TH400 build-pictures
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Has anyone noticed if the Alto red frictions take a little to bed in? I had one set seemed to shift a bit starnge at first but a few street miles was all good..
Also any more details on that valve for the modulator to use with boost? If a non return valve and a bleed hole is used ,what dimensions for the bleed hole between nonreturn and mod?
Also any more details on that valve for the modulator to use with boost? If a non return valve and a bleed hole is used ,what dimensions for the bleed hole between nonreturn and mod?
The reds in a 200-4R application need some bed in time. Not sure about a 400 application. I just put them in and raced them. They seemed to do fine. I thought someone posted something on that mod valve. Transgo, I think.
87buickracer
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with a 10"- 3800 converter it will hit alot less than running a 12"- 2000 stall,so if it does I will switch back to the 5 check balls, change the valvebody plate,and put the wave plate back in intermediate.
thanks for the input.
87buickracer
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i will post info for you on the valve.
Well,
Good luck with it, BUT let me say this.
You are thinking in terms of how it "feels" on the shift to you sitting in the drivers seat based on converter selection.
You aren't thinking in terms of how hard it is actually shifting internally.
Just because the converter is masking the shift firmness, doesn't mean you aren't killing the sprag everytime it shifts to 2nd gear with no control at the orificing, and no waveplate.
I use the specs I listed in transmission to over 800 HP without regard to converter selection.
The converter will be easier on parts to an extent, but it isn't how you determine shift calibration.
We all know it kills the shift firmness at light throttle, that is just part of the game. You can't have a 4000 rpm converter and tire chirping shifts at 2000 rpm, no matter what you do to the trans.
I'm sure it will work fine, just be prepared for more frequent sprag replacements.
I try to build a reliable unit that shifts firm and doesn't break parts. I think I've found that happy medium that works. The sprags don't die, the clutches stay in 700+ HP combos (540 Chevelle) for seasonS at a time, and the customers are happy with the shift quality.
The first TH400 I built for myself had 2 checkballs in it. It worked great until the first WOT pass.
I understand what Jake is saying completely. I built my trans with the shift set on killer for my car. I knew that it would need to be fast shifts to live in my situation. I was using the standard HD sprag setup at first, until I had to replace it for the 4th time. The previous 3 complete setups (drum, sprag, race) would flip on the first or second pass. Now that's a hard shift! I even resorted to using a spring and roller clutch. It did last quite a bit longer than the sprags, but when it failed, it was messy. If I was going to stick with the firm shift, I knew I'd have to step up to the new super sprag setup. I did and am very happy with the decision. If you're trying to keep this budget and have that std. HD sprag setup have a long life, I would listen to Jake.
87buickracer
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point taken,I will run with the 5 check balls,don't want to go back in it for a while,thanks..
I haven't really experimented with using smaller orificing and 2 checkballs so you could be the guinea pig 
One thing I've learned about doing VB mods...
Sometimes trying to outthink the GM engineers will get you in trouble.
In many cases the checkball is a downshift control. It may have little function on a normal upshift, but it may seat in a hole to force the fluid through a smaller orifice on a forced downshift. It acts as an accumulator in this fashion, sorta a one way valve to allow hard upshifts, but control the downshift apply.
What many guys don't realize is that many auto transmission failures happen on a downshift. Manually forced or detent, accel and decel.
We can pretty well figure out how to eliminate most of the VB's function (look at a Griner brake for a TH400) and make it a simple, fully manual fluid transfer device for upshifting only.
However it takes a smarter guy than me, and lots of trial and error to figure out how to control auotmatic and manual upshifts, AND automatic and manual downshifts without breaking parts.
Some of it is beyond the VB's control anyway. A forced 3-2 downshift under hard decel can be brutal to the intermediate sprag on a GM 3 speed. Same effect as the 4-3 downshift is for the 700/4L60 forward sprag.
It is relatively easy to find literature stating what checkball has what function, as far as "leave out checkball #x and the 1-2 shift will be harder", however nobody is saying what the side effects are of that modification. If that was all that checkball controlled, the OEM's would have just saved the 12 cents, left the checkball out, and had the plate made with a smaller hole.
Without actually sitting down and studying the hydraulics IN DEPTH it's a shot in the dark. Even after studying you can get it mixed up and be "thinking backwards" and realize your mistake when you've wasted another $40 sprag, outer race, $50 drum, as well as another filter, pan gasket, possibly pump gasket, 12-15 qts of fluid, and an afternoon of work.
My first TH400 I did for myself was in my '69 Chevelle SS. I was working as a tech at a GM dealership. Fairly newlywed, 3 small kids, in other words on a very limited budget.
I overhauled it. I had a very pitted original '69 core that had been in the weather, and another previously hot-rodded core.
Between the two I ended up with an early style drum with stock 16 element sprag and a deep pan. I was doing good. :biggrin:
I rebuilt it using the HP Books TH400 rebuild manual by Ron Sessions. I did all the blocking the 2-3 accum mods I had been doing for awhile, and used a set of B&M kit instructions to know which holes to drill and which two checkballs to leave in....
It worked good while the car was in process of restoration. Shifted very firm at all throttle openings. Great for a young guy with a musclecar...
I finally got the car together, had made a couple of partial runs with it, tuned it up good, and left to drive it to the local 1/8 mile track one Friday after work.
Enroute to the track is a nice section of road for testing. So not wanting to show up at the track and embarass myself, I made a test pass.
The 1-2 shift felt like double hit, and then it revved to the moon.
I shifted to third (column shift) and let off, all was OK.
I slowed to a stop and ran through the gears manually nice and easy, all was OK, so I proceeded to jump in it again, and what do you know, 2nd gear revved to the moon.
Classic symptoms of a rolled sprag but I didn't know it at the time. I knew I had wounded the TH400, but I was less than 2 miles from the track and went anyway.
I ran it probably 6-8 passes with low and 3rd. I would rev the piss out of the 427 in low, let off, shift to third (remember column shifter ) and get back into it, just in time to cross the 1/8th. It sounded like I had a 3 speed manual with a worn out column shift.
It still ran high 8's in the 1/8th at 80 mph.
I took it back to the dealership on Monday and asked the trans guy what he though, he told me the sprag had failed, told me what to get, and so off I went to get a 34 element sprag. Got the trans apart and also needed a drum. Ordered the drum and waited another day...
Didn't like the 3rd gear clutches, so ordered a set of those and waited another day. They had gotten heated from the big ratio change.
Finally got all the parts and a sparre trans a friend gave me that had the early style reaction carrier with a HD sprag in it (actual sprag).
I put the trans together all fixed up and used a TransGo -2 kit at the advice of a really sharp trans guy online. He explained where I had gone wrong, what had actually caused my sprag failure, and how to prevent it.
I backed the car out of the bay, put it in low and it wouldn't move, nor in any other forward gear. It was like a transbrake. I had experienced a similar situation before when I cooked the forward clutches together in another TH400 ( I learned to rebuild these things because I'm exceptionally good at breaking them :biggrin: )
Once again, I walked across the parking lot to ask the trans builder WTF I did wrong. He told me I installed the sprag backwards. I was SURE I had installed the sprag right, it shows the proper direction in the manual right?
Next evening, 5 pm sharp, I have a bunch of co-workers help me push the car into my lift bay. 5:05 it was going up. 5:45 it was out on the bench. I completely disassembled it and looked for my mistake. I took me probably 15-20 minutes to find it and I did so because I looked at how the regular roller clutch reaction carrier spun on the center support. I reversed my mis-installed low sprag, slid the thing back together, put the VB back on, pan, etc, Put it on the jack, put it in the car, let it down, re-installed my distributor cap, filled it with fluid, double checked the fluid level, and pulled out of the parking lot at 7:10 pm... With the transgo kit it would chirp going into 2nd and 3rd at anything above 2-3 throttle. I was using a $99 Summit 2200 converter at the time.
I've never done the 2 checkball method since. I've also since learned a better way to get the dual feed done and spend the money elsewhere instead of on the TransGo kit. I got away from the TG kit when I started building them for local racers and 500 HP cars would kill the directs in a season or less. I finally narrowed it down to a too slow 3rd gear feed, no matter how big the orificing was.
Many other builders won't tell the average guy what works, they want to sell you a transmission, and there is nothing wrong with that. However when i was a struggling novice with not much $$, someone was kind enough to help me along so I have passed most of what I have learned along to many others.
I still have to keep some secrets close, mostly due to requests by those who have taught me but the VB calibration that works, it's out there for anybody who wants it.
Lots of good stuff in this topic by several very good builders.
One thing I've learned about doing VB mods...
Sometimes trying to outthink the GM engineers will get you in trouble.
In many cases the checkball is a downshift control. It may have little function on a normal upshift, but it may seat in a hole to force the fluid through a smaller orifice on a forced downshift. It acts as an accumulator in this fashion, sorta a one way valve to allow hard upshifts, but control the downshift apply.
What many guys don't realize is that many auto transmission failures happen on a downshift. Manually forced or detent, accel and decel.
We can pretty well figure out how to eliminate most of the VB's function (look at a Griner brake for a TH400) and make it a simple, fully manual fluid transfer device for upshifting only.
However it takes a smarter guy than me, and lots of trial and error to figure out how to control auotmatic and manual upshifts, AND automatic and manual downshifts without breaking parts.
Some of it is beyond the VB's control anyway. A forced 3-2 downshift under hard decel can be brutal to the intermediate sprag on a GM 3 speed. Same effect as the 4-3 downshift is for the 700/4L60 forward sprag.
It is relatively easy to find literature stating what checkball has what function, as far as "leave out checkball #x and the 1-2 shift will be harder", however nobody is saying what the side effects are of that modification. If that was all that checkball controlled, the OEM's would have just saved the 12 cents, left the checkball out, and had the plate made with a smaller hole.
Without actually sitting down and studying the hydraulics IN DEPTH it's a shot in the dark. Even after studying you can get it mixed up and be "thinking backwards" and realize your mistake when you've wasted another $40 sprag, outer race, $50 drum, as well as another filter, pan gasket, possibly pump gasket, 12-15 qts of fluid, and an afternoon of work.
My first TH400 I did for myself was in my '69 Chevelle SS. I was working as a tech at a GM dealership. Fairly newlywed, 3 small kids, in other words on a very limited budget.
I overhauled it. I had a very pitted original '69 core that had been in the weather, and another previously hot-rodded core.
Between the two I ended up with an early style drum with stock 16 element sprag and a deep pan. I was doing good. :biggrin:
I rebuilt it using the HP Books TH400 rebuild manual by Ron Sessions. I did all the blocking the 2-3 accum mods I had been doing for awhile, and used a set of B&M kit instructions to know which holes to drill and which two checkballs to leave in....
It worked good while the car was in process of restoration. Shifted very firm at all throttle openings. Great for a young guy with a musclecar...
I finally got the car together, had made a couple of partial runs with it, tuned it up good, and left to drive it to the local 1/8 mile track one Friday after work.
Enroute to the track is a nice section of road for testing. So not wanting to show up at the track and embarass myself, I made a test pass.
The 1-2 shift felt like double hit, and then it revved to the moon.
I shifted to third (column shift) and let off, all was OK.
I slowed to a stop and ran through the gears manually nice and easy, all was OK, so I proceeded to jump in it again, and what do you know, 2nd gear revved to the moon.
Classic symptoms of a rolled sprag but I didn't know it at the time. I knew I had wounded the TH400, but I was less than 2 miles from the track and went anyway.
I ran it probably 6-8 passes with low and 3rd. I would rev the piss out of the 427 in low, let off, shift to third (remember column shifter
) and get back into it, just in time to cross the 1/8th. It sounded like I had a 3 speed manual with a worn out column shift.It still ran high 8's in the 1/8th at 80 mph.
I took it back to the dealership on Monday and asked the trans guy what he though, he told me the sprag had failed, told me what to get, and so off I went to get a 34 element sprag. Got the trans apart and also needed a drum. Ordered the drum and waited another day...
Didn't like the 3rd gear clutches, so ordered a set of those and waited another day. They had gotten heated from the big ratio change.
Finally got all the parts and a sparre trans a friend gave me that had the early style reaction carrier with a HD sprag in it (actual sprag).
I put the trans together all fixed up and used a TransGo -2 kit at the advice of a really sharp trans guy online. He explained where I had gone wrong, what had actually caused my sprag failure, and how to prevent it.
I backed the car out of the bay, put it in low and it wouldn't move, nor in any other forward gear. It was like a transbrake. I had experienced a similar situation before when I cooked the forward clutches together in another TH400 ( I learned to rebuild these things because I'm exceptionally good at breaking them :biggrin: )
Once again, I walked across the parking lot to ask the trans builder WTF I did wrong. He told me I installed the sprag backwards. I was SURE I had installed the sprag right, it shows the proper direction in the manual right?
Next evening, 5 pm sharp, I have a bunch of co-workers help me push the car into my lift bay. 5:05 it was going up. 5:45 it was out on the bench. I completely disassembled it and looked for my mistake. I took me probably 15-20 minutes to find it and I did so because I looked at how the regular roller clutch reaction carrier spun on the center support. I reversed my mis-installed low sprag, slid the thing back together, put the VB back on, pan, etc, Put it on the jack, put it in the car, let it down, re-installed my distributor cap, filled it with fluid, double checked the fluid level, and pulled out of the parking lot at 7:10 pm... With the transgo kit it would chirp going into 2nd and 3rd at anything above 2-3 throttle. I was using a $99 Summit 2200 converter at the time.
I've never done the 2 checkball method since. I've also since learned a better way to get the dual feed done and spend the money elsewhere instead of on the TransGo kit. I got away from the TG kit when I started building them for local racers and 500 HP cars would kill the directs in a season or less. I finally narrowed it down to a too slow 3rd gear feed, no matter how big the orificing was.
Many other builders won't tell the average guy what works, they want to sell you a transmission, and there is nothing wrong with that. However when i was a struggling novice with not much $$, someone was kind enough to help me along so I have passed most of what I have learned along to many others.
I still have to keep some secrets close, mostly due to requests by those who have taught me but the VB calibration that works, it's out there for anybody who wants it.
Lots of good stuff in this topic by several very good builders.
MOST of the checkballs in the 400 are used to speed exhaust of oil that applies a friction element after it is applied.This is done by using 2 holes next to each other in the plate.On apply the feed oil seats the checkball against a hole in the plate(larger than its companion feed hole) and the feed oil now flows(restriced by orifice diameter) to the friction element at a rate controlled by feed pressure. The feed hole can be alot smaller than the necessary exhast hole because the clutch feed is pressure fed and the exhaust is not.The exhaust relies on the retraction of the apply piston or servo piston return spring(s),the larger orificing gained when the pressure to the friction element is closed off and the checkball falls away from the plate creating 2 exhaust holes ,and the exhaust hole or holes at the shift valve that is opened to dump when the shift valve retracts.It is a poor quality kit that removes the balls before trying to accomplish proper shift apply and feel without first experimenting with the checkball design,truly a unique system although relatively simple from a design standpoint.
87buickracer
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87buickracer
Member
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Transgo vacuum bypass (VBP-VAC)
This is the transgo vacuum bypass for supercharged and turbocharged engines.a very nice piece for the price.(part#vbp-vac)
I will list the information at the bottom of page and contents used in vacuum bypass.
Important:
rule#1:Vacuum line must connect to a port on the intake manifold or throttle body that has vacuum at idle and with throttle.
rule#2on't use parts store vacuum hose, it just is not good enough for this use.
Use 1/4" copper tubing or 1/4" air hose.Zip tie it to the wire loom in 3 or 4 places along the trans and 2 to 3 places under the hood.Make sure the hose or tube is secure under the hood and is not putting an angled strain on the "T".
If you are using more than 10 PSI of boost,use air hose,and clamp all hose connections.
contents:
48-BSH-55 48-VL-308A
7/8" of 1/4" air hose
3/16" steel ball
1/16 x 3/4 cotter pin N\blower\bsh
This is the transgo vacuum bypass for supercharged and turbocharged engines.a very nice piece for the price.(part#vbp-vac)
I will list the information at the bottom of page and contents used in vacuum bypass.
Important:
rule#1:Vacuum line must connect to a port on the intake manifold or throttle body that has vacuum at idle and with throttle.
rule#2
on't use parts store vacuum hose, it just is not good enough for this use.Use 1/4" copper tubing or 1/4" air hose.Zip tie it to the wire loom in 3 or 4 places along the trans and 2 to 3 places under the hood.Make sure the hose or tube is secure under the hood and is not putting an angled strain on the "T".
If you are using more than 10 PSI of boost,use air hose,and clamp all hose connections.
contents:
48-BSH-55 48-VL-308A
7/8" of 1/4" air hose
3/16" steel ball
1/16 x 3/4 cotter pin N\blower\bsh
Attachments
Drilling that hole 3/16 is the "B&M" trick. It's not necessary. A .140" hole is on the upper end of what TransGo suggests, and with the 2-3 accumulator blocked, and the dual feed it will hit 3rd HARD at WOT. Hard enough to break 10" wide slicks loose on a prepped track in many combos.
However, on a 2-3 upshift, there isn't any sprag to break, so you aren't really hurting anything to make shift harder. That is to say, I don't think you'll see any catastrophic parts failures internal to the trans.
the circled hole feeds the 2/3 shift valve .getting it to the clutch is a different story.it is a good idea to omit 1 of the balls at the point where direct oil flows down the long passage of the case to the support to feed direct.i install all balls but leave out this one.
Chris,
It's the same checkball that ATSG considers "non-functional" right?
Here are the ones I install.
http://i32.photobucket.com/albums/d8/jakeshoe/th400checkballs.jpg
The one omitted is near the 2nd servo, 1 o'clock position, across the bolt hole from the other red X.
1st Lt Dan
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Just a kind thought from an older rebuilder. The internet was designed for doctors and scientist to talk about real cures for mankind's ailments across governmental borders. It is good to see folks like yourselves talking through real problems we all face with mechanical repairs. There is much to be learned by the younger ones from our trail and errors we had encountered through our years. However, we can learn much from the younger mechanics and technicians. The few websites I have visited like this one I have learned more about what I had forgotten and understand it better now than I did years ago.
A Turbo 400 was the first transmission I learned to work with. The Ford 5R55E Ford Explorer I worked on last fall was a challenge with the valve body plate leaks. First one I had done. Studied other websites and learned of warped valve body issues. Long story short: After dyno test and no 4-5 shift, I pulled valve body, disassembled, had machine shop mill the valve body down, reassembled, dyno tested with all working well. Studying and researching problems others run into prepares you and shows you don't know it all. It proves you are smart enough to do your home work before starting a project.
Keep up the good work you folks are doing. You are teaching people to fish and feed themselves from your knowledge you share. They will earn their living off this type of information and that is something you can be proud to be a part of. Good Day.
A Turbo 400 was the first transmission I learned to work with. The Ford 5R55E Ford Explorer I worked on last fall was a challenge with the valve body plate leaks. First one I had done. Studied other websites and learned of warped valve body issues. Long story short: After dyno test and no 4-5 shift, I pulled valve body, disassembled, had machine shop mill the valve body down, reassembled, dyno tested with all working well. Studying and researching problems others run into prepares you and shows you don't know it all. It proves you are smart enough to do your home work before starting a project.
Keep up the good work you folks are doing. You are teaching people to fish and feed themselves from your knowledge you share. They will earn their living off this type of information and that is something you can be proud to be a part of. Good Day.
This thread's been quiet for a little while but I've been reading it with interest-
I'm in the process of doing a TH400 for a friend, on tearing it down it's got an unknown spacer plate which totally blocks off the 2-3 accumulator, and is running with the "bare minimum" two check balls. I've read all the comments above about the potential issues with going too crazy throwing out most of the check balls, and I've got to thinking - assuming you go down the route of blocking the 2-3 accumulator, thereby taking it out of the equation altogether, does that not render some of the check balls useless anyway?
I've been looking at the hydraulic diagrams trying to figure out which balls might be "pointless" in that situation - I can see why you need to keep the low/reverse and the mod/int switching balls in at all costs, but how about the three that feed and drain the 2-3 accumulator? If it's being blocked anyway, why not take them out? I've got my own first ideas about which ones might not be necessary, but I could easily have missed something and would really appreciate a second, or third, opinion!
Cheers
Theo
I'm in the process of doing a TH400 for a friend, on tearing it down it's got an unknown spacer plate which totally blocks off the 2-3 accumulator, and is running with the "bare minimum" two check balls. I've read all the comments above about the potential issues with going too crazy throwing out most of the check balls, and I've got to thinking - assuming you go down the route of blocking the 2-3 accumulator, thereby taking it out of the equation altogether, does that not render some of the check balls useless anyway?
I've been looking at the hydraulic diagrams trying to figure out which balls might be "pointless" in that situation - I can see why you need to keep the low/reverse and the mod/int switching balls in at all costs, but how about the three that feed and drain the 2-3 accumulator? If it's being blocked anyway, why not take them out? I've got my own first ideas about which ones might not be necessary, but I could easily have missed something and would really appreciate a second, or third, opinion!
Cheers
Theo
87buickracer
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- Messages
- 798
This thread's been quiet for a little while but I've been reading it with interest-
I'm in the process of doing a TH400 for a friend, on tearing it down it's got an unknown spacer plate which totally blocks off the 2-3 accumulator, and is running with the "bare minimum" two check balls. I've read all the comments above about the potential issues with going too crazy throwing out most of the check balls, and I've got to thinking - assuming you go down the route of blocking the 2-3 accumulator, thereby taking it out of the equation altogether, does that not render some of the check balls useless anyway?
I've been looking at the hydraulic diagrams trying to figure out which balls might be "pointless" in that situation - I can see why you need to keep the low/reverse and the mod/int switching balls in at all costs, but how about the three that feed and drain the 2-3 accumulator? If it's being blocked anyway, why not take them out? I've got my own first ideas about which ones might not be necessary, but I could easily have missed something and would really appreciate a second, or third, opinion!
Cheers
Theo
I have a few friends running with 2 checkballs and the 3rd feed hole drilled to 3/16 with all the other mods listed in this thread with no problem.I'm starting out with the checkballs shown in jake's picture in this thread and maybe later try a few things different.Maybe we can get a little feed back on this topic to help you in making your decision.
