Thread: TH400 Slips in 2nd gear

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DETAILS: TH400 behind a mild 454, bought this transmission as a rebuilt core with a "shift kit" and no other mods. Running a stock torque converter and a B&M ratchet shifter which I like to manually shift due to it shifting too early (no kick down switch either). Vac modulator is connected, no leaks.

PROBLEM: Noticed recently that it seems to slip real bad when I ratchet into second gear under throttle. Also, when cruising in 2nd and you let off the gas, the engine drops back to idle. The motor does not "drag" like is does in 1st and 3rd (the way a standard trans does when you let off in gear).

QUESTION: What is about to fail? Do I need to rebuild this thing? Are my driving habits causing this problem?

Thanks,
-Kevin

ttt. just a bump

All the symptoms you describe are internal.
A few come to mind like a broken intermediate sprag, too loose clearances in the clutch packs and/or shaft assemly, servo leakage, converter sprag busted, bushings set too loose.......the list goes further.
Time for a tear down whether you do it or somebody you trust.

every time a busted a 2nd gear sprag .i lost all of 2nd gear you may want to see if the shifter is out of justment. if the trans shift out fine by it self

I don't know much about transmissions but mine was rebuilt with "waffle" clutches and have held up great under a lot of punishment. Converter sprag you'd have problems all gears and any broken sprag the trans will overheat pretty quick.... I'd say time to tear down and beef up.

Considering 2nd gear would be where we're most likely to be having a little fun on the street, I'm sure driving habits are a contributor Don't change your habits just beef up the weak links!

-Chris

all of my 400s i think just have borg warrner red paper clutches. to just beef up 2nd gear sprag be hind the 632 was a coan super sprag$$

So basically it seems like something a rebuild kit might cure ? As far as I know it is not overheating but I am not running a temp sensor. There are no other symptoms really.

I have never torn a transmission apart but a friend of mine has and claims it is easy but tedious. He is also running a TH400 that has handled way more abuse, way longer than mine, behind a much hotter 468ci. Any recommendations on a kit? Any parts outside of a standard rebuild kit that may warrent replacement?

Thanks for the feedback.

Another thought, if the second gear sprag is in backwards it will drive the car under mild throttle application, but ratchet (slip) when you wack the throttle.

Seeing as how you don't know anything about the rebuilder it might be as simple as that.

At any rate, it sounds like it needs a teardown.

they can flip i have been told? not sure on that any time i took out a sprag it was just another N and a two speed

Originally Posted by Geezer2

Another thought, if the second gear sprag is in backwards it will drive the car under mild throttle application, but ratchet (slip) when you wack the throttle.

Seeing as how you don't know anything about the rebuilder it might be as simple as that.

At any rate, it sounds like it needs a teardown.

Well, possible I suppose but the problem only recently surfaced. It used to hit 2nd gear hard and really put you back in the seat . Now...not so much. I will pursue the rebuild.

Thanks,
-Kevin

the one way intermediate sprag in a 400 is its down fall. one way to insure it is a sprag is put it manual 2nd. this allows the front band to hold the same drum to the case as the sprag. this is done to give extra holding power when hauling. if it does not move when you do this there could be valve body issues but i doubt it. in 2nd gear forward,intermediate clutch are applied and one way holds. if it was the intermediate clutch you would have no third and if it was the forward clutch you would have no forward at all. try manual second and let me know

i just noticed that you also said it happens when you manually shift it. there is an issue. if you get a rebuild try to get the later model style sprags. they have more sprags that the orginal old school 3l80's hopely your direct drum isn't screwed.

Originally Posted by Jason383454

.....try manual second and let me know

I'd like to think he's gotten the problem fixed in two months time.

Originally Posted by nitrowarrior

I'd like to think he's gotten the problem fixed in two months time.

Two months?? That's nothing..... I have problems that last WAAAAY longer than that...

i know but if he just had it sit you never know