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My55buick

A dynaflow interchange question

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I've been on multiple sites, and haven't been able to find any credible info. Everyone thinks but isn't sure. A long time ago someone told me you can swap the bellhousing and torque converter from a later Dynaflow on to an earlier one, and also the other way around. Is there any fact to this? I bought 2 Hollander manuals to see if I can compare cases and tail shafts but I didn't see a section for it.  Let me know what you guys think.

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I'm looking to swap a 57 or newer into a 55. I know you can use a 56 if you use the 56 cross member and 55 tailshaft. That's actually in the Hollander manual.

Edited by My55buick (see edit history)

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the man you need to be talking to is Gene Berck, owner of transmissions by gene, salinas, calif. 831-320-2726, he also has a great website, restorationhydramatic.com

 

charles l. coker

1953 pontiac tech advisor

tech advisor coordinator

pontiac oakland club international

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I used to work in an automatic transmission shop, where we rebuilt and stocked used transmissions on our shelves. I recall that many of those older GM transmission designs were not so wonderful performance-wise, compared to later designs like the Turbo 350 and Turbo 400. I once asked a more experienced technician if you couldn't simply switch out a newer GM automatic trans for the old units in Pontiacs, Olds, and Buicks of the 50's and early 60's. His answer was that steel floor pans prevented using more modern transmissions in many older GM cars, such as those equipped with the "Slim Jim" transmissions. It was just a minor curiosity to the young kid that I was. But now once again I find myself wondering if it might be possible to adapt newer auto transmissions in those cars.

 

First off, does anyone know if common B.O.P. engines have bolt flanges which would bolt up to newer B.O.P. auto tranny's? I'm sure adaptors could be made. I have no interest in actually doing this kind of switch, and don't even have any B.O.P. cars at this time. But I used to admire some of the Catalinas, Oldsmobiles, etc. I always thought that if I ever owned one which was equipped with an automatic, I would try to switch it out myself. 

 

Anyone know? 

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 I don't think they I don't think they went to the BOP bellhousing until the turbo hydramatic came out the 350 and 400, I know that my Buick has a different bellhousing from any other engine, even the nailheads had two different bellhousing I can't speak for other models. The other problem is that Buick until I believe 1960 use a torque tube rear end so now you have to engineer a newer transmission to accept the torque tube with a torque ball pivot, otherwise you have to redesign the rear suspension using a newer rear end upper control arms and have a custom driveshaft made. The only way something like that could work is to use some kind of transmission adapter, then take the tail shaft off of say long tail 400 and then make a plate to add the end of the dynaflow where the torque ball and shaft sit. But without some real metal working equipment I don't think it's possible.

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The first TH400 (actually called the Super Turbine 400 that year) was used in the 1964 Rivieras and Cadillacs.  The Buick version had a unique rounded case that mates with the nailhead motors.  The BOP bolt pattern was also introduced with the new-for-1964 Olds 330, Buick 300, and Pontiac motors on the Super Turbine 300 trans. Several vendors sell conversion kits to put newer GM automatics behind the 1950s motors.  This requires either an adapter plate or a modified bellhousing on the trans.  It also requires a custom flexplate and nearly always requires significant floorpan mods to clear the larger trans case.  Obviously there are also custom crossmember and driveshaft mods.  Many have done this,  but it is not a bolt-in change.

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My55buick:

In your first post on this topic, the person who told you about swapping a later Dynaflow torque converter and bell housing may have been referring to the use of the 1953 Buick Special only (straight eight engine 263 cubic inch) bell housing and torque converter that would bolt up to older straight eight Dynaflow cars possibly back to 1948.  The 1953 torque converter was called a twin turbine and had better torque multiplication starting out from a standstill.   The 1948-52 Dynaflow transmissions were basically all the same.

Joe, BCA 33493

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On 12/18/2018 at 8:01 PM, My55buick said:

I'm looking to swap a 57 or newer into a 55. I know you can use a 56 if you use the 56 cross member and 55 tailshaft. That's actually in the Hollander manual.

I put a 1956 dyna in my 55 Cent and posted alot about it. If you have a 55 Roadmaster or Super the 1956 is indentical in lengthand basically a bolt in. Its not the tailshaft needing to be changed, its the 56 fine spline ujoint, 55 has a coarse spline ujoint. 55 Spec and Century are 1" shorter. What model 55 do U have?

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I don't know if this is of any value, but I have a 1988 Jaguar XJSC. It uses a V12 mated to a TH 400, but as I recall it has a unique, much thinner housing. This was a stock application, but I don't know whether it was used on anything else. A little research could prove beneficial, as any XJS with this setup could be easily found.

 

As an aside I had a 1963 Cutlass convertible, years ago, and former brother in law had a full sized Olds, both with  a Slim-Jim-what a piece of junk those were! The mechanics called them jerk-a-matic, need I say more? I own both a 1963 and a 1965 Riviera, the former with the last iteration of the Dynaflow, the later TH 400. They are definitely different, but I like both. I honestly don't know why so many don't like the Dynaflow, they are so smooth. The power and toque of that engine, and the multiplier affect of the torque-converter,  just take smooth to a different level.

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I am just breaking in a rebuilt dynaflow in my 49 Roadmaster.  I think I found the shift point around 38 mph but hard to tell.  It is a very nice cruising trans but just likes to drip.  No matter how you drive it will just start with the drips. I once trailered mine for 800 miles and backing it out of the trailer it puked out the dip stick for no reason. like 2 pints. After it sat still for a day it never happened again.  Remember it was also used in Tank Destroyers in WW2

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