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Old 08-13-2008, 10:37 PM   #1 (permalink)
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turbo 350 downshifting at random

ive got a turbo 350 trans the problem is after driving 5 miles or so it shifts back to second gear and will not go to third also it only does it after its warmed up .. am i screwed here or is it as simple as a new tranny filter ive checked the fluid and its clean and full
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Old 08-14-2008, 06:17 AM   #2 (permalink)
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Do you have a Adjustable downshift cable?
If so give it some slack.
But it sounds like you may need a rebuild.
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Old 08-14-2008, 12:42 PM   #3 (permalink)
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no adjustable cable its got the vacumn modulator and its been changed already
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Old 08-14-2008, 12:47 PM   #4 (permalink)
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TH350 also has a manual kick down cable......
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Old 08-14-2008, 01:01 PM   #5 (permalink)
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vacuum mod. adjustment
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Old 08-14-2008, 01:04 PM   #6 (permalink)
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not on this one i havent seen one anyway and i looked all over but i jups to 2nd at cruisin speed without flooring it
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Old 08-14-2008, 04:45 PM   #7 (permalink)
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what style th-350 is it? some were electric while most others use the Kickdown cable from the carb to the passenger side right by the cooler lines.

if your missing that cable, it would cause your tranny to maintain a gear. for example you would be in third, mash the gas and it would try and take off in that gear while cruising rather then kicking down to 2nd and going for it.

Im not sure you need a rebuilt trans since yours is shifting, and actually has 2nd and 3rd gear.

If its electronic i would contact a tranny shop and ask a few questions, ive never had an electronic th350, but i have heard they are problematic from a few people.

worst case senario, its your valve body, something might be clogged, or messed up inside.

did you install a shift kit or any of that? if it was installed properly, make sure the right bolts were put in, in the right order and torqued correctly. I know people who have had tranny shops do half ass install jobs and the trans went out about 2 months later. (luckly warrantied and replaced correctly)

of course my ideas could be total shit and you could just have a vac mod problem too.

edit: automatics suck the biggest ass, thats why i went with a 465
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Old 08-14-2008, 05:01 PM   #8 (permalink)
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automatics suck the biggest ass, thats why i went with a 465 agreed totally just trying to make this auto junk work right till i get a few more duckies saved up to swap in a 465 i guess im just gonna take it to a tranny shop and let them figure it out but if i needs a rebuild its going to the junk pile!!
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Old 08-14-2008, 06:41 PM   #9 (permalink)
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what about the obvious?fluid level and more importantly condition.is it discolored?correct level?how many miles on the trans to start with?
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Old 08-14-2008, 09:01 PM   #10 (permalink)
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yes i checked the fluid its fine smells good looks good tastes bad lol dont know how many miles are on it i did find the kickdown (cable) its not hooked up ..
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Old 08-15-2008, 01:38 PM   #11 (permalink)
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Quote:
Originally Posted by sperkinsnwfl View Post
not on this one i havent seen one anyway and i looked all over but i jups to 2nd at cruisin speed without flooring it
Pull the vacuum hose off and look in the nipple. Allan key or flat blade.
[clockwise = more pressure/more "twitchy", counter clockwise = less pressure/less "twitchy"]
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Old 08-15-2008, 02:01 PM   #12 (permalink)
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the vacuum modulator has nothing to do with gear changes on a turbo 350. it only changes the line pressure accordin to how hard you are on the gas... you either have a problem with the governor assembly, that is on the tailshaft, which is my best guess, or in the valve body..
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Old 08-15-2008, 05:11 PM   #13 (permalink)
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Originally Posted by sperkinsnwfl View Post
automatics suck the biggest ass, thats why i went with a 465 agreed totally just trying to make this auto junk work right till i get a few more duckies saved up to swap in a 465 i guess im just gonna take it to a tranny shop and let them figure it out but if i needs a rebuild its going to the junk pile!!
You could come up on a 465/205 combo for a very decent price. just do some searchin at the local PNP or JY. I spent 450 on my combo but i got everything....bell, trans, t-case, shifters, boots, drive stafts, crossmember and clutch assembly including the pedal. It was clean too out of the same year truck so I couldnt complain.

as far as junking that 350...if the case is good, sell it, A lot of people i have met would shit to find a good case without cracks. your pumps,planetaries and VB might be dust, but shit you can make some dough on the case cause everyone cracks them once in a while. espcially guys with doublers and poorly designed crossmembers. just a heads up for yah.
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