Question on M37 serialization vs servicing data

[cuz]

Maybe someone here can help with the following arithmatic:

Tranny fluid servicing

New Process Model 88950

Thru engine serial T245-3955 (TM 9-8030-2, May 53) (TM 9-2320-212-10, Nov 1973) (TM 9-2320-212-20 Nov 73)

WO-PTO 9 Pt’s
W-PTO 10.5 Pt’s.

After engine serial T245-3955 (TM 9-8030-2, May 53) (TM 9-8030, May 55) (TM 9-2320-212-10, Nov 1973) (TM 9-2320-212-20 Nov 73 Note: This TM has the capacities backwards for after SM T245-3955)

WO-PTO 6 Pt’s.
W-PTO 7 Pt’s.

Note 5 Lube Chart LO 9-3030 (TM 9-8030, May 55) Fill thru filler plug to level of the right PTO panel top rear screw hole.

New Process Model 420

5.5 Pt’s (TM 9-2520-232-35, Jul 59)


Latest LO as specified in TM 9-2320-212-20 Nov 73 is LO 9-2320-212-12.

M37 series production from 1951 thru 1955 = 63,200
M37B1 series production from 1958 thru 1968 = 47,640

If the manuals seem to agree that the split in servicing capacities occurs at engine serial T245-3955 and engine serials in 1951 started at T245-1001 that would mean only the first 2954 M37's used the 9Pt's WO-PTO and 10.5 Pt's W-PTO. If the engine serials started at 0 then that would mean only the first 3955 M37's used the 9 Pt's WO-PTO and 10.5 Pt's W-PTO. That leaves the remaining 60,246 or 59,245 1951 thru 55 M37 series trucks with the model 88950 tranny using the 6 Pt's WO-PTO and 7 Pt's W-PTO.

Does anyone have more data on the engine serialization?

Also note that the TM pertinent to only the 420 shows an entirely different number of 5.5 Pt's and does not list W or WO PTO.

Let me make this very clear. I started a second topic because my intention is not to contradict the previous topics figures but to simply work these errors or misprints through and make pen and ink corrections to manuals as appropriate. I would expect this topic to address the how and why of the difference in data not what is the best level to service anything to.

[MSeriesRebuild]

The answer to the question is this. With the high oil level listings that were first put into print, problems occured with oil getting out through the front bearing and spilling into the flywheel housing, where it got on the clutch, and drained out the inspection cover drain hole. After a while, a change order was printed saying to use the top SIDE bolt on the trans PTO cover on the passenger side as the oil level check point rather than the fill plug opening. There are 6 bolts that hold the cover in place, 2 on the front and rear sides, and 1 in the center at the top and bottom of the cover. The new level check is at the top side bolt nearest the rear of the trans case; not the extreme top bolt. This lowered the oil level sufficiently to stop the spillage in most operating conditions; thus the various fluid capacities you mentioned. Shielded input shaft ball bearings were also installed in some transmissions at rebuild time which helped with the spillage issue also. Different trans cases had the fill/level plugs located in different areas and at different heights on the case. Each one showed a different fluid capacity in the specs.

[Frank Irons]

Interesting reply. I have always been under the impression that axles, transmissions , and transfer cases were filled to just under the fill plug level, never thought that the fill plug could be too high, and the consequences of such placement. I have never concerned myself with fluid capacities and just filled to below the fill plug.

Frank

[powerwagontim]

Same here Frank,
I guess we both learned something today!
Tim

[cuz]

The explanation of the correct level determination for filling was explained in the manual and made perfectly good sense.

This serial number break occurs early in early M37 (51-55) production and has nothing to do with the M37B1 series.

Can someone now explain how the serial number T245-3955 fits in to all of this. What characteristics did the transmission bolted to engines before that serial have and how did they differ from the characteristics that transmissions bolted to those engines after that serial have that justified such a difference in fill levels. It makes absolutely no sense to say that transmissions before that engine serial were serviced to the filler plug and those after were only filled to the PTO cover bolt hole unless there was a pronounced physical difference between them before and after that serial. So it stands to reason that the modified fill level applies equally to all the M37 series (Not B1 series)before and after that serial.

According to the 1954 Ord 9 only two minor hardware changes occurred on the early trans and only one case was used. This would lead one to believe that possibly the only real change to the case was in a blueprint that lowered the filler plug yet left the part number of the case unchanged.

Does anyone have access to any historical factory documents or drawings for the either New Process or Dodge?

[MSeriesRebuild]

It will be an interesting read if you can get to the bottom of this mystery, What you are searching for was never explained to us in the military like the above info that I posted was. I guess they just didn't feel it was important; I honestly don't know. Possibly some of the first trucks could have used an earlier transmission; as far as I know, the manuals never suggested that in the publications that I've read, but I have heard people say the theory holds water. I can't ever recall seeing one of the earlier units in a M37, however some say it did happen. If that is true, then there is the question of whether it was factory installed or a trans someone stuck in just to get a truck rolling again in a critical situation. Good luck in the search.

[cuz]

Charles mentioned seeing different height filler plug locations on early trannies. Can anyone post any photos of that side of the tranny so we can compare the two different heights?

[MSeriesRebuild]

I have an early series and a 420 sitting in the shop, The 420 has a slightly higher fill plug hole than the early trans. Early is
4 3/8" from the bottom of the case, the 420 is 4 13/16". This is measuring to the bottom (oil level of the hole) from the outside bottom of the case. Just looking at the outside of the 2 cases, the early series appears slightly wider in the bottom portion, (not really a good way to get an accurate measurement because of the shape.) I would guess this is the reason for the increased fluid capacity, if my assumption of the wider case is accurate.

[cuz]

I am starting to think the 88950 trans came with two different height filler plugs with the change occurring at eng 3955 which would have been during the 1951-53 years of production. With the early (pre 3955) cases having the higher filler that probably generated the filling note in the early service manuals. The gold chalice here would be a case blueprint showing the evolution of the case changes by amendments.

[MSeriesRebuild]

I don't have a print, but I'll mention this. On the early case I was looking at this morning; it has a centered indent directly above the fill hole that is cast into the case. This could have very well been a centering point for a fill hole that would have been higher up on the case. Measuring from the center of the fill hole, the center of the indent is 2" higher on the case, this would have made a significant difference in oil capacity. It may be the key piece of evidence you were searching for. I may have seen the plug in the higher location, but just never paid attention, can't say for sure.

[cuz]

Charles you hit the nail on the head. I have received photos of very early NP 88950 cases that have the filler plug at that upper location. I'll be posting an edited version of the photos as comparisons showing relative position of the filler plugs and correct servicing level determination tomorrow.

[hbb]

Great information shared Charles and Cuz!
I havent gotten that far in my personal restoration but great stuff to be aware of and I am sure that would have been a head scratcher for me and maybe many others watching.
hb