1956322

Dynaflow reliability

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So I'm curious on another Buick group the dynaflow was being looked down upon etc as being just junk.. Besides the leaks. How many people have actually had drivability problems with there's and what were they..

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Probably the most misunderstood ,by the know it all folks , transmission there is.  I have none now. Have had in the past.  In late '56-'57 my brother had a '56 . It  would outrun almost anything thrown at it. Including the police. Did he break the transmission? You betcha. Several times.  But then he had a lead foot and a couple BRASS ones.  He learned to take it out , tear it down and back in in a day. Long one.  He was 19 at the time.

 

  Ben

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Mine had to be rebuilt in 1978 because it was flooded in 1972 and not drained till I got it in 1975. My other 56 lost reverse when I failed to warm the engine to the regular idle speed before trying to scoot out of a parking space.

Other than those two direct failures any percieved driveability issue has been with the engine or suspension.  It is too bad the trans got the reputation of being sluggish.  

 

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I'd say performance wise it's a little slow off the line nothing bad or anything.. Once it hits about 15 then it goes just fine... In low it definitely takes off much much better but at least on mine it's very harsh shifting from low to drive.. Tried on and off the gas so I just don't do that.

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The trick with a Dynaflow is to keep the engine at its torque peak and let the fluid couplings do their thing. Buicks with Dynaflows will actually go slower if you rev them too high and thats why alot of guys cooked they're Dynaflows. You can almost feel the sweetspot when your accelerating in a Dynaflow Buick. 

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On 10/5/2018 at 10:28 PM, 1956322 said:

So I'm curious on another Buick group the dynaflow was being looked down upon etc as being just junk.. Besides the leaks. How many people have actually had drivability problems with there's and what were they..

Most of those have never even driven a properly functioning dynaflow.  

You should ditch the dynaflow if you want to be jerked around by a step gear transmission hunting for gears shifting up and down.

You should ditch the dynaflow if you would rather have an overdrive transmission with lockup torque converter so that you lose throttle response until you stomp it rather than a nudge; so that you lose engine braking during slow down ( now you have to convert to disc brakes ).

If you need a faster takeoff then that is what Low is for; the 1956 and later transmission had switch-pitch that worked in Low...stomp one and you have the ultimate hole-shot.  I was telling my transmission builder and mentor how I "abused" my dynaflow by holding in Low up to 60 mph; I was expecting a lecture from the crusty old dude when he said "won't hurt it".

I drove my first dynaflow like that for 250,000 miles and replaced with a $100 used unit due to severe leaking.

With the outer torque ball retainer kits available, 90% of the leaks are stopped; others just need gaskets and some sealing around some bolts and studs that go into a fluid cavity.

The dynaflow is a relatively simple transmission that any of us could rebuild following the shop manual.

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From what I've observed over the past few decades, when people arbitrarily toss around the word "junk", it's usually because they haven't sought the knowledge or orientations which led to a particular device.  No "learning how and why it works, OR why it is that way", apparently.  The best part is learning these little quirks and using them to best advantage, from experience.  Rather than drivers expecting a vehicle to adjust to THEM, automatically!

 

IF a person is used to a modern 3-speed Simpson Step Gear automatic, not having the same feels in a DynaFlow is "different" to them.  But then people drive many CVT Nissans every day.  As with the DynaFlows, they have a different feel to them, which is quite nice once you learn how to use it.  As with other automatic trans of that time, there probably are a few weak points, but when they fail, most builders knew what caused them, despite what the owners might have claimed.

 

I believe that DynaFlows did have design/performance improvements with almost every early model year, which was also common with other automatics back then, too.  

 

The other thing is that traffic patterns are much faster than in prior times.  Even from when 3-speed automatics were in everything.  Now almost all automatics have a geared 4.50 low gear ratio (6+speed automatics).  Combine that with the torque converter multiplication and "Launch" is much better than the earlier 4-speed automatics with their 2.75-3.06 low gear ratios.   In those respects, the DynaFlow is an antiquity, but then is the Chevy PowerGlide (which is the basis for many top fuel drag racers).

 

While I have no first-hand experiences with DynaFlows, I'll suspect that if you drive them as they were designed to be driven, they'll be as reliable as anything else back then.  Which Old-Tank tends to confirm.  Heat is the "death" of automatic transmissions (and their fluid!), so regular ATF changes are as important as with modern automatics.  Getting "old gaskets" to seal with modern sealer applications can be done, too.

 

Just some thoughts,

NTX5467

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I agree with everything said.. Any ideas what would cause my harsh shift while moving from low to drive.. Mounts are pretty new and tight... Didn't know holding it in low that long wouldn't seem to cause it any harm.. Might just cruise from light to light in low and not worry about shifting into drive

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It's the nature of the beast.  Because Low is not a part of the sequential progression of gears as Low is in a convential automatic transmission, you're not just shifting gears.  If you'll read your chassis manual, it states that the Low Range is not a driving gear but mainly for use in getting out of sand or snow when a more direct drive is needed.  Stick it in Drive and forget that Low even exists.  If you truly want a low gear in your transmission, swap out the Dynaflow for an ST300 or a Powerglide.

Edited by RivNut (see edit history)

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1 hour ago, 1956322 said:

I agree with everything said.. Any ideas what would cause my harsh shift while moving from low to drive.. Mounts are pretty new and tight... Didn't know holding it in low that long wouldn't seem to cause it any harm.. Might just cruise from light to light in low and not worry about shifting into drive

You are the right track with the mounts.  With the carb set on the high idle cam have someone shift through the gears (with a foot firmly on the brake pedal) while you observe any abnormal movement of the engine.

The L-D shift on some is just harsher. Could be blamed on new clutches that are more aggressive, properties of the fluid used...

Using L generates the highest pressures to hold a band around a drum; when shifted to D fluid at lesser pressure is directed from the band to the clutch pack (similar to what happens when a step gear transmission shifts).

I only use L for a seldom needed fast getaway, for crawling congested traffic driving mainly to keep the rpm up to avoid overheating, mountain driving for increased engine braking and increased power at lower speeds at high (low engine power) altitudes... and sometime just for the hell of it to lay down a 20 ft black strip:o.

 

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If they live near I can take them for a ride. My car doesn't have air bags, but the occasional wind bag will show up from time to time.

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Lol makes sense I just chalked it up to nature of the beast and rarely shifted from low to drive as it really is harsh..I believe this tranny was rebuilt but I have no history or paperwork on it.. Other then a few leaks it performs great..daily drive it and have to add about a pint every six months so I guess I can't complain to much.. The mounts are newish but every nut was completely loose as in not making contact.. Now everything is tight.. Helped some but far from enough.. I'll have to take a closer look see if something is cracked.. Also kinda harsh going into reverse but not to bad going into drive.

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Hello I have a 1949 Super with Dynaflow,it is a different driving experience.As mentioned in previous posts the best way to drive it it to let the engine accelerate moderately,allowing the torque converter to work together. The Dynaflows are much smoother the the early 4 speed Hydromatics that I had . Main complaint was leaking,I would imagine that owners that didn’t check the fluid level may consider them “junk” . Buick used a similar setup in the M18 “tank destroyer “ the Hellcat of WW 2.one of the fastest armored vehicles of that time. The main problem I had with mine was the nuts that held the torque converter on loosened up as they cracked from over torqueing not a fault of the transmission,these replaced with  Nylon lock type.

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1 hour ago, 1956322 said:

Lol makes sense I just chalked it up to nature of the beast and rarely shifted from low to drive as it really is harsh..I believe this tranny was rebuilt but I have no history or paperwork on it.. Other then a few leaks it performs great..daily drive it and have to add about a pint every six months so I guess I can't complain to much.. The mounts are newish but every nut was completely loose as in not making contact.. Now everything is tight.. Helped some but far from enough.. I'll have to take a closer look see if something is cracked.. Also kinda harsh going into reverse but not to bad going into drive.

 

 The harsh going into gear is likely caused from too fast idle.  

 

  Ben

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6 hours ago, old-tank said:

 

If you need a faster takeoff then that is what Low is for; the 1956 and later transmission had switch-pitch that worked in Low...stomp one and you have the ultimate hole-shot.  I was telling my transmission builder and mentor how I "abused" my dynaflow by holding in Low up to 60 mph; I was expecting a lecture from the crusty old dude when he said "won't hurt it".

I drove my first dynaflow like that for 250,000 miles and replaced with a $100 used unit due to severe leaking.

 

 

I have a 56 and believe me I love to drop it in L at a light and stomp one.  Matt @wndsofchng06 can attest to that he would probably even use the term "abuse" as well. 

 

I have never ever babied my nailhead or dynaflow and never had any issues. I've run it three quarts low until it started knocking to tell me to check the fluid. 

 

I know the buick group the op is referring to and of course they are going to say it's a junk transmission. It's heavy and it's not designed to be a street racing transmission and most of the guys on there race their Buicks and most have big block Buicks anyways. 

 

They obviously can't be pure junk, Buick used it from 47-63 pretty long run for a junk transmission. 

 

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The fast idle is a possibility I'm running an aftermarket carb that likes it at about 650...

21 minutes ago, Ben Bruce aka First Born said:

 

 The harsh going into gear is likely caused from too fast idle.  

 

  Ben

 

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Then again it could also be the slop in my diff but with no bad noises and no gears available anyways I'll keep on keeping on 

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28 minutes ago, 56buickinga said:

 

I have a 56 and believe me I love to drop it in L at a light and stomp one.  Matt @wndsofchng06 can attest to that he would probably even use the term "abuse" as well. 

 

I have never ever babied my nailhead or dynaflow and never had any issues. I've run it three quarts low until it started knocking to tell me to check the fluid. 

 

I know the buick group the op is referring to and of course they are going to say it's a junk transmission. It's heavy and it's not designed to be a street racing transmission and most of the guys on there race their Buicks and most have big block Buicks anyways. 

 

They obviously can't be pure junk, Buick used it from 47-63 pretty long run for a junk transmission. 

 

Yea. No going easy on that poor thing. I might have found religion on that tour of Georgia...  😉😀

Edited by wndsofchng06 (see edit history)
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Dynaflow, good. What other transmission in a production car had passing gear in reverse?

 

1956 and later Dynaflows would switch the pitch of the torque converter with the accelerator position. So, it works in reverse too! Go ahead, try it if the area is clear. A LARGE area!😁

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https://www.hotrod.com/articles/modernizing-1954-buick-updated-transmission-rearend/

 

Get a load of this garbage. 

 

1956322, my Buick idles about 600 RPM and its a slightly rough shift. I get a rough shift into reverse, too. These engines are supposed to idle at 450 in Drive from the factory, but I've never gotten mine so low without rough running. That being said, after a good drive around, the shifting gets easier. 

 

The Dynaflow can be quick. I made a Lexus smoke their clutch at a light once, though racing a Lexus isn't much to brag on. It's a good transmission, but I wouldn't say its the greatest by any means. I always have reservations about future transmission swaps. It took 20 years to kill the Dynaflow in my car the first time, though, and after a rebuild, I figure I have 18 more years to go before I consider it... though the deciding factor will probably be swapping the rear end for something that's more available, but that's entirely a different subject (no ring/pinion so you gotta get lucky finding a replacement, not to mention there's no carrier bearings available - trust me, I looked everywhere).

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Umm that's an interesting article there Beemon lol well I can honestly say mine keeps up with traffic just fine including highway.. Starting off on a hill is a tad slow but no one has ever honked or rode my tail so it must not be to bad lol. I've had this car for about eight years and been truly daily driving it for about three now.. Tranny has always shifted the same... Just out of curiosity how does yours shift if moving at say 25mph or so and shifting from low to drive Beemon? I've seen specs on many different classic cars and a lot have very low idle speeds.. I've never been able to get them that low almost always around 600-650 is where they settle at and they don't seem to high I'd be curious how many people really do have them idling that low.

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Hmmmm...I was reading the shop manual for the 56 in respect to setting the ignition timing. The manual says bring the idle down to 350 rpm in order to properly set the timing and then take it back to 450. But the lowest idle rpm I can obtain is about 700.

 

So I have been curious as to how exactly I am supposed to lower the idle. I was wondering whether I needed to reset all the throttle linkages if that would make a difference...

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Your idle is probably too high because you're running rich. Someone correct me if I'm wrong, but you're supposed to set your mixture screws at the same idle you set timing, so about 350 or thereabouts. That way, your idle is predominantly based on the idle speed screw and not the idle mixture at say 600 RPM.

 

1956322, my Buick shifts fine at 25 mph. Not rough or bumpy at all. How do you think I made that Lexus smoke its clutch? lol Sometimes I take my foot off the gas, sometimes I leave it on. It's a little softer without the throttle at WOT, though.

 

For the record, I can get an idle of 450 out of my 4GC, but not really out of my WCFB (worn throttle shafts so idle mixture screws don't do a whole lot for me). When I was using an Edelbrock, I could get it down low, too. If you idle low, be sure to use the dashpot, otherwise the engine will bog when you snap the throttle shut. Also, Ethanol needs a little more kick to fire, so idling low on Ethanol can lead to its own problems... I only set the idle to 450 going into cruise meets where I want it nice and quiet, but otherwise re-adjust to 600.

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The idle speeds noted are not that important since it idles higher than that on the high idle cam until the choke opens.  The main problem with any idle speed is to be sure to have your foot firmly on the brake before shifting into any gear, especially  reverse with any torque tube drive.  When in a forward gear power is transmitted into the thrust pad which is attached to the frame by way of the transmission support.  In reverse the power is pulling through the thrust pad, which can be damaged.

(don't try backing uphill with a defective thrust pad:  you will get some bucking then it will jump into Low:o).

I don't know what my idle speed is...it is set to give some charging with the A/C on, some extra circulation of the water pump, and compensation for worn throttle shafts.

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