A TH350 in a '79 Estate Wagon, Seriously Buick!!!!! And let's talk shift kits

[MrEarl]

Because TH400's had been out for years and given the size and weight of the wagon, I had always just assumed that my estate wagon was carrying a TH400. Knowing that the oil pan on a 400 looks like the state of Texas on drugs,

 

 

 

imagine my surprise when I'm looking under the car yesterday and see this freakin state of Utah thing lookin back at me. 

 

A bit disappointing. Please somebody, tell me I'm wrong or  that the 350 really isn't that bad of a transmission and that it's lighter and can handle torque well and blah blah... Please....

 

 

 

 

 

 

Edited May 2, 2019 by MrEarl (see edit history)

[avgwarhawk]

29 minutes ago, MrEarl said:

Because TH400's had been out for years and given the size and weight of the wagon, I had always just assumed that my estate wagon was carrying a TH400. Knowing that the oil pan on a 400 looks like the state of Texas on drugs,

 

 

 

imagine my surprise when I'm looking under the car yesterday and see this freakin state of Utah thing lookin back at me. 

 

A bit disappointing. Please somebody, tell me I'm wrong or  that the 350 really isn't that bad of a transmission and that it's lighter and can handle torque well and blah blah... Please....

 

 

 

 

 

 

 

I have yet to blow up a 350.  My era of burn outs and neutral drops consisted of the 350 transmission.  Keep the fluid changed and she'll go for miles upon miles like nothing.  

[avgwarhawk]

Quote

Since its inception into the 1969 passenger cars, the TH350 transmission is considered to be “Ol’ Reliable,” becoming a mainstay in the production lineup up until 1986. It backed countless General Motors production cars, and is basically considered a three-speed version of the old Powerglide gearbox found in many cars built during the ’50s and ’60s. It continues to be a popular transmission today with drag racers and street rodders, and we feel that there’s always going to be an interest in them, despite the rising popularity of the late-model electronic transmissions.

 

 

Enough said! 

 

https://www.chevyhardcore.com/tech-stories/diagnosing-gm-transmissions/

[avgwarhawk]

As a side note and you are already on top of it....heat is a transmission killer.  You are working on a separate cooler.  Once best thing you can do for the 350 when pulling your trailer!   

[JohnD1956]

I had two 78 estate wagons with the turbo 350. I endorse that tranny. But isn't yours an overdrive unit? 

[avgwarhawk]

2 minutes ago, JohnD1956 said:

I had two 78 estate wagons with the turbo 350. I endorse that tranny. But isn't yours an overdrive unit? 

 

 

I do not believe the  OD was an option in 78 if I remember correctly.  I seem to recall the OD on 80's models with low HP V6 or V8 ahead of them.   Not the best combo from my recollection. 

[MrEarl]

OK, my apologies Buick, sounds like you were good for that time.  Thanks guys for words of support, guess I had just heard so much about the 400 and wasn't giving the 350 it's due.

So, no JD no overdrive that I have found.

 

 

If there was one I think I would have found it yesterday when I took her out to stretch her legs on a newly opened stretch of a local by pass and the speedo pegged out.  But here's a question I hope someone familiar with driving the 350 can explain. I'm not feeling it hitting a definite passing gear at any speed above say 35. Below 35 and yea it feels like a definite downshift but above that just more power from accelerating. Make sense. Thoughts?

 

Topic edit: It has been suggested by a few here to install a shift kit. From what I read they will improve shifts in tired and worn as well as newly rebuilt. I've  have learned there are two kits, one for towing/RV and one for street and strip. I was looking at ordering one and using the towing/RV kit. Thoughts?

Edited May 2, 2019 by MrEarl (see edit history)

[Ronnie]

27 minutes ago, MrEarl said:

I'm not feeling it hitting a definite passing gear at any speed above say 35. Below 35 and yea it feels like a definite downshift but above that just more power from accelerating. Make sense. Thoughts?

 

The TV (throttle valve) cable might need to be adjusted to get it to downshift properly.  I would go with the towing/RV shift kit. Some of the racing shift kits can be harsh feeling when they shift.

[SpecialEducation]

We did plenty of damage pulling a camper with our '77 403/400.  Not all they are cracked up to be.

 

350 is more efficient, but truth be told, I'm gonna put a well built 200-4R in Bertha.  Better gear ratios, OD, and lockup converter.

I don't remember when the 350Cs came along.  I'd at least consider a swap to a lock-up converter if it ever comes to it.  

[avgwarhawk]

I would not bother with a shift kit.  It only helps to catch second gear, a squeal at the back drive tire and possibly broken parts before long. 

 

As for the kick down,  you should feel it even at 55 mph if I remember correctly.   It may be mimicking a kick down at 35 but is not really kicking down a gear.  I would check the cable at the throttle is in good knick(if it is set up with one)  or check the down shift modulator on the side of the trans(more than likely has this set up).  Vacuum and holds vacuum...etc.  If this gets a hole in the diaphragm it will pull trans fluid up to the carb.  Smoke will pour from the tailpipe.  Probably a good item to replace with new anyway.  Easy install no frills replacement.     

 

 

 

   

Edited May 2, 2019 by avgwarhawk (see edit history)

[JohnD1956]

2 hours ago, avgwarhawk said:

 

 

I do not believe the  OD was an option in 78 if I remember correctly.  I seem to recall the OD on 80's models with low HP V6 or V8 ahead of them.   Not the best combo from my recollection. 

 

I had a 78 Electra and it did have the overdrive.  But the two wagons had the turbo 350's.  Both wagons were much more satisfying to drive in terms of usable power. 

 

As to the passing gear question, @MrEarl  Can't remember if I ever tried to pass people with the wagon.  Also can't remember if that car has a lock-up torque converter.  If it does there-in may be the cause.  That usually locks up above 40 mph.  and at 85 mph it may not be willing to unlock.  

 

[NTX5467]

Mr. Earl,  perhaps you're getting things wadded up too soon?  Not ALL THM350s were internally equal!  Not "generic" by any means.  Number of clutches in the clutch pack can vary, for example.  The most HD version was in the '81 Corvette L82/Camaro Z-28 cars.  Most clutches in the clutch pack, V-6 converter for a higher stall speed, lockup converter to boot.

 

The THM350 takes about 15 horsepower LESS to run than a THM400, but the THM200 family takes a bit less.  End result, MORE useable power to the rear wheels.

 

Not sure about your "kick down" issues.  Of course, you can always manually downshift when needed!  The vacuum modulator controls part-throttle kickdown and upshift firmness, with the cable linkage doing the WOT inputs.

 

Back up to the side of a door frame.  Stand up straight, take a deeeeep breach, and say "Somebody knew what they were doing when they designed my car.  I will have faith . . ." as you exhale.  Repeat ten times.

 

NTX5467

[MrEarl]

On 5/2/2019 at 1:54 PM, SpecialEducation said:

We did plenty of damage pulling a camper with our '77 403/400.  Not all they are cracked up to be

 

Probably nothing I really want to hear I suppose. 

[MrEarl]

19 hours ago, NTX5467 said:

 and say "Somebody knew what they were doing when they designed my car.  I will have faith . . ." as you exhale.

 

Oh I never doubted the Buick engineers and after driving her around the countryside this last week I’m gaining faith in her everyday. So no need in me doing all that breath, hyperventilating, passing out and giving Rita a scare 

[SpecialEducation]

It’s been said here before. Heat is your enemy.

 

In ‘82 we brought our camper down to Kansas from Michigan. Remember that it was nationwide double-nickel back then, so it’s not like we were pushing it hard. 

 

Terrible headwind across Missouri & Kansas. The Olds 403 didn’t break a sweat; it was in its element. Even though the wind chill was -10°F, we cooked that 400. Damage wasn’t obvious right away, but it reared it’s ugly head soon enough. 

 

Even today in my 2018 2500HD, the #1 thing I watch when pulling the monstrosity in a headwind is trans temp (I don’t have the stomach to look at fuel economy).

Edited May 5, 2019 by SpecialEducation (see edit history)

[NTX5467]

The  nice thing about your 2500HD is that somewhere in the DIC stuff, could well be a transmission oil temp page.  Just use the steering wheel controls to go back and forth to it, every so often.  Fuel economy is in there, too.

 

No need to hold your breath for any time at all, just a full methodical exhale until your chest deflates, then a slow inhalation of air.  That whole deal might take only about 2-3 minutes.

 

Enjoy!

NTX5467

[avgwarhawk]

2 hours ago, MrEarl said:

 

Oh I never doubted the Buick engineers and after driving her around the countryside this last week I’m gaining faith in her everyday. So no need in me doing all that breath, hyperventilating, passing out and giving Rita a scare 

Always nice to have ones vehicle prove itself. 

[JohnD1956]

2 hours ago, SpecialEducation said:

It’s been said here before. Heat is your enemy.

 

In ‘82 we brought our camper down to Kansas from Michigan. Remember that it was nationwide double-nickel back then, so it’s not like we were pushing it hard. 

 

Terrible headwind across Missouri & Kansas. The Olds 403 didn’t break a sweat; it was in its element. Even though the wind chill was -10°F, we cooked that 400. Damage wasn’t obvious right away, but it reared it’s ugly head soon enough. 

 

Even today in my 2018 2500HD, the #1 thing I watch when pulling the monstrosity in a headwind is trans temp (I don’t have the stomach to look at fuel economy).

 

I wonder which rear axle ratio was in that car?  Being a '77 it may have had the 2:48 rear axle, especially if it was a coupe or sedan.  That rear axle was a real power killer!  The Electra we had with the 350 motor and the overdrive also had that 2:48 rear axle, and the only way you could pass someone was if your lane of traffic opened up while everyone else was stopped!   That car almost soured me on ever buying another Buick! 

[MrEarl]

The limited slip in the wagon is a 3.23 and you can you certainly tell it when you let off the gas abruptly, sorta throws your head forward. Within the invoices I received from the original owner was one for a new set of gears and bearings installed at like 105k. Hopefully I get another 105 out of this set. 

[NTX5467]

12 hours ago, JohnD1956 said:

 

I wonder which rear axle ratio was in that car?  Being a '77 it may have had the 2:48 rear axle, especially if it was a coupe or sedan.  That rear axle was a real power killer!  The Electra we had with the 350 motor and the overdrive also had that 2:48 rear axle, and the only way you could pass someone was if your lane of traffic opened up while everyone else was stopped!   That car almost soured me on ever buying another Buick! 

 

Back along about '83, my company truck was a C10 5.0L V-8, but back then, everybody was about "fuel economy" and the std axle had become 2.56.  Now, with that rear axle gear, it would run all the way to 57mph in Low in "D", all by itself, at WOT.  "Five FULL LItres of Throbbing Torque", I said each time.  It got worse in hot weather, for some reason.  One day, on a metro divided street, I came up behind a lady in a 5-cyl Mercedes diesel.  I was/thought I was in a hurry, but as I moved to the inside lane after a red light, she didn't know I was desiring (key word!) to pass her.  Had to give up!  Even the earlier 5.7L GM diesel we had in '78 could have passed her, with a 2.76 rear axle ratio.

 

There was one place I went regularly.  When I pulled out, if I caught it "right", a bit of rear wheel spin would elevate the engine rpm enough for better acceleration.  Hitting the on-ramp just before the 1-2 shift at 57mph.  That was on a good day.

 

When the TBI 5.7L V-8s came in '87, everybody raved about the new power.  Until the 3000 mile free oil change, when they complained about lower fuel economy.  But with careful driving and cruise control use, I logged many tanks of fuel at 20mpg, with a 3.08 axle ratio.  With the THM700OD we had back then.

 

Those "downhill highway" gears did one thing.  They reduced engine rpms and resultantly kept the "grams/mile" of emissions down so the vehicle would pass EPA regulations.  In the real world, a little lower ratio would have worked best for fuel economy with carbureted engines.

 

Back to my earlier comment about "having faith", that doesn't seem to work with some of the newer GM 8-speeds.  Not sure what they think they need to do!  FAR too many complaints of "shifting funny" issues and/or failures.  Especially with computer controls, which tends to relate back to "programming" issues.  Only in some applications, it seems.  Where's the aftermarket when you need them?

 

Even so, there has to be a reason they were programmed that way, from the factory.  Possibly that the OEM code helps them barely get by something they need to get by from?  Fuel economy with the much-needed horsepower production advantage?  Gotta be "a story" in there, somewhere!  The other thing seems to be the extreme computerization of getting information "from the cloud" to check for programming errors and related "re-flashes".  LOTS of TSBs, so "they" know about it, but the fixes seem too involved for what they are, to me.

 

Can't forget about the "beyond Dexron VI" atf some of them need.  About $45+ a quart?  But in relationship to the cost of the affected vehicles, that's "not much".

 

Enjoy!

NTX5467

[SpecialEducation]

On 5/4/2019 at 9:48 PM, JohnD1956 said:

 

I wonder which rear axle ratio was in that car?  Being a '77 it may have had the 2:48 rear axle, especially if it was a coupe or sedan.

 

Hard to know what the axle was this many years later, but we bought that car to haul, and it would HAUL! 

 

It left many a Mustang & Camero in its dust wondering what had just happened.  If it had something as tall as a 3.08, I’d be surprised. The way it would light up the tires off the line, I’m sure it was a 3.23 or shorter. 

[dmfconsult]

On ‎5‎/‎2‎/‎2019 at 9:45 AM, MrEarl said:

I'm not feeling it hitting a definite passing gear at any speed above say 35. Below 35 and yea it feels like a definite downshift but above that just more power from accelerating. Make sense. Thoughts?

 

A little late to this thread, but I have my wagon a test run, and it will in fact drop down to a passing gear above 35 mph or even above 55 mph.  It sure makes a bunch more noise, but I'm not sure if accelerates any faster, and seems to be best for dropping a gear while climbing a long gear.   I do have the TH350 and 3.23 rear end (non-posi) and the 350 engine.  Seems like an adjustment on yours is in order.

[NTX5467]

Part-throttle kick-down is the domain of the vacuum modulator on the rh rear edge of the trans case.  It operates from intake manifold vacuum levels and also somewhat compensates for "altitude changes".  WOT kick-down is the domain of the cable linkage from the carb to the trans, on the lh side of things.

 

EACH downshift should be noticeable, but smooth, whether in engine busyness or acceleration increases.  If you need a reference point for engine noises, start with the trans in manual "1", get to a certain speed (probably about 35mph), upshift to manual "2", and notice any changes.  Then continue to about 60mph and shift into "D".  Noticing how things sound and feel.  Then go WOT and see what happens.  You might want to do this with the driver's window "down".

 

IF you had an Olds 307 in that wagon (as later Buick full-size wagons did), then any downshift at highway speeds would just cause more engine noise, with little increase in velocity, unless you were going downhill, by observation of the one I drove for a customer, one time.  AND it was rated to tow a trailer, too!

 

Even with the 3.23 rear axle, those cars were NOT "hot rods", although the connecting rods would probably get hotter under full-rated load.  Lubed the u-joints?

 

Just some thoughts,

NTX5467

[Barney Eaton]

I'm a big fan of auxiliary transmission coolers.......heat kills transmissions and the trans fluid is going to the radiator to get cooled.........so how hot is the transmission fluid if it gets cooled in the radiator

that is around 190 on a good day?

 

In Georgia you could eliminate the radiator cooler and just a big auxiliary cooler that is in ambient air.  

In theory,   by taking the trans fluid out of the radiator,  it will be more efficient since it is not cooling the transmission.

[60FlatTop]

20 hours ago, dmfconsult said:

It sure makes a bunch more noise, but I'm not sure if accelerates any faster,

 

They spent a lot of time making sure the doors made the correct thunk sound, too.

 

Lots of high performance and engineering speculation here. Have you put a pry bar under the motor mount ear to be sure the rubber is still attached to the metal? Might be the weakest link.

Bernie

[MrEarl]

 

 

Good news: Transmission shop got the passing gear back by adjusting

 

On 6/2/2019 at 8:38 PM, NTX5467 said:

the cable linkage from the carb to the trans, on the lh side of things.

 

 

Bad news: When changing out the oem pan to a deep sump pan he found this

 

 

the broken off end of a band along with a bunch of glittery stuff in the fluid

 

Fix: Total rebuild including installation of a RV/towing shift kit  $1620 

 

Thanks for all the feedback my friends 

sorry to be so long getting back, just been a bit busy having fun working on cars

 

 

 

 

 

 

 

 

Edited June 5, 2019 by MrEarl (see edit history)

[avgwarhawk]

Some glittery stuff in the fluid is generally seen. At least in my experience with transmission services on all makes of automatics.  The reason for the magnet in the pan is to catch clutch plate glittery metals and the added filter keep things in check.   As far as the chunk of metal,  I would not lose a bit of sleep over it.  I have seen many with a mystery chunk of metal yet the transmission works like a charm.      

[NC-car-guy]

36 minutes ago, avgwarhawk said:

Some glittery stuff in the fluid is generally seen. At least in my experience with transmission services on all makes of automatics.  The reason for the magnet in the pan is to catch clutch plate glittery metals and the added filter keep things in check.   As far as the chunk of metal,  I would not lose a bit of sleep over it.  I have seen many with a mystery chunk of metal yet the transmission works like a charm.      

He had it rebuilt already

[60FlatTop]

34 minutes ago, avgwarhawk said:

I would not lose a bit of sleep over it.

 

Just a quick phone call and bump the towing mileage on the AAA.

 

$1650 is not a bad price for the transmission, but it is just a car and nudging 40 years old.

 

Don Knotts planned big trips with his new Plymouth. And knew the fun was in the planning.

 

[avgwarhawk]

13 minutes ago, 60FlatTop said:

 

Just a quick phone call and bump the towing mileage on the AAA.

 

$1650 is not a bad price for the transmission, but it is just a car and nudging 40 years old.

 

Don Knotts planned big trips with his new Plymouth. And knew the fun was in the planning.

 

 

There are many cars nudging more than 40 years old on this very forum running the original factory transmission. 😊 

[avgwarhawk]

21 minutes ago, NC-car-guy said:

He had it rebuilt already

 

 Yes, I understand.  

[MrEarl]

 

 

 

Appreciate what you're sayin Chris but the band was actually loose and flopping. Knowing that the wagon has years and many miles of towing ahead of it I had no problem telling him to rebuild. Plus he put it in front of the line knowing I was in a time crunch. She shifts great now.   This is the second tranny he has rebuilt for me, the first being in the 93 Riviera.

[avgwarhawk]

8 minutes ago, MrEarl said:

 

 

 

Appreciate what you're sayin Chris but the band was actually loose and flopping. Knowing that the wagon has years and many miles of towing ahead of it I had no problem telling him to rebuild. Plus he put it in front of the line knowing I was in a time crunch. She shifts great now.   This is the second tranny he has rebuilt for me, the first being in the 93 Riviera.

 

Ah, did know the band was that bad.   Over the years performing trans services I have seen large chunks of metal in the pan or stuck to the magnet.  The transmission worked fine.  I can understand the rebuild. 

 

When you decide to part ways with your wagon, call me cause the wagon has been rebuilt from the ground up!!!          

[MrEarl]

7 minutes ago, avgwarhawk said:

When you decide to part ways with your wagon, call me cause the wagon has been rebuilt from the ground up!!!    

 

. and you don't know the half of it...... ☹️😁     I won't be around but will tell Rita to put you on the list

[avgwarhawk]

4 minutes ago, MrEarl said:

 

. and you don't know the half of it...... ☹️😁     I won't be around but will tell Rita to put you on the list

 

Happy Motoring! 

[60FlatTop]

1 hour ago, avgwarhawk said:

There are many cars nudging more than 40 years old on this very forum running the original factory transmission. 😊 

 

I understand that. I have a couple. But when I needed a few tons of stone I didn't think about hitching a trailer up and doing truck work.

 

A few entries ago, after a string of transmission mods I mentioned checking the 40 year old motor mount that have never really been taxed. It's the "whoda thunk of that stuff" that will bite you".

 

I am all for doing it. Even the Navy does a couple of shakedown cruises, mine are constant, looking under the hood, poking under the car, stuff like that all the time.

 

Ooop, 1 PM, I'm going out and check the torque on the front wheels of the BMW and grab some lunch. First thing I bought for that car was a Stant cooling pressure adapter.

 

Bernie