TH400 shift lever
Thread Starter
Racer
Joined: Jul 2005
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From: GA
TH400 shift lever
I'm trying to remove the shift lever so I can r/r the shifter shaft seal. Puttng torgue on the nut causes the lever to move to the 1st position.
How can I get the nut off without damage to the shift internals?
How can I get the nut off without damage to the shift internals?
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It won't hurt anything. When it hits the stop just finish loosening the nut.
JIM
JIM
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Racer
Joined: Jul 2005
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From: GA
Race Director
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Not off hand. Never used a torque wrench on it. It's just a 3/8" nut so not much. I built transmissions for years and that's one I never worried about a torque spec on. Just tighten it up.
JIM
JIM
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You can usually get two seals in there on top of each other if the shaft is a little worn. That way the seal(s) are in a new wear area.
JIM
JIM
Team Owner
Joined: Jan 2006
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From: Crossville TN
You still have to get the nut off to insert another seal.
Use a box wrench on that nut. If the transmission is in PARK position, the shift shaft should only turn a little before it binds and the nut will loosen.
Once it is off, remove the linkage from it; then clean all the crap off the outside so that none of it can get into that area as you work on the seal.
The post above states that you can just drive a new seal over the top of the old one. That is absolutely correct....IF is doesn't already have two! If you can do so, it's actually a better fix than just replacing it. You end up with an old one that seals almost all of the oil from getting out. The new one only restricts the little oil that gets by the old one! Works well; I've done it. 10 years without another leak.
You need to put some grease on the sealing lip before you try to install it AND you need to VERY CAREFULLY place it over that shaft, as the edges of those flats are very sharp and can cut the new seal if not handled properly.
Once in place, use the 'drive' end of a 1/2" drive, deep-well socket (having diameter that is nearly the same as the O.D. of the seal) to drive it down to seat. The 'paint' on the O.D. of that new seal is actually sealant; so you do not want to put additional sealant on it.
Good luck.
Use a box wrench on that nut. If the transmission is in PARK position, the shift shaft should only turn a little before it binds and the nut will loosen.
Once it is off, remove the linkage from it; then clean all the crap off the outside so that none of it can get into that area as you work on the seal.
The post above states that you can just drive a new seal over the top of the old one. That is absolutely correct....IF is doesn't already have two! If you can do so, it's actually a better fix than just replacing it. You end up with an old one that seals almost all of the oil from getting out. The new one only restricts the little oil that gets by the old one! Works well; I've done it. 10 years without another leak.
You need to put some grease on the sealing lip before you try to install it AND you need to VERY CAREFULLY place it over that shaft, as the edges of those flats are very sharp and can cut the new seal if not handled properly.
Once in place, use the 'drive' end of a 1/2" drive, deep-well socket (having diameter that is nearly the same as the O.D. of the seal) to drive it down to seat. The 'paint' on the O.D. of that new seal is actually sealant; so you do not want to put additional sealant on it.
Good luck.
Last edited by 7T1vette; Jul 25, 2017 at 10:56 AM.
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
You still have to get the nut off to insert another seal.
Use a box wrench on that nut. If the transmission is in PARK position, the shift shaft should only turn a little before it binds and the nut will loosen.
Once it is off, remove the linkage from it; then clean all the crap off the outside so that none of it can get into that area as you work on the seal.
The post above states that you can just drive a new seal over the top of the old one. That is absolutely correct....IF is doesn't already have two! If you can do so, it's actually a better fix than just replacing it. You end up with an old one that seals almost all of the oil from getting out. The new one only restricts the little oil that gets by the old one! Works well; I've done it. 10 years without another leak.
You need to put some grease on the sealing lip before you try to install it AND you need to VERY CAREFULLY place it over that shaft, as the edges of those flats are very sharp and can cut the new seal if not handled properly.
Once in place, use the 'drive' end of a 1/2" drive, deep-well socket (having diameter that is nearly the same as the O.D. of the seal) to drive it down to seat. The 'paint' on the O.D. of that new seal is actually sealant; so you do not want to put additional sealant on it.
Good luck.
Use a box wrench on that nut. If the transmission is in PARK position, the shift shaft should only turn a little before it binds and the nut will loosen.
Once it is off, remove the linkage from it; then clean all the crap off the outside so that none of it can get into that area as you work on the seal.
The post above states that you can just drive a new seal over the top of the old one. That is absolutely correct....IF is doesn't already have two! If you can do so, it's actually a better fix than just replacing it. You end up with an old one that seals almost all of the oil from getting out. The new one only restricts the little oil that gets by the old one! Works well; I've done it. 10 years without another leak.
You need to put some grease on the sealing lip before you try to install it AND you need to VERY CAREFULLY place it over that shaft, as the edges of those flats are very sharp and can cut the new seal if not handled properly.
Once in place, use the 'drive' end of a 1/2" drive, deep-well socket (having diameter that is nearly the same as the O.D. of the seal) to drive it down to seat. The 'paint' on the O.D. of that new seal is actually sealant; so you do not want to put additional sealant on it.
Good luck.
I got the shift lever off and I will just put the new seal on top of the old one. Seems like a great idea.
When the lever is pushed all the way FORWARD, is it in PARK or 1st?
Team Owner
Joined: Jan 2006
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From: Crossville TN
Asking that question is like asking a bowler, "What foot do you use to start your approach?" It's something you SHOULD know, but now that you ask it, I haven't got a clue!!! You'll just have to move your shift lever a bit to find out for sure. 
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LOL...I had to sit here and think for a second too! "Forward" should be park. Looking at the end of the shaft....if you rotate it clockwise it will be park.
http://repairguide.autozone.com/znet...3f8020d6b6.gif
JIM
http://repairguide.autozone.com/znet...3f8020d6b6.gif
JIM
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
Now another problem
LOL...I had to sit here and think for a second too! "Forward" should be park. Looking at the end of the shaft....if you rotate it clockwise it will be park.
http://repairguide.autozone.com/znet...3f8020d6b6.gif
JIM
http://repairguide.autozone.com/znet...3f8020d6b6.gif
JIM
I noticed when I removed the pan that 2 bolt holes were stripped. The hole in the "corner" by shift lever had a bolt/nut and another had a larger screw.
What is the best way to repair these holes? Tap for a larger screw or HELICOIL?
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
The problem with fixing those threaded holes is that most of them are 'blind'...meaning they only go so deep and a special 'bottoming' tap and automated tooling are used to create the threads. There is not enough depth to drill a larger hole and tap it adequately to insert a helicoil on those 'blind' holes. Thru holes are a different story.
Usually those threaded holes get stripped because of an oil pan leak and the owner cranks on those steel bolts (in soft aluminum housing) to force the joint to seal. It doesn't, because the threads get stripped with any significant amount of over-torque.
Usually those threaded holes get stripped because of an oil pan leak and the owner cranks on those steel bolts (in soft aluminum housing) to force the joint to seal. It doesn't, because the threads get stripped with any significant amount of over-torque.
Thread Starter
Racer
Joined: Jul 2005
Posts: 433
Likes: 14
From: GA
The problem with fixing those threaded holes is that most of them are 'blind'...meaning they only go so deep and a special 'bottoming' tap and automated tooling are used to create the threads. There is not enough depth to drill a larger hole and tap it adequately to insert a helicoil on those 'blind' holes. Thru holes are a different story.
Usually those threaded holes get stripped because of an oil pan leak and the owner cranks on those steel bolts (in soft aluminum housing) to force the joint to seal. It doesn't, because the threads get stripped with any significant amount of over-torque.
Usually those threaded holes get stripped because of an oil pan leak and the owner cranks on those steel bolts (in soft aluminum housing) to force the joint to seal. It doesn't, because the threads get stripped with any significant amount of over-torque.
Are you saying I can't use a helicoil?
If the torque spec is only 8 ft/lb would the locktite thread fixer work?
I don't want to resort to using a nut and bolt.
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I think you could get a heli coil in there. Just drill straight.
Rather than thread fixer I'd probably go to a stud with some JB Weld. You could stud all of them and use nuts and save threads in case from wear. Hardware store has studs.
JIM
Rather than thread fixer I'd probably go to a stud with some JB Weld. You could stud all of them and use nuts and save threads in case from wear. Hardware store has studs.
JIM
