shift points for '72 250c w114

[jw_in_Cali]

Ok so I have a super solid '72 250c runs great and everything works great including the radio and a/c. But when driving I'm feeling it shift (what I think) is out of second gear in the low 20 mph range and then again around 40mph. The engine feels and sounds like it's revving high and doesn't sounds right.

Any help would be appreciated.

[ScooterABC]

Just to clarify, it's a 4 speed automatic that typically starts in 2. So when it's up to 4 it pops back into 3 at 40 mph? or back to 2 at 40 mph? It should not do that, I would be somewhat suspicious of the shift linkage being out of adjustment.

[Frank Reiner]

jw:

The '72 250 (M130 engine) was equipped with the 722.200 transmission. The 722.2xx trans starts in 1st, and if at light throttle then makes a rather quick shift to 2nd. The 1-2 shift can occur so quickly that it may not be apparent, leading many drivers to think that the trans has started in 2nd.

Shift points:
Light throttle-
1-2: 6mph
2-3: 16
3-4: 24
Full throttle-
1-2: 15
2-3: 32
3-4: 72

The above shift points are with 3.92:1 final drive gearing.

[jw_in_Cali]

Thanks Frank and Scooter. With light throttle, I do feel the quick shift into 2nd almost immediately. My 2-3 shift happens in the low 20's mph and then 3-4 shift around 40. From what you posted, something is a miss with mine. The question is where to start looking?

[Mike D]

There is a shift control rod which can also affect shift points. It runs from the accelerator bell crank located on the intake down to the transmission. I know the M110 engine cars have it, not sure about the M130 engine models.

[Frank Reiner]

Originally Posted by jw_in_Cali

Thanks Frank and Scooter. With light throttle, I do feel the quick shift into 2nd almost immediately. My 2-3 shift happens in the low 20's mph and then 3-4 shift around 40. From what you posted, something is a miss with mine. The question is where to start looking?

Originally Posted by Mike D

There is a shift control rod which can also affect shift points. It runs from the accelerator bell crank located on the intake down to the transmission. I know the M110 engine cars have it, not sure about the M130 engine models.

jw:

Mike D has started you in the right direction; the rod referred to is the control pressure rod, which does indeed form a link between the carburetors and the transmission. As the throttle is progressively opened, control pressure in the transmission is simultaneously increased, which has the result of increasing the road speed (and engine speed) at which shifts occur. The control pressure rod is equipped with an adjustable rod end at the upper connection. Unscrewing the rod end (lengthening the rod) will lower the shift points.

[jw_in_Cali]

Thanks Mike D and Frank. I unscrew the rod end two full rotations and still the same. Is there a ratio between retations unsrewing the end vs mph shift point? And again shifting 1-2 is below 5mph while 2-3 is around 24mph.

Someone mentioned to me the lockdown switch under the throttle pedal may be stuck or broke (which it appers to function when I push on it by hand) any thoughts on this?

[Frank Reiner]

Originally Posted by jw_in_Cali

Thanks Mike D and Frank. I unscrew the rod end two full rotations and still the same. Is there a ratio between retations unsrewing the end vs mph shift point? And again shifting 1-2 is below 5mph while 2-3 is around 24mph.

Someone mentioned to me the lockdown switch under the throttle pedal may be stuck or broke (which appears to function when I push on it by hand) any thoughts on this?

No need to incarcerate the switch ; it's a "kickdown" switch.
The KD switch supplies power to the KD solenoid, which is located on the right front corner of the transmission, just above the pan gasket. If the switch is stuck, and powering the solenoid continuously, by disconnecting the wire from the solenoid there should be a change in shift timing.
Late shifts can also be caused by low governor pressure, but test the KD solenoid first.

[jw_in_Cali]

LOL thanks Frank. I'll try disconnecting the KD solenoid and see if that does anything.

With regard to the control pressure rod, I unscrewed (extended) the rod end two full rotations, would that be enough to notice a shifting difference or would I need to go further?

Also is there something on the transmission side of the control pressure rod that I should look at as well?

Thanks again for all the guidance on this.

[jw_in_Cali]

Ok so was able to crawl underneath, I first unplugged the squarish box on the drivers side of the trans, turns out that was part of the neutral safety switch hence it wouldn't start, so I plugged that back in and then unplugged the kick down switch under gas pedal from underneath the car. No difference in shift points. I'm next going to try to find the KD solenoid, unsure if it matters at this point but worth a try.

[jw_in_Cali]

So I went ahead and ordered a new vacuum modulator. When I took out the old one, the old one has a pin attached to it, which does easily come off (not sure if it is suppose too?)

I've seen a picture showing a clipped on spring over this pin.

Can anyone confirm if there should be a spring over the pin?
Also can anyone confirm if the pin on the old one can be removed to use on the new one?

[Frank Reiner]

Originally Posted by jw_in_Cali

So I went ahead and ordered a new vacuum modulator. When I took out the old one, the old one has a pin attached to it, which does easily come off (not sure if it is suppose too?)

I've seen a picture showing a clipped on spring over this pin.

Can anyone confirm if there should be a spring over the pin?
Also can anyone confirm if the pin on the old one can be removed to use on the new one?

A spring would be used only on fixed pressure, diesel applications.

Install the original pin in the replacement modulator. Sometimes the pin is glued in for convenience during installation.

[jw_in_Cali]

Excellent, thanks Frank.

[barry12345]

If the new modulator does not help. Consider trying a can of transmission treatment. You can be losing pressure control past old shrunken seals in he transmission. It may take 1000 to 1500 miles to see if it works.

I am not a fan of additives. This does work though sometimes. By expanding the seals. Worth a try and did help in the same transmission I have in my 1972 250c.

As for the control rod. I purchased a parts car where the control rod had parted company at the front with a rusted out ball. The car was drivable but rusty beyond belief. The transmission shifted up really, really quick. As a test as I have no ideal of how much effect only two turns on the rod linkage would have in an attempt to deal with an issue. I might disconnect the rod and put it in the earliest upshift position to see what you have.

I wanted the transmission out of that rust out in case mine went bad in time even though the seal treatment had worked. For some reason I removed the valve cover and discovered that the cam and rocker arms where pretty new. The engine actually ran great as well. So I pulled it and kept it. Maybe it was a total rebuild. Or just the top end.

Generally I do not post on this section of the site. Yet since I went through essentially the same issue at one time. I thought my experience might help. If not no harm would be done.

As well as keeping the transmission. I had no past owners information on the car.

Anyways having owned a few of the m130 engines. This was a really good one. I have also had failure of the number one cam lobes on two of their gas engines. It was cheap in those days to have that lobe built up and the cams turned. The repairs also seemed to last.

Not as bad as their earlier gas engines. Just do not neglect to check the valve clearances at reasonable intervals. If you detect an adjuster that moves easier than the others. Change it. Neglecting these things can cost you a burnt exhaust valve. There is probably a torque specification on their valve adjusters to be found somewhere. The tightness of their valve adjusters fit had been really improved by the time the m130s used in the 1972 models had arrived. .

Gas is over five dollars an American gallon here in eastern Canada. The M130 is not the best on fuel. So I drive primarily diesel cars. Any vehicle with this engine in is very rust prone here. So I limit the use of my cars with this engine even in the summer. I daily drive back and forth to our beach place in the summer as well.. These cars are just not practical with the cost of fuel here for even this use unfortunately.

Another item. If you are going to let the car sit unused for longer periods of time. Run the carbs out of fuel somehow. Otherwise the gas evaporates and leaves a residue that will cause issues. Faced once with kitting two carbs. I disconnected the fuel line just under the drivers foot well. Put the line in a quart of laquer thinner. Started the engine and let the carbs fill up with it and shut the engine down. Remember to run them out of gas before doing this.

Removed the idle adjusters. In about twenty minutes the gum was dissolved and gas started to come from one adjuster hole. A few minutes later the other one opened up as well. What I also observed is the engine will run well on the thinners after until the gas takes over again. Plus those carbs where operating better than they ever had. It became my go to for carbs over the years in many things. I even use it as part of a tune up sometimes. No it will not fix a bad part. But it will clean various forms of residue that accumulate in carbs. I have found that the idle passages in the zenith carbs do like to gum up. If the car is not in pretty much constant use.

Just a few things I want to leave on this portion of the site. As I will probably not return to it for a long time. I can be contacted on the diesel portion of the site with a private message if there are any questions about anything I have mentioned.

[jw_in_Cali]

Thanks Barry12345 for the helpful hints and info. The shifting is slightly better after the new vacuum modulator.

I was wondering when adjusting the vacuum modulator with a hex key (Allen wrench) is there a direction for increasing shift points vs decreasing them, for example turning clockwise makes it shift sooner or later?