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.

matt69olds

Stand the transmission with the bellhousing up.

I assume you used a couple large hose clamps to align the pump half’s before torquing the pump bolts? The pump will never seat if the pump half’s aren’t centered.

Pull the pump back out. Carefully grab the input shaft splines with a pair of Vice grips. Use a rag or something similar to protect the spline. You don’t need a lot of clamping force, don’t get crazy.

Wiggle the input shaft back and forth, hopefully the drums drop down.

Make sure the the pump bearing or thrust washer is in place. Use a blob of Vasoline to hold it in position, make sure the sealing rings are in place. Install the pump, slowly tighten the pump bolts while stopping frequently to make sure the input shaft turns. Torque the bolts, if the shaft still turns check for proper endplay. If the endplay is good, relax.

joe_padavano

^^^THIS! It's very easy for parts to move out of alignment unless the trans is oriented bellhousing up.

getmygoat

Thanks.. Turns out when I pulled the front pump out the direct/forward clutches disengaged slightly from their splines. Forcing the front pump in damaged the clutches in the drum in front (is that direct or forward IDK). Have new clutches on order. Should receive them for install this weekend.

I screwed it up in other words... but the trans will have some new clutches.

I've made some stupid mistakes in my history of wrenching.. this one is up pretty high on the list.

matt69olds

Every transmission builder has done it before. Look at it this way, that’s a mistake you are very unlikely to make again!!

Fun71

And you have new clutches. That’s a good thing.

getmygoat

Thanks for the encouraging words. So new clutches installed but I still can't get the front pump to sit flush. I jiggle and jiggle the drum assembly and slowly it clunks down further and further as the clutches align. Eventually it stops dropping, but it doesn't seem low enough. I'm running out of ideas. This project really went south on me.

If anyone has any thoughts, it would be much appreciated. Ideally I could confirm both that the direct drum is all the way down and the forward clutch is all the way down in some more quantitative way than the front pump fit. The band that goes around the forward drum seems correctly oriented on the drum (e.g. not too far back) but I don't really know what a correct install would look like. There's a ridge in the case that somewhat looks like a resting place for the intermediate clutch backing steel? - but that is definitely lower than the flat surface on the forward drum so that might be an indicator things are too high... but if that's the case I don't know why.

I made a video explaining why I'm pretty sure the drum is sitting too high. I just don't know why:


Thanks again for any thoughts.

matt69olds

Will the input shaft turn with the pump snug?

If the shaft is locked, maybe a thrust washer fell out of place? Refresh my memory, did you change any parts inside the transmission? There are pumps that take thrust washers, other that take s bearing. If you put a bearing on a thrust washer style, it will lock. If you go the other way, you will have a ton of end play.

What exactly have you done on this project?

getmygoat

Project started as a simple "replace front pump seals to stop leaks" - but when I pulled the front pump out with the transmission horizontal, I unknowingly dislodged at least one of the forward clutches (in front of the direct drum) - thus bending it when reinstalling the pump. Purchased new clutches and replaced all clutches in direct and forward drums. Now trying to reassemble. I did not disassemble the front pump. As shown in the above video, I'm now 90% sure the drum assembly is too high and its not a pump fitting problem. You can also contrast what's in my video with the screen shot below of a correctly assembled trans. You can see how the drum in the screen shot is lower relative to the steel than in my trans.

I didn't rebuild anything else. All washers, bearing etc should be as original. There is a plastic washer behind the direct drum and I am making sure that is in place before every reassembly attempt.

matt69olds

Ok, if everything is the same as before it’s just a matter of reassembly.

Make sure the thrust washer under the annulus gear is positioned correctly. Some of the later models use a bearing there, make sure it’s on position. Use a blob of Vasoline to hold things together.

Place the bearing on the forward clutch housing, set the direct drum in position and shake and wiggle until it is fully seated. Then place the entire forward/direct clutch in the transmission and wiggle the input shaft until the forward clutches are all lined up. Place the intermediate clutch backing plate and clutch stack in place. Put the gasket on, use old bolt with the head cut off as an alignment tool. Set the pump in place, slowly tighten the pump bolts while frequently checking to make sure the shaft turns. Once the bolts are tight, the input shaft should still turn. Recheck the endplay. Once it’s tight, you should be good.

getmygoat

Shouldn't the pump sit flush when I drop in? Did you watch my video showing the issue with the intermediate clutch in relation to the backing steel and the forward drum? Seems wrong. (I assume forward drum is forward of the direct drum)

That plastic washer at the bottom (behind direct drum) with the three tabs sometimes sticks to the bottom of the drum assembly so that indicates the direct drum is all the way down. The forward drum doesn't touch the direct drum when it seems fully seated but I wonder if there is a reason for a gap there as the gap is not tiny.

Also I don't think the forward drum? tabs are all the way down into those slots in whatever that outer shell thing is called.

matt69olds

For whatever reason, I can get the video to play.

The picture of the pump seated in the trans looks normal.

You never answered, with the pump bolts tight, will the input shaft turn? And if so, is the endplay within reason? From the factory, th350s are built with some sloppy endplay, after decades of use I’m betting it’s worse

getmygoat

I think I might have figured it out. Dumb but the trans is sitting on output shaft (vertically). If I lift the weight of the trans off the output shaft I get more clearance at the front intermediate pressure plate. Will confirm tomorrow.

Fun71

Well that sounds reasonable. Kinda one of those forest for the trees things. Glad you figured it out|