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TH350 Lost 3rd gear HELP AHH Im gona burn it!

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Old 01-31-2002, 12:38 PM
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Transmission: 4l80e this year
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TH350 Lost 3rd gear HELP AHH Im gona burn it!

It has reverse, neutral, and first gear. When i put it into gear it bangs a little. When i take off in D (Drive) it wont shift out of 1st Gear. If i manually shift it down to first, then up to second, it will shift to second REALLY HARD and BANG. If i then shift it up to D(3rd) it wont go it stays in second. The fluid looks brand new, the filter IS brand new, the tranny was just rebuilt, the shifter is brand new and correct, <b>was working fine yesterday</b>, and now this. The vaccume hose it connected well with no leaks. The detent cable is disconnected and at its rest position.

Suggestions? Car drives fine in first and second, cant get third, and when it shifts it hits HARD. i DO have a shift-kit but it never shifted THAT hard. BANG shift, no tire chirp, its like eating my shift power.
Old 02-01-2002, 08:28 PM
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Checked troubleshooting chart in Ron Session's Turbo 350
Handbook. Your symptoms point to pressure regulator/ boost
valve sticking in valve body. When you shake the valve body from
front to rear, you should be able to hear the boost valve rattle.
Carefully pry the valves from their seated positions. They should
slide smoothly and return to their seated position without binding.
You should be able to buy new valve body gaskets at any
tranny shop for a few dollars. A Gil Younger SK 350 NO YO- YO
kit ( clean shifts-but not harsh) and a different valve body would be good alternative to
fixing yours if it is unusable.
Old 02-01-2002, 11:58 PM
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the valve body is brand new, and i just installed a shift kit, which everything seemed fine till all of the sudden.... i will pull it off and see what i find. thank you!
Old 02-05-2002, 06:23 PM
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Car: 240sx
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What does it feel like when a tranny is trying 2 gears at once, or not completelly shifting out of 1st or 2nd gear...

My old TH350 would tear my tires up when i shifted into 2nd, it would also have a "POSITIVE" shift feel, like you were being pulled forward.
This one, when it shifts, doesnt really "feel" like anything, you just get a little Nudge and it kinda just "drops" or "bangs" into 2nd gear, and takes forever to get into 2nd (i shift, it waits, then suddenly, bang 2nd gear) and there is no "positive" shift feel, no tire chirp, no nothing. Whats wrong? and now i have no 3rd gear... if the tranny was screwing up and not shifting right, would it burn up 3rd gear like it did? Why dont i have a positive shift feel that chirps second?
i installed a TCI shiftkit as well, just like the old one had. Way different shift feeling.
Should i just trash it and buy a "street / Strip" Tranny instead? or maybe i can save this one and make it shift correctly?
Old 02-05-2002, 06:50 PM
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A good place to start would be to test the vacuum modulator and be sure the modulator valve in the trans is not stuck, then check the governor for proper operation and calibration and check it's gear. All can be done without pulling the pan off.
Another possibility might be the center seal being left out of the direct drum for a greater fluid appy area in third, you need to block a reverse passage when doing this or reverse will come on with third. This plug may have come loose if it actually worked at one time.

Last edited by Jay 727; 02-05-2002 at 06:53 PM.
Old 02-05-2002, 07:05 PM
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Car: 1986 Trans Am, 1991 Firebird
Engine: 355 TPI, 3.1L V6
Transmission: 700R4 in both
Reminds me of the interesting problem I had with my TH350. Still don't know what caused it but mine would shift from 1st to 3rd and skip 2nd all together. The weird thing is that when I manually shifted it into 2nd it would go into 2nd but as soon as the car reached 3000 rpms it would rev up like I was in neutral. TH350s are weird trannys.

I got two 4 sale for $50 a piece if you're interested. Both are BOP though so you'll need an adapter plate. Email me if you're interested or want more info on them.
Old 02-08-2002, 09:46 PM
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now suddenly it will go into third again... somthing in the valve body???? maybe tommarow it wont go into third, then the next day it will...and the next day... hahahahahah im getting hysterical...
Old 02-09-2002, 08:47 PM
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My guess is that you don't have filters in the case. I always
replace them when I rebuild a tranny, even though most are
full of trash and ripped open. I figure that those highly paid
transmission engineers probably knew what they were doing. :hail:
Old 02-09-2002, 09:36 PM
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Eh the filter is brand new. I put that in myself. yes its still there where it should be.
Old 08-09-2007, 11:36 PM
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Re: TH350 Lost 3rd gear HELP AHH Im gona burn it!

i got a th350 with something they same too just started happenin two days ago thrid is only gear affected its there some times then out of nowhere it drops of into a neutral feeling and second at same time!! wtf changing fluid and filter tom. was a little crud on the stick prob something in the valve body
whatya think is this toasted or what
Old 08-14-2007, 06:05 PM
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Re: TH350 Lost 3rd gear HELP AHH Im gona burn it!

WHOA! Im still subscribed to this!
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