40 transmission problem

[alanwoodieman]

owner went to down shift from 3rd to second, a big bang, trans stuck in gear thought it was second but turned out to be 3rd gear, the syncro blockers over rode the syncro ring. the blockers were wedged on top of the syncro ring, all three. it appeared at first that the ring stuck to the input shaft (3 rd gear), don't know what happened but looking for answers, ideas. we are rebuilding a different trans but I would like to know what happened to cause this.

[JM 35 Sedan]

It would help to know some of the past history on that failed transmission. Just a few of the many questions might be......
• was this the original trans to that car as it came off assem. line?
• had anyone made any previous internal changes/modifications/complete rebuilds over the years?
• what type of driving was the present owner doing before or when failure occurred.
• was there enough, and the correct type, gear oil being used?
• is it possible that some other failure occurred first, and then caused the transmission to fail?
• what is the condition of the shifter cover and its inner and outer mechanisms, such as, external levers, bushings, detents, internal shifting parts, including the forks?......etc, etc, etc.

I know some, if not all of these questions would be tough for you, and /or the present owner to answer, but there are so many things/variables that could have lead up to this failure, that trying to pinpoint a cause would most likely be guess work on anyone's part.

Any possibilities for posting any pictures of the failed internals of this transmission as they appear when side cover is removed, and maybe after disassembly, showing the individual parts and pieces laid out together.

[alanwoodieman]

original trans was rebuilt about a 1000 miles ago by the previous owner, stock, driven on a few local tours, driven by a "old car guy" not abused at all. nothing external problems, full of unknown doping. no other failure occurred. only previous problem was an out of adjustment shift rod, corrected a long time ago.

[zzlegend]

I just ordered parts from Mac at Van Pelts. You might want to give him a call. Very helpful guy. Just a thought.

http://vanpeltsales.com/

[Terry,OH]

the syncro blockers are the syncro brass rings. Hard to imagine the three syncro hub inserts coming out. especially a transmission that has been in service but did the thrust washer in back of the intermediate gear brake off? If it did then the 2nd gear (intermediate) end play could be way toooo much and result in your problem???? Got a photo?

[deuce_roadster]

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I would tend to think along the lines of Terry,OH. Maybe the endplay in the mainshaft was too much from the beginning. Those washers behind 2nd gear come in different thickness to adjust this and the person who rebuilt it might not have known anything about that or maybe even left the washer out. I can't imagine what you are describing. Maybe MVP has seen this.

[alanwoodieman]

no the syncro blockers are steel rectangles with a hole for the spring/ball to go thru them these jumped up on to the top of the bronze syncro rings. will have some pictures of the damage this week-end I am going back to his house Saturday. I thought the same but the thrust washer was there and looked to be correct thickness. I am beginning to the that the syncro hub was in wrong. to many hands/questions to be sure

[rotorwrench]

Those balls & springs come apart some times. The blocker rings are the brass rings with the spline teeth & tapers . The part with the balls & springs is the synchro hub.

[alanwoodieman]

roto--the balls/springs were still there, I have never in over 40 years of Ford trans of this era ever seen this problem. We had three other sets of hands in the disassembly of the trans

[alanwoodieman]

picture of the syncro ring and the blocker

[Mac VP]

That bronze synchro ring is shot and all three inserts are hammered. At the least I would replace the rings and change over to the 51A-7109 type inserts and springs. The early style inserts with the balls and springs are problematic.

Sometimes other parts can have domino effects on parts. I don't know what other parts are in your transmission so it's impossible to say from here what other issues may be going on. Let me just throw one out there. Compare your main drive gear to the ones in the attached picture......particularly the tapered cone. Does it look like the 81A type?

http://www.vanpeltsales.com/FH_web/F...comparison.jpg

[alanwoodieman]

Mac--never thought of that, I will look at the input shaft more closely today. I now have the trans/parts and another 40 trans that belongs to the same man. hope to make one out of two. Thanks!

[Admiral]

That's some nasty damage! Good luck getting it back on the road.

Not to hijack this thread, but Mac, what makes the 51A-7109 inserts and springs better?

[Floyd]

I have seen this one time and a friend of mine who has rebuilt many trans (properly) has seen it happen one time to one of his. The one I built for a guy was done correctly with NOS or excellent used parts, new bearings, thrust washers, all gaps within spec, second gear gap at 0.0055" etc. After a few hundred miles from an experienced early V8 driver, it did pretty much what you had happen. I never did find out what the real cause was. Installed a NOS synchro assembly and it went back on the road. The one my friend had go bad in the same manner was examined and no real answer as to the failure mode. He also replaced the torn up parts and all was well. No idea what happened. really strange.
Just an opinion

[alanwoodieman]

Thanks Floyd, Mac V, I had to get a T-Bird back together today, will work on the trans in the am and will let everyone know what I discover!

[Mac VP]

Re the question about the two styles of synchro inserts.......I used to think the 39-44 ball and spring type was better and that the solid insert was going to hold up better. In practice, the three little coil springs have a tendency to catch at their top coil, becoming bent over and dragging under the rectangular insert. This situation causes shifting problems.

Ford changed to the pressed steel inserts with the two wire springs in 1945, and stayed with this design from then on. Unless the pressed steel insert breaks one of its folded sides (and this can happen after time) this design is more reliable in my opinion. Ford apparently felt so too.

You can use the 51A type insert kit on the 39-44 hubs just like the 45-54 hubs. Naturally if you wanted to use those 39-44 springs-balls-inserts (cuz you just love 'em) you're limited to placing them on the 39-44 hub. The 51A-7105 hub doesn't have the pockets for the balls and springs.

I'm still puzzled about the obvious wear on his inserts. The bronze synchro rings are softer material and are expected to suffer most of the wear......but not so much as what we see in his pics.

[alanwoodieman]

owner said he heard a loud bang when he attempted to down shift from third to second, he said it was not under load, just had slowed down to turn a corner. To me it appears there was too much clearance in the main shaft and/or that the 3rd gear ring stuck to the gear face. I am at a loss, but plan to investigate tomorrow. Mac V what doping do you recommend?

[Mac VP]

Check that main drive gear to make sure it isn't the early style in the gearset. Recheck all parts for the correct match. Make sure the 2nd/high shift fork is the correct 91A type. Check the caged roller bearing on the mainshaft to make sure it didn't come apart. Incorrect oil did not cause the problem in my opinion, however we recommend regular GL4 gear oil only. Keep everyone posted on what you find.

[George/Maine]

I had a problem with a new rebuilt my a know trans builder.
When they put the UJ back in they DIDNT put the center bolt in.
I chipped a tooth in first and took about 5 teeth out of cluster.
New cluster gear seemed to be very brittle.

[sidevalve8ba]

alanwoodieman,
Any other photos of the transmission or parts that you can post? Might be helpful to us. Ted

[JM 35 Sedan]

Originally Posted by alanwoodieman

original trans was rebuilt about a 1000 miles ago by the previous owner, stock, driven on a few local tours, driven by a "old car guy" not abused at all. nothing external problems, full of unknown doping. no other failure occurred. only previous problem was an out of adjustment shift rod, corrected a long time ago.

I feel the need to ask this question.......I'm wondering if you know/knew the previous owner who rebuilt this transmission ~ 1000 miles ago, well enough to judge his level of skill sets, mechanical abilities, and the knowledge required to rebuild one of these early Ford transmissions?

As other folks have already mentioned, this failure seems to be nearly impossible to happen, UNLESS, parts were not assembled/installed correctly or maybe left out completely, incorrect parts were installed, or something broke and dropped out of place. Any or all of these things mentioned could have allowed parts to move far enough out of possition allowing those rectangular synchro inserts to move out of place and cause the type of damage shown in your pictures.

[alanwoodieman]

took the trans the rest of the way apart, all the correct pieces are present. The cluster gear and 1st and reverse slider gears are really beat up, chipped teeth some teeth almost worn to a point. This trans led a hard life for a long time. Took second "rebuilt" trans apart, miss matched cluster (28 tooth) and input shaft (15 teeth), cluster gear looks very good. glad he did not try to run it. cluster gear was very tight, no clearance at all, had a hard time getting it out. Took everything to the vat and let them soak for awhile, will take some pictures and post. right now I would believe the problem was a lead footed driver!!

[alanwoodieman]

JM-- I have no knowledge of the gentleman in Fla. who restored the car. I am now pretty sure it was just abuse long before he even worked on it.

[JM 35 Sedan]

Originally Posted by alanwoodieman

JM-- I have no knowledge of the gentleman in Fla. who restored the car. I am now pretty sure it was just abuse long before he even worked on it.

Alan, it's my best guess that he and the quality (or lack there of) of his rebuild on this transmission are directly related to the main reason or reasons why this transmission has failed.

The first picture is not the best example for this purpose, but if we could have seen some pictures of this failed transmission, done like these pictures, it might have been possible to determine what lead to the failure of your friends transmission.

The first picture was taken of a 40 to 48 side load transmission that we were thinking about buying as a gear donner to use in an earlier top loader case. The second and third pictures were very nice gears that I removed from another side loader transmission, to use in an early pn 48-xxxxx top load case. Last picture was the rebuilt top loader case, rebuilt with 46-48 gears, all ready to be installed in a 36 Ford touring sedan.

[alanwoodieman]

pictures would look like any other trans, except for the pictures I already posted of the badly damaged syncro ring and the blocker. If I had a guess, I would say somehow the syncro hub moved and allowed the shift ring to get off the syncro blockers/balls/springs
Thanks to all for the suggestions and help.

[JM 35 Sedan]

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Originally Posted by alanwoodieman

pictures would look like any other trans, except for the pictures I already posted of the badly damaged syncro ring and the blocker. If I had a guess, I would say somehow the syncro hub moved and allowed the shift ring to get off the syncro blockers/balls/springs
Thanks to all for the suggestions and help.

What I was implying, by showing some of my pictures, would have been a picture that might have been taken showing what that transmissions internal gearing looked like just as you removed the side shift cover, especially in the hub, sliding collar, syncro areas, and how those inserts actually looked up over top of the syncro rings. Also, by showing the internals after the cover was removed, and a shot of all the individual parts, we may have noticed a part that was missing from the group or some relative damage to other parts. I guess "with three other sets of hands in the disassembly of the trans" no one was thinking quick enough to take pictures that might have helped you and others being asked to help understand this later, and determine what might have actually happened to cause this failure.

[alanwoodieman]

when I took the trans fully apart and washed up these parts it became apparent why the trans failed--should have failed earlier!!, some one removed the ring spacer on the main shaft and substituted a long needle bearing where a short one should have been, the syncro hub had been damaged on the thrust face and had ruined the brass spacer the main shaft lock pin had been cut off--all of this resulted in loose condition of the syncro hub which allowed the shift, 2nd/3rd ring to move off the balls/springs and blockers which allowed these blockers to get locked up on top the syncro brass rings

[JM 35 Sedan]

Originally Posted by alanwoodieman

when I took the trans fully apart and washed up these parts it became apparent why the trans failed--should have failed earlier!!, some one removed the ring spacer on the main shaft and substituted a long needle bearing where a short one should have been, the syncro hub had been damaged on the thrust face and had ruined the brass spacer the main shaft lock pin had been cut off--all of this resulted in loose condition of the syncro hub which allowed the shift, 2nd/3rd ring to move off the balls/springs and blockers which allowed these blockers to get locked up on top the syncro brass rings

Okay Alan, that sounds like a good analysis and final conclusion of what happened and why it failed.

We may need to find the guy who did this rebuild, and the spare transmission that came with this car, make him sit in the corner of his garage/repair shop with a pointed dunce cap on for the next week, plus confiscate all his tools on the way out....until he graduates with honors from the Early Ford Transmission Rebuilding School

Never mind, we just found him.....

[sidevalve8ba]

Originally Posted by JM 35 Sedan

Okay Alan, that sounds like a good analysis and final conclusion of what happened and why it failed.

We may need to find the guy who did this rebuild, and the spare transmission that came with this car, make him sit in the corner of his garage/repair shop with a pointed dunce cap on for the next week, plus confiscate all his tools on the way out....until he graduates with honors from the Early Ford Transmission Rebuilding School

I think he could stand to read Mac Van Pelt's book.

[alanwoodieman]

John that would be too easy on him, we should just relegate him to working on some sort of foreighn car, like a toyoto!!