Author Topic: Need a good TH-350 replacement:  (Read 486 times)

Offline Stewart G Griffin

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Need a good TH-350 replacement:
« on: June 23, 2018, 07:42:56 PM »
Looking for a good quality TH-350 transmission replacement.

Must be 9" tailshaft, thank you.

Unfortunately, TCI is out because too many bad reviews.  This is unfortunate because the street rodder model is a direct bolt in.

i am waiting for ATI to get back to me if they offer any with a  9" shaft.   They are relatively close to me, i've done business before with Jim Beattie Sr. on a different project and they are, in my opinion, a first class operation.
http://www.atiracing.com/
« Last Edit: June 23, 2018, 08:02:01 PM by Stewart G Griffin »

Offline kcwis

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Re: Need a good TH-350 replacement:
« Reply #1 on: June 24, 2018, 05:15:30 PM »
I have one that came out of a 87 c10, tailhousing measures 9 inches, tailshaft,filter changed recently.

Offline VileZambonie

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Re: Need a good TH-350 replacement:
« Reply #2 on: June 24, 2018, 05:42:50 PM »
TH350 is such an inefficient trans, why wouldn't you upgrade if you're going to fork out the coin for a new one?
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Offline irk_miller

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Re: Need a good TH-350 replacement:
« Reply #3 on: June 27, 2018, 10:18:20 PM »
I agree ^.  I'm running a TH350 I took from my old G10 van.  Had I not rebuilt it and only had 15k miles on it when I needed one for my truck, it wouldn't be in there.  I'm going 700r4 this fall. 
Only dead fish follow the stream.

Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #4 on: June 30, 2018, 11:00:52 PM »
TH350 is such an inefficient trans, why wouldn't you upgrade if you're going to fork out the coin for a new one?

Well, what would it take to put a 200r4 in there?

The other thing to remember is that i have a 2.56 rear, so it's not that bad.

Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #5 on: July 30, 2018, 08:49:09 PM »
Ok, it's out.   And what a thrashing it was........     i'll get into more detail about all that later.


But for now, does anyone know where i can get some good quality seals----specifically the dipstick and kickdown cable seals;  These are the "top hat" type.

i know you can get the at the autoparts store, but i'm unsure of their quality.

Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #6 on: August 05, 2018, 06:31:03 PM »
Alright, it's in.  It's physically bolted to the engine.  i would say that for someone who's never removed a trans from underneath a car, this could be involved and not something that will be out "by the second cup of coffee."   For those who have done it a few times AND have the right tools and know which ones to use AND actually get the car high enough, yes it's pretty straightforward only requiring maybe an hour or two.

i will provide more detail and pics on all this soon.

Anyways, does anyone have any idea what the trans mount to trans, bolt sizes are?     Not trans mount to crossmember, but trans mount to trans, bolts.

i'm replacing the TH-350C with a TH-350;  Some of the bolts on the lockup trans are apparently metric and don't work on the non-lockup versions apparently.   Example, kickdown cable on the 350C is an m6 while the non lockup is 1/4" X 20 thread.

The bolts out of the TH-350C required a 15mm socket to remove and say "9.8" on the head?
« Last Edit: August 05, 2018, 06:35:05 PM by Stewart G Griffin »

Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #7 on: August 12, 2018, 09:40:35 PM »
i've made a few notes for reference:

i got the Harbor Freight Trans jack, #60234, which did pretty good.  My only complaints are i wish the adjustments for the support arms were underneath the saddle rather than on top-----so you can adjust them easier when the trans is on the jack.  And, the tilt knobs i thought are too high up such that there can be interference between them and the trans depending on what angle you need.





As seen here, IF you are going to the roll the trans under the car with this jack, then you need minimum 26", UNLESS you tilt the trans forward;  In that case, you might be able to get by with as little as 18".      If you slide the trans under the car w/out the jack, and then put it on the jack while underneath the car, then you could also get by with less height, although i'm not sure how you could do this unless you had a helper?

i underestimated the amount of height needed, using only ramps under the rear wheels, but i still got it in by tilting the trans forward as necessary AND lifting the rear axle by about 1/4"----i think the new pan may be a little deeper than stock?

i am not totally sure on the actual size of the hardware, but these at least are the wrench/socket sizes:

Driveshaft  7/16"
Cooler lines   11/16" flare =  fittings that go into the trans, although could be 5/8" flare
                     1/2" flare  =  fitting that screws into the large fitting that goes into the trans. as well as fitting that screw into radiator trans cooler.

Kickdown cable retainer = 11mm

torque converter to flexplate =  15mm if later lockup models,  9/16"  both bolt and nut if  non-lockup or pre 78?

Transmount to crossmember = 5/8"
Transmount to Trans   = 5/8"   However, later models (after 77) and lockup units may take 15mm

Crossmbember to frame =   nut is 11/16", bolt is 5/8"   There are 8 total
For the upper crossmember support to main cross member =  three 9/16" nuts and bolts.

Bracket for TCC wiring plug  =  15mm  (note, only applies to lockup models)   


Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #8 on: August 12, 2018, 09:50:17 PM »
Some additional food for thought:

There was mention of upgrading.   i'm not clear on the dimensions of a 7004r or 200r4 vs. a TH-350, BUT the frame rails appear to be completely flat in that area such that you could simply slide the crossmember back or forwards as needed to match the new transmount location and simply drill new holes in the frame?

The 700 crossmember should exist though since these did come in some trucks?

Offline Stewart G Griffin

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Re: Need a good TH-350 replacement:
« Reply #9 on: August 14, 2018, 05:00:28 PM »
Any idea how much more fluid, generally, needs to be added to get this trans to work?

1) About 1 qt. was added to the new converter.

2) i flushed out the cooler, but that was only a few pints.


Offline bd

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Re: Need a good TH-350 replacement:
« Reply #10 on: August 14, 2018, 06:02:04 PM »
Generally about 10 quarts or slightly more on a totally dry fill, but be careful that you do not overfill.  ATF fill approaching or over 10 quarts should be added a little at a time with the engine running, transmission in park, periodically shifting between reverse and forward gears.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)