Technical 1938 Buick transmission + 1956 Pontiac gears, tail housing

Hey HAMB family. I've seen lots of posts and beautiful photos of the 1937-1938 Buick heavy-duty 3 speed transmission converted to open drive using Oldsmobile tail housings and gears (1951 - 1956 if I'm not mistaken). I am working on a similar conversion with parts from the Pontiac version of this transmission. I am using a 1956/57 Pontiac tail housing, full 1956 Pontiac gear set, and what I believe I've identified as a 1938 Buick case -- no provision for bolt-on bearing retainer.

I haven't seen any photos whatsoever of Buick top-shift cases converted with Pontiac parts. So I'm sharing mine. I am using Pontiac parts because I already have the tail housing, and I already have a driveshaft to fit. I am replacing a stock 1957 Pontiac column-shifted transmission behind the 55 287 V8 in my 54 Chieftain.

 

Anyone familiar with this conversion, with Pontiac or Olds parts, knows the rear of the case must be modified to match the bolt pattern of the chosen tail housing. A bearing was installed at the rear of the case to keep the housing centered, when placing the new holes. Unused holes must be plugged. New holes were drilled using the drill press.





Always check the length of the lower left bolt/stud carefully -- if it is too long, it will contact the reverse idler thrust washer.



And just like that, your case and tail housing are now matched.

 

The right-side (1/R) shift rail protrudes out of the trans case 1/4" in the first-gear position. Your Pontiac bellhousing will not have clearance for this. I understand some Oldsmobile guys like to make a small bore in the bellhousing at this location, and fit a freeze plug in the hole to allow clearance and prevent oil seepage into the bellhousing. Fantastic idea if you have that kind of access to the bellhousing. Mine is still in the car. You can also shorten the shift rail 1/4", and it will still be long enough to be supported in the reverse position. This is what I did. Now the rail is flush with the front of the trans case in the first-gear position.

 

I'm in. Couple questions. What is your end play set up at on the main cluster? How is the spring in your shifter housing? Everyone that I have received in the shop has been broken.

 

I bought the trans case and gear set from a trusted mentor who has done the Olds conversion many times, beginning in the 60s. Shifter setup, spring, etc. is perfect.

The cluster gear was shipped installed in the case. It had two extra thin washers between the rear of the case and the thrust washer.

Sent from my ONEPLUS A3000 using The H.A.M.B. mobile app

 

Well that saved you some time and effort for sure. Never had that kind of luck.

 

I've had such bad luck with those transmissions! I hope yours is better. I totally hated the high 1st gear. Those trans' were great for 30s-40s cars with a 4.30/3.90 rear gear but in a heavy car [57 Pontiac] with a higher 3.63 gear, starting from a stop uphill was unpleasant to say the least. Maybe my worn out column shifter was partly to blame for the 4 trans' failures...and maybe because I drove like an idiot, thinking I had a hot rod, I dunno but after I replaced the 4th broken trans [and 4 smoked clutches] with a muncie 4 speed, I was really happy.
I hope your mileage may vary.
signed.........the guy who's still nursing a grudge.

 

I've had the stock 57 trans in there since July 2016, and I can live with the ratios. The only thing I hated was the sloppy Ansen floor shifter I had on it. I figure one of the HAMB's novelty shifter collectors will want to buy it off me.

 

One thing I did like was the 1st and 2nd gear whine. Those things are noisy but a "good" noisy.
That said, I had a 41 Pontiac with the little 5 bolt trans and it was pretty quiet. Go figure.
The 239 flat 6 didn't have enough juice to bust the trans or maybe I was old enough to drive it like a sane man.
I also believe the 5 bolt had a lower 1st gear. I put a set of 3.23s in the rear and I really don't remember that car having trouble starting off. Huh....I dunno.
Sorry for wandering O/T on your thread..I love talking old Pontiac stuff

 

I might be the guy interested in the shifter, same as an olds?

 

Send me a message and I'll send you my pictures. I believe it should fit an Olds. It attaches with the two upper tail housing bolts. I made my own linkage rods to replace the ones that were missing, and made my own bracket to replace the one that was cut and welded past the point of any usefulness.

 

Skankin send shifter pics to me also. I have a Vt member who this week end said he would like to have one so he could use it to make a new unit from scratch. He is a fab machinist. Does it look like this one

 

Good thread. I'm following along!

 

That is nicely designed and constructed. I can imagine duplicating it if a person needs one..........

Ray

 

Only after modifying the rear of the case did I spot the crack in the left side. I dropped it off with Motorheadz in Patchogue to have it magna fluxed and nickel welded. Magna flux revealed an additional small crack in the bottom. They patched up both of them nicely.

 

I also fell in love with the music of the gears the moment I drove with them.

I have to wonder though, how the general public would have received such a noisy transmission in the modern days of the mid 50s. Must have seemed kind of outdated.

 

Years ago, I bought a '61 Cad Cp. Deville from an elderly lady whose husband had passed. Perfect black Cad 'Bubbletop' had burned up the automatic transmission. Aamco told her $2k to fix it. She told them...@#&^%!!!
Car sat in front of her condo, I asked and after some pleading got it for $200! (this was 1964)
My pall Muff found an adaptor, then made a plate, bought an aluminum stick flywheel and I installed a Friction Mat'ls clutch kit, '61 Olds clutch pedal, fork, T.O. brg, and '37 LaSalle box! Did the driveline at home, smooth as glass.
Stick was left long, large black knob. Too-tall 1st gear made smooth takeoffs, but took awhile to get 'underway'. Gear ratio was in the two's...(2.91 or some such) Take off alongside a '59 Impala or El Camino...gear noise would make the driver (and passenger(s)! turn and look at what was alongside...then I'd shift the giant canelike stick...smoothly into 2nd, gas a little, act 'aloof'...like it was 'normal'...
Loved the whine the gears made in 1st and 2nd! Sometimes purposely grind 1st by scraping it from neutral to 1st with clutch out...Guys fell out with: "Hey! That Cad's got a floor in it!"
Cad would do 65 in low gear...won money with bets on that one...

 

Glad you caught those cracks! That could have messed with you....

 

Cool! Must have really had some people scratching their heads. People assume my Chieftain is auto too -- most don't bother to look too close at a 4dr. Especially since it still needs paint and body.

Of course the car was originally straight 8, automatic, and came with a 3.08 rear. When I first completed the 3-speed conversion, I hadn't re-geared yet, and takeoff was ridiculously sluggish. I'm a lot happier with the 3.64s I swapped in.

 

I think my little 287 probably wouldn't have hurt it, but I'm always thinking long term. My next engine will be a 59 or 60 389. That's why I'm also installing heavier-duty bearings on the input shaft and main shaft.

 

Nothing like a little paint to build the anticipation. This case gets Pontiac blue-green to match the engine and the donated tail housing.

 

looks great, now assembly begins. Take lots of pics.

 

The last thing I needed from the selector trans was the speedo drive gear, and the Pontiac-specific spacer. Spacer slips right off once you pull the gear.



Assembly begins. First is the reverse idler. I used the Buick shaft so it's already drilled for the retaining bolt.



Next, place the cluster gear in the case. Leave the countershaft out at this point, leave the cluster gear down low, so you will be able to get the input shaft past it. My cluster gear is installed with two extra washers at the rear of the case, in addition to the two stock thrust washers. Against the stock rear thrust washer is a bronze washer that measures 0.030" thick, and against the rear of the case is a steel washer measuring 0.090" thick.

 

The new bearings I'm installing at the front and rear of the case are heavy-duty --- greater torque capacity than stock equipment. Right off the bat you may notice they contain more bearing balls. Part numbers are:
Front / Input shaft - 1207SL
Rear / Main shaft - 1306SL
My front is a Timken from NAPA, the rear is an older NOS BCA I sourced from eBay to keep them all American-made.

 

Going to take a moment to document what I've learned about distinguishing a 56 Pontiac transmission (or gears) from a 57.
- 1957 has a thrust washer behind 2nd gear on the main shaft that 56 does not.
- 1957 has three thrust washers behind the cluster gear, where 1956 has two.
- 1957 introduced a new gear ratio --- 18 teeth on the input shaft, 20 on the front of the cluster gear. 1st gear ratio of 2.15 is higher than the 56 ratio of 2.39 (17T input, 21T cluster)

I myself will be going from the 2.15 first gear to 2.39. Should make driving a little more fun.

Thanks to pontiacsafari.com for the original shop manual scans --- I plan to make a printable/searchable PDF from these diagrams that I may submit to that website. Private message me your email address if you want a copy.

 

good info right there for sure. Just got a 57 Olds in Sunday so i will check to see if they are identical. The 57 Olds tranny has a bolt on yoke making it a bit different than other selectors and it has a huge output shaft....bigger is better they say!

 

Proceeding with the assembly process ...

Once the input shaft is in place, you can install the countershaft. Same as with the idler, I used the Buick countershaft, which is drilled for the retaining bolt.

For my own peace of mind, the next thing I did was slip the mainshaft into place with all the gears and the synchro assembly, but no rear bearing, no snap rings -- to make sure my assembly sequence was going to make sense. What's photographed here is the final procedure.

Rear bearing is installed on the mainshaft as seen in a previous post.

Poke that shaft in the back, slip on the slider gear, install the retainer.



If you are working with a 57 transmission, install your second gear thrust washer here. 56 lacks this thrust washer.

Slip second gear onto the shaft, with the washer that lives in front of it. The washer has one tooth, which fits only one groove on the main shaft.

 

At this point there were a lot of hands in the case, and I didn't get good pictures.

Start the second-gear snap ring down the front of the mainshaft. Slip the synchro assembly into place, taking care not to get it backwards. The center of it is recessed on the mainshaft side only. You have just enough room to get the second-gear snap ring into place as you slide the mainshaft forward.

The hard part's over!

 

Spacer and speedometer drive gear are installed next, followed by the tail housing.



Doesn't that look nice!

 

Install shifter rails and forks. The bolts for the forks are drilled for safety wire -- supposedly they are not self-locking threads. Safe bet is to safety wire them.




I popped the top on to put it away for another day. The shifter action on this transmission is sweet, even without the detent balls & springs installed.



All that's left is:
- Heating/bending the shifter lever if it is too close to the dashboard
- Cleaning and painting the shifter assembly
- Install shifter with detent balls & springs
- Final install! The installation of this transmission will be documented in my build thread, which is in my signature.