55 and 56 dynaflow differences?

[old-tank]

Here is what I think know and have heard. There are two different transmissions for 55, the differences being the length. The dynafow for the 40/60 series is shorter than the 50/70 series, the difference being in the length of the rear bearing retainer or tail shaft. The 56 dynaflow is longer than the 55 40/60 series but the same as the 55 50/70 series. The increase length of the 56 is due to the fatter torque converter and bell housing. The 56 also has an aluminum bell housing.

I have been talking to a very pleasant gentleman (1200 miles away) who found a stash of dynaflows that have been rebuilt years ago. He found one labeled 1955. I asked for dimensions (length of the rear bearing retainer and overall length = 9.5" and ~29"). This matched my (series 63) measurements. Just to be sure I asked for some pictures and (gaaak!) it has and aluminum bell housing. What the...?

I am not opposed to using a 56 tranny in a 55 if it will fit. Does anyone have any different info on lengths, interchange, etc?

Willie

[KAD36]

Hi Willie

Here's some information that might help what you've heard as I have been asking similar questions over the years of local Buick people in anticipation of getting my unit rebuilt. Unfortunately, I have few specifics regarding measurements, which is probably what you're looking for. I can at least pass on all the information I've been "told" in conversation - maybe it provides some help - or confidence - or sparks others with more specifics to help?

I've been told that the length of all the 56s is longer and equal to the 50/70 series 55's. Never measured it to verify, but have heard it from a couple of sources. So your first paragraph, including the aluminum bell housing, matches what I've heard also.

The cooler, as most of us know, is more traditional in a 56 (heat exchanger mounted inside of the radiator with oil piped up front) vs a 55 (external heat exchanger on the tranny with cooling water shipped to the back) and you could easily replumb the lines on a 56 trans to hook up to a 55 cooler. Because of the extra stage in the 56 torque converter, you would anticipate more heat generated, and I don't know for sure if the 55 cooler "as-is" has enough capacity to cool the oil in a 56 trans. I'd try it running a 160 deg thermostat and see and if necesary, an external air cooled one could always be used.

I've also been told output splines going to the driveshaft are different between the two - again I never measured or have seen specs. I have 2 spare U joints and an output shaft ( or input shaft - not sure which) on the shelf from a 55 in the garage, but don't know what a 56 measures. If you keep the 55 driveline, you'd have to work backwards into the trans to see where the transition between the splines can be made, perhaps at the output shaft or U joint.

I haven't yet heard of any differences in trans mounts to the crossmember, the speedometer gears, the control valve linkage, variable pitch linkage or the external housing. Maybe someone else knows for sure?

About 2 years ago, when my Dynaflow rebuild was a higher priority and I was really digging to find a reputable rebuilder with references on the East Coast, I was referred to Transmissions Unlimited in Port Clinton Ohio - web site http://www.transmissions-unlimited.com. Maybe they can help.

Good luck - keep us posted - this could be a good informative thread, as most of yours are!

[GMPARTSMAN]

I'll give you what information that I can from past experience.

I installed a '56 Dynaflow in my '55 Special about sixteen years ago.

What series the Dynaflow came out of, I don't know as it was in a street rod.

It was a '56 322 though, and the Dynaflow was definitely a '56 model,assuming it was a Special or Century with the short wheelbase and the aluminum bell housing.Length measurements of the Special's three-speed were the same as the original Dynaflow, and were the same as the '56 Dynaflow, hence the original torque tube was always used,except the torque ball was rotated to match the hole pattern to bolt the torque tube to the transmission The Dynaflow would not mate up to the original torque tube as the splines on the u-joint were fine,unlike the original which were

coarse. As my car was a factory Dynaflow, later converted to three-speed, I did not have the original transmission. I temporalily took the yoke of the '55 manual transmission and found it would fit the '56 Dynaflow, unfortunately losing for awhile the speedometer as the manual transmission speedo drive gear is on the mainshaft, while the Dynaflow is on the yoke. But I picked up a NOS '55 yoke for a Dynaflow, and installed it in the transmission in '92, good since then.

'55 detent linkage bolted to the '56, the variable pitch works fine. The only function diference is that the '56 has the dual range feature in ALL speeds, including reverse, unlike the '55 that has the dual range feature in drive range only. The cooler was a issue, solved temporarily (?) with a Hayden external cooler mounted in front of the radiator since '90, with a trans temp gauge. So far, so good. The car will be undergoing a transformation to a late 50's style "hot rod", with a change to a 322, so at that time I change the radiator to a '56.

Hope this has been some help.

[old-tank]

Thanks for the replies. This gives me something to "chew on".

Maybe I have it backwards as far as length of 55 trannies. Maybe the 50/70 series is the shorter? I wonder if Ken could and would measure the rear bearing retainer on his Super? Please...

Willie

[KAD36]

Willie - will be happy to squirrel under the car tomorrow or Tues night and measure it up. I think I know what you're looking for. Putting my Terrible Towel away for another year.....

GMPartsMan - also some good information - what do you mean by Dual Range? The switch pitch?

[GMPARTSMAN]

Yes,mechanical actuation instead of electric solenoid actuation on the Hydra-Matic transmissions.Quoting from the 1956 Buick Shop Manual,"Stator variable pitch operation is controlled by a valve in the high accumilator which is operated through external linkage by the throttle linkage at wide open throttle position." Also, I'm sorry, that Dynaflow was not the "Dual Range", but it was called Variable Pitch.

The major diferences in the 1956 transmission over the 1955 version, Quoted from the 1956 Buick Product School Manual were: (Abbreviated to cut the size of posting)

1. New stator added to improve low speed performance and to provide a more solid feel under pat or normal throttle acceleration.

2.Converter stall ratio increased from 2.1 to 1 to 3.1 to 1 (Improves low speed efficency)

3.Variable Pitch stator control passages have been changed (allows low and high stator blade angle changes through all ranges for better performance instead of just Drive range)

Hope this helps someone out.

[KAD36]

Willie - Heres the measurements on the 55 Super, starting from the front and working back. Naming convention - Bell housing is obvious - case&extension housing in my measurements is the combined length of the case (what the pan is bolted to) and the extension housing that contains all the Dyna-guts. Outer retainer, torque ball and torque tube I'm assuming is obvious.

Bell Housing - measured from mounting point at engine block to attach point on case&extension housing - 6 inches

Case&Extension housing - measured from bell housing attach to attach point of outer torque ball retainer - 19.25 inches

Outer Torque Ball Retainer and Torque Ball - measured from mounting point on case&extension housing to mounting point of torque ball onto the torque tube - 4.25 inches

Torque Tube - measured from mounting point on torque ball back to mounting point on third member of axle housing - 64 inches.

Unit length - Bell housing mounting point at engine to the end of case&extension housing, where the outer retainer is bolted to - 25.25 inches

Overall length - Bell housing at engine to mounting point of torque ball to torque tube - 29.25

I measured each part seperately then the overall length and - jeese - it even added up. I believe I'm acurate to within .25 inches on the overall length.

After measuring, I then jacked the car up in the air so it would be easy to re-measure everything just in case someone tells me my numbers can't be right.

I did go back and measure up 9.5 inches from where the outer retainer mounts to the back of the case&extension housing. If I measure 9.5 inches from there, I'm approx 6 inches down the length of the torque tube, so I'm unclear on how that 9.5 show up.

Now we need JohnD1956 to weigh in and see if he can measure his....com'on John - its 15 deg outside in Binghamton and the wind is absolutely howling - no better time to head into the garage for a few minutes and warm up with a hot cup of joe and some apple pie.

GMPartsman - I'm confused after re-reading your post - what part did you replace in the 56 trans to match up with the driveshaft splines on the 55? I got lost in the manual trans to dynaflow conversion somewhere. Whats the yolk - are you referring to the U Joint or the torque ball or something else? Thanks for clarifying. This is good stuff.

[old-tank]

Hey Ken

Thanks for all the grunt work getting the measurements. Now I am more confused than ever. I always thought that there was at least 2" difference in the 2 transmissions in 1955, but it seems that there is less than an inch. Let's see if some 56 measurements show up. Attached is a scan of the rear bearing retainer and parts. The retainer "L" on my 63 is 9.5 inches and that is the only part on a 55 that is different between the series 40/60 and 50/70. And the overall lenght from the bellhousing to the torque ball flange is ~29". My case and rear bearing retainer is 18.5" and yours was 19.25.

Willie

[KAD36]

Willie - You're smart in putting that picture up here because I may have gotten my nomenclature mixed up (I thought the rear bearing retainer = outer torque ball retainer) and that could be the problem in the numbers. Or there was too little coffee in my Baileys last night...either way I knew I wasn't done yet.

BTW - my reprint of the chassis and body parts book I got from Bobs Automobilia is missing a page - that would be page 116 of your manual!! - I can see Group 4.600 on your left hand page and I have no such page showing the case and oil pan - this will help get the names right! My manual has exploded views of (in order) Torque Converter, Front Pump, Direct Drive Clutch, Oil Cooler-Retainer-Torque Ball. Could you please scan and email me a copy of your page 116?

Using your diagram as a reference then, the new and improved measurements are as follows:

Part L = 10.75 Inches - straight edge up against the TBD part number the pan bolts to and reading at where the outer torque ball retainer Z attaches to L.

Overall Length - Part AL front to Part X Rear = 30 inches (was 29.5). This was measured as a straight line along the bottom of transmission length, holding the ruler on the lower edge of the bell housing in front of the inspection plate and ran a straight edge from the ruler up to end of the torque ball, part X, instead of "eyeballing it" from the ruler to the end of the torque ball.

Length of Case (pan is bolted to) plus Retainer L = 19.75 inches (was 19.25 - thanks for clarifying)

Looks like the 50/70 is 1.25 inches longer, however I would have expected that the 30 inch overall length should be 30.25. I could see the outline of the paper gasket between the torque ball and torque tube and thats what was measured. Can't get a camera under there unfortunately - running out of hands to hold everything. Maybe I can hold it in my teeth but we'd probably end up with non-useful pictures of the gas tank or muffler instead of the trans.

Let me know if this helps you or if you need me to duck under there again.

[old-tank]

Ken...So it is somewhere around and inch. And all 56 transmissions are supposed to be the same length as the 55 50/70 series (still looking for guidance from the 56 crowd).

Willie

[Guest imported_MrEarl]

Home for lunch, ran down to the barn and measured a what I think is a 56 DF. sittin on a pallet. It has an alum bellhousing. a DYNAFLOW 132992-4 molded into top in 1/2 inch letters. The retainer mesures 9 1/2 in.. From the front top of the bellhousing measured diagnaly down to the end of the retainer is 25 1/8 inch . I realize this is a new measurement for you but I didn't have time to flip it over and plumb up on it. I can do that later if needed. Hope this helps.

hi ho, hi ho it's back to work i go...

[old-tank]

Thanks Lamar

Try to get a measurement of the bellhousing only and then the total length (bellhousing to torque ball flange)

Willie

[Guest imported_MrEarl]

Fixin to head home. Will get Jordan to hold the flashlight while I measure. It's hell not seeing daylight for days at a time.

[Guest imported_MrEarl]

Bellhousing - 5 3/4"

Front Pump Cover - 1/4" + -

Convertor reaction flange - 1"

Transmission Case - 7 1/4"

Rear Bearing Retainer - 9 1/2" (possibly 9 9/16)

OVERALL LENGTH 23 3/4"

Hope this helps

[old-tank]

Thanks Lamar

I guess we can let this topic die until I get the tranny out of my 55 and measure precisely like you did.

Willie

[KAD36]

Lamar - It looks like your overall measurement is less the torque ball and outer torque ball retainer. If I take my overall length of 30" and subtract off the 4.25 for the outer torque ball retainer and torque ball shaft, I'm at 25.75. 2 inches longer than yours.

Willie - if we knock off the 4.25 from yours, you're at 24.75.

Lamars comes in at 23.75.

So Willie - your transmission is at nominal. Lamar and I are clearly on the high and low side of the manufacturing tolerance.

Can't wait to see how we resolve this!

[GMPARTSMAN]

KAD36, sorry, but haven't been on-line since my last posting.

To clear up my posting about the rear yokes:

My car was a Dynaflow originally, in the early 80's I swapped a manual transmission into it. When the manual transmission had a major failure, I changed over to the only availble trans, the '56 Dynaflow. The output yoke on the '56 transmission to the torque tube was a fine spline, but the splines on the torque tube were coarse. I took the torque ball off the '56 took th yoke of, and found that the splines on the '56 transmision were coarse on the mainshaft, like the '55 manual trans was. I also remembered that the '55 had a coarse transmission mainshaft spline on it. A quick measurement of the '56 Dynaflow yoke to the '55 syncromesh yoke was the same overall length, the only difference externally was the speedometer drive gear was missing from the syncromesh as it was on the mainshaft instead of the yoke like the Dynaflows were. Splining was the same on the mainshaft. So slipped the syncromesh yoke onto the '56 Dynaflow, bolted everything up and drove it until I could find another '55 Dynaflow yoke at a swap meet. So to sum it up, if the '56 transmission you find has the same overall length, you should be able to mount it up, just be sure to change the output yoke of the '56's transmission with th one off of your '55 so it wil mate to the torque tube.

[GMPARTSMAN]

Sorry, forgot to add something, but look at the time of my posting! In the blowup of the Dynaflow in the earlier posting, it is item "R", joint, that had to be swapped from the '55 trans to the '56 trans.

[KAD36]

GMPM => Thanks very much for the response and clarifying the swap - that makes more sense. This was really interesting and I was scratching my head trying to figure it out.

[rmartens]

My '56 Dynaflow is sitting on the floor waiting to go back into my Century (Model 60) It's too bad I put it together already--would've been easier to measure when it was in its major sections.

I'm getting about 6 3/8" for the bell housing, measured at sides of the transmission (bellhousing to the reaction flange 6 11/16" minus 5/16" for the front pump cover)--couldn't get square enough to trust my measurements at the top--but it's a bit different from Lamar's measurements (same alum. bellhousing).

From the bell housing to the tail housing is 8 1/2", and the tail housing is 9 3/4 to the outer edge of the lip that secures the torque ball retainer at the sides--there's a notch at the top that would probably read 9 9/16" These measurements just about match what Lamar came up with above...

That's 24 1/2" overall. On the diagonal I get Lamar's 25 1/8" from the top of the bellhousing to the notch at the end of the tail housing.