Author Topic: Th350 no third gear...  (Read 17208 times)

Offline 454Man

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Th350 no third gear...
« on: May 02, 2012, 08:59:20 am »
Is there something I can do while it is still in the truck? I'm going to have the 700r4 rebuilt in a month, but for now this one will have to do.what you guys think can be the problem?

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Offline jaredts

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Re: Th350 no third gear...
« Reply #1 on: May 02, 2012, 09:34:20 am »
Does first to second shift normally or is it delayed?

Offline 454Man

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Th350 no third gear...
« Reply #2 on: May 02, 2012, 10:29:31 am »

Normal as can be, just no third... Idk I do have a new modulator I could try
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Offline 454Man

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Re: Th350 no third gear...
« Reply #3 on: May 02, 2012, 11:00:15 am »
Oh and it is a th 350c

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Offline 454Man

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Re: Th350 no third gear...
« Reply #4 on: May 02, 2012, 12:17:06 pm »
I've been wondering why my gas mileage has gone down, so this morning I listened to my trans shift and I realized I only have a first and second.

Offline jaredts

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Re: Th350 no third gear...
« Reply #5 on: May 02, 2012, 12:25:41 pm »
If its just third I doubt its modulator related, but it would be worthwhile to check the line and make sure it has vacuum and is a steel line instead of rubber.  It should be rubber hose only at the ends.  Have you tried to nudge the shifter toward neutral to see if it goes into third?  It could be a problem there where you're halfway between "2" and drive.  Beyond that there's sticking valve body balls and governor and pump pressure issues that you can look for in the vehicle but you need better help than I can give for that.

Offline 454Man

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Re: Th350 no third gear...
« Reply #6 on: May 02, 2012, 12:39:55 pm »
Ill try adjusting the shifter before i get on the road to my second job and see if that helps, sadly I did notice my seal for the front pump is leaking, hope that isn't it

Offline ehjorten

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Re: Th350 no third gear...
« Reply #7 on: May 02, 2012, 02:31:34 pm »
My bet is shifter adjustment.

Three things are working for you in 3rd gear: 1) Forward Clutch is engaged, 2) Direct Clutch is engaged 3) Intermediate Clutch is engaged, and 4) Intermediate Sprag begins to over-run.

Since the Forward Clutch is engaged in 1st, 2nd, and 3rd you can rule that out.  The Direct Clutch is engaged in 3rd and Reverse so you can rule that out.  The Intermediate Clutch is engaged in 2nd gear Auto as well as 3rd, so that should be ruled out.  If the Intermediate Sprag was shot you wouldn't have 2nd gear it would wind-up really high in 1st and then dump to 3rd.

So...if you truely lost 3rd gear, I am betting it is a shifter adjustment issue.  But...how did it come about?  Now take in mind that this is all coming from memory and I am not clear on the finer details of the TH350c.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline 454Man

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Re: Re: Th350 no third gear...
« Reply #8 on: May 02, 2012, 02:56:34 pm »
My bet is shifter adjustment.

Three things are working for you in 3rd gear: 1) Forward Clutch is engaged, 2) Direct Clutch is engaged 3) Intermediate Clutch is engaged, and 4) Intermediate Sprag begins to over-run.

Since the Forward Clutch is engaged in 1st, 2nd, and 3rd you can rule that out.  The Direct Clutch is engaged in 3rd and Reverse so you can rule that out.  The Intermediate Clutch is engaged in 2nd gear Auto as well as 3rd, so that should be ruled out.  If the Intermediate Sprag was shot you wouldn't have 2nd gear it would wind-up really high in 1st and then dump to 3rd.

So...if you truely lost 3rd gear, I am betting it is a shifter adjustment issue.  But...how did it come about?  Now take in mind that this is all coming from memory and I am not clear on the finer details of the TH350c.
ok so while we are talking shifter adjustment ithe same night I posted about quaker state defy oil I was at walmart and was about to leave when the truck wouldn't shift. So I got out and noticed the shifter linkage was loose:(? Idk so I adjusted it while the linkage was in park thinking all would be ok. Wasn't until today... I realized I wasn't getting a 3rd gear. Man I hope that's all it is. This time I will adjust it while the trans is in drive... truck off and parkin brake set. If I'm correct shift pattern is. P.N.D.2.1. IS this right?

Offline VileZambonie

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Re: Th350 no third gear...
« Reply #9 on: May 02, 2012, 06:33:32 pm »
Do you have to push it backwards or is reverse an option too?  ;)

Are you saying you have no 2-3 up-shift or are you saying 3rd gear slips?

It sounds like you are saying no 2-3 shift. If that's the case and the linkage is working properly then check that you have vacuum at the modulator and inspect the governor.

As far as the linkage, one up from what you perceive as drive will either give you drive or neutral.
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Offline 454Man

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Re: Th350 no third gear...
« Reply #10 on: May 02, 2012, 07:06:26 pm »
It ended up being the linkage.  The screw that clamps down on the rod was loose

Offline ehjorten

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Re: Th350 no third gear...
« Reply #11 on: May 03, 2012, 09:00:31 am »
Glad to hear that it was something relatively simple!  Also glad I wasn't way off kilter with my advice!  ;D
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6