SLOW 1-2 SHIFT ON TH400 [Archive]

olds48

01-01-2008, 01:21 PM

ANYONE ELSE RUN INTO THIS? GOT A TCI FULL MANUAL REVERSE VALVE BODY. ALL NEW COMPONENTS INSIDE TRANNY,RED EAGLE CLUTCHES AND KOLENE STEELS, GOOD SPRAGS. I SHIFT AT 6200 RPM,BUT WHEN I BANG INTO 2ND THE MOTOR WILL CLIMB ANOTHER 2-400 RPM BEFORE TRANNY SHIFTS. IT SHIFTS GOOD AND SOLID AND DOESN'T SLIP AT ALL,JUST HAS A SPLIT SECOND DELAY .2-3 SHIFT DOES FINE,REAL INSTANT. I CAN COMPENSATE MY 1ST GEAR SHIFT POINT TO CORRECT IT,BUT WOULD RATHER ADDRESS THE REAL ISSUE. ANY HELP OR ADVICE WILL BE GREATLY APPRECIATED

SST4530

01-02-2008, 08:38 PM

Sounds like the intermediate clutch pack to me. I would pull everything out including the center support, restack and air check the the clutch packs through the center support. Should be little to no leakage.

It could also be leaking between the valve body and case or pump and case.

Good luck! :)

olds48

01-03-2008, 12:02 PM

I got to thinking about things,and thought about my pump.When I "rebuilt" my transmission,the valvebody came with a new spring for the pressure regulator in the pump.I put the new high pressure spring in,but you know what,my pump has over 175,000 miles on it.

OneBadGMC

01-03-2008, 12:46 PM

You've got a leak somewhere, and it's taking too much time to build pressure to engage 2nd gear.

SST4530

01-03-2008, 01:24 PM

Could be the pump has to much clearance. But you do definately have a leak, either gasket, seal, stator ring, cracked drum, piston, or pump. Just take it apart and start checking everything. If the drums all air check good, move to the next item on the list. Be sure the clutches and steels are installed in the drums when put air to them or you may blow a seal. Probably have burned those intermediate clutches already. :(

olds48

01-03-2008, 02:10 PM

:shock: Hope I ain't burnt no clutches.Thanks for letting me sleep good tonight,BLITTLE.Don't think it could be just a weak pump?

lively

01-03-2008, 02:19 PM

DOOOOM/ DOOOOOM

SST4530

01-03-2008, 02:29 PM

:shock: Hope I ain't burnt no clutches.Thanks for letting me sleep good tonight,BLITTLE.Don't think it could be just a weak pump?

:lol: :lol: :wink:

Depends on how bad it's been slipping. Maybe it's all OK and just the pump. I'd still take it back apart and check everything. Better yet put a C4 in it!.....LMAO!!!!! :lol: :lol: :lol:

olds48

01-03-2008, 02:45 PM

C4....ain't that what they make bombs out of? The tranny doesn't slip at all.Has a real firm shift,occasoinally will chirp the tires.It just has a small delay

jmarksdragster

01-03-2008, 07:53 PM

Put a C4 in it and it will look like a bomb went off... 8) 8) 8) Does that VB still use the shift valves to send fluid to the clutches? You may have one hanging. Pull the VB out and pull it apart and clean.

olds48

01-05-2008, 03:27 PM

Pulled the valvebody out and checked the valves today.Everything looked okay,went ahead and cleaned everything up,but none of the valves seemed to be sticking at all.The tranny doesn't slip at all,so I hate to tear it down to air check the clutches.Maybe I'll run a pressure test and see what my line pressure is before I yank it out.

jmarksdragster

01-05-2008, 07:07 PM

One more thing to check is the manual valve/shifter alignment. Make sure when the shifter is in second, the manual valve is correctly aligned.

olds48

01-06-2008, 03:06 PM

WILL DO

OneBadGMC

01-06-2008, 07:11 PM

olds48

01-10-2008, 06:03 PM

Balls look good..well.......breast look good to me.......you know what I mean :oops:

olds48

01-18-2008, 04:07 PM

Okay.clutches not leaking and pressure test showed about 160 pound.Talked to I guy I know who runs 4.50 in the 1/8.He said that he went to a glide to get away from that problem.Said he was told that the clutches/drums are so heavy in a TH400 that it can't be prevented to have a little lag.Don't sound right to me.

SST4530

01-18-2008, 04:09 PM

Mine shifts instantly, no lag time. :?

olds48

01-18-2008, 05:22 PM

Any other suggestions?One guy I talked to at a local transmission shop said to drill 1/8 holes ("about 20 holes in all")in the clutch drum to help fluid escape quicker???Sound like anything ya'll ever heard

jmarksdragster

01-19-2008, 11:08 AM

There is no reason for you to have any delay with a 400 if all is right. You either have a valve body issue or a pressure leak in the trans itself. Second gear is in the center support which is fed from the center support bolt area. Is there a bolt in it? That would give you a fair leak. Lip seals on the intermediate piston could leak, last would be the valve body itself.

olds48

01-19-2008, 12:50 PM

Are you talking about the bolt that holds the center support in place?How could that leak,and how would I fix it?

jmarksdragster

01-19-2008, 01:38 PM

It would leak if it was missing or loose.

olds48

01-19-2008, 01:55 PM

Okay.I thought maybe you were saying it could leak around the threads,like it needed sealant or something

SST4530

01-19-2008, 03:24 PM

If you checked everything I already suggested, the only other thing I can think of is check the front servo piston on the valve body and the case. Not sure if you left the band in or not but the piston still needs to seal off. Also the intermediate sprag could be bad. Sometimes they will rotate a bit before they lock.

This online diagnosis is a bitch!

olds48

01-20-2008, 12:10 AM

This online diagnosis is a bitch!

I know,and I really appreciate you taking the time to help.You could always come to VA and fix it for me :D

SST4530

01-20-2008, 10:25 AM

This online diagnosis is a bitch!

I know,and I really appreciate you taking the time to help.You could always come to VA and fix it for me :D

That's what we're here for, to help each other. I may be in Atlanta in a few weeks for a project. Virginia isn't to much farther. :)

olds48

01-20-2008, 11:57 AM

I'll meet you halfway :D

SST4530

01-20-2008, 12:40 PM

I'll meet you halfway :D

ha-ha-ha :lol:

olds48

01-20-2008, 12:47 PM

Was looking at your backhalf on showoff.Got any more pics?

insane4fbodys

01-20-2008, 03:08 PM

I know this is something you don't really want to hear. A long long long long long time ago in a different galaxy. Oops mean my younger days, I ran into this problem too. I had a great tranny but when I went to a manual valve body, and didn't get it to low for a burn out I melt second gear out of it. Rebuilt the thing 4 times and always had that delay. Pulled everything out of that case and put it in to another case. First time out it shifted instantly, and has ever since. I never did really figure out what it was, but chalked it up to a cross leak some where in the case. If you have 1 avaliable you may want to try that. Thats a long shot but worked out for me. Don't care what kind of car it is, I hate to have a zipper on the tranny, LOL.

olds48

01-20-2008, 04:53 PM

:shock:

SST4530

01-20-2008, 09:30 PM

Was looking at your backhalf on showoff.Got any more pics?

I'll have to get some more posted, haven't been working on it much since those photo's. Business has been keeping me busy.

olds48

01-23-2008, 08:18 PM

That's a good problem!Lack of business is what is slowing me down.No time is better than no $$$$ :D

lively

01-23-2008, 08:20 PM

That's a good problem!Lack of business is what is slowing me down.No time is better than no $$$$ :D

THE COLD WEATHER IS KILLING ME :oops: :oops: :oops:

olds48

01-23-2008, 08:26 PM

I hear you!!I go up to the barn and take a whiff out of the VHT jug every so often,just for medicinal purposes

shithead2

01-29-2008, 03:55 PM

Are you running a filter or a screen in the sump? Had problem like yours and it was starving the pump. Went to a screen and fixed it.

cepx111

01-29-2008, 11:33 PM

Dude you'd be much faster and more consistent with a powerglide.
They take allot less Hp to turn than a T400 plus if it's built right it will be more bullet proof than a T400.
I ran a T400 in my bbc nova for almost 8 years, finally made the change to powerglide and it made a profound difference in my et's being much more consistent ( one shift, verses 2 ) plus the car picked up about 2 tenths and hell I even slept at better knowing it was easier on the motor....lol

JMO

>< Cp

olds48

01-30-2008, 12:59 PM

cepx111

01-30-2008, 11:20 PM

I always felt the same way till I got one. I was like noway a 2 speed is going to be quicker than a 3 speed thinking it would kill the 60 foot which in turn would kill the ET but they don't if you got the torque I guess, if you have it ( torque) they will fly if not then maybe you'll need the three speed, a 350 turbo will be quicker than a t 400 as well I've always heard that a T 400 kills the most HP of all the autos but they are the stoutest out of the box hands down though.
><Cp

olds48

01-31-2008, 03:34 PM

The clutches in a TH350 are SCARY!!They are tiny.It always amazed me that the clutches in my 400 could actually jerk a car on to it's rear bumper,then I saw inside of a 350 and was like :shock: .Teeeeny-tiiiny.Wonder what your glide looks like?

cepx111

01-31-2008, 09:41 PM

Clutches in a powerglide are huge, there's plenty there to stand up the heaviest car. Here's a scenario for you, so you think T350 clutchs are small, look at the inards of a ford C4 and you'll think that the T350's are huge in comparison, But that little C4 has stood up many a stang on the rear bumper and propelled them into the sub 7's in the 1/4.
I had a friend that built up a 501 caddilac motor and put in in a mid eighties cutlas, welded up the spider gears in the inheritly weak 7.5 to make a red neck posi and get this, put a bone stock 250 r over drive tranny behind that torque monster, ran low sevens in the 1/8 and never missed a beat in the three years of that I knew he had the car. So it goes to show size doesnt really matter in a tranny as far as the clutches are concerned anyway, most times its the other things that fail like planetaries, sprags etc.
JMO
><Cp

SST4530

01-31-2008, 10:44 PM

TH250 and TH350 are almost identical units.

olds48

02-01-2008, 06:17 AM

I've always been amazed at the durability of stock "junk".It really holds up alot better than the aftermarket would like you to think.

jmarksdragster

02-01-2008, 08:46 PM

I do run a filter,not a screen.Cheap generic filter at that.Never crossed my mind. Cepxx,I always figured a 2-speed would kill my 60'.Then one night I accidentally took off in second gear(manual v-body),60' was the same,et was the same,picked up 4 mph in the 1/8!!!Gets you thinkin'....
A PG will ALMOST always be faster than a 400 with the correct converter.
There are exceptions, but for most cases the PG will win out.

olds48

04-15-2008, 05:17 PM

Well..finally found out what was causing the lazy shift.My pump was worn so bad that the rings couldn't seal.Low pressure.Actually broke one of them.Took out 1st and 3rd clutches,2nd looks like new :shock: Just goes to show that if you don't know what you're doing,take it to the tranny guy.You CANNOT beat a man at his own game. :D