dynaflow transmission

Hello can anyone tell me is a dynaflow transmission from 1950s era buicks troublesome and are parts hard to obtain any help appreciated .

Sincerely

WildOne

Loaded question. While the Dynaflows are usually very reliable, the probability of trouble on something subjected to thousands of heat/cool cycles, not to mention the stress of moving 2 ton vehicles, and 55-65 years old, is pretty good. The definition of trouble is also varies widely, just like the makeup of the Dynaflows over this ten year period. For a better answer, what year is the subject of the discussion?

Hello and thank you for your reply think it was a 1956 model.

The Dynaflow is a fairly simple transmission not especially trouble prone. Parts are readily available. A knowledgeable person to install them is another matter. Also trans removal is labor intensive since either the rear must be pulled back or the engine removed..............Bob

I have had a '56 Roadmaster for almost 40 years, and have driven it about 90,000+ miles in that time. I was rebuilt once, in 1985 due to an issue with reverse gear, and 2 years ago I had to change the front seal, otherwise, I just drive it!

They tend to leak sometimes, and reverse will not take any abuse, but otherwise they are quite reliable.

Like Bob mentioned, there are a few vendors that sell most anything you will need for a rebuild.

Driving a car with one is different from any other as there is no shifting. I think that they are a great luxury car transmission, as they are so smooth.

Are you thinking of buying a '56?

Keith

You might want to separate "trouble" into "mechanical" and "fluid leaks". Gasket leaks can sometimes be minimized by simply putting a skim-coat of silicone gasket sealer on both sides and edges of the paper or cork gasket, then letting it cure overnight, before installing it on the transmission. This effectively seals the gasket from wicking fluid as time progresses, plus can make gasket removal, if needed at a later date, easier to clean up .

The rear "torque ball" can be another source of leaks, but some have had good luck in that area, too. One hint might be to not fully tighten things down until the rear axle is at "ride height" rather than hanging by the shock absorbers on a chassis-contact lift. Similar to not completely tightening rubber bushing locations in the suspension until the vehicle is at "ride height" rather than on a chassis-contact lift.

One enemy of automatic transmissions is "heat", which degrades transmission fluid if it continues for a longer length of time. Considering how the DynaFlow works, paying attention to the color of the atf and changing it when it might start to darken, might help prolong its service life. Others have addressed the more mechanical issues above.

Enjoy!

NTX5467

To me, Keith hit on the biggest trouble spot. That is a drivers misinterpretation of what it feels like to drive the car.

In Drive, the dynaflow is set up like a Constant Velocity transmission. You will not feel the upshift from low to drive. My theory is that new owners at some point start the car in low and shift to drive, where there is a perceptible shift, and then believe the trans does not function correctly when starting out in Drive.

While one would think Low gear in Drive is the same low gear as in Low, in a Dynaflow that is not the case.

As to the reverse issue Keith mentions, the problem is the strut ( a straight bar between the trans case and the band itself) that holds the reverse gear in place. A 56 Buick normally idles around 450 to 550 RPM when warmed up. Cold engine idle however is around 1500 RPM. Dropping the trans into reverse at 1500 RPM will cause the strut holding the reverse band to drop out of position, rendering the vehicle reverse-less. There is a chance of replacing that strut without removing the trans. But no guarantee of success.

Other than that, any of the bands can be worn, and need replacement. But that can happen to any transmission.

What is posted here is all very good information.

I would add that the "thump" that the Dynaflow gives when shifted into drive or into reverse is alarming to the uninitiated.

As John says, the fast idle exacerbates that "thump". So, it's best to wait until the nailhead is warmed up, before driving away. Waiting for warm up will give you an all around better performance anyway

And, If I understand correctly, the '56 dynaflow has a two stage stator for low as well as Drive. (I know that the '55 has a two stage stator in Drive only)

Edit: and, don't drive over 35mph in low,

However, i've found that driving low around town or parking lots will help keep the engine temp down

I agree, it is a good trans for cruising. Climbing grades or pulling a trailer will create heat, so changing the oil and cleaning the pan regularly is a good idea. Problems with reverse will often be solved by a new thrust pad and engine/trans mounts. I've driven them over 80k miles over 30 years. Don't abuse it, and enjoy the uniqueness and smooth, quiet surge.

Another misdiagnosed problem is low trans fluid. These units operate under high oil pressures to hold them in the designated mode of operation. So sometimes they will leak under operation and you may not notice the loss of fluid. Other times the rear seal (The Torque Tube seal) will leak when the unit is not used for a period of time, and you will probably notice that leak.

The problem for my 56 is when it is two quarts low, the trans will begin to feel like it's slipping, or just isn't right. It will still move the car, but I can notice it's not the same. Put those two quarts back in and you definitely will notice it's perkier. For the external leaks, some leaks can be fixed while the unit is in the car. Same for the rear seal as noted above. However sometimes regular use ( which I would describe as weekly use) will cause those leaks to self seal and or minimize fluid loss. For several years ( decades actually) I would top off my trans at the beginning of a driving season, use the car and find, at the end of the season it was still topped off. Then over the winter it would leak some out and it would be low again in the Spring.

To be fair though, my transmission also was rebuilt, in 1977. My car was a flood victim, and was left with water in the trans for approximately two years before I got it. That did ruin the bands and cause the fluid to burn up in a short period between 1976 and 1977. Otherwise, in 2005 I had the torque tube seal replaced and just this year noticed a leak at the Low Accumulator. Meanwhile this car has been all over the Northeast, including two runs to Flint Michigan, for National Meets. If I did not have the other cars, it would still be going to Nationals.

Dynaflow undeservedly gets a bad rap.

It is in reality a very durable transmission.

And not as sluggish as the reputation that it has been wrongly given

Who's going racing, anyway?

There is not a smoother transmission

The Dynaflow was very sluggish in it's earliest appearance, let's say 1948 through 1953 or 1954. Then "sprags" were installed and the transmission was very perky. I had a '56 that gave me a problem with reverse when I took it to Texas to be restored. It wouldn't back off of the trailer. The restorer took it to a trans shop and they did some kind of an adjustment. No sooner did I get it home that the 2nd or 3rd time I put it into reverse it totally tore out the big ring gear, stripping of 2/3rds of the inside teeth. I think the restorer may have shifted into reverse while driving it, since reverse gear is all the way down. But I don't know that. Getting it fixed was the problem; but I finally found a retired Buick transmission mechanic. Now I have found a transmission shop in Eustis, FL who is familiar with all of the 1950's transmissions. Still, I swore I wouldn't buy a Dynaflow because of the difficulty in getting one fixed. What if you're on a trip to a tour and it goes bad. All the parts in the world won't help if the mechanic doesn't know how to fix it, or refuses to pull the rear end back. All that said, ha, I'm interested in a '58 for sentimental reasons. We had two of them back in the early to mid-60's. Neither was a great car, lots of problems. My wife asked me why in the world I'd want another one. All I could say was "for sentimental reasons". Our kids were very young in those years. But, because of windshield wipers, speedometer, heater control valve, universal joint experience, I wonder if I'm not crazy.

Dynaflow is really a simple transmission where the torque converter does nearly all the work. There are no gear changes as with the Hydramatic. In 1953 they simplified the torque converter and improved the acceleration from a standstill by using one pump, one stator and two turbines (this was called a Twin Turbine Dynaflow) coupled together with a planetary gear set inside the torque converter. This torque converter, as with all earlier and later Dynaflows, was operative if the the selector was in drive, low or reverse. I always start off in Drive and would only use Low if ascending a very steep hill. Fr. Buick is correct about the common loss of reverse being due to a bad transmission mount or thrust pad. Since a torque converter generates more heat than a fluid clutch (as used in the Hydramatic) it is important that the Dynaflow cooler be connnected to the heater hoses correctly so that the cooler gets cooler water from the bottom of the radiator. Fluid changes are also important. When changing the fluid, the torque converter can also be drained as well as the accumulators. With regular service and sensible driving, the Dynaflow will last a long time.

Joe, BCA 33493

Question:

Reading here that heat is a concern (not unlike other transmissions) would adding an auxilary trany cooler be a benefit for a dynaflow?

When I bought my '63 Riviera back in '82, the owner had installed an auxiliary transmission cooler between the radiator and the transmission. He did that because he used this Riviera to pull a rather larger Airstream trailer. I still have the car and it now has 197K on the clock and the original transmission. It leaks a little around the shifter input shaft but that's something I've learned to live with.

I just got the ST400 (for my '64 Riviera) back from the transmission shop and I asked about installing an auxiliary cooler on it. The old guy who worked on it told me that I'd be better off with just an auxiliary cooler in front of the radiator and to eliminate the cooler in the bottom of the radiator. He told me that the radiator cools the tranny fluid to some degree but not as good as bypassing it and using the auxiliary cooler. Has anyone else heard the same?

Ed

Question:

Reading here that heat is a concern (not unlike other transmissions) would adding an auxilary trany cooler be a benefit for a dynaflow?

It is essential for all automatic transmissions to operate in a warmed up temperature zone. Always install a external aftermarket oil cooler so that the hot or warm side coming from the trans to be cooled goes to the aftermarket cooler first, and then routed to the radiator oil cooler. This ensures a faster warm up of fluid and a "even" normal running temperature. Transmissions are designed just like engines to run at certain warmed up temperatures. Pushing a engine or trans hard when not fully warmed up speeds up the wear process. If you route the coolers in the opposite flow direction ( radiator cooler first and then to the aux external cooler ) the trans will stay in the cool zone much longer and possibly never get to operating temps, especially on cold days.

It is essential for all automatic transmissions to operate in a warmed up temperature zone. Always install a external aftermarket oil cooler so that the hot or warm side coming from the trans to be cooled goes to the aftermarket cooler first, and then routed to the radiator oil cooler. This ensures a faster warm up of fluid and a "even" normal running temperature. Transmissions are designed just like engines to run at certain warmed up temperatures. Pushing a engine or trans hard when not fully warmed up speeds up the wear process. If you route the coolers in the opposite flow direction ( radiator cooler first and then to the aux external cooler ) the trans will stay in the cool zone much longer and possibly never get to operating temps, especially on cold days.

Ad if the transmission does not reach operating temperature it may not shift right.

To wildone's original post "are 50's dynaflow transmissions troublesome" and my question about "auxillary trans cooler":

I have this bucket list idea (dream if you will) to have a period Shasta 16 - 18 ft house trailer to go to car shows with and do a bit of travelling when the wife retires. I do not often see pictures of '58 Buick's hauling trailers and wonder if the dynaflow was not a good choice, thinking due to performance or the troublesome question?

Anyone have experience with this or opinions?

Of course everyone has opinions but would appreciate them anyway before I get in too deep!

To wildone's original post "are 50's dynaflow transmissions troublesome" and my question about "auxillary trans cooler":

I have this bucket list idea (dream if you will) to have a period Shasta 16 - 18 ft house trailer to go to car shows with and do a bit of travelling when the wife retires. I do not often see pictures of '58 Buick's hauling trailers and wonder if the dynaflow was not a good choice, thinking due to performance or the troublesome question?

Anyone have experience with this or opinions?

Of course everyone has opinions but would appreciate them anyway before I get in too deep!

I think that if your cars driveline is in good shape you would have no problem. I would add a engine and transmission oil cooler for the job though. Not to long ago I read a article about a 52 Pontiac straight eight with HydraMatic going across the country with no problems and the trailer was bigger than 18 ft. It is no doubt that the Pontiac's HydraMatic was put to full use, lucky for the engine that 52 was the first year for Dual Range ( ability to control 3&4th gear for city driving and to be able to down shift into 3rd for braking coming off hills and mountain grades) HydraMatic. The Buick has a bigger and more powerful engine than the straight eight Pontiac. I see no problem.

Dynaflow is really a simple transmission where the torque converter does nearly all the work. There are no gear changes as with the Hydramatic. In 1953 they simplified the torque converter and improved the acceleration from a standstill by using one pump, one stator and two turbines (this was called a Twin Turbine Dynaflow) coupled together with a planetary gear set inside the torque converter. This torque converter, as with all earlier and later Dynaflows, was operative if the the selector was in drive, low or reverse. I always start off in Drive and would only use Low if ascending a very steep hill. Fr. Buick is correct about the common loss of reverse being due to a bad transmission mount or thrust pad. Since a torque converter generates more heat than a fluid clutch (as used in the Hydramatic) it is important that the Dynaflow cooler be connnected to the heater hoses correctly so that the cooler gets cooler water from the bottom of the radiator. Fluid changes are also important. When changing the fluid, the torque converter can also be drained as well as the accumulators. With regular service and sensible driving, the Dynaflow will last a long time.

Joe, BCA 33493

the single and dual range hydra-matic transmissions do not have or use a fluid clutch, it is properly and correctly known as a fluid coupling. true the fluid coupling generates a lot less heat than a torque converter, because in the fluid coupling, there is just enough slippage at idle in gear to prevent the engine from stalling. to help smooth the very firm gear shift nature of the hydra-matic, there is a set of six coil springs in a ring pattern built into the torus bowl.

charles l. coker

1953 pontiac tech advisor

tech advisor coordinator

poci

the single and dual range hydra-matic transmissions do not have or use a fluid clutch, it is properly and correctly known as a fluid coupling. true the fluid coupling generates a lot less heat than a torque converter, because in the fluid coupling, there is just enough slippage at idle in gear to prevent the engine from stalling. to help smooth the very firm gear shift nature of the hydra-matic, there is a set of six coil springs in a ring pattern built into the torus bowl.

charles l. coker

1953 pontiac tech advisor

tech advisor coordinator

poci

Charles, I don't want to seem picky, as you know I value your opinion greatly but the HydraMatic Service manuals refer to the fluid coupling as a fluid clutch.

A Dynaflow in good repair behind a sound nailhead , along with a sound driveline , would have no trouble towing an 18 ft trailer.

To me, Keith hit on the biggest trouble spot. That is a drivers misinterpretation of what it feels like to drive the car.

In Drive, the dynaflow is set up like a Constant Velocity transmission. You will not feel the upshift from low to drive. My theory is that new owners at some point start the car in low and shift to drive, where there is a perceptible shift, and then believe the trans does not function correctly when starting out in Drive.

While one would think Low gear in Drive is the same low gear as in Low, in a Dynaflow that is not the case.

As to the reverse issue Keith mentions, the problem is the strut ( a straight bar between the trans case and the band itself) that holds the reverse gear in place. A 56 Buick normally idles around 450 to 550 RPM when warmed up. Cold engine idle however is around 1500 RPM. Dropping the trans into reverse at 1500 RPM will cause the strut holding the reverse band to drop out of position, rendering the vehicle reverse-less. There is a chance of replacing that strut without removing the trans. But no guarantee of success.

Other than that, any of the bands can be worn, and need replacement. But that can happen to any transmission.

Just curious, How is Dynaflow set up like a CVT? In DynaFlow everything is done through the converter. In CVT yes, torque multiplication, lock up ( Lock up unlike Buick) and engine connection is done through a converter, however unlike Buick the ratios are constantly changing by a belt between sets of cones constantly altering the transmission ratio's. Did you mean it feels like Dynaflow? Because it doesn't even feel or have the same driving habits as CVT. Once CVT is cruising the converter is locked up.

One other point that CV transmissions do differently is they talk and take commands from the ECM just like the engine does. All engines have a horsepower and torque peak. When the throttle is depressed to full throttle in a CVT car the engine goes straight to where the horsepower peak and the peak engine torque intersect. This is accomplisher by the engine and the CVT acting in unison, and in the case of my Nissan means 6,200 RPM until you let off the throttle. It is possible to be in this mode at wide open throttle from less than 20 MPH to 135 to 140 MPH. On the other hand cruising at 80 MPH on the flat and level the engine is only turning 1800 to 1900 RPM at 35 MPG. Cruising at 65MPH and the same RPM gives you 40-42MPG.

I meant to say the Hydramatic used a fluid coupling, however, I have seen the term fluid clutch used in this context.

The Dynaflow has no low in Drive, it just has high torque multiplication when the pump is moving much faster than the turbine or turbines. When the car is cruising under light throttle at 45-50 MPH there is little torque multiplication and the torque converter is acting like a fluid coupling and there is very little slip. In those days there was no lockup capability as there is today on modern torque converters. When the Dynaflow is in LOW, there is an actual gear ratio change through the planetary gearing using the application of the low band and there is of course the torque multiplication of the torque converter that is between the engine and the planetary gearing. So in Low, there is a significant torque multiplication ratio. The Dynaflow does all the torque multiplication through the hydraulic interaction of the pump, stator and turbine whereas in the CVT transmission this is accomplished by a belt that runs between two pulleys that can vary their diameter depending on the need for torque or speed. I have never driven a CVT car so I cannot compare the two.

Joe, BCA 33493

A Dynaflow is a CVT transmission, in that it is continuously variable between its' two extremes, which on a '56 is about 2.5:1 (if memory serves me), and 1:1, ie. direct drive. It is sluggish off of the line, since the gear ratio you're using is more like 2nd, than 1st. When starting up from a standing start under part throttle, you can feel the car speed increase, but when you reach 20-30 MPH, the car will accelerate, but the revs will not change much as the torque convertor upshifts.

A modern CVT has a much wider range to provide the performance that we have grown to expect. I have driven a number of modern CVT's, and some of them seem to have ratios programmed into them, to give drivers an experience similar to a typical automatic, but otherwise within the constrains of comparing new tech to old tech, I have found them similar to a Dynaflow.

Keith

I meant to say the Hydramatic used a fluid coupling, however, I have seen the term fluid clutch used in this context.

The Dynaflow has no low in Drive, it just has high torque multiplication when the pump is moving much faster than the turbine or turbines. When the car is cruising under light throttle at 45-50 MPH there is little torque multiplication and the torque converter is acting like a fluid coupling and there is very little slip. In those days there was no lockup capability as there is today on modern torque converters. When the Dynaflow is in LOW, there is an actual gear ratio change through the planetary gearing using the application of the low band and there is of course the torque multiplication of the torque converter that is between the engine and the planetary gearing. So in Low, there is a significant torque multiplication ratio. The Dynaflow does all the torque multiplication through the hydraulic interaction of the pump, stator and turbine whereas in the CVT transmission this is accomplished by a belt that runs between two pulleys that can vary their diameter depending on the need for torque or speed. I have never driven a CVT car so I cannot compare the two.

Joe, BCA 33493

Packard was the first to use a lock up torque converter beginning in 1949. Like Dynaflow and early Chevrolet Powerglide in 1950 to 1952 also starts off in high range. CVT on the other hand uses the converter, the converter lock up and the various and continuous ratios always in mesh to achieve either no reduction or full reduction.

It also seem that with Dynaflow, Packard Ultramatic, and Chevy Powerglide, owners did some damage ( after some time) to these cars with the usage of the low gear starts. Chevrolet and Packard modified their transmissions ( chevy in 1952 ) later on to start in 1st gear.