Indyhac

I need to find somebody that knows things to try on my '50 Oldsmobile to get it to take off in 1st gear when the column shifter is put into the Lo position. It works like it is supposed to when put in D. That is, it takes off in 2nd then shifts into 3rd and then 4th. I know that GM made this engineering change for the 1950 model run from 2 articles that I read some years ago but I have no 1st gear in the Lo selector position and it should be there and then shift into 2nd at the proper speed. However, I only have 2nd gear in Lo. I have my car in a transmission shop and they've replaced some worn clutches but they haven't quite figured out how to make 1st gear engage in the Lo position. The repair guy told me that he is going to see if maybe something is wrong with the valve body. I've consulted my shop manual but my head starts spinning with all of the technical verbiage in there about all of those oil pressures and the valves & pistons that control them. The shop manual is pretty specific about removal and replacement of the transmission plus disassembly & reassembly but not much detail about service. The trouble shooting list doesn't address my problem. I loaned my extra shop manual to the transmission shop but they're moving pretty slow on this. I think that they may be stumped! Scott

redoldsman

Does the transmission shop actually have anybody that know about these old 4 speed hydros? Unfortunately there are not many people around that still know anything about them since they have not made them in a long time.

Tedd Thompson

As I remember you are correct about the early hydro's skipping first on start up because of customer complaints of to much wheel spin. Some where in the past on this site this problem has been addressed and as I recall there is a fix for it, hopefully someone here can remember the thread and pass the link on.... Tedd

droldsmorland

I just learned something. The pre and post-war Hydra-Matics were a 4 gear auto???
Id start out simple with a fluid pressure test to see if each circuits operating at the correct pressure spec. Check the shift linkage to see if it has full travel. The linkage could be out of adjustment, binding or bent. Does this car have a TV cable? If so it may be out of adjustment? Then its time to go in deeper. Governor may need a look. Sounds like the pan and fluid have been inspected.
Im having a hard time following the post...Does the trans down shift into 1st automatically when coming to a stop, then start out in 2nd? Or do you need to force it in to first to obtain 1st gear? You do you have 1st gear, right? Does this trans have the 2nd gear start option? If so then Id be examining that circuit as well. The pressure test will show the bad circuit if there is one. A bad circuit means fluids leaking internally (bypassing) somewhere in that circuit causing it to malfunction. Yes valve body valves, pistons and springs can contribute to these kind of malfunctions if they are broken or stuck. If it was me Id definitely find a competent Hydra-Matic person, unless you do feel confident with the one you have? Unfortunately my data only goes back to 1961. Look for a Motors or Chiltons transmission manual online that has the 1950 data. It will contain a troubleshooting chart as well as every thing else you or the trans tech will need. Close the loop here when you find the problem.

Indyhac

1.( redoldsman), I think the transmission man at the repair shop knows old transmissions since lots of guys I know recommended him and he rebuilt the hydramatic in a 57 Pontiac Safari that I used to have. He's just never encountered one like the 50 Olds that starts out in 2nd gear.

2. (Tedd Thompson), I sure hope that someone remembers that old thread that you mention and steers me to it.

3. (droldsmorland), All of the early pre & post war hydramatics were 4-speeds until around 57 I believe. They were not all configured the same. Early ones had R, Lo, D, N. In D they took off in 1st and shifted thru 2nd, 3rd, & 4th; in Lo they took off in 1st and would only shift into 2nd. Then in 1950 GM made this change in Oldsmobile's only where, because of that powerful V8, they didn't need to take off in 1st so they bypassed 1st and took off in 2nd. But when moving the shift lever to Lo, they would start out in 1st. In 1952 Gm configured the Pontiac hydramatics with two marks in the D range on the selector so the driver could put the gearshift where the lower mark was which kept the transmission in 3rd gear. You could move the shift lever into the upper position allowing the transmission to shift into 4th gear. This allowed the driver to manually downshift into 3rd gear for passing or for going up or down hills and was good for in-town driving where 4th gear wasn't needed. Gm called it "Dual-Range Hydramatic. My issue with my 50 Olds is that when I put the gearshift into Lo, it still takes off in 2nd not 1st. It is supposed the take off in 1st when in Lo. Scott

redoldsman

Sounds like you are dealing with somebody you know which is a good thing. These guys are getting to be few and far between.

redoldsman

I tried to edit my last response but it would not let me for some reason. I sold a 50 convertible from an estate I was executor of and I drove it a number of times. It for sure took off in first gear. The one thing these old transmissions do is shift from 1st to 2nd and you cannot control it. By the way, nice car.

Ozzie

It sounds to me like the transmission is just not going into 1st speed. Here are the eight possibilities I know of that can cause it to happen.

1. Governor valves sticking or improper valve travel.

2. Internal leak in governor.

3. Broken governor ring or land.

4. Valves sticking in control valve assembly.

5. Leak between front servo valve body and front servo. This generally only occurs on the 1953-56 models, but I'm including it in case the transmission is not original.

6. Leak in front servo apply passage. (You can air check the passage.)

7. Gear set failure, locking the front unit in direct drive.

8. Oil passages inter-connected or not drilled in case. (Again, air check the passages.)

With so much work done, I'm assuming that new fluid of the proper kind is being used and fluid level is correct.

Indyhac

I have managed to find & contact Bill Ehrsam. He is very knowledgeable about older Oldsmobiles like my '50. He thinks that he can provide me with a valve body that will make my hydramatic downshift into 1st gear. I will update results as I obtain them.
I lost touch with bill Ehrsam after he left for California; no responses to my emails or voice messages. Scott

oldcutlass

Glad to hear your getting somewhere with your issue.

oldspackrat

Hey Scott this is Scott you talked to you last week. Glad to see you found this website and that you are finding some help.

d2_willys

I have a '50 Olds 98, which does exactly what your trans does. Only difference is that mine will shift down to 1st when mashing the gas pedal to the floor. This was done in Lo, dunno if that does the same in DR.

Someone said that a spring was missing (I think 1-2 shift valve return). Maybe I will take a dual range valve body apart, and investigate.

Oldsmobile and GM trucks would start in 1st in any range, including low. Others start in 2nd when in Lo.

Rocketowner

X2 on Tedd's post #3. GM did "block out" low in the 1950 because in '49 you couldn't take off without spinning. I had a '50 and my brothers (who rebuilt early Hydramatics ) ask me if I wanted my low gear 'unblocked" so it would take off in low gear. I said yes,they brought it in and changed it ,took no more than 30 minutes,and sure enough,I bought rear tires more often or swapped fronts to back.
Not taking off in low when lever was in that position sounds like it might be a "governor problem" or valve body problem, or maybe the linkage is not actually pulling it far enough to actually engage . Best of luck, and please keep us posted on the problem. Larry

d2_willys

Larry: Do your brothers remember what they actually did to unblock the low gear start? If so, please share. Thanks

Rocketowner

Sorry but no,one is deceased and the other has Alzheimer's. I just wish I would have ask the question at the time . The younger of the two learned the Hydramatics while in service working on Army Tanks (the M5 Stuart and the M24 Chaffe lightweight) were equipped with dual Cadillac engines and dual Hydramatics. Some very interesting info concerning is available on (revolve.com/main/index.php?s=Hydramatic . Larry

classicmuscle442

Cool picture, looks like trans was tied into blocks cooling system.

redoldsman

That is a cool picture. That is a Cadillac flathead that was used in tanks.

Rocketowner

I sent an Email to Fatsco transmission Co.explaining our concern about the low range difference
In the 1949 and the 1950 Olds Hydramatic and told them that I knew there . was a way to "Unblock the low gear in the fifty to make it take off in Low when gearshift was in Drive position".
Will post as soon as I get an answer. They have been making and selling automatic transmission parts since the 1940's,and are the largest supplier in the U.S in this business.
I know that there is a simple solution to do this, because it was done to my personal car.
If anyone knows anyone else that might have a valid answer please contact me by PM.
(Rocketowner). Larry

Indyhac

I finally gave up on the 1st transmission shop that had my olds for more than 6 months. Now I've left it with an older gentleman who worked on Hydramatics in the early '50s. He is not familiar with this problem but thinks it's connected with the valve body. I'm not very optimistic about finding anyone who can solve this problem! Scott

d2_willys

Since no answers on the 2nd gear start, I will take apart a valve body from a 52 Lincoln hydramatic I have dismantled. I am believing that the 2-1 detent spring is missing on 2nd gear start transmissions. I will let you know what I find out.

Indyhac

I am definitely interested in what you discover about the 2-1 detent spring.

Scott

d2_willys

I remembered that I do have a 50 olds hydramatic out of a car, so I will compare it's valve body with the 52 dual range hydramatic valve body. If the same, then I am thinking G1 spring in governor.

d2_willys

Well, I found a decent valve body description document and this is what I found:

In either Dr ranges, the first to second shift is controlled by the G1 circuit and feeds the 1-2 shift valve directly.
So, I am thinking that in transmissions with 2nd gear start (1950 Olds) in Dr, the 1-2 shift valve spring is not installed, or a lighter spring is used. This means that the 1-2 shift valve is always open (except for 2-1 forced downshift), therefore 2nd gear start.

In LO range, the 1-2 shift is controlled by G1 circuit and feeds both the 1-2 shift valve AND the 2-1 detent plug.
My feeling here is that the second gear start is acccomplished in one of two ways - 1) The 2-1 detent spring is not installed, there by making a 2nd gear start easier to be accomplished (no spring tension) 2) The 2-1 detent spring is installed, BUT the spring tension is lighter than if there is a 1st gear start.

Now for the 2-1 forced downshift circuit. This is done quite simply by spring pressure on 1-2 shift valve due to G1 pressure being very low (at 10mph). This is for either Dr range 2-1 downshift.

For LO range, detent oil circuit, derived from T and TV valve actions, causes pressure on the back side of the 2-1 detent valve, thereby allowing 1-2 shift valve to close, and downshift to 1st.

All of this sounds complicated, but now it gives me a place to start to dissect valve bodies to find out what is needed for 1st gear start in Dr and Lo ranges.

The 52 Lincoln valve body is dual range and has 2nd gear start in LO, so that should give me some idea as to how the Lo range works on this transmission. It will also show me the 1-2 shift valve spring for 1st gear starts in Dr.

The 50 Olds valve body might give me a clue as to Dr range 2nd gear start, and what Lo range is set up to do.

Well, enough of Hydramatic lesson for today. Hopefully I can get to analyzing the real deals.

Indyhac

d2 ******, I will take this latest info to the "Old time transmission guy" who has my car now and see if this will help him. If you discover any further info or analysis, send it along.
Thanks, Scott

d2_willys

Got to looking at a 1949 Olds hydramatic and this is what I found:
No springs in any of the governor plugs
In Dr range, 1st gear provides mainline pressure to 1-2 regulator plug and to the spring side of the 1-2 shift valve, which keeps the 1-2 shift valve from moving till G1 pressure is high enough.
In LO range, it is different: Besides mainline pressure (selected in LO range) on the 1-2 regulator plug, TV pressure is used on spring side of 1-2 shift valve. This allows Lo range to extend the 1-2 shift to a higher speed than in DR.

Looking at the diagram, I think there may be a different 1-2 regulator plug in yours than in others that start in 1st when in LO. Feeling here is that it may have two passages for both mainline and TV pressure to push against the shift valve. The following link will show the 1949 valve body. If you go back in pages at this website you will see the valve body actions and descriptions.

http://edge-op.org/1949_Oldsmobile/index.php?page=301

Hope this helps.

Indyhac

d2 ******,
If I understand your research correctly, you have a '50 Olds transmission from which you can get the valve body off of and compare the difference between it and the '49 hydramatic document that you've found? If I could find out the difference, maybe my valve could be converted to be like the '49 valve. Unlike your 98, mine won't take off in 1st gear even if I mash it to the floor. I looked at the troubleshooting section of the link you posted and it states that if the transmission starts in 2nd speed but makes all other shifts (which mine does) the cause is sticking valves in the valve body or governor. It would be nice if all I had to do is to put a stronger or weaker spring in the valve body to fix this. Scott

d2_willys

Scott, your transmission may just need a proper TV rod adjustment. As I said, in the 49 transmission, the LO range uses TV pressure to allow the 1st gear start. Perhaps the valve body is just clogged up too.

Mine starts in 2nd gear in both DR and LO. Only way to get back to 1st (in LO) is to mash the pedal to the floor while moving slow (under 10mph).

I will try and get to the 50 Olds valve body this weekend. I will need to get the serial number off it too.

I will also try and get the 52 Lincoln valve body and see what the 1-2 shift spring looks like between the two.

Indyhac

d2 ******,
Linkage adjustments is the 1st thing that the "Old Time" transmission guy, who presently has my Olds, did. Now he suspects the problem is in the valve body. He is limited to the amount of time he can devote to my problem because his wife has Alzheimer's so he has to keep an eye on her. Scott

d2_willys

Good news! I got the 50 olds valve body apart, and guess what? There is a spring between the 1-2 governor plug and the separator plate. This means that it will start out in 2nd, whether LO or DR.


I will try and send some pics of my valve body to this site tomorrow. But for now I would try either removing the spring, or putting in a lighter spring, same length. The G1 pressure passes thru the spring, so don't choke off that passage by putting a longer, weaker spring. Everything else looks same or equivalent to 1949 valve body. The governor plugs are on the side of the valve body where the 3 tubes come in from the governor.


Good luck, and let us know if this is the secret to the 2nd gear start.

d2_willys

Here are some photos of my 1950 Olds hydro valve body.
Valve body numbering for reference.

Governor plug cover removed, showing 1-2 governor spring. This is the one to either be removed or a weaker spring installed.

Shift valve springs with cover removed. Notice regulator valve extending outside of cover at middle bottom.

1-2 regulator valve.

1-2 regulator valve. Notice the hole in the top. It is for sending modulated pressure to shift valve.

Other side of regulator valve. This is the side the extends outside of the shift valve cover.

Governor plug housing and separator plate.

Valve body passages.

1-2 spring is not pressing on the 1-2 governor plug, therefore passage in middle is closed, thereby starting in 1st gear.

I am pressing on the 1-2 governor plug spring. Notice the middle passage is open, causing 2nd gear start.

Indyhac

d2 ******,
These are great photos. I'm taking them to my hydramatic transmission expert. If he can't fix my transmission after seeing these pictures, I'd be totally surprised. I will let you know.
Scott

Tedd Thompson

This is what I like about this forum, you learn something everyday. That took a lot of mind twisting time and effort for D2 to pull down those parts and take those pictures.Thanks again for passing on the knowledge... Tedd.

d2_willys

Thanks Tedd! Actually it was pretty easy, since I have a spare 1950 Olds hydro on my bench. 15 minutes to take out of transmission. Then I took valve body home and opened it up next day. I sure hope this works for Scott. Then I know I can fix my 1950 Olds 98 when I get it out of storage. This can be done in car. 4 bolts and the valve body comes off the transmission. Remove the governor plug cover and remove spring. Put back together and that's it.

Indyhac

d2 ******,
I took the pictures and your printed analysis plus some of the '49 documentation from the link you provided to the transmission guy yesterday. He said that it was good information that is not included in the training manuals that he has. It may be awhile before I find out the results but when I do, I will post here.

oldcutlass

If this works I will make this thread a sticky. Very good info.

kirkwoodken

I am under the impression Olds did a first gear delete to make it easier to get the car unstuck from mud and snow. But in drive, it started in first. This has been common in other brands of automatics. Could have been a one or two year thing that was dropped because some didn't like it. All I've had experience with is "R" series, which start in 1st, and were the transmission of choice in early drag cars. During my military time, the 2 1/2 ton trucks had 302 GMC engines and 4 speed hydros. When the transfer case was in "Lo" range, the 1-2 shift would pull the front wheels off the ground. They were stock Hydramatics with only an increase in hydraulic line pressure. The "R" series Hydros were very good transmissions. No way would I replace one with a newer TH350 or 400, unless you just wanted to knock a 150 pounds of weight off your Olds. Before I would take one to be rebuilt, I'd put a can or two of K&W "Trans-X" in it. Some times that will soften seals and clean stickiness out of valves. It's worth a try. Hydromatic also does not need an oil cooler, as do newer models. They also lock up to the crank in 4th gear, and give reasonably good mileage on hyways.

Rocketowner

I am very appreciative that D2 ****** has become interested in this post and finally proved that I was not "Dreaming" that there was a simple matter to unblock the low gear in a '50 Olds where it would take off in low gear ,instead of second when in the "D" position.
As I stated in post # 13 I knew it was possible, and a very simple process, but I have tried numerous times without success to find the answer. Thanks again, Larry

d2_willys

The R type hydramatics, along with some of the truck hydramatics did start in 1st when the transmission was in LO or either DR range. Other dual range hydramatics were configured to start in 2nd when in LO. You could get a 1st gear start, but you had to floor the gas pedal from a start. I am currently looking into the difference in the R type and the rest, to see if it is easily possible to configure to make 1st gear start in LO. It may be as simple as blocking off the mainline pressure to the 1-2 governor valve (or detent valve as they call it). Some of these transmissions also use a spring to put pressure on the detent valve to oppose the mainline pressure, so it may be as simple as putting a spring in the valve body. (Please note, this is for DUAL RANGE hydramatics, not single range.)

The hydramatics sort of locked up in 4th gear, but only a percentage (60%) was a mechanical lockup. The hydramatic did a torque split in the front planetary, where 40% of the torque was thru the fluid coupling, and the rest thru the front clutch. This, I believe was to avoid breakage in a case of an emergency stop in 4th gear. (I could be wrong)

kirkwoodken

kirkwoodken

Found the above info in a 1955 Motors Manual. Somehow it didn't print as I wanted it to. Does the Hydro in the OP's car have a 1950 serial number? Original could have been replaced with a later year transmission. Not unusual back in the day.