Howcum my Transmission jumps out of gear?

[Terry, NJ]

I know I've posted this before, but the problem still exists. I took the shifter-plate off the top of the trans and things look good in there, at least I think they do. Nothing was excessively loose Third gear (The one it jumps out of) is more of a couple of splines, than gears that mesh. A male and female that mesh. I can't see the female, but the male is a little shiny where the female (slider) goes over it. And (This may be significant) it looks like it's not going the full distance or travel. I miked the forks and the front one was .219 and the rear fork was .221. I don't know what they're supposed to be. But overall the trans is tight and it should be working fine. Any suggestions?
Terry

[160B]

Here is a search "jumps out of gear"

https://www.fordbarn.com/forum/search...archid=8162814


look at this thread


https://www.fordbarn.com/forum/showth...ght=jumps+gear



also look at the search and find other similar threads

[J Franklin]

The Service Bulletins have good articles with proper specifications for the model A transmission. I had that problem with new gears but the clearance of the gear splines to the main-shaft was too loose. You may have something else causing it to jump.

[JohnLaVoy]

In the tower there is a keeper that engages with the slides, the spring could be week or the plungers worn to where they won't seat correctly. We did an article regarding this and the plungers that were incorrect and the ones that were in the Model A Times a few years ago.

[Terry, NJ]

OK! I've got the cover/shifter of the trans. Here's what I see there square "Ball" part of the shift lever is nicely "square or is it "Squared off"? These things are supposed to be round aren't they? The gap between the the slot in the shift fork and the "square" Ball is about 1/16th (1.5 MM), what should it be? Can the balls be welded and reshaped? Ditto for the slots in the forks. I also have reason to believe that the detent is not working as it should. I'll be ordering some new parts and I don't want to miss anything.
Terry

[Tom Wesenberg]

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Yes, I made a special grinder so I could weld the balls up, then grind them round to 1/2".
Too bad my special grinder walked away.

The throw from neutral to third is less than the other gears. Other gears need a full throw to engage the length of the gear teeth, but third is straight through and only needs a short distance to mesh the internal teeth with the external teeth.

[midgetracer]

I have found that the plungers on the detent are often seriously worn. I would check them. It is a big job to tear the whole top apart, but well worth it when you are done.

[Terry, NJ]

Tom, Your tool must have worked pretty good , or it would still be "your" tool. I was contemplating making a false center to support it in a lathe, or a "clamping block" to spin it against a wheel.
Terry

[Terry, NJ]

YES! From every thing I've read and heard in the last few days, The detents seem to be an almost automatic replacement item. Put in the detents and then we'll go from there! I had forgotten about the postings I made in the summer. We had to go to Texas to see one daughter, and Denver to see another daughter and our new Grandson and what with my memory being what it is and all. I forget things!
Another item that no one has mentioned was given to me off offline. The rivet in the 2/3 rail gets loose! Sure enough, I had skipped over it when I did my first inspection. I felt the wiggle, but I thought it was in the rail itself. On a second inspection, the rail was tight and the looseness was in the rivet.
Terry

Originally Posted by midgetracer

I have found that the plungers on the detent are often seriously worn. I would check them. It is a big job to tear the whole top apart, but well worth it when you are done.

[Terry, NJ]

I just got back and I'm not all warmed up yet, In fact, I'm still shivering! Here goes, I changed the tower for a better one, only a little wear on the shifter ball. It still jumps out of gear. I will order some new parts and rebuild these towers. Funny though, always above 40 mph, not below and I held my hand loosely on the shift lever and I couldn't feel when it would let go. Again, The parts in the Trans look and feel good, not loose. The car was restored not too long ago and I think the gears are new. If I can't get it with a new tower, I will have to go the drastic route and take the whole car apart. Any suggestions?
Terry

[Tom Wesenberg]

I'd start by making sure the flywheel cover is dialed in to .006" or less.

Then while the tranny is out I'd check the bearings and fit of the 2-3 gear on the shaft. No slop at all, just loose enough to slide on the shaft.

[Jerry Kzoo]

Terry,

Pictures always help to diagnose a problem. The experts on here have great detective skills when they can see the parts. If you can get a pic of the gears with the tower off and also a pic of the ball to shift fork in the tower(s) and post those it might help.

I would think if it was walking out of gear the shifter knob would be moving forward as you were driving. You could try to "hold" it in gear by having some pressure on the shifter and see if that would keep it in gear and if so maybe a tower rebuild would fix it.

Good Luck!

Jerry

[Terry, NJ]

Jerry, I would love to post pics! But I never mastered the art. That's why I refer to my album (My A) sometimes. I don't think it would be much help in this case, but I agree about the skill levels though.
Stubbornly, I took the coupe to the flea market this AM. I wanted to see how it was running otherwise (Good!) A trip of 15 to 17 miles. Most of it was highway miles and I got her to 65 MPH and I noticed something odd. It only tried jumping out of gear between 40 and 50 MPH and I held the shifter in gear, once I got over 50 it seemed to stop fighting me. Next revelation! Some times, the engine seemed to rock, pitch,tilt as I accelerated it. Is this a tip off to something?
Terry

Originally Posted by Jerry Kzoo

Terry,

Pictures always help to diagnose a problem. The experts on here have great detective skills when they can see the parts. If you can get a pic of the gears with the tower off and also a pic of the ball to shift fork in the tower(s) and post those it might help.

I would think if it was walking out of gear the shifter knob would be moving forward as you were driving. You could try to "hold" it in gear by having some pressure on the shifter and see if that would keep it in gear and if so maybe a tower rebuild would fix it.

Good Luck!

Jerry

[RockHillWill]

According to Ron in Quincy in one of those above links refers to: "According to Mitchell, who builds Overdrives and Overdrive Transmissions, the problem is the bearings retainer castings; if they are too thick by a few thousands, the gears do not fully engage. Steve said customers, when rebuilding their transmission, send the front and rear bearing retainers to him and he machines them to the proper thickness."

Ron, or anyone, can you expound on that? I cant grasp that in my mind right away - Thanks!

I am in agreement with all that Tom W. mentioned.

Just some random thoughts:

I have always been of the opinion that if the crank, clutch housing, bell housing and transmission shafts are not in correct alignment their is a STRONG potential for erratic gear movement, and as such have never been a proponent of the flexible rear motor mounts. It's my thinking that the solid original rear motor mounts form a 'solid' cross member that contributes to minimizing chassis flex when running on an un-even highway. They also greatly minimize fore and aft movement of the motor/transmission in the chassis.

Consider this: with flexible motor mounts in place if you back up rather hardly into a curb of some sort, the tires hit the curb imparting a load to the rear end. The rear end pushes on the transmission/motor, and flexes the limber front motor mount forward. It is most common in my experience that the space between the front fan shaft/nut is around only 1/4" to 1/2", so even minor flex in those rubber rear motor mounts can contribute to the water pump shaft hitting the radiator. This same, or similar degree of movement allowed by the rubber pads allows the rear of the transmission to move in the up/down and left/right positions as well. If all those centerlines (per Tom's input) are all in line and the bolts are all tight, this might be of minimal concern when using original rear motor mounts, but other assembly issues can still be more problematic.

Ball bearing type pilot bearings should minimize input shaft wear if installed by applying pressure at the outer race, but if you use an old input shaft or a tool that only contact the inner race, there is the potential of misaligning the inner/outer races and making the radial resistance/load on the input uneven.

A common issue that I have encountered are issues related to the shims at the top of the clutch housing, normally specified at .010". If I recall correctly (from an actual archive drawing), the 'paper' gasket between the block and the clutch housing is .015" indicating a 'crushed' thickness of .010", matching that of the upper shims. It has been my experience that aftermarket gaskets are between .025" and .030". This 'cocks' the clutch housing making the .006" tolerance VERY difficult to obtain, if you take the time to try that. MANY of the clutch housings that I have tried to use have been cracked, and even a few of the non-cracked ones required surfacing or Blanchard grinding. If it is not a fine point project, I have used an aftermarket gasket, bought two of them and cut the two 'shims' from the same material. On a fine point project I have used the .010" upper shims and cut the lower gasket from an ordinary paper grocery store bag. They are the right thickness and the same color as well.

Regarding the bullits and the spring that goes inside them at the shifter rails, I have had quite a few issues with them being slightly larger in diameter that the original ones, so I save the very slightly used ones, chuck them in the lathe and use 220 grit +/- and touch them up to being round while spinning them. I have no way of testing the spring pressures, and being wary of repro's, I use the original ones and add a piece of small diameter cardboard inserted in the bullits before inserting the spring. It is my opinion that this is at least equall to the original spring pressure and will maintain their position in the shift rails indents.

Bent shifter forks will not let the gears mesh in alignment.

Also, as Tom already mentioned, the faces of all the straight cut gears should be parallel, as any taper at all will vector a small amount of the driving force towards disengaging the gears.

If you disassemble a motor transmission that has a bronze input bearing, and the input shaft is worn radially with the tip of it larger than the rest of the shaft, it should be readily apparent of MISALIGMENT some where.

As I have looked into some of these transmission issues, it is becoming more and more evident that transmission 'issues' are often not always with the transmission.

[Y-Blockhead]

Originally Posted by Tom Wesenberg

Then while the tranny is out I'd check the bearings and fit of the 2-3 gear on the shaft.

Tom, If you google the word "tranny" I guarantee you will NEVER use it again...

[Tom Wesenberg]

Originally Posted by Y-Blockhead

Tom, If you google the word "tranny" I guarantee you will NEVER use it again...

That's a new one on me, but I'll not let some screwball's idea stop me from using a proper term.

------------------------------------------------------------------------------------

Tranny is a slang term used chiefly to describe people who are transgender, transsexual, wearing drag, transvestites, or cross-dressers. The term is considered a slur by some transgender activists, such as Roz Kaveney.[1] The Gay & Lesbian Alliance Against Defamation (GLAAD) state that the term is "usually considered offensive and/or defamatory" by members of the transgender community.[2] The trans and drag performer community is believed to have originated the term.[3] When asked whether he is bothered by the word “tranny,” drag queen RuPaul responded by saying, “No! I love the word tranny.”[4]
According to Kate Bornstein, a popular and controversial trans writer and performer, the word originated in Sydney, Australia, and was intended to unite trans people and drag queens under an umbrella term.[5]

[Terry, NJ]

Wll, Thanks for the the very detailed explanation! I'm going to copy it for future reference. Terry

Originally Posted by RockHillWill

According to Ron in Quincy in one of those above links refers to: "According to Mitchell, who builds Overdrives and Overdrive Transmissions, the problem is the bearings retainer castings; if they are too thick by a few thousands, the gears do not fully engage. Steve said customers, when rebuilding their transmission, send the front and rear bearing retainers to him and he machines them to the proper thickness."

Ron, or anyone, can you expound on that? I cant grasp that in my mind right away - Thanks!

I am in agreement with all that Tom W. mentioned.

Just some random thoughts:

I have always been of the opinion that if the crank, clutch housing, bell housing and transmission shafts are not in correct alignment their is a STRONG potential for erratic gear movement, and as such have never been a proponent of the flexible rear motor mounts. It's my thinking that the solid original rear motor mounts form a 'solid' cross member that contributes to minimizing chassis flex when running on an un-even highway. They also greatly minimize fore and aft movement of the motor/transmission in the chassis.

Consider this: with flexible motor mounts in place if you back up rather hardly into a curb of some sort, the tires hit the curb imparting a load to the rear end. The rear end pushes on the transmission/motor, and flexes the limber front motor mount forward. It is most common in my experience that the space between the front fan shaft/nut is around only 1/4" to 1/2", so even minor flex in those rubber rear motor mounts can contribute to the water pump shaft hitting the radiator. This same, or similar degree of movement allowed by the rubber pads allows the rear of the transmission to move in the up/down and left/right positions as well. If all those centerlines (per Tom's input) are all in line and the bolts are all tight, this might be of minimal concern when using original rear motor mounts, but other assembly issues can still be more problematic.

Ball bearing type pilot bearings should minimize input shaft wear if installed by applying pressure at the outer race, but if you use an old input shaft or a tool that only contact the inner race, there is the potential of misaligning the inner/outer races and making the radial resistance/load on the input uneven.

A common issue that I have encountered are issues related to the shims at the top of the clutch housing, normally specified at .010". If I recall correctly (from an actual archive drawing), the 'paper' gasket between the block and the clutch housing is .015" indicating a 'crushed' thickness of .010", matching that of the upper shims. It has been my experience that aftermarket gaskets are between .025" and .030". This 'cocks' the clutch housing making the .006" tolerance VERY difficult to obtain, if you take the time to try that. MANY of the clutch housings that I have tried to use have been cracked, and even a few of the non-cracked ones required surfacing or Blanchard grinding. If it is not a fine point project, I have used an aftermarket gasket, bought two of them and cut the two 'shims' from the same material. On a fine point project I have used the .010" upper shims and cut the lower gasket from an ordinary paper grocery store bag. They are the right thickness and the same color as well.

Regarding the bullits and the spring that goes inside them at the shifter rails, I have had quite a few issues with them being slightly larger in diameter that the original ones, so I save the very slightly used ones, chuck them in the lathe and use 220 grit +/- and touch them up to being round while spinning them. I have no way of testing the spring pressures, and being wary of repro's, I use the original ones and add a piece of small diameter cardboard inserted in the bullits before inserting the spring. It is my opinion that this is at least equall to the original spring pressure and will maintain their position in the shift rails indents.

Bent shifter forks will not let the gears mesh in alignment.

Also, as Tom already mentioned, the faces of all the straight cut gears should be parallel, as any taper at all will vector a small amount of the driving force towards disengaging the gears.

If you disassemble a motor transmission that has a bronze input bearing, and the input shaft is worn radially with the tip of it larger than the rest of the shaft, it should be readily apparent of MISALIGMENT some where.

As I have looked into some of these transmission issues, it is becoming more and more evident that transmission 'issues' are often not always with the transmission.

[RockHillWill]

Just as an aside, I was thinking about those flexible rubber rear motor mounts. If they do allow the rear of the motor to move side to side (and they do) there are other concerns beyond any transmission concerns. Because these Model A rear ends are floaters, and not the limit slip variety, some consideration should be given to the results of acceleration and deceleration. On acceleration, the tire with the greatest diameter and/or corner weight/load will be the tire that provides the forward movement. For example, if the right rear tire is the larger diameter of the two, that forward load will push the torque tube, trailing arms, transmission, motor and wishbone forward, and because the force is applied thru an angled trailing arm the force will have a vectored force component that wants to move the rear of the transmission to the left. The 'flex' in the rubber motor mounts will allow this to occur, allowing side to side movement in the front wishbone cup, and that will cause the right side of the front axle to move to the rear, having at least a minor effect on the steering. All that I have mentioned above will have a negative effect on the loading and subsequent wear on each of the shackles.

In the previous post, I neglected to mention that some of that forward movement allowed by the rubber rear motor mounts should be resisted by the rear of the front wishbone 'cup' assembly, but that area of the front suspension is noted for its inability to maintain tightness. Those issues are not easily attended to unless you take the time to machine and install bushings from the top side of the bell housing where the pins are. The hardened steel of the pins rapidly wears the upper countersunk area inside the bell housing. this cannot be repaired by anything done to the lower portion of the bell housing.

Sorry about the rambling. Too much coffee and time this morning.

[Chris Haynes]

If your engine is not securely mounted that will cause the tranny to pop out of gear. Make sure all the motor mount bolts are tight and no holes are out of round.

[30ccpickup]

I will go out there to the far left... My spring and shackles were well worn. With every bump/bounce things would shake and occasionally my springs would touch the rear axle and I would pop out of gear. Replaced springs/shackles and shocks... No problem with it bouncing out of gear.