Turbo 400 Disassembly

hotrodpc · 03-21-2009, 11:56 PM

Ok members. I need some help here. Hopefully there is a Trans guru here somewhere. I have done many many Turbo 350's, several T 400's. But it has been about 18 years since I did a T400 and I must be forgetting something here. This is the 400 out my newest 86 project vehicle. As you can tell by the dark brown fluid this one burnt pretty bad. Lots of clutch material in the pan. Believe it or not I expected to find lots of metal but didn't so far. Of course I am not all in it yet. Here is where I am stuck. I can't seem to get the direct drive clutch drum and input shaft out of the case. On a T350, you can get the band out around the drums and it gives you more room to get the drums out. The 400 has a pin holding the band in place and the disassembly instructions I found, say to remove the drums, then the band. I believe that to be true since the pin is holding the front band in place. The servo is already out, in fact both band servo's are out. Can anyone tell me what I am missing here to get these front drums out of the case? I can't find my ATSG books for any help. Anyone know of a good site with good illustrations?

Case 7230 · 03-22-2009, 06:42 AM

I think you should find diagrams at transtar1.com and of course, Murphy`s Law I can`t the Th400 in any of my books. Hope this helps.

mrjohnwayne · 03-22-2009, 12:28 PM

hmm. I can't remember cause it has been several yeas as well but I don't think there is anything special you have to do.. wonder the the clutches and steels got welded together keeping it in place...

hotrodpc · 03-22-2009, 01:10 PM

Yes, You are on the right track john.. As you can tell in the pic, it got very hot. I did not think there was anything special either, but I have made a bit of progress, by rolling over the case and shaking the input shaft pretty rough like. I am getting hard parts and chunks of metal to fall out of it now. It is bound up, and hanging up, likely on the steels and cluthches. I am going to replace the bands anyway since they got so hot, but I got half the band out by pulling and bending it, then cut it off with one of mudseekers favorite tools. That is giving me more space to work with. After I did that, it was bedtime. I am glad I figured out it was hung up on something. I started feeling a bit inadequate when I did not think there was anything special, like a snap ring, servo or valve I was forgetting about. I am just hoping the broken hard parts have not damaged the case. The parts I am getting out of it, appear to be most likely be the sprag cage. Which is a bit wierd cuz if my memory serves, the sprag is a ways back in there and I was thinking it was behind the center support before I got to a sprag. As also suggested, I ought to look at a diagram and jog my memory.

hotrodpc · 03-23-2009, 12:22 AM

Well, I am about to give up on it. Something in there is welded together. Probably clutches and steels. I can turn the output shaft fine by hand. The input shaft is stuck. Even with vise grips on a section that does not matter, I can not get the input shaft to spin. I can wobble the input shaft and drums all over the place, just can't get it come out, or get it to spin. I was hoping if I could get it to spin, it may line up some steels or clutches and release. No luck. I keep prying on stuff, I am going to break the case. Probably going to call it a night, take a breather and calm down a bit and try again later. If anyone has experiecned this type of problem on a Turbo 400, please let me know what you did to get past it.

hotrodpc · 03-23-2009, 02:16 AM

OK Gentlemen. For those of you who are interested. I couldn't sleep and wasn't going to let this beat me. I got an idea to pry from the top (actually the bottom) coming in from the valve body voids. I was able to get a thin phillips in there to get started, and with patience which I had few of, and persistance I was able to persuade it to give up and let me have the input shaft and drums. It was the intermediate clutches and steels that were giving me the problem and burt or welded to the back of the splines on the direct clutch drum, which is connected to the back of the forward clutch drum and input shaft. The clean pic here is what the failed part is supposed to look like. The dirty pic in the case, is what it actually looks like. That is to be the intermediate piston that is not much left of. As a result, you see the clutches and steels. The clutches are burnt to non existance and down to thin metal disks, and the bent teeth are what I had to do prying them apart. The picture with the funky looking stuff with the springs inbedded in it, is what is left of the intermediate piston that is supposed to be that pretty yellowish brown ring in the clean pic. Of all the transmissions I have built, I have never seen a failure like this. I still have not gotten the center support out, but now that I got this far, I can sleep. Stay tumed. I expect to have it all the way apart in the morning and I have a feeling the sprag behind the center support is trashed as well. Although not much, I did get some metal chunks of what appears to possibly be sprag cage. That doesn't hurt my feelings. I just hope it is a wedge sprag and not a roller sprag which will mean I can use the smooth drum and replace it with a 34 element sprag which I inteded to do anyway. If its a roller sprag drum, then I have to purchase a drum to use the 34 element. Those aren't cheap. Thanks for the suggestion MrJohn. You or I was not wrong and not forgetting anything. My old memory is not so bad after all after 18 or so years. That makes me happy.

mrjohnwayne · 03-23-2009, 08:12 AM

WOW.. Glad you got it apart. That is one Toasted tranny!

hotrodpc · 03-23-2009, 09:40 AM

Yes, Toasted would be an understatement. I have done a T350 that was this bad before as far as color of fluid and case, but it wasn't stuck together like this one. Its all good though. I like the occasioanlly challenge and seeing something and learning something new that I have not seen before, and I didn't let it beat me although I was getting pretty frustrated with it. The people I bought the truck from, were moving from Arkansas, to Dyess, AFB in Abilene, TX, loaded heavy and towing a tandem axle enclosed U Haul trailer, so that trans was working hard in its later day of life. Lucky for the people, it did make it to Abilene from Ark. They had to have it towed the last 7 miles of the trip to the base. Once they unloaded the truck the military base started hounding them to get it running or get rid of it. So if it were not for the trans going bad, I wouldn't have gotten such a deal on the truck. So, I say the bad tranny was good to me. My daughter is stationed on base across the street from these people is how I knew about the truck. I just killed 2 birds with one stone. Went to visit my daughter and towed it home to OKC with a tow bar. Hahaha, now I can laugh though. I pulled the driveline thinking I would keep from doing more damage to the trans while towing it the 300 miles @ 70mph. Although, it probably helped for the tow vehicle, a little less resistance and not as much drag. As soon as I get motivated, I want to get it the rest of the way apart and take the case and tailshaft to the machine shop for a bath.

mrjohnwayne · 03-23-2009, 10:03 AM

LOL yeah I don't think you could of damaged it anymore by towing it home with the drive shaft in it.

hotrodpc · 03-24-2009, 01:50 AM

I did get it the rest of the way apart without any issues. Its one filthy case. Going to the machine shop soon to get a bath. A bit disappointed that this trans has the roller sprags in it. I want the 34 element wedge sprag, and I will get it when this is rebuilt. As promised, it was the intermediate sprag that broke and caused the entire failure incuding the piston as pictured above. T400 do not fail often, but when they do, you can almost bet it is the roller or 16 element sprag. I won't have that problem again when I am done with this one. It will just take me some time to acquire all the right parts. You can see in the pic, the outer race gear tried to come off the sprag. It wedged and bound up. That is why I could not get it apart. The gear was cocked in there and bound up with the cluthes and steels in the intemediate clutch pack. Those one that were all burned up and chewed up.

03-21-2009, 11:56 PM	#1
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	Turbo 400 Disassembly Ok members. I need some help here. Hopefully there is a Trans guru here somewhere. I have done many many Turbo 350's, several T 400's. But it has been about 18 years since I did a T400 and I must be forgetting something here. This is the 400 out my newest 86 project vehicle. As you can tell by the dark brown fluid this one burnt pretty bad. Lots of clutch material in the pan. Believe it or not I expected to find lots of metal but didn't so far. Of course I am not all in it yet. Here is where I am stuck. I can't seem to get the direct drive clutch drum and input shaft out of the case. On a T350, you can get the band out around the drums and it gives you more room to get the drums out. The 400 has a pin holding the band in place and the disassembly instructions I found, say to remove the drums, then the band. I believe that to be true since the pin is holding the front band in place. The servo is already out, in fact both band servo's are out. Can anyone tell me what I am missing here to get these front drums out of the case? I can't find my ATSG books for any help. Anyone know of a good site with good illustrations? Attached Thumbnails

03-22-2009, 12:28 PM	#3
mrjohnwayne Senior Moderator Join Date: Apr 2005 Location: Texas Posts: 3,722	hmm. I can't remember cause it has been several yeas as well but I don't think there is anything special you have to do.. wonder the the clutches and steels got welded together keeping it in place... __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

03-23-2009, 02:16 AM	#6
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	OK Gentlemen. For those of you who are interested. I couldn't sleep and wasn't going to let this beat me. I got an idea to pry from the top (actually the bottom) coming in from the valve body voids. I was able to get a thin phillips in there to get started, and with patience which I had few of, and persistance I was able to persuade it to give up and let me have the input shaft and drums. It was the intermediate clutches and steels that were giving me the problem and burt or welded to the back of the splines on the direct clutch drum, which is connected to the back of the forward clutch drum and input shaft. The clean pic here is what the failed part is supposed to look like. The dirty pic in the case, is what it actually looks like. That is to be the intermediate piston that is not much left of. As a result, you see the clutches and steels. The clutches are burnt to non existance and down to thin metal disks, and the bent teeth are what I had to do prying them apart. The picture with the funky looking stuff with the springs inbedded in it, is what is left of the intermediate piston that is supposed to be that pretty yellowish brown ring in the clean pic. Of all the transmissions I have built, I have never seen a failure like this. I still have not gotten the center support out, but now that I got this far, I can sleep. Stay tumed. I expect to have it all the way apart in the morning and I have a feeling the sprag behind the center support is trashed as well. Although not much, I did get some metal chunks of what appears to possibly be sprag cage. That doesn't hurt my feelings. I just hope it is a wedge sprag and not a roller sprag which will mean I can use the smooth drum and replace it with a 34 element sprag which I inteded to do anyway. If its a roller sprag drum, then I have to purchase a drum to use the 34 element. Those aren't cheap. Thanks for the suggestion MrJohn. You or I was not wrong and not forgetting anything. My old memory is not so bad after all after 18 or so years. That makes me happy. Attached Thumbnails

03-23-2009, 08:12 AM	#7
mrjohnwayne Senior Moderator Join Date: Apr 2005 Location: Texas Posts: 3,722	WOW.. Glad you got it apart. That is one Toasted tranny! __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

03-23-2009, 10:03 AM	#9
mrjohnwayne Senior Moderator Join Date: Apr 2005 Location: Texas Posts: 3,722	LOL yeah I don't think you could of damaged it anymore by towing it home with the drive shaft in it. __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

03-22-2009, 06:42 AM	#2
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	I think you should find diagrams at transtar1.com and of course, Murphy`s Law I can`t the Th400 in any of my books. Hope this helps.

03-22-2009, 01:10 PM	#4
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	Yes, You are on the right track john.. As you can tell in the pic, it got very hot. I did not think there was anything special either, but I have made a bit of progress, by rolling over the case and shaking the input shaft pretty rough like. I am getting hard parts and chunks of metal to fall out of it now. It is bound up, and hanging up, likely on the steels and cluthches. I am going to replace the bands anyway since they got so hot, but I got half the band out by pulling and bending it, then cut it off with one of mudseekers favorite tools. That is giving me more space to work with. After I did that, it was bedtime. I am glad I figured out it was hung up on something. I started feeling a bit inadequate when I did not think there was anything special, like a snap ring, servo or valve I was forgetting about. I am just hoping the broken hard parts have not damaged the case. The parts I am getting out of it, appear to be most likely be the sprag cage. Which is a bit wierd cuz if my memory serves, the sprag is a ways back in there and I was thinking it was behind the center support before I got to a sprag. As also suggested, I ought to look at a diagram and jog my memory.

03-23-2009, 12:22 AM	#5
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	Well, I am about to give up on it. Something in there is welded together. Probably clutches and steels. I can turn the output shaft fine by hand. The input shaft is stuck. Even with vise grips on a section that does not matter, I can not get the input shaft to spin. I can wobble the input shaft and drums all over the place, just can't get it come out, or get it to spin. I was hoping if I could get it to spin, it may line up some steels or clutches and release. No luck. I keep prying on stuff, I am going to break the case. Probably going to call it a night, take a breather and calm down a bit and try again later. If anyone has experiecned this type of problem on a Turbo 400, please let me know what you did to get past it.

03-23-2009, 09:40 AM	#8
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	Yes, Toasted would be an understatement. I have done a T350 that was this bad before as far as color of fluid and case, but it wasn't stuck together like this one. Its all good though. I like the occasioanlly challenge and seeing something and learning something new that I have not seen before, and I didn't let it beat me although I was getting pretty frustrated with it. The people I bought the truck from, were moving from Arkansas, to Dyess, AFB in Abilene, TX, loaded heavy and towing a tandem axle enclosed U Haul trailer, so that trans was working hard in its later day of life. Lucky for the people, it did make it to Abilene from Ark. They had to have it towed the last 7 miles of the trip to the base. Once they unloaded the truck the military base started hounding them to get it running or get rid of it. So if it were not for the trans going bad, I wouldn't have gotten such a deal on the truck. So, I say the bad tranny was good to me. My daughter is stationed on base across the street from these people is how I knew about the truck. I just killed 2 birds with one stone. Went to visit my daughter and towed it home to OKC with a tow bar. Hahaha, now I can laugh though. I pulled the driveline thinking I would keep from doing more damage to the trans while towing it the 300 miles @ 70mph. Although, it probably helped for the tow vehicle, a little less resistance and not as much drag. As soon as I get motivated, I want to get it the rest of the way apart and take the case and tailshaft to the machine shop for a bath.

03-24-2009, 01:50 AM	#10
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,145	I did get it the rest of the way apart without any issues. Its one filthy case. Going to the machine shop soon to get a bath. A bit disappointed that this trans has the roller sprags in it. I want the 34 element wedge sprag, and I will get it when this is rebuilt. As promised, it was the intermediate sprag that broke and caused the entire failure incuding the piston as pictured above. T400 do not fail often, but when they do, you can almost bet it is the roller or 16 element sprag. I won't have that problem again when I am done with this one. It will just take me some time to acquire all the right parts. You can see in the pic, the outer race gear tried to come off the sprag. It wedged and bound up. That is why I could not get it apart. The gear was cocked in there and bound up with the cluthes and steels in the intemediate clutch pack. Those one that were all burned up and chewed up. Attached Thumbnails

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