Ok transmission started making a nasty noise but gears still work . I took it out of car and I'm contemplating tearing it apart to see what happened . I don't know much about the inners on a transmission , but I have nothing to lose either really by trying to take it apart a bit to see . The rear shaft towards drive shaft has a lot of play in it , I can wiggle it back and forth . The shaft on the other end where torque converter sits is all chewed up it looks like .

 

What were the symptoms? That stator support smtibe looks like trash, most of the splines appear missing.

There will be some slop in output shaft movement. The output shaft is centered by the drive shaft yoke, which in turn is centered by the bushing in the extension housing.

There are dozens (probably hundreds) of teardown videos on YouTube. The th350 is pretty easy to build. Very few special tools are needed, abd those tools are easily fabricated by stuff most people have laying around the garage.

 

Good to know , I'm definitely going to check out some videos while I'm attempting this .

 

These are two of the better videos on rebuilding the TH350
I watched these before I rebuilt mine, along with a ton of help from Matt (Matt69olds)


My rebuild thread
https://classicoldsmobile.com/forums...=TH350+rebuild

 

There are a few areas of a transmission that are unique and are a lot easier with special tools and some special knowledge. Most of it is straight forward though. I rebuilt a th350 in college with basic hand tools. The pump ended up destroying itself because I didn't know how to check them, and I trashed the piston return spring cages by using the "2 c-clamp trick" to disassemble the baskets.
Decent drum compressors are now available very cheap on amazon. The only really interesting one in the 350 is the low/reverse piston which is down in the bottom of the case. You can just leave that in place for a quick rebuild though.

That stator support is trashed! that would have sent a lot of metal through the converter and the trans, likely causing quite a bit of damage.

 

Thanks for the input on this , this will come in handy

 

Started watching 1st video from above . I'm bagging / tagging everything at this point .... before I get started I was wondering where 1 and 2 sits on ( torque converter and ? ) .

 

Ok , 1. there's no filler tube boot , 2. No kick down cable o-ring , 3. Does this look like the cover snap ring to you? There's no slot to put a screwdriver in to get it out if there is one .

I have no idea if this transmission is original ( I seriously doubt it ) . The engine was long gone when I bought the car . I'm fairly confident that the transmission went with the original motor . Maybe a 76 because that's what year engine was in this car when I bought it.

 

I got the snap ring out after finding the little hole covered in old dirt / grease. Took the accumulator out and no spring like it shows in the video .

 

It’s common to omit the spring. I think certain calibrations from the factory had no spring. No big deal.

The original dipstick used a o-ring on the dipstick. The later boot style seal is much preferred. The o-ring tubes tend to crack and leak.

The later kickdown cables used a boot.

 

Ok , so the stator support is trashed , or at least the splines on the shaft where it engages is trashed ? Sorry , I don't know very much about transmissions or how they tick . I know my life threw me a ton of curve ***** and I'm once again running out of money . I want to enjoy this car and drive it again , that's why I'm doing this . I also like to tinker and learn at the same time so try to be patient with me . I'm kinda throwing this out there ahead of time because of the jack wagon that had to come into my u-joint thread and talk stupid .

 

I'm also beginning to wonder if a portion of the problem was my fault to begin with , because the plastic torque converter cover was absent for a period of time . It seems kind of obvious at this point that the torque converter caused the splines to get ground off . I know I put everything on right because it drove just fine for 5 years or so without any issues .

 

These look like cracks to me . I'm not sure what would cause this .... overheating ?

 

I only have one check ball 😆 , no pun intended .

 

Ok , forget what I asked 7 posts ago , I get it now . That was one long spline with part of it chewed up . What would cause the torque converter or whatever to move ? I'm assuming that's what was sitting on that spline .

 

I thought that maybe I installed the torque converter incorrectly but wouldn't the wear be on the outside of the spline , not the inside ? I put the transmission in about 6 years ago give or take

 

It’s not common, but occasionally th350 tear up the splines on the pump. Replace the pump and converter more than likely all will be good.

Since the trans has only has one check ball, someone has put a shift kit of some kind, either store bought or homemade.

Post a pic of the spacer plate and the parts under the transfer plate.

 

Yes I will post a picture , and yes on the shift kit . I bought this transmission from a speed shop

 

The stator support is the part that, well, supports the stator. There are some decent videos about torque converters on yourtube these days. There are three main parts in a torque converter: the back part of the case is the "pump" and spins with the engine and pumps the fluid. The inner forward portion is the "impeller" which sits on the forward-most and smallest shaft on the transmission - that's the input shaft. When the pump pumps fluid it tries to make the impeller move and when it does move, it turns the transmission. To improve efficiency there's a "stator" put in the middle which helps redirect the fluid. It's held in correct alignment by the stator support, and it has a one-way clutch so it can only spin one direction.

Splines tear up because the load put on them is too high. It could be that was a low quality stator support (many transmissions end up requiring a hardened stator support when put in performance applications), it could be something went wrong inside the torque converter and it locked up forcing the stator to turn the wrong way. Regardless, that torque converter needs to, at a minimum, be cut apart and rebuilt.

The aluminum castings for the TH350s just look like that. Consider it a style choice.

 

Thanks for the information

 

I'm assuming this is the spacer plate . I'm not sure what other pictures you wanted and where it's located

 

A performance shift kit will include a couple extra plates that are sandwiched between the valve body plate and the thick factory transfer plate. The extra plates are part of the dual feed modification.

If you look at the direct drum, you will notice there is a seal inside the drum. For some reason, HydraMatic decided to split the direct drum into 2 separate chambers, one chamber for reverse, the other for high gear. The dual feed medication combines both chambers of the drum, almost tripling the clamping force.

There are a couple of ways of doing the dual feed. One involves just installing a shift kit. The special transfer plates block off and redirect oil as needed. The advantage of this method is it requires no major transmission disassembly, and can be done with the transmission still in the vehicle.


The other way involves removing the center seal, removing one seal from the pump support, and blocking a hole in the case. This is the preferred method, it eliminates potential hydraulic leaks, and shortens the hydraulic path tge oil has to take to do its job. The disadvantage: it requires transmission removal and partial teardown.


Pay attention to the direct drum when you disassemble it. Note if there is a seal inside the drum, there should be 2 seals on the piston. Once you have that info, report back and I’ll have a better idea of what was done.


What was bolted here? Just one single thick plate, or a thick plate with a couple thinner plates sandwiched in between?

 

Direct drum ? It looks like the shifting linkage / piston is in that area with that S hook clip.

 

Performance shift kits include a special spacer plate in addition to the stock plate that bolts into the area I circled. You can do the exact same thing by plugging a hole in the case, and leaving a couple seals off in the direct drum and pump.

In other words, is there are 3 plates total (the factory plate, and 2 transfer plates) then the direct drum/pump needs the seals. If there is only the stock plate, then for the dual feed modification to work correctly you need to plug a hole and omit the seal on the drum.

 

There's a metal plate , a thin gasket that connects to that and the thick cover where all the bolts go through . I'll look at the pump for seals

 

Quick question. My 75 Delta doesn't seem to have reverse. I checked the fluid and it seems fine. Car only has 54K original miles. I was wondering if this is normal. Complete tear down and rebuild?? Just looking for input . Thanks

 

It's going to be a while before I can do anything because of financial issues . I'm worried about replacing parts and having it fail again because there was another issue I wasn't aware of because I don't know jack about transmissions . I may end up just getting another transmission and keep this one for parts or use as a core charge / trade in

 

I guess I have to ask .... What are the chances that the pieces of spline got inside the transmission itself and if there are any other risks involved by fixing instead of replacing ?

 

Ok , how about a 700R4 transmission . Will that drop in without any welding involved or any other special tricks?

 

I thought about moving your last post to a new thread.

​​​​​A 700R4 isn't a direct swap. Many folks end up using a 2004R instead (BOP bellhousing).

Whatever happened with the TH 350 you were going to rebuild? Even if hard parts came apart inside the transmission I wouldn't worry about any lasting damage if you do a full rebuild. Give us an update.

 

I'd love to rebuild the T350 , but this was my first time opening up a transmission. I figured i was probably out of my element . I thought having overdrive would be nice .... if the 200R4 doesn't have overdrive then I may as well get another T350 / T400 , unless someone convinces me to rebuild the current one I have

 

The 2004R is an overdrive transmission as well. You have to have the right gears in your differential to use an overdrive transmission though. Do you know what rear gears you have? Of course, swapping in a 700R4 or 2004R is going to be just as difficult; if not more so, than rebuilding an automatic transmission.

BTW, what car do you have? You mentioned earlier that you thought it had a swapped engine/transmission already.

 

I have a 72CS that had a 76 350 in it when I bought it . I since then put a 455 in it from a 68 Toro. The car was your basic 350 single exhaust one wheel wonder . I haven't replaced the rear axle yet . I'm confident the rear has a 2. something in it . I'd probably have to do a bit of research to confirm the actual gear ratio

 

I'm guessing drive shaft length may be an issue on the 200R4 perhaps ? What other things may I need to know in order to drop that in ? It was a lot of work when I put the T350 in / out , but fairly straight forward. I'm just paranoid about getting the torque converter on there correctly now after what happened . 5/8 of an inch from the top of bellhousing from what I read .

 

The 200R4 is an easy swap. The driveshaft can be reused as is. The transmission crossmember needs to be slide back, using the factory holes in the frame that a TH400 transmission uses. It’s no harder than reinstalling a TH350 trans.

The easiest and most foolproof way to avoid plump damage from mid-installed converters is to SLOWLY tighten the bellhousing bolts, while frequently checking to make sure the converter will still spin if the converter locks solid with space between the block and transmission, stop immediately and find out why.

 

Thanks , much appreciated. It's kinda foggy , but I remember having to inch the converter a bit towards the flexplate when I had the bellhousing bolted to the engine because there was space in between the two . I drove the car without issues for like 5 years before I started hearing a clicking noise that gradually got louder in time. Then one day it started making a loud awful noise. That's when I stopped and had it towed back home

 

I had my 350 turbo replaced in my 75 Delta a few weeks ago and wow what a difference. Took it for a ride before I put it in the garage for the winter and was very satisfied. Can't wait for the warm weather. Carry on and enjoy the day

 

Ok , so I'm at a crossroad on repairing this transmission or getting another one . I could get a nicely done 200R4 for around 2K , but I may be able to fix it for around 600 . There seemed to be way too much play on the rear shaft IMO . I might be better off with the extra gear / fresh rebuild. What do you think

 

The output shaft will kinda flop around without the yoke. I wouldn’t base my decision on that alone.


If you’re willing to spend the money to do it right, I wouldn’t hesitate to use a 200R4 trans. The deeper first gear will make the car feel like the engine has an extra 50hp, and the overdrive and lockup converter will make the car much more comfortable on the highway.

 

Say no more , im convinced lol . This was and is a great learning experience . I feel more comfortable tearing into a transmission if needed in the future . I'm actually learning / realizing things along the way .... like there's no way pieces of splined shaft have any way of getting inside transmission from torque converter that I can obviously see , so I don't have to worry about contamination inside transmission . I'm still leaning towards the new transmission either way