle.
By "lag" or "hiccup" I'm trying to explain that while already in motion in forward or reverse it feels as thought the transaxle disengages or internal gears skip. You have a momentary pause in forward motion then the gears catch and you lurch back into forward progress.
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Does that transaxle have a chain & sprockets inside for reverse ?..if so maybe it is loose enough or the sprockets teeth are worn enough to let it skip over them instead or driving it properly..
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That's similar to my symptoms. My differential would also "hold" in a test like that, despite its gears being worn. I'd get more hiccuping when driving in a circle, as that would make the diff gears rotate against each other, while under a load.
I also tried feeling for jerking while changing the engine speed, vs the ground speed. A high gear at idle will move at a similar ground speed to 1st gear and full throttle. Does the behavior "scale" with ground speed, or engine speed? Staying with ground speed means it relates to the tranny output. Engine speed means it's closer to the input side of the tranny. Mine related to ground speed.
You could maybe try jacking up 1 rear wheel. Put the tranny in neutral, and spin that wheel. With the other wheel stationary, you're forcing the diff to work. If you start getting jerking/hiccuping, vs smooth rotation, you've learned something.
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If you 'dance' a bit on the clutch pedal, does that mimic the surge or jerk you feel?
Any differential with wear would generally show the wear in the bushings the spider gears ride upon, moreso than the actual gear teeth. When in straight line motion, the spider gears in the differential are not rotating on their shafts, they are sitting still. As redoctober mentioned, the spider gears will be moving when driving in a circle, and if they were skipping teeth, you should notice it more. Also if the spiders were worn, or loose on their shaft, or the shaft loose in the carrier, you should notice something with one wheel jacked up and the other held still. In that condition, rotating the wheel will rotate the spider gears, walking them around 100% of the time, as if one wheel was totally slipping, and would drive the input shaft & pulley at more than normal speed. You would/should feel if there was any 'give' or 'slippage' of the spiders.
If you inspected the spider gears and shafts, and the differential in general, and found no wear, or minimal looseness of fit, it should not skip teeth. AND, when it did skip a tooth, you would feel a 'jump' or 'bump' as the gear accelerated past the skipped tooth, and banged into the next one where it finally grabbed, and imparted more motion. It would not be a smooth slippage, but more of a 'bang' or the grind of teeth.
If you ever shifted a manual transmission, and didn't get fully engaged, you would have felt the teeth of the collar grinding against the teeth of the gear. When you finally get it into gear, unless you are quick with the clutch, you'd feel the slight bang as the teeth engaged.
If you haven't I would be sure to lubricate all the clutch linkage, and make sure the brake cross-shaft(left to right side) and the lever on the side moves freely. It should apply and release with not jerkiness or hesitation. If that moves, then check the clutch engage mechanism for free motion. The spring could get out of position and bind, making the cluch(belt) slip...
tom
Any differential with wear would generally show the wear in the bushings the spider gears ride upon, moreso than the actual gear teeth. When in straight line motion, the spider gears in the differential are not rotating on their shafts, they are sitting still. As redoctober mentioned, the spider gears will be moving when driving in a circle, and if they were skipping teeth, you should notice it more. Also if the spiders were worn, or loose on their shaft, or the shaft loose in the carrier, you should notice something with one wheel jacked up and the other held still. In that condition, rotating the wheel will rotate the spider gears, walking them around 100% of the time, as if one wheel was totally slipping, and would drive the input shaft & pulley at more than normal speed. You would/should feel if there was any 'give' or 'slippage' of the spiders.
If you inspected the spider gears and shafts, and the differential in general, and found no wear, or minimal looseness of fit, it should not skip teeth. AND, when it did skip a tooth, you would feel a 'jump' or 'bump' as the gear accelerated past the skipped tooth, and banged into the next one where it finally grabbed, and imparted more motion. It would not be a smooth slippage, but more of a 'bang' or the grind of teeth.
If you ever shifted a manual transmission, and didn't get fully engaged, you would have felt the teeth of the collar grinding against the teeth of the gear. When you finally get it into gear, unless you are quick with the clutch, you'd feel the slight bang as the teeth engaged.
If you haven't I would be sure to lubricate all the clutch linkage, and make sure the brake cross-shaft(left to right side) and the lever on the side moves freely. It should apply and release with not jerkiness or hesitation. If that moves, then check the clutch engage mechanism for free motion. The spring could get out of position and bind, making the cluch(belt) slip...
tom
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