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#1 |
Registered User
Join Date: Jan 2015
Location: Los Angeles California
Posts: 927
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TH350 woes
History: Rebuilt buy a supposed quality shop less than 2 years ago, less than 6000 miles since. Here is what they said they did
TH350 Performance Package includes Alto Red Eagle Clutch Plates Kolene Steels Alto Red Eagle Band Teflon Rings High Endurance Gaskets, Seals and Bushings TransGo Reprogramming Kit I added a trans cooler and have run a temp gauge since new and never been hotter than 190*. Royal Purple synthetic since new, cast B&M 3 quart sump. Today I went to the store which is only a mile a way, no problems or weird noises. Got back started the truck, shifted into reverse no problem, then to drive again no problem. Drove out of the lot and noticed it wasnt shifting to 2nd or 3rd. Pulled over and went through the detents put it back into drive and took off, same thing. Got home checked the linkage and everything looked good, a bit loose but no binding or anything. Now no other gears including reverse except 1st. Anyone have any idea what might be going on? Did I mention I HATE automatics!!!! |
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#2 |
Registered User
Join Date: Oct 2009
Location: hobbs nm
Posts: 29
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Re: TH350 woes
Did you check fluid level and for burnt smell or material?
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#3 |
Registered User
Join Date: Feb 2015
Location: friendship WI
Posts: 174
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Re: TH350 woes
pull out the governor and check if the plastic gear is worn out
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#4 |
Cluster King
![]() Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,263
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Re: TH350 woes
The first and easiest thing to do is to make sure the vacuum modulator has a good source of vacuum from the engine. If it does not, the transmission will not shift correctly.
Hope this helps, Tom
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Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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#5 |
Registered User
Join Date: Jan 2015
Location: Los Angeles California
Posts: 927
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Re: TH350 woes
Fluid level fine, but the purple stuff stinks. Doesnt smell burnt but not what I am used to with regular ATF.
Ill check the hose and modulator tomorrow. Thanks for the replies |
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#6 |
Moderator
![]() Join Date: May 2007
Location: Southern Cal
Posts: 19,994
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Re: TH350 woes
X2. I had the same issue a while back and it turned out to be a cracked vacuum line.
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1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man |
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#7 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,466
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Re: TH350 woes
It's the vac line, burnt fluid will give indications of slipping before going out
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#8 |
Registered User
Join Date: Jan 2015
Location: Los Angeles California
Posts: 927
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Re: TH350 woes
Never driven an auto that was slipping, whats it supposed to feel like? I have a low stall converter in it ~1500 rpm, shifts felt firm as far as I know. Is it similar to a oil soaked disk on a manual?
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#9 |
Registered User
Join Date: Jan 2015
Location: Los Angeles California
Posts: 927
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Re: TH350 woes
Been thinking about this more, I can see how a vacuum leak would cause problems with up/down shift but why no reverse?
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#10 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: TH350 woes
Third and reverse out means the direct clutch is out.
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#11 |
Registered User
![]() Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
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Re: TH350 woes
x3
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68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
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#12 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: TH350 woes
Modulator/Governor have nothing to do with reverse.
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#13 |
Registered User
Join Date: May 2014
Location: Freedom Pa
Posts: 139
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Re: TH350 woes
Pull the pan check for for metal shavings or pieces. I had a TH350 do a very similar thing it blew apart the low/reverse sprag. The weird part was it happened backing out of a parking spot not doing a burnout or racing. Had to drive home in 1st gear. Keep us posted what you find.
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#14 |
Registered User
Join Date: Jul 2015
Location: Central Coast, CA
Posts: 500
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Re: TH350 woes
I'd vote for OldBlueChevy's diagnosis on this one.
Notice that the two sprags are not in the rebuild kits but should be IMO.. The low/reverse one costs about $22 - and not all that hard to replace except for pulling the trans.. If he is right definitely wouldn't be good to spin the trans until you know - risk is that all those sprag pieces may go to the cooler, torque converter & rest of the trans. Here is a photo of the sprag or roller clutch.. |
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#15 |
Registered User
Join Date: Jan 2015
Location: Los Angeles California
Posts: 927
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Re: TH350 woes
Replaced modulator and inspected governor today, vacuum lines are fine and plastic gear was in good shape weights worked as they should and the valve moved freely and was free of debris. Disconnected linkage to rule that out and attempted to shift directly but no dice. Today it felt different in park, kind of felt like it had a trans break and would lurch forward when shifted in whats supposed to be reverse. Didnt get to drain the fluid and drop the pan as the 1 year old only gives me an hour max to work on stuff. Ill try again tomorrow but not expecting any easy fix.
Thanks all for the recommendations, Ill take pics of the carnage tomorrow. Now looking for Z bar and engine stud to convert this **** box to SM465 |
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#16 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: TH350 woes
The problem with the above hypothesis is the low roller is used for (only) first gear, not reverse.
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