Technical Hydromatic hard shifts cold, shifts like butter when hot

On going issue with out 56 Pontiac Chieftain 2dr wagon. The engine and transmission were rebuilt probably 7 years ago and have about 8k miles on them. As the title proclaims when its cold it shifts horribly. It hits real hard for every gear change (will bang or chirp the tires), sometimes gets stuck in second when at a light or coming up to a yield sign and thus can only chug away unless I slip it into neutral and then back into drive to get first, and just generally is cranky. Put 30+ miles on it and get it good and hot and it is wonderful, smooth and goes up and down the full range with no issues at all. Winters coming (it does get down to 30*F occasionally here) and cold temps make it worse. Most trips in it are too short and it doesn't get hot enough running around the corner to the ACE hardware or grocery store thus it has issues more often than not. I'm absolutely sure I have the linkage correct per the factory manual. I'm thinking its got to be the modern ATF. When it is hot the fluid must be getting thinner and it works great, when it cold its thicker and has issues, sound plausible? I believe it has synthetic Castrol ATF but its been so long I cannot truly remember what is in it. I opening to listening to other options/ideas?

 

Time for a fluid change....

 

Sounds like morning sickness. Internal seals become hard and do not seal properly until the warm fluid begins to soften them up and they begin sealing properly. Had the problem in my 55 olds and would just drive easy until fluid came up to temp and then shifted fine. Drove it that way for 20 years

 

I'd change the fluid and ensure it has the correct type. Has it been like this since rebuilt or is this a new development.

 

Don't put synthetic fluid in it.

 

My Uncle had a 56 wagon he bought new and was the grocery store delivery car when I worked there in the mid 60's. It never shifted very smoothly hot or cold. I didn't drive it hard as I was delivering groceries in the neighborhood. My Uncle drove the heck out of it. It would chirp the tires from 1st to 2nd at full throttle. His big thing was seeing how fast it would go in a city block from a dead stop.

 

It has always done this. It was worse before I got the rod that tells it where the throttle is at set properly. Never been totally happy except when well warmed up. The old guy that built it was THE guy here in Atlanta to go to for old automatic transmissions. Unfortunately this was the last one he did and Benny died not long after.

I tend to drive it easy as I have felt the transmission was the weak link and feared not being able to replace it if I really broke something. But when it is warm Ive been known to stand on it and she boogies pretty good.

I'm going to drain and re-fill it and see if it helps. Any recommendations on ATF?

 

I'd drain the synthetic ATF as well as possible and refill with a mineral based ATF. Modern transmissions use the synthetics because of the newer friction materials used in the clutches and bands. Some newer synthetic gear lubes can cause similar problems in older manual transmissions with brass synchronizer rings.

And who knew? You can still get the older, traditional "Type A Suffix A" A/T fluid. Though I don't know where you go to get this Maxoline stuff.

http://www.maxoline.com/our-products/product-listing/item/automatic-transmission-fluid-a-t-f-type-a-suffix-a#:~:text= MAXOLINE Automatic Transmission Fluid A.T.F. Type A,an ATF-A type mineral oil fluid is required.

 

You should have a drain on your pan and one in your torque converter.

drain and fill it, if you can remove the pan and see if thee is any debris in there.

find out what fluid your tranny recommends, but type 3-4-5 dexron is supposed to be fully backwards compatible, except for Ford type f fluid used in the 70’s to mid 80’s.

a fluid change is cheap and should be done anyways as part of maintenance.

you can also try a bottle of Lukas atf fix , if it is indeed “ morning sickness” it can help to swell and soften seals .

 

The two Hydros I had shifted like they had a shift kit hot or cold and that is why I liked them,if its wanting to start out in second it could be the governor sticking. I was kind of disappointed when I got one with a Jetaway as it shifted wimpier but some adjustments got it better.

 

I believe some of the earlier auto transmissions had a thermostat for the fluid. But I'm not sure if the Hydramatics used them, and if they failed I don't know how it affected the operation of the trans.

And as Vandenplas mentioned above, I suspect that any of the conventional Dexron fluids should work just fine and be easier to source. Though there is a synthetic Dexron I believe that I would try to avoid.

 

Thanks for all the suggestions and stories. I'm going to drain and refill. Going to try and look into that Moxoline stuff,

This transmission does not have a torque converter it is something called a torus, its a round thing in two halves with vanes, I think it is more of a fluid coupling design.

 

Why would synthetic fluid have anything to do with this. Maybe @Blues4U could shed some light on this? I also don’t buy into the argument that the synthetic is “too slippery “.

 

Theoretically Ford designed their trannys with restricted ports for soft shifts thus type F fluid is less 'slippery'. Conversely GM had bigger ports and Dexron is slippery to modulate shifts. Performance fluids have a coefficient of friction profile similar to type F fluid for firmer shifts in all trannys. Don't know if I believe it (have a good source that says both cans are filled with the same fluid at the factory) but I run type F in my '54 Hydro. Have always had nice shifts even @ the infamous 2-3 shift. Sounds like something is sticking in your control circuit when cold. Might consider removing the control valve and cleaning it. I rebuilt my whole tranny a couple times and wasn't a totally terrible experience.

 

Type F is easier to find in a name brand than type A which just seems to be base mineral oil with red dye.


It looks also like F a is equivalent to power steering fluid. Might be thinner at start up I'm going to try the F

 

Back in 1961 I put a 55 Pontiac single coupling hydromatic in the first 49 Ford coupe that my brother built. In 1962 when I was 17 and I was taking shop class I decided it was a good idea to take it out and take it apart and do the upgrades that were in Hot rod magazine done by B&M as I recall. It was a beast... the first time I floorboarded it I broke both engine mounts on the 58 Pontiac tri-power engine. I always kind of liked that neck snapping shift!!! As I recall the guts are fairly simple to take apart and put back together.

Your transmission is probably going to have to come out anyway so get your jack stands out!! There is a shop in Amarillo Texas that does some pretty amazing things with all kinds of automatics and if you want to I'll see if I can track him down I don't remember the name of his shop right now I'm old.

Just like most of you guys I could shoot myself for ever selling it,, so I just built another one,...The Judge, and she's even more badass..

EDIT: I just remembered that one of the tricks for raising your pump supply pressure is to put one or two old style spark plug copper gaskets inside the pressure valve that's accessible in the top of the case right behind the converter.

 

You got it! Two spark lug washers do the trick. I also built a firstgear lock slide valve (cuts into the top governor tube) copied after the B&M valve that made tnem famous. Have to plug one exhaust port in the tranny case behind the control valve body to complete that conversion. Als grind a detent notch in the gear selecgtor shaft and grind the tip of the parking paul in half os it isn't engaged @the first gear position. My traanny only had 3 planet gears on the reat planetary so I swapped in a 4 gear pack from a donor. As I recall I also machined the front planetary clutch piston to allow addition of a 4th clutch plate and steel. I use a small "Chevy" torus set inside a large Olds can which is a tad looser (higher stall) than stock.

As I mentioned in several threads, these trannys were originally developed to go in WWII military tanks so start out virtually bullet proof from the factory. They are really easy to work on, just get a good set of snap ring pliers, the whole thing is held together with snap rings.

Watch this guy's 5-part series on the Hydro. It will make you a foremost authority and make working on it qa breeze. I downloaded all 5 episodes to my computer from YouTube.






Another Hydro series.




Another guy tearing one down and rebuilding it.

 

The passenger car automatic transmission fluids market is a bit of a nightmare. While most OEM's (except GM) can come together to agree about engine oil spec's, when it comes to ATF's it seems everybody has to have their own specs, which makes things hard for lubricant suppliers and for auto parts stores, and especially for consumers, nobody knows what to use anymore. It's a mess.

The guys above who said that Dexron ATF' are backwards compatible are correct. Over the years the specs for the various Dexron fluids have improved with each new version, while each new version remained backwards compatible with the previous. The change to Dexron VI included a lower viscosity, but also more stable viscosity with less permanent shear loss of the viscosity. To meet the specs I think most or all Dexron VI atf's are made with synthetic oil, just to meet the demands of the specs.

I'm no Hydra-Matic specialist, but as I recall those transmissions always shifted very firm, and chirping the tires under moderate acceleration on the 1 - 2 shift was common. That's what I liked about 'em. If the OP's trans was rebuilt by a performance minded guy, I think he may have intended it to have firm shifts like that. But maybe this particular trans shifts too hard, I don't know. As @BigRRR mentioned above, it might be due to hardened seals/o-rings. Maybe it shifts easier as it warms up because they soften? Again, I'm not a Hydra-Matic specialist, maybe someone that knows the inner workings of those trans can answer that.

Re the idea that the atf thins as it warms, and maybe that provides a softer shift; this is true of all oils, the viscosity decreases as the temperature increases, but with a Dexron VI fluid the viscosity is very stable, it's starts out very low viscosity, and it remains very low, but vs say a Dexron III atf it probably remains as thick at operating temp, and throughout the service life of the oil. Dexron III will shear over time, Dexron VI not so much. Whatever the issue with the OP's transmission, I doubt that it's due to the atf, but changing it as a first step to addressing a problem with shift quality is probably a good idea.

Some have mentioned Type F fluid, the biggest difference with Type F fluid is the friction characteristics. Atf's contain friction modifiers, to soften the engagement of the clutch plates. Dexron and Mercon fluids are highly loaded with friction modifiers, F Type not so much. So Type F fluid will provide less slippage of the clutch plates for a more aggressive engagement, i.e. firmer shifts. Since the problem here is the shifts are too firm I don't think Type F is the answer.

Also, the comment about power steering fluid. It's been very common for years for power steering systems to use atf. Think about what's needed for power steering system, low viscosity for easy steering when cold, anti-wear to prevent wear of the pump and actuators, anti-foam additives to prevent the buildup of foam, rust and oxidation inhibitors to prevent the formation of rust in the system, high temperature capability to prevent degradation of the fluid at high temp operation, high detergent to keep the system clean, atf makes a great power steering fluid. Lot's of manufacturers of construction and mining equipment over the decades have used atf in the hydraulic systems for the same reasons.

And then there is the question of synthetic vs mineral. Like I said, I think most all Dexron VI or Mercon LV atf's I've seen are all synthetic. I think the demands of the spec are such that only a synthetic oil will do the job. Certain types of synthetic oil (PAO) can be hard on seals, and early synthetic engine oils were known for causing hardening and shrinkage of seals, and leaks. But I like to think the additive companies have figured this out by now, I've not heard of this being a problem in many years. Group III base oils are not as hard on seals as PAO, and probably most synthetic atf's are made with Grp III due to the lower cost.

If I was in the OP's shoes, I think I would use something like this:


https://www.castrol.com/en_us/united-states/home/motor-oil-and-fluids/auto-transmission-fluids.html?msclkid=853ee57a0b281fde33c7841931d808d8&utm_source=bing&utm_medium=cpc&utm_campaign=Brand_Transmission Fluids_BMM&utm_term=+castrol +atf&utm_content=Transmission Fluid Core#tab_transmax-high-mileage

It meets the old Dexron III spec, and i has additional additives to soften and condition the seals, and extra detergents to clean up a dirty transmission.

 

Thanks @Blues4U for the recommendation.
And thanks to @willys36 for the videos. I had watched the John Dodd ones years ago but the 5 part series is new to me. I also have a 51 olds 303 with its original Hydro that is slated for my '40. I have been dreading the transmission issue because of the one with the Poncho. I know they are supposed to be great and the Poncho is at times. With nobody left here to work on it it has come down to me to build the Olds Hydro and these videos will be key, thank you so much!

 

Thank you Blues4U, once again I have learned something. When I was at Technical College (1992-94), my instructor told us that Type F had a higher coefficient of friction than Dexron. He also told us Ford was able to get away with using 1 less clutch plate in the clutches due to Type F. I don’t know it if helped, but I always used and still do, Type F in GM transmissions in Hot Rod applications. The rumor was that B&M Trick Shift fluid was really just Type F.

 

I don't know how much extra I'd pay for the Maxoline ATF, and considering it's produced in the Netherlands it might not be the easiest stuff to find on this side of the pond.

I'd say stick with any traditional, brand name, mineral based, fluid that's Dexron rated. Type F fluid would probably be OK, but Hydramatics seem to shift pretty firmly as they are. And you don't want it to shift so smoothly that you can't feel it shift. I was always taught that if you can't feel it shift, you're feeling it wearing itself out.

 

I had this very same issue when I had my 4 speed Super Hydro #315.. This hydro is different then your but they do share some of the parts.. I had Ames oil synthetic transmission fluid in it right after the rebuild. It was doing the same exact thing.. I called the builder who's 68 and was in GM training school for this transmission. He said it is the transmission fluid and I needed to find some of the old stuff on e-Bay.. As luck would have it, I found two cases of Pennzoil Dextron transmission fluid doing this job in an old factory. It must of been there for years. So I drain the hydro and fluid coupling. Then I ran a few quarts through the trans and buttoned it all up put it in and that was it. It shifted rear nicely and the car was so different..

Hope you find the issue.

 

According to what I have read the 1956 Pontiac transmission was changed from the 55 back style and was used thru 1960. I’m no expert either but would make sure you adjusting it to the 56 specs and not the earlier.

 

Some 56 Pontiac models got the new transmission (Jetaway), some have the 55 dual range transmission design. The 55 style transmission does NOT HAVE A PARK position, the later newer design has a park position. The newer Jetaway trans was used on full size Pontiacs fron 56 to 64.

 

Change the fluid in both the pan and the torus and try. If still very hard shifts, then two things to look at:
1) TV rod is adjusted too tight.
2) Some one put those "washers" in the Mainline pressure regulator. This is the big hex plug at the top left front of the transmission. Pulling out those washers will reduce mainline line pressure and possibly soften shifts.

 

I have the 56 without park.

This is what I wanted to find, somebody with the same issue. I looked on eBay for NOS ATF. Not going to be cheap and easy that way as its a collectable for some and on top of that it is possible it has become rancid as the original type A contained whale oil from what I have read. Hard to search for Dexron I as it comes up as VI mostly and I didn't find any in quantity. There are a bunch of Dexron II unopened lots on ebay with varying price/shipping. Dexron III seems to still be commercially available from a bunch of sellers. I did find the Chalet Type A available through a few resellers at $95 for a case of 12 quarts (its a USLubricants product so at least that is someone i've heard of) and one wholesaler (half the cost of retail but you need to by a pallet of it!). It seems like truck stop/convenience store ATF but if its the right stuff.......http://www.uslubricants.com/product/type-a-atf/

 

From what I have been told if your hydro does not shift firm enough have it rebuilt with bus parts.

 

Real easy to tell by looking. Hydro is cast iron and looks like a loaf of bread. Jetaway is aluminum and looks like a modern tapers case design.

 

This Castrol Transmax "M" A/T fluid shouldn't be too hard to find.

Check the description at the link below. It seems to be a mineral based oil (rather than a synthetic) and it's rated to GM Dexron II specifications.

http://www.lubricantsonline.co.za/uploads/Transmax M.pdf

If the discount stores don't carry it you might try a local transmission shop. If you buy it online the shipping charges will probably get your attention.

 

That's not a North America product, look at the web address. I don't know where it is, maybe New Zealand? But it's not U.S. you won't find it here.

I'd quick dicking around looking for obsolete oils and grab some of that high mileage Dex III stuff I posted earlier.