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I am currently trying to rebuild the th400 out of my 88 C1500 to put it back behind a turbo 5.3 and am having trouble with the direct clutch pack. This is my first time working with a 3 speed so I'm not too familiar with them. Mine appears to be a very late th400. During disassembly I found that the dished bellville plate in direct clutch broke into pieces and destroyed most everything possible, direct piston, direct drum, and direct hub. After some studying I found that people say the bellville style wave plates are notorious for breaking so I ordered a waved plate from WIT (part #34127) and after receiving it, it appears not to be waved at all and just a regular steel. It measures the correct thickness that is listed as a wave plate by WIT so I am unsure whether I received the wrong part or if the waves in the th400 wave plate are just that minor. I am also having issues stacking the clutch when using the "wave" plate I received. With the clutch pack set up with a friction directly on the wave and 5 total frictions I end up with approximately a 1/8"-3/16" gap between the pressure plate and top friction. the gap is so large that the clutch will not apply. What am I doing wrong? I've tried every possible combination of friction and steels with no success. The only way I can make it work is by stacking a steel under the wave plate on the bottom of the pack. Is it a issue of trying to replace the original dished plate with a wave?
I am currently trying to rebuild the th400 out of my 88 C1500 to put it back behind a turbo 5.3 and am having trouble with the direct clutch pack. This is my first time working with a 3 speed so I'm not too familiar with them. Mine appears to be a very late th400. During disassembly I found that the dished bellville plate in direct clutch broke into pieces and destroyed most everything possible, direct piston, direct drum, and direct hub. After some studying I found that people say the bellville style wave plates are notorious for breaking so I ordered a waved plate from WIT (part #34127) and after receiving it, it appears not to be waved at all and just a regular steel. It measures the correct thickness that is listed as a wave plate by WIT so I am unsure whether I received the wrong part or if the waves in the th400 wave plate are just that minor. I am also having issues stacking the clutch when using the "wave" plate I received. With the clutch pack set up with a friction directly on the wave and 5 total frictions I end up with approximately a 1/8"-3/16" gap between the pressure plate and top friction. the gap is so large that the clutch will not apply. What am I doing wrong? I've tried every possible combination of friction and steels with no success. The only way I can make it work is by stacking a steel under the wave plate on the bottom of the pack. Is it a issue of trying to replace the original dished plate with a wave?
The 34127 is actually a wave plate but ever so slightly. You almost have to put it on a flat work bench to see the waves. It could also be a miss-packaged .060 commercial steel plate part #34126B. They do sometimes get things mixed up. I have been dealing with WIT for more than 15 years.
The direct steels should be .090 thick & the forwards .077 thick. I juggle both sizes to get approx. .030-.050 clearance. I have also put 2 steels together to get proper clearance. It always seems to be a juggle fest. If you have the steel pistons with the ring, make sure you don't have the ring or the pistons themselves mixed up. They will fit either drum. They have to have a relief ball in the drum with the steel pistons. So make sure you aren't putting an aluminum piston without a check ball into a drum without a check ball. It will apply the drum but not release it. It is OK to have 2 relief ball checks.
Hope this helps
The 34127 is actually a wave plate but ever so slightly. You almost have to put it on a flat work bench to see the waves. It could also be a miss-packaged .060 commercial steel plate part #34126B. They do sometimes get things mixed up. I have been dealing with WIT for more than 15 years.
The direct steels should be .090 thick & the forwards .077 thick. I juggle both sizes to get approx. .030-.050 clearance. I have also put 2 steels together to get proper clearance. It always seems to be a juggle fest. If you have the steel pistons with the ring, make sure you don't have the ring or the pistons themselves mixed up. They will fit either drum. They have to have a relief ball in the drum with the steel pistons. So make sure you aren't putting an aluminum piston without a check ball into a drum without a check ball. It will apply the drum but not release it. It is OK to have 2 relief ball checks.
Hope this helps
I have a late style aluminum piston with no check ball and a 5 clutch drum with a check ball. I was about to swap a 4l80 style wave plate into it but I did also find that the 400 style wave only has about a .008” wave in it so it is pretty much unnoticeable. Could you swap a 4l80e wave into the direct or forward clutch? My forward clutch also has the failure prone spring steel dished cushion plate and I would like to replace it with a wave but don’t really want to wait for another to ship and I can probably find a new or lightly used one in my stash. I was wondering if it was ok to stack two steels on one another because the 4 speeds do that quite often putting a steel on a wave and that would solve quite a bit of my issues.
I have a late style aluminum piston with no check ball and a 5 clutch drum with a check ball. I was about to swap a 4l80 style wave plate into it but I did also find that the 400 style wave only has about a .008” wave in it so it is pretty much unnoticeable. Could you swap a 4l80e wave into the direct or forward clutch? My forward clutch also has the failure prone spring steel dished cushion plate and I would like to replace it with a wave but don’t really want to wait for another to ship and I can probably find a new or lightly used one in my stash. I was wondering if it was ok to stack two steels on one another because the 4 speeds do that quite often putting a steel on a wave and that would solve quite a bit of my issues.
You can pretty much do what ever need to be done to get the task at hand done. No wave plate, 2 steels together, mismatch steels. The only concern would be the groove in the lower portion of the drum. You have to make sure that what ever bottom steel that goes against the piston cannot twist and get caught by the groove. It binds the apply of the clutch.
In the direct I would just eliminate the wave / dish Use a thick steel .090 at bottom then fill with frictions and steels 5 or 6 either way and you can use various steel combos to get clearance as mentioned. Just make sure the bottom steel is thick enough to not be able to go under the ledge at apply piston.
The forward depending on what set up you have i would either just add the wave and just stack and set clearance or if the piston lets wave go below again the bottom ledge use a .090 steel at bottom then stack and put the wave at top, Some drums even will allow a 090 steel at bottom then a wave then another steel and still get a stack of 5 frictions, What I do not care for is running frictions against waves directly.
You can just not run waves at all in FWD or DIR but may give overly uncomfortable N-D engagement when left out of fwd,
Always keep wave in the INT set it will help save your case and sprag but still do not care for friction against wave so I use a thinner 4L80E steel in center of pack then do wave-steel-friction .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
In the direct I would just eliminate the wave / dish Use a thick steel .090 at bottom then fill with frictions and steels 5 or 6 either way and you can use various steel combos to get clearance as mentioned. Just make sure the bottom steel is thick enough to not be able to go under the ledge at apply piston.
The forward depending on what set up you have i would either just add the wave and just stack and set clearance or if the piston lets wave go below again the bottom ledge use a .090 steel at bottom then stack and put the wave at top, Some drums even will allow a 090 steel at bottom then a wave then another steel and still get a stack of 5 frictions, What I do not care for is running frictions against waves directly.
You can just not run waves at all in FWD or DIR but may give overly uncomfortable N-D engagement when left out of fwd,
Always keep wave in the INT set it will help save your case and sprag but still do not care for friction against wave so I use a thinner 4L80E steel in center of pack then do wave-steel-friction .
Would leaving the wave out of the direct clutch cause a harsh N-R shift? Also you seem to be pretty well experienced with the 400, I've read some things talking about the forward pressure being so high it kills the thrust in the engine, I am installing a shift kit that raises line pressure and am wondering if I should restrict the converter feed to prevent damage to the thrust. would you suggest restricting the converter feed or is that unnecessary?
Would leaving the wave out of the direct clutch cause a harsh N-R shift? Also you seem to be pretty well experienced with the 400, I've read some things talking about the forward pressure being so high it kills the thrust in the engine, I am installing a shift kit that raises line pressure and am wondering if I should restrict the converter feed to prevent damage to the thrust. would you suggest restricting the converter feed or is that unnecessary?
Harsh P-R is unlikely if you plan to dual feed (hate that term) the direct drum as it will act as its own accumulator, The more common complaint is slightly delayed engagement.
If you are using a modulated system not really necessary to restrict , But if you like install a set screw with a .110 to .125 hole in center at converter feed in pump. It wont hurt anything . But as long as PR is modulator regulated and ends up around 200 to 240 max will be ok either way, Me I do them all just because.
Most important however is to make sure you do hook the kickdown solenoid up functionally as it does a bit more with line pressure not just kick down.
Now if you are going non modulator full manual then yes the restrictor in the converter feed is a must and I would do .110 max size.
Most shift kits do have you "dual feed" the direct.
Replace the 3rd accum with an aluminum one if not already done and leave spring out. Some block the feed but I just leave spring out same end result.
As for the rear washer , You can actually easily install a bearing, Use the TH350 late pump bearing and then when you install the case bushing leave just enough out to support the bearing then no worries.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
My Father has a Great Solution/ Modification for the 3rd Accumulator and Spring that pretty much no one else does for Units that use an Intermediate Overrun Band, use the Full Area of the Direct Piston to Apply 3rd-Gear, and have a Forward Shift Pattern.
I'll go review it and Post it here.
I'm sure He has Posted it before.
I did reinstall all the seals in the direct & forward drum. The shift kit I have is a transgo 400 pro and claims to dual feed the drums using the three layer separator plate it includes. Transgo also claims internal "dual feeding" doesn't play well with their separator plate. I am going to swap the rear washer for a bearing, already have the bearing and shim kit ordered. I will probably restrict the converter feed with a .110" hole in a set screw just to be safe, as the last LQ4 6.0 I bought came from in front of mild th400 and had a wiped thrust.
If my memory serves me correctly. Around 1970 GM on certain TH400's used in High Performance Buicks, had 2 splines missing on the input shaft (180 degrees apart) to prevent the overloading of their motors thrust bearing. Chevrolet never did this, and they were notorious for wasting thrust bearings with a 454 ci. motor in front of them. I have been doing this modification to the input shaft, ever since I found this GM modification many many years ago.
Notes from Dads 1,000+ Page Self written Photo Encyclopedia on THM400/ 3L80 + 4L80E.
(If this thing did not have an Index, it would probably take me Three Months to read through this thing to find anything).
There is no need to touch and possibly damage the Turbine-Shaft if installing an Orifice in the Pump to Control Cooler Oil Flow.
Create an Orifice/ Jet by Drilling a Hole Through a Brass/ Aluminum Set-Screw. (Steel can be used, but Brass it much easier to work with/ Drill).
Create a 0.1250" - 0.1570" Orifice for Line-Pressures that Correlate: 200.00Psi - 160.00Psi.
Install a Brass/ Aluminum Set-Screw (5/16"-18 Thread) into the Passage shown below:
There is No need to Drill the Passage, as it will accept a 5/16"-18 Tap with no effort at all.
Harsh P-R is unlikely if you plan to dual feed (hate that term) the direct drum as it will act as its own accumulator, The more common complaint is slightly delayed engagement.
If you are using a modulated system not really necessary to restrict , But if you like install a set screw with a .110 to .125 hole in center at converter feed in pump. It wont hurt anything . But as long as PR is modulator regulated and ends up around 200 to 240 max will be ok either way, Me I do them all just because.
Most important however is to make sure you do hook the kickdown solenoid up functionally as it does a bit more with line pressure not just kick down.
Now if you are going non modulator full manual then yes the restrictor in the converter feed is a must and I would do .110 max size.
Most shift kits do have you "dual feed" the direct.
Replace the 3rd accum with an aluminum one if not already done and leave spring out. Some block the feed but I just leave spring out same end result.
As for the rear washer , You can actually easily install a bearing, Use the TH350 late pump bearing and then when you install the case bushing leave just enough out to support the bearing then no worries.
It's painful to see you post so much wrongful info or bad advice.
It's painful to see you post so much wrongful info or bad advice.
I am not gonna argue with you Jake, You do you Ill do me , Not sure what's wrong with the info I gave , it is pretty much in line with what I have experienced and what other have posted.
You don't even post here except to generally say some crap about someone , Who actually does take the time to try and help people.
Anyway have a nice day, If you have better advice for the guy in your infinite indisputable end all be all expertise feel free to address him and leave me be.
Thank you.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
So this Configuration helps support the Intermediate Overrun Band, while blocking the Third Accumulator, and has the Full Area of the Direct Piston Applied from One Feed Source (the Direct Passage of the Center-Support).
First perform what most people refer to as the "Dual-Feed" Modification.
In this situation it is actually a Single-Feed from the Direct Passage of the Center-Support, Blocking the Reverse Passage of the Center-Support, with the Full Area of the Direct Piston Applied.
Generally the "Higher Performance" Stock Valve-Bodies would have a Softer Spring for the Third Accumulator to help Firm Up the 2-3 Shift.
This reduces some cushion for the Intermediate Overrun Band.
Instead this will use a Very Firm Spring for the Third Accumulator.
If the Third Accumulator was Active, this would Soften the 2-3 Shift.
Remove the Plug or Electrical Switch from the other side the the Valve-Body that enters the Bore of the Third Accumulator.
Leave it Omitted. Do not re-install anything here.
Now Tap and Plug the Feed into the Third Accumulator Bore in the Valve-Body with a Set-Screw and Thread Locking Compound.
Install an Aluminum Accumulator Piston with a Teflon Seal and the Firmer Third Accumulator Spring all into the Bore, held in with the Retaining Clip.
Direct Fluid will not use the Third Accumulator anymore, But the Piston and Spring will still function and cushion the Intermediate Overrun Band.
The Plug from the other side of the Valve-Body must remain Omitted so that Air can move in and out of the Third Accumulator Bore.
It is to bad you can accumulate all your dads observations and notes into some sort of publishable book. I had not given thought to using the 3rd accum with a spring that way , I learn new stuff and ideas daily. I also like the idea of the aluminum plug with a hole as restrictor. I in past have tapped and used a steel plug . Aluminum would be alot easier to drill . Wonder if my hardware store would have any of those plugs. I know they have brass.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Unfortunately the Files on GM transmissions show as over 6,000 Pages.
Then there are Non-GM Transmissions, Transfer-Cases, Differentials, Engines of all kinds, All different types of Components, Electrical/ Electronics, and tons of other stuff.
He has more stuff typed up than I can count.
I have no idea what I am going to do with it all.
From growing up with Two highly intelligent Parents, I learned at a very young age that there is a nigh Infinite amount of information out there in the world...
It is impossible to learn everything (regardless of what some people may believe) however we can learn something new from someone else nearly everyday of our lives.
Just make sure to share information with others as well, that way we can all continue to learn and prosper.
From growing up with Two highly intelligent Parents, I learned at a very young age that there is a nigh Infinite amount of information out there in the world...
It is impossible to learn everything (regardless of what some people may believe) however we can learn something new from someone else nearly everyday of our lives.
Just make sure to share information with others as well, that way we can all continue to learn and prosper.
Yes on sharing and exchanging info. This is how we all learn and create. Though I have noted some actually do not like when you share info (giving away the farm) I don't really see it that way as in my case since I started working by myself. Even with no advertising other than post here I get more than enough to keep busy through this and word of mouth.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
I ended up using a 5/16-18 brass set screw as an office with a .125” hole drilled in it as my input shaft did not have the two missing splines to allow fluid out of the converter.
Leaving the spring out of the 3rd accumulator in the VB does not do the same thing as blocking the feed.
Blocking the feed also has the additional advantage of killing a potential crossleak.
And let's just give a generic .110" converter feed size and not take into account any of the other factors involved like input shaft orifice size, etc. Great plan!!!
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TH400 direct clutch issues. 
