TH350 Reverse in First

[Cyborg]

I am completely lost here. I rebuilt my first TH350 with all new bushings, seals, torque converter, transgo 1&2 shift kit, etc... I was very meticulous and have been turning wrenches for nearly 20 years. Took my time on everything and it was easy and I am not sure why I didn’t attempt this years ago. Everything pressure checked with air. The forward and direct on the bench through the pump. Then again all four circuits pressure checked good through the valve body.

Anyway, fired it up my pressure gauge installed. I got no pressure in park. Drop it all the way down to L1 and it is going in reverse. All the pressures are right about 110 at idle and up to about 230 or so if you gas it. Only problem being it is supposed to be in first! Manually shift to second and it slows down and changes direction to forward. Pressures are about 110 or so. I am shifting it manually at the transmission to eliminate any linkage issues.

Dropped the valve body thinking something is obviously not right there. Everything is in order no evidence of cross leaks or anything. I compared everything in the valve body to the factory manual and everything is in order.

This never happens but I am stumped and don’t know where else to turn. I don’t know the history of the transmission but was told second hand it was good before I rebuilt it. I am leaning toward a crack in the case somewhere that I can’t see. Any ideas?
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[aggie91]

Since you say you don't know the history of the trans, could it have a reverse pattern valve body in it? just guessing at this point...

[YoungPup1977]

Take a pic of the VB and internal linkage to the manual valve please....

Did you adjust the manual valve so its even with the casting of the VB ? The "S" piece that fixes into the manual valve installed correctly ?

Second hand information can bite ya most of the time, i always wonder why they pulled the trans out, ya know ?

I like pics, provide some pics and we can see if anything is wrong for starters....thanks.

Did you put a shift kit in it that came with a separator plate ? The plate that goes down over the separator in front of the VB is known for leaks....In the Transgo kit, they provide a thick gasket that goes under this plate (not the separator plate) but the plate that goes onto the separator plate......hope that makes sense.....

[YoungPup1977]

Take a pic of the VB and internal linkage to the manual valve please....

Did you adjust the manual valve so its even with the casting of the VB ? The "S" piece that fixes into the manual valve installed correctly ?

Second hand information can bite ya most of the time, i always wonder why they pulled the trans out, ya know ?

I like pics, provide some pics and we can see if anything is wrong for starters....thanks.

[Cyborg]

Thanks so much for the replies! GM valve body so I know it’s not reverse. It’s doesn’t have the s link it’s an early 69 style more of an L. I took a break and looked at it again after work and realized there is two ways to put it in. I believe this is the problem and will be filling it up shortly. Will let you know how it works out and send a picture if not.
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[Cyborg]

I am an idiot that was it. I didn’t follow my number one rule. When something doesn’t work out walk away for a while. Things always seem to work there way out after that.
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[61K10]

Glad you figured out. Funny how that rule seems to work all the time.

[YoungPup1977]

Here is a pic of the L type of linkage used on 1969 T350's and earlier....in 1970 GM changed this to the S type linkage which can not be installed incorrectly....