Help with a possible transmission issue

Also, if you are rebuilding and don't have a good parts cleaner, I have found it to be well worth it to disassemble and inspect, then put everything into a large tub and take it to a local machine shop or trans shop and have them run everything through the industrial heated parts washer. Depending on the shop, you can often have them run it through whenever they don't have anything else running through it(as in drop off in the morning and pick up in the afternoon) for well under $100. Considering how time consuming it is to manually put things through a small parts washer, scrub them, rinse them, then dry them off... I consider it time and money ahead to have the shop do it.

FishingJake said:

I did this fluid stayed in the marks. Still won’t go into D , D1 or D2. It’s a Th350.

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Sounds like low roller one-way clutch failure which is somewhat common on those units...I see it from time to time and retro a 4L60E center support w/the wider one-way clutch assembly to prevent further failures.
I have an entire playlist on Youtube for that transmission, including detailed tear down and inspection and reassembly videos.

Check out my TH350 Information Thread for more details; let me know if you have any questions...

If you do decide to jump in and do it yourself, start a TH350 Rebuild thread of your own...Take plenty of pics (or film) and post it in your thread as you make progress.

NickTransmissions said:

Sounds like low roller one-way clutch failure which is somewhat common on those units...I see it from time to time and retro a 4L60E center support w/the wider one-way clutch assembly to prevent further failures.
I have an entire playlist on Youtube for that transmission, including detailed tear down and inspection and reassembly videos.

Check out my TH350 Information Thread for more details; let me know if you have any questions...

If you do decide to jump in and do it yourself, start a TH350 Rebuild thread of your own...Take plenty of pics (or film) and post it in your thread as you make progress.

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Nick I'm glad you posted up,I was thinking of you earlier and forgot. I need to rebuild 2 700r4s and a th350. Wondering if there are enough of the upgrade parts in the 4l60e that I should by some cores just to have incidentals,also are the 4l60s in the 4.3 V6 trucks/s10s the same as the V8 ones. 700s are 85 and 87/88 TH350 No idea on year. All 2wd

Ricko1966 said:

Nick I'm glad you posted up,I was thinking of you earlier and forgot. I need to rebuild 2 700r4s and a th350. Wondering if there are enough of the upgrade parts in the 4l60e that I should by some cores just to have incidentals,also are the 4l60s in the 4.3 V6 trucks/s10s the same as the V8 ones. 700s are 85 and 87/88 TH350 No idea on year. All 2wd

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Grab a 1997-2000 4L60E core...If buying a two-piece case, ensure it has the 298mm input shaft as that (and the drum it's pressed into) will work in your 1988 700R4 and feature the updated return spring for which you can use the 4L60E 97+ bonded steel/rubber pistons....If you find two such cores, grab both and retro the forward drum as well as the reverse input drums, their respective cushion plates, tubular/vented steels and snap ring into each of your 700R4s. You can install one of the two 4L60E center supports into the TH350 along with a Borg Warner 4L60E low roller clutch.

My recommendation for your 3/4 clutch in each 700R4: 4L65E spec clutch pack...It has 7 high energy friction plates, six lindered steel plates (lindered = Kolene coated but GM doesn't use the term 'Kolene'), an HD-stamped one-piece apply plate and HD-stamped backing plate.

My video here shows that clutch pack, along with an ALTO Power Pack (also a viable option):

I'd also start a build thread once you have everything ready to go - this way we can see the progress, answer questions and provide any input as needed.

Bextreme04 said:

Also, if you are rebuilding and don't have a good parts cleaner, I have found it to be well worth it to disassemble and inspect, then put everything into a large tub and take it to a local machine shop or trans shop and have them run everything through the industrial heated parts washer. Depending on the shop, you can often have them run it through whenever they don't have anything else running through it(as in drop off in the morning and pick up in the afternoon) for well under $100. Considering how time consuming it is to manually put things through a small parts washer, scrub them, rinse them, then dry them off... I consider it time and money ahead to have the shop do it.

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I appreciate this advice.

NickTransmissions said:

Sounds like low roller one-way clutch failure which is somewhat common on those units...I see it from time to time and retro a 4L60E center support w/the wider one-way clutch assembly to prevent further failures.
I have an entire playlist on Youtube for that transmission, including detailed tear down and inspection and reassembly videos.

Check out my TH350 Information Thread for more details; let me know if you have any questions...

If you do decide to jump in and do it yourself, start a TH350 Rebuild thread of your own...Take plenty of pics (or film) and post it in your thread as you make progress.

Click to expand...

Thanks I’ll check it out . I’m trying to figure out if we can do it. Problem is time. Two other kids and all three play multiple sports usually don’t get home till 9pm. His Grandpa maybe able to help him

Maybe not a good time to introduce the idea of overdrive.....or NV4500 conversion I assume? I have pedal assemblies just sayin.