TH400 build-pictures

[87buickracer]

picture courtesy of jakeshoe..
for a more positive shift.one of our local expert dragster tranny builders
recommended I drill 3rd feed hole to 3/16".has anyone tried this mod and what effect if any would it have on parts with running 5 checkballs?

[87buickracer]

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

[Gregaust]

Thank you , very interesting .. Not seen that before until on here ...

[jakeshoe]

Originally Posted by 87buickracer

picture courtesy of jakeshoe..
for a more positive shift.one of our local expert dragster tranny builders
recommended I drill 3rd feed hole to 3/16".has anyone tried this mod and what effect if any would it have on parts with running 5 checkballs?

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.

[chris718]

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.

[jakeshoe]

Originally Posted by chris718

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...checkballs.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]

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.

[chris718]

Jake it is the ball in the passage that flows to the right side center support feed passage.Thanks for the support "OLD TIMER".We all have learned alot from each other on this sight,thanks for showing your appreciation.

[theo]

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

[87buickracer]

Originally Posted by theo

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.

[jakeshoe]

I was building a TH400 at 3 a.m. last night and had the same thought.

I haven't spent much time looking at them yet but I will check them out when I have a chance.

The Th400 will operate with only one checkball in place near the modulator valve.

One issue you'll find here,
shift calibration is somewhat subjective, mostly opinion.

I try not to make them shift killer hard, not reason to, and doing it from 1-2 will kill the sprag.

You could omit most of the checkballs on the TH400 and with a stock plate you'll still have pretty hard shifts becuase there is no restriction at many locations.

To do good testing you would need a solid unit (fresh), a stout car, and the time (spare is hard to come by), and play with it.
You would also want a combo with a tight near stock converter, so you get a better judgement of shift feel getting progressively harder with throttle.

I know the setup I use works, and works well, and doesn't break parts.

However it would be fun to spend a day and test about 6-7 different calibrations in the same combo.

I may try it sometime on my car. '69 Chevelle, 427 BBC, variable pitch converter (very tight in low stall).

Mine is setup to the above specs.

Pre- VP setup vids:

YouTube - Chevelle

YouTube - Chevelle Video

[jakeshoe]

Also,
some of the factory 1-ton TH400's had the 3rd feed drilled to about 3/16". But they still had all the checkballs and accumulators.

[chris718]

jake most of the time you have a bathtub used for a splitter circuit.this is true at the low reverse passage.w/out this ball reverse oil will leak out the manual low circuit and cause no reverse.or intermittent loss of movement in reverse.like you said ,you are not breaking parts.that is where those balls and controlled orificing comes into play ,and without low throttle shift shock OF COURSE.