Author Topic: TH-350 slips in all 3 gears.  (Read 913 times)

Online MIKE S

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Re: TH-350 slips in all 3 gears.
« Reply #15 on: January 05, 2020, 10:30:12 PM »
If you had a clutch slipping it would not have gotten better. Once a fiber clutch starts to slip in an automatic transmission it will be toast in a matter of minutes. With it returning back to normal after a stall test I suspect that the one way roller stator clutch inside the torque converter may not be holding on acceleration. The clutch operates like the starter drive on a starter. Locks in one direction and freewheels in the other. On acceleration it holds to multiply torque and freewheels when turbine speed and vehicle speed increase. There is really no way to test it since it is sealed inside the converter. You kind of have to know what it’s supposed to feel like normal and abnormal. I don’t know if a transmission shop could diagnose it since it is not very common. Typically when You rebuild your transmission you will get a remanufactured converter. I don’t think they would change the one way roller unless they could see something wrong with it. It could hold while testing it by hand but slip when putting 200 horsepower to it. I’m not sure what they use in “performance” converters.
 
« Last Edit: January 05, 2020, 10:32:32 PM by MIKE S »

Offline VileZambonie

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Re: TH-350 slips in all 3 gears.
« Reply #16 on: January 06, 2020, 04:15:22 PM »
Was there anything in the pan? Do you have a tachometer? Have you performed a stall speed test?


3) i REALLY didn't want to do a stall test----GM and ATI recommend against it, but i'm sort of glad that i did----because something funny happened-----after i did the stall test in drive, the slipping went away for a while.

The converter stalls at about 1500 in both Drive and Reverse.

Doesn't sound like it was slipping. You have to perform a stall test to verify that that the converter is working and the stator is locking. Either you were stuck in a higher range or the stator was overrunning. This is not a TH350C right?

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Offline VileZambonie

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Re: TH-350 slips in all 3 gears.
« Reply #17 on: January 06, 2020, 04:16:28 PM »
If you had a clutch slipping it would not have gotten better. Once a fiber clutch starts to slip in an automatic transmission it will be toast in a matter of minutes. With it returning back to normal after a stall test I suspect that the one way roller stator clutch inside the torque converter may not be holding on acceleration.

Agreed
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Offline Stewart G Griffin

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Re: TH-350 slips in all 3 gears.
« Reply #18 on: January 06, 2020, 09:32:29 PM »
Yes, it's a "regular" non-lockup 350.

i have my fingers crossed that it's the converter as well.

Will respond in more detail soon, just very busy with work right now.

Offline philo_beddoe

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Re: TH-350 slips in all 3 gears.
« Reply #19 on: January 07, 2020, 09:56:59 PM »
If i can jump in here for a quick post....Earlier in this post you mentioned it goes into reverse real hard, mine also does, maybe not real hard, but hard. Nothing clunks at all! The tranny shifts and works great, it just goes into reverse hard. I'm jumping in here because VZ responded to this thread and he knows my tranny real well. He installed it!! So.....VZ, why does it go into reverse hard? Any adjustments?? Thanks...

I saw a couple other th350 posts and didnt want to start a whole new one, since my problem was mentioned here.
Behold, the day of the LORD cometh, and thy spoil shall be divided in the midst of thee.  Zechariah 14:1

Offline VileZambonie

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Re: TH-350 slips in all 3 gears.
« Reply #20 on: January 08, 2020, 06:15:30 PM »
Probably backlash in your rear end. You might want to tighten up your rear  :o You also have a TH400
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Offline philo_beddoe

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Re: TH-350 slips in all 3 gears.
« Reply #21 on: January 09, 2020, 08:05:08 AM »
Lol,,,yes, i knew i had a th400, but a th350 output (yolk) correct?

Anyway, how do i tighten up the rear diff. ? (i wont say rear end)

It does shift into R smooth when the idle is low, of course.
Behold, the day of the LORD cometh, and thy spoil shall be divided in the midst of thee.  Zechariah 14:1

Offline VileZambonie

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Re: TH-350 slips in all 3 gears.
« Reply #22 on: January 09, 2020, 03:31:58 PM »
Well if you are dropping it into gear at fast idle, it is going to engage hard.

PS Yolk = Eggs

Yoke
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Offline philo_beddoe

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Re: TH-350 slips in all 3 gears.
« Reply #23 on: January 09, 2020, 09:23:06 PM »
Drat! I knew you'd catch that.

How many times have we seen it...

Yolk- yoke
Grill- grille
Behold, the day of the LORD cometh, and thy spoil shall be divided in the midst of thee.  Zechariah 14:1

Offline Stewart G Griffin

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Re: TH-350 slips in all 3 gears.
« Reply #24 on: January 11, 2020, 09:44:11 AM »
If i can jump in here for a quick post....Earlier in this post you mentioned it goes into reverse real hard, mine also does, maybe not real hard, but hard. Nothing clunks at all! The tranny shifts and works great, it just goes into reverse hard. I'm jumping in here because VZ responded to this thread and he knows my tranny real well. He installed it!! So.....VZ, why does it go into reverse hard? Any adjustments?? Thanks...

I saw a couple other th350 posts and didnt want to start a whole new one, since my problem was mentioned here.

That's perfectly fine to interject---we're all here to learn.

i have been swamped at work, thus unable to respond but will do something with the trans today, and will discuss in more detail.

We'll solve this together........or i'll get a new(er) truck.

Offline Stewart G Griffin

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Re: TH-350 slips in all 3 gears.
« Reply #25 on: January 11, 2020, 05:12:30 PM »
Someone on one of the blazer sites said that these look bad.   i didn't think so myself, but maybe they are?




Online MIKE S

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Re: TH-350 slips in all 3 gears.
« Reply #26 on: January 11, 2020, 09:42:29 PM »
A little bit of brass is normal. Silver metal chunks are not. Discolored fluid is normal. Very dark and burnt smell is not. If you have metal chunks then you will have to dismantle trans to find problem. If you cannot determine we’re the metal came from after tear down then you have to assume it came from inside the converter. Metal can cause valves to stick.



Offline Stewart G Griffin

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Re: TH-350 slips in all 3 gears.
« Reply #27 on: January 12, 2020, 02:47:07 PM »





BTW, i scraped my finger along the bottom of the pan because i was wondering about some of the comments i was getting on the blazer site;   i had originally assumed the bottom was also black----same as the outside as the pan is painted black (mr. gasket pan, i believe?).   The metal sluge is CAKED on there and the bottom of the pan is actually supposed to be silver, not black.

i'll be pulling the unit today............

Offline VileZambonie

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Re: TH-350 slips in all 3 gears.
« Reply #28 on: January 12, 2020, 05:05:20 PM »
Yeah, that's trashed dude. Most of the cores out there are junk too which is why you are probably getting what you are getting. Make sure you flush that trans cooler good.
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Offline Stewart G Griffin

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Re: TH-350 slips in all 3 gears.
« Reply #29 on: January 12, 2020, 07:14:47 PM »
So, how do you flush an in-radiator trans cooler?