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Old 10-20-2013, 07:29 PM   #1
'68 Short Step
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Transmission question

I'm trying to figure out if my torque converter is bad or whats going on with my transmission. When I first crank up the truck and drive around everything works perfect. After I drive it around for a while (20+ miles) the transmission starts to act funny when I accelerate hard or when taking off. feels like the transmission is sightly in neutral or something because the rpm's will go up but the truck is barely moving. After I get up to speed it's ok. Its a th350 trans. Thanks for any advice
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Old 10-20-2013, 07:47 PM   #2
trac209
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Re: Transmission question

Could be a number go things when it come to slippage. Could be a clogged trans filter,low fluid,bad clutches etc. check fluid level first and smell to see if it's burnt.
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Old 10-20-2013, 08:34 PM   #3
'68 Short Step
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Re: Transmission question

Fluid is full and doesn't smell burnt. The filter is new. Not sure what it could be. May have to take it to a local shop and have them diagnose.
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Old 10-20-2013, 10:56 PM   #4
truckdude239
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Re: Transmission question

Time for a rebuild
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Old 10-20-2013, 11:01 PM   #5
'68 Short Step
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Re: Transmission question

It shifts really well. I'd put a 700r4 in before I rebuild the th350.
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Old 10-20-2013, 11:06 PM   #6
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Re: Transmission question

Check filter first thing. I wonder if the governer is getting sticky or weights binding.
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And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9
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Old 10-20-2013, 11:14 PM   #7
'68 Short Step
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Re: Transmission question

I put a new filter on it a few months ago
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Old 10-20-2013, 11:16 PM   #8
Longhorn 70
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Re: Transmission question

were there any chunks in the pan? Did it immediately start acting funky or did it take time? Does it make any sucking nor growling noises?
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11.
1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar

And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9
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Old 10-20-2013, 11:21 PM   #9
'68 Short Step
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Re: Transmission question

It was doing this even before I changed the filter. Nothing in the pan and no weird noises.
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Old 10-20-2013, 11:44 PM   #10
Longhorn 70
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Re: Transmission question

Very rarely have I seen a converter fail unless there is something catastrophic. Also they don't usually work then not then work again.

The governer is a more likely failure point. You can pull it from the outside and take a look. Sometimes they look like a chewed up apple core but still work.....kinda. I don't want to keep making suggestions and have you pour $$$ into it though with no results.
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11.
1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar

And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9
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Old 10-21-2013, 12:04 AM   #11
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Re: Transmission question

If you think its the torque converter, does it do the same thing in reverse...you say it does it on take off, right ? if its the torque converter the same thing would happen in reverse I would think.... If it does not do it in reverse, I am thinking your forward clutches are burnt up, IMO...slipping issue normally is not caused by the gov....not to say its good or bad, I am not there driving your truck.....slipping on take off means to me that you are in first gear and has not shifted yet, so no point of gov/modulator issue yet...and not slipping during shifts right ? just taking off ? any clutch material in pan on your fluid change, did you put the gasket under the filter and tighten the two screws that holds the filter ? power brake the truck in forward and than in reverse...see when its breaking loose ?
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