HillsvilleScott
New member
Tuff Torq K46BN re-built, forward & reverse backwards..."Ramp" is fat side up.
I have a 2007 Craftsman MTS 5500 (917.287420) lawn tractor. I regularly cut no more than 2 of the 8.2 acres I have here in SW Virginia, very hilly country. No such thing as "flat" around here. I bought the tractor new from a local Sears dealership and it has done very well until recently. The tractor has a 26hp V-twin B&S motor and a Tuff Torq K46BN transaxle. The tractor had developed what seems to be the classic Tuff Torq K46 loss of speed and torque for climbing hills. According to Sears, the tranny is "not serviceable" and their exploded parts diagram for the tranny consists of only outside of case parts. Nothing about the insides. I read several threads online pertaining to the K46 of which there are 58 different variations listed on TT's website, each with several different serial number ranges with possible part differences.. (Some 26 major transaxle models
The first step toward solving the problem was change the drive belt. I had done that task once before. However, this time I didn't get the same positive results as last time. Getting more specific with the tranny, I read how the oil (recommended synthetic 5W50) is probably 10W30 and therefore probably not as protective. "Not serviceable" means, no drain plug or filler hole accessible while the transaxle is in the tractor. Out of the tractor there is a rubber cap that when removed can serve both purposes. The apparent service frequency of oil change is preferably around 50 hours or once a year in most cases.
I dropped the tranny, drained the oil and refilled with 2 qts of Castrol Edge (formerly 'Syntec') and re-installed the transaxle into the tractor. The same problem existed and was more like what I had read were the common complaints than I experienced to begin with, that being a loss of power after running for 15-20 minutes due to heat. The first time, I had been running for well over an hour before coming to a stand still. BTW, conventional oil thins with heat. Synthetic tends to thicken with heat. Hence the recommendation (and availability on Tuff Torq's site) synthetic 5W50 oil as opposed to probably requested by the manufacturer, 10W30 conventional oil.
I decided after more reading to split the case and replace the three most common mortality parts causing this power loss, the cylinder block motor, the cylinder block pump and the center case. After doing the change the 'smoke test' provided the pedals causing tractor motion in the reverse order, ie: forward pedal caused reverse and reverse pedal caused forward. The only explanation I could find was that I had re-installed a shaft of parts containing one part, referred to as the 'motor housing" (#36), being put in upside down. Before starting this extensive surgery, I had found two different threads explaining the procedure. One was a YouTube video and the other was the now very lengthy thread originated by "LotsOfGreenGrass", a text presentation with pictures. Adding to those the actual parts exploded diagram from Tuff Torq's site for the "K46BN" version of the tranny, I figured I had enough reference to help with parts orientation, even to the extent of special notations that it could go in upside down and to watch the orientation when re-installing.
I'll be honest, I did not take note or click a pic before I started but I left the 'motor housing' (#36) installed the same way that all three references picture it as the correct position, the wide end of the block facing upward (and an opposite narrow end downward) creating the ramp or diagonal surface the five spring loaded pistons of the cylinder block motor come in contact with.
All that said, I have a call into the guru whose name was all over the several year old threads, Derrick Dalton at Tuff Torq questioning any other reason for the direction being reversed. I am not interested in just flipping the motor housing, closing the case for the third time, hang it back up in the tractor's rear end for the fourth time while knowing no good reason why I should make it look different than three independent pictorials show. Wondering if Craftsman had any say in special design. Apparently that is not an unheard of practice thus the 58 different suffixes of the basic K46 tranny, one of 26 different major transaxles models they have available.
Anyone who has ventured into this surgery for the K46BN in a Craftsman with success, please post. Thanks in advance.
Later in the same day: I have gone onto the Tuff Torq website and compared the exploded parts diagrams of my K46BN and that of the K46AC, the model transaxle in the two John Deere tractors in the YouTube and text with pictures presentations I found online and referenced. The K46 BN has the position of the "motor housing" (#36) wide side up which is the way I have it installed and directions reversed. The diagram for the K46AC has the part wide side down, opposite from the pictures and video I viewed online. Either TT has some editing to do for their diagrams to be accurate as a reference of part installation position...OR those two tractors moved in the opposite directions their pedals said it should have gone in.
I have a 2007 Craftsman MTS 5500 (917.287420) lawn tractor. I regularly cut no more than 2 of the 8.2 acres I have here in SW Virginia, very hilly country. No such thing as "flat" around here. I bought the tractor new from a local Sears dealership and it has done very well until recently. The tractor has a 26hp V-twin B&S motor and a Tuff Torq K46BN transaxle. The tractor had developed what seems to be the classic Tuff Torq K46 loss of speed and torque for climbing hills. According to Sears, the tranny is "not serviceable" and their exploded parts diagram for the tranny consists of only outside of case parts. Nothing about the insides. I read several threads online pertaining to the K46 of which there are 58 different variations listed on TT's website, each with several different serial number ranges with possible part differences.. (Some 26 major transaxle models
The first step toward solving the problem was change the drive belt. I had done that task once before. However, this time I didn't get the same positive results as last time. Getting more specific with the tranny, I read how the oil (recommended synthetic 5W50) is probably 10W30 and therefore probably not as protective. "Not serviceable" means, no drain plug or filler hole accessible while the transaxle is in the tractor. Out of the tractor there is a rubber cap that when removed can serve both purposes. The apparent service frequency of oil change is preferably around 50 hours or once a year in most cases.
I dropped the tranny, drained the oil and refilled with 2 qts of Castrol Edge (formerly 'Syntec') and re-installed the transaxle into the tractor. The same problem existed and was more like what I had read were the common complaints than I experienced to begin with, that being a loss of power after running for 15-20 minutes due to heat. The first time, I had been running for well over an hour before coming to a stand still. BTW, conventional oil thins with heat. Synthetic tends to thicken with heat. Hence the recommendation (and availability on Tuff Torq's site) synthetic 5W50 oil as opposed to probably requested by the manufacturer, 10W30 conventional oil.
I decided after more reading to split the case and replace the three most common mortality parts causing this power loss, the cylinder block motor, the cylinder block pump and the center case. After doing the change the 'smoke test' provided the pedals causing tractor motion in the reverse order, ie: forward pedal caused reverse and reverse pedal caused forward. The only explanation I could find was that I had re-installed a shaft of parts containing one part, referred to as the 'motor housing" (#36), being put in upside down. Before starting this extensive surgery, I had found two different threads explaining the procedure. One was a YouTube video and the other was the now very lengthy thread originated by "LotsOfGreenGrass", a text presentation with pictures. Adding to those the actual parts exploded diagram from Tuff Torq's site for the "K46BN" version of the tranny, I figured I had enough reference to help with parts orientation, even to the extent of special notations that it could go in upside down and to watch the orientation when re-installing.
I'll be honest, I did not take note or click a pic before I started but I left the 'motor housing' (#36) installed the same way that all three references picture it as the correct position, the wide end of the block facing upward (and an opposite narrow end downward) creating the ramp or diagonal surface the five spring loaded pistons of the cylinder block motor come in contact with.
All that said, I have a call into the guru whose name was all over the several year old threads, Derrick Dalton at Tuff Torq questioning any other reason for the direction being reversed. I am not interested in just flipping the motor housing, closing the case for the third time, hang it back up in the tractor's rear end for the fourth time while knowing no good reason why I should make it look different than three independent pictorials show. Wondering if Craftsman had any say in special design. Apparently that is not an unheard of practice thus the 58 different suffixes of the basic K46 tranny, one of 26 different major transaxles models they have available.
Anyone who has ventured into this surgery for the K46BN in a Craftsman with success, please post. Thanks in advance.
Later in the same day: I have gone onto the Tuff Torq website and compared the exploded parts diagrams of my K46BN and that of the K46AC, the model transaxle in the two John Deere tractors in the YouTube and text with pictures presentations I found online and referenced. The K46 BN has the position of the "motor housing" (#36) wide side up which is the way I have it installed and directions reversed. The diagram for the K46AC has the part wide side down, opposite from the pictures and video I viewed online. Either TT has some editing to do for their diagrams to be accurate as a reference of part installation position...OR those two tractors moved in the opposite directions their pedals said it should have gone in.
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