[getmygoat]

Hi all,

Attempting to reseal the front pump on my turbo 350 '76 cutlass. Pulled the pump and replaced the seals no problem. However, reinstalling the pump not going well. I can get it to where the case of the pump meets the transmission case, but then it stops. Won't go in any more despite lots of jiggling. The first time, I was able to get the bolts started and started cranking them down fairly evenly. The pump seemed to be going in but the bolts were getting tighter w/o pump being flush and I started to worry maybe something was binding and didn't want to damage anything.

I've done some internet searching and it seems that in some cases a washer deeper in the trans can become dislodged and then the stuff behind the pump sits too far forward for the pump to go in.

I'm not sure if that's my problem or if I'm just being too timid cranking down those front pump bolts. Have seen videos where the front pump just drops into position with no resistance so I'm suspecting something isn't right.

Any thoughts on how to proceed? Ideally I could somehow determine definitively whether the rest of internals are sitting too forward or they are in ok position. I'd hate to wade deeper into the trans if not necessary.

Thanks for any insights.

[73LeMans]

Ive only done one TH400 so it might be different on a TH350.....but if the center support bolt and/or snap ring wasn't removed, everything below that to the tail should be fine. Working up from that, my guess is the forward drum came needs the forward clutches realigned to seat properly. Its also possible the direct hub did the same with the intermediate/direct clutches.

[getmygoat]

Thanks, would I need to pull the valve body to adjust those items or can I just do it from the front? Some videos I saw suggested maybe the valve body would have to come off, which I'd like to avoid (I just had it off a month ago to install a trans go shift kit but prefer to not revisit). One video on youtube showed a plastic washer coming out of its location behind the drum which was holding things up. Thanks

[Half-Inch Stud]

Yea well, the clutch packs are not seated fully through the frictions. Expect to see some bent frictions upon disassy-discovery.

[73LeMans]

Originally Posted by getmygoat

Thanks, would I need to pull the valve body to adjust those items or can I just do it from the front? Some videos I saw suggested maybe the valve body would have to come off, which I'd like to avoid (I just had it off a month ago to install a trans go shift kit but prefer to not revisit). One video on youtube showed a plastic washer coming out of its location behind the drum which was holding things up. Thanks

Valve body can remain in place

[getmygoat]

OK so I tore things down somewhat. Had to remove the valve body to get that band out so I could remove that forward drum. No obvious damage to anything. That plastic washer at the back was out of place but unknown if that was from disassembly or the original problem.

Tomorrow will configure trans vertically somehow and try to reassemble.

How would I look for damage? I doubt the most forward clutch pack would be damaged as the pump would have been pushing against the forward drum I think? So then it would be the clutch pack in the forward drum that might have been damaged?

Thanks for all the advice thus far!!!

[chuckies76ta]

I'm like post #2. I've only done Th400's. Few thoughts. Make sure to put a bit of tranny fluid on the pump o-ring when installing so it doesn't bind.
Also, does the pump use sealing washers on the bolts? You can also put a tiny bit of sealer on the washers. Did you change your front seal if your having leaking issue while your at it?
Never put bolts in and try to tighten or force the pump into place. It should go into place with a few soft taps, back of wooden hammer handle. Taping back and forth. The best way to install the pump is with a few dowels. Take a couple of bolts and cut the bolt heads off and use them to guide the pump into place. Make sure after you install the pump, you should had some endplay on the input shaft.
Depending on how much pressure you put on the bolts when first installing, I doubt you damaged any clutches of steels. You could check the forward drum.

[Half-Inch Stud]

Same here; I've only done TH400s, and 4L80s. Vertical stacking is a good plan.

[getmygoat]

Thanks guys.

I really screwed this one up. Need to verify front pump this AM also I think.

[73LeMans]

Apologies for misleading you on the VB.

On the bright side these folks here on this thread, and videos from Mountains Garage on YouTube to name one, were instrumental in getting me though my trans. You get this one nailed too.

I had the same pump problem and resolution for me was the direct drum wasn't seated properly. If you aren't using lightweight aftermarket stuff, and even when you are, there is so much weight there, its hard to know if it engages all the clutches successfully. By the looks of the pump, its not off by much. I had to do it a few times before I realized the drum wasn't fully seated.

[getmygoat]

Originally Posted by 73LeMans

Apologies for misleading you on the VB.

On the bright side these folks here on this thread, and videos from Mountains Garage on YouTube to name one, were instrumental in getting me though my trans. You get this one nailed too.

I had the same pump problem and resolution for me was the direct drum wasn't seated properly. If you aren't using lightweight aftermarket stuff, and even when you are, there is so much weight there, its hard to know if it engages all the clutches successfully. By the looks of the pump, its not off by much. I had to do it a few times before I realized the drum wasn't fully seated.

Yup - turns out I damaged a clutch in the direct drum. It is difficult to know what's seated. I kept focusing on the set of clutches below that - but then light bulb finally went on and I checked out the direct drum clutches and bingo. Not sure if it shows up in the pic but its messed up.

[getmygoat]

Not sure if anyone has any words of wisdom to offer... So I replaced the clutches in both the direct and forward drum, but am still not able to get the pump to go in flush. I giggle and jiggle with the clutches progressively aligning and the assembly dropping further and further down. Eventually it stops going down, but the pump still sits too high.

Thanks for any advice!

[getmygoat]

I made a video describing why I'm pretty sure the drum assembly is too high.. but I've tried and tried to get it to drop down further and I'm out of ideas. Any thoughts appreciated!

https://youtube.com/shorts/ugNaK3lS8_Q?feature=share

You can contrast my video with the attached screen shot of a correctly assembled trans. Note the difference in the relative position of the outer steel and the drum flat surface.

[Lemans64]

There should be up and down play in the input shaft when seated if no play you have something wrong. But i'm no expert on this. Just my 2 cents.

[beemergary]

I'd start taking some measurements. Just did a 400 and had your problem. Something not dropping in place. I worked in a Gm transmission factory in 1968-71. Those assembly lines where really going fast and lots of trannies went to repair.

[chuckies76ta]

Go get yourself this book and checkout how the parts are removed and installed. When fitting the pump at the end, leave off the pump o-ring and gasket till you get the pump sitting in properly.