TH350 Valve Body, used and ready to install. Fits the TH350. Ships fast from the USA.
A TH350 that bangs into gear, slips on the 1-2 shift, or hesitates before it engages Drive is almost always telling you the valve body has worn past spec, not that the whole transmission needs to come out. This is a used OEM valve body, GM reference 8640996, pulled from a running TH350 core and checked before it goes out, so you get a known-good factory part instead of guessing whether your own unit is savable.
Inside the TH350, the valve body is the hydraulic switchboard that takes pump pressure and directs it to the clutch packs and bands in sequence to produce each shift. Every bore in it is machined to a tight tolerance against its matching spool valve, and once that tolerance opens up from normal wear, pressure leaks past the valve instead of building against the clutch piston, which is what turns a clean shift into a soft, slipping, or delayed one.
Before you replace the valve body, rule out the other usual suspects the same symptoms point to. Our TH350 common problems guide covers the modulator, no-2nd, and no-reverse failures that overlap with valve body symptoms, and if the main complaint is a pause before the transmission takes off, the TH350 delayed engagement guide walks through isolating a worn pump or converter from a valve body problem.
This valve body fits the TH350 as used across the GM lineup, but it does not carry a specific year range in this listing, and the TH350 went through several internal revisions during its production life, including the switch to the TH350C lockup version. Match the casting and modulator connection against the unit coming out of your vehicle, or send us your year, make, and VIN and we will confirm this is the correct version before it ships. The full lineup for this transmission is on the TH350 parts page.
Drop the pan and change the fluid and filter at the same time as the valve body so any debris already circulating does not wear in the replacement part the same way it wore out the original. Torque the attaching bolts in the correct sequence and to spec rather than snugging them down in one pass, since an uneven valve body will bind the spool valves and bring the same symptoms right back. Run Dexron ATF, and if the clutch packs or bands are also showing wear, pair this with our TH350 master rebuild kit or a TH350 clutch drum rather than reusing worn components behind a fresh valve body.
| Fits | TH350 |
| Part type | Valve Body |
| Condition | Used |
| Brand | OEM |
| Reference | 8640996 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
This is a used OEM valve body, GM reference 8640996, pulled from a running TH350 core and checked before it ships. It carries a 1-year warranty.
The listing does not carry a specific year range, and the TH350 went through several revisions during production, including the later TH350C lockup version. Match your casting and modulator connection, or send us your year, make and VIN and we will confirm the correct fit before you order.
Change the fluid and filter at the same time so old debris does not wear into the new unit. If the clutch packs or bands are also worn, add a master rebuild kit or clutch drum rather than putting a good valve body behind worn internals.
Both can cause slipping, but a worn valve body tends to show harsh or flared shifts and delayed engagement that is worse after the vehicle sits, while worn clutches tend to slip consistently under load at a specific gear. Our common problems guide walks through separating the two.
Dexron ATF. Refill to the correct level with the transmission at operating temperature after any valve body or pan service.
No. The TH350 is a mechanical-hydraulic transmission with no onboard shift computer, so there is nothing to relearn. Confirm the modulator or vacuum line is connected correctly and road test for shift quality.
